///////////////////////////////////////////////////////////////////////////////
//
// File: Expansion3D.cpp
//
// For more information, please see: http://www.nektar.info
//
// The MIT License
//
// Copyright (c) 2006 Division of Applied Mathematics, Brown University (USA),
// Department of Aeronautics, Imperial College London (UK), and Scientific
// Computing and Imaging Institute, University of Utah (USA).
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// Description: File for Expansion3D routines
//
///////////////////////////////////////////////////////////////////////////////

#include <LibUtilities/Foundations/Interp.h>
#include <LibUtilities/Foundations/InterpCoeff.h>
#include <LocalRegions/Expansion2D.h>
#include <LocalRegions/Expansion3D.h>
#include <LocalRegions/MatrixKey.h>
#include <LocalRegions/QuadExp.h>
#include <LocalRegions/TriExp.h>
#include <SpatialDomains/Geometry3D.h>

using namespace std;

namespace Nektar::LocalRegions
{
//  evaluate additional terms in HDG face. Note that this assumes that
// edges are unpacked into local cartesian order.
void Expansion3D::AddHDGHelmholtzFaceTerms(
    const NekDouble tau, const int face, Array<OneD, NekDouble> &facePhys,
    const StdRegions::VarCoeffMap &varcoeffs, Array<OneD, NekDouble> &outarray)
{
    ExpansionSharedPtr FaceExp = GetTraceExp(face);
    int i, j, n;
    int nquad_f = FaceExp->GetNumPoints(0) * FaceExp->GetNumPoints(1);
    int order_f = FaceExp->GetNcoeffs();
    int coordim = GetCoordim();
    int ncoeffs = GetNcoeffs();
    bool mmf = (varcoeffs.find(StdRegions::eVarCoeffMF1x) != varcoeffs.end());

    Array<OneD, NekDouble> inval(nquad_f);
    Array<OneD, NekDouble> outcoeff(order_f);
    Array<OneD, NekDouble> tmpcoeff(ncoeffs);

    const Array<OneD, const Array<OneD, NekDouble>> &normals =
        GetTraceNormal(face);

    DNekScalMat &invMass = *GetLocMatrix(StdRegions::eInvMass);

    DNekVec Coeffs(ncoeffs, outarray, eWrapper);
    DNekVec Tmpcoeff(ncoeffs, tmpcoeff, eWrapper);

    IndexMapKey ikey(eFaceToElement, DetShapeType(), GetBasisNumModes(0),
                     GetBasisNumModes(1), GetBasisNumModes(2), face,
                     GetTraceOrient(face));
    IndexMapValuesSharedPtr map = GetIndexMap(ikey);

    StdRegions::MatrixType DerivType[3] = {StdRegions::eWeakDeriv0,
                                           StdRegions::eWeakDeriv1,
                                           StdRegions::eWeakDeriv2};

    // @TODO Variable coefficients
    /*
    StdRegions::VarCoeffType VarCoeff[3] = {StdRegions::eVarCoeffD00,
                                            StdRegions::eVarCoeffD11,
                                            StdRegions::eVarCoeffD22};
    Array<OneD, NekDouble> varcoeff_work(nquad_f);
    StdRegions::VarCoeffMap::const_iterator x;
    ///// @TODO: What direction to use here??
    if ((x = varcoeffs.find(VarCoeff[0])) != varcoeffs.end())
    {
        GetPhysFaceVarCoeffsFromElement(face,FaceExp,x->second,varcoeff_work);
        Vmath::Vmul(nquad_f,varcoeff_work,1,FaceExp->GetPhys(),1,FaceExp->UpdatePhys(),1);
    }
    */

    //================================================================
    // Add F = \tau <phi_i,in_phys>
    // Fill face and take inner product
    FaceExp->IProductWRTBase(facePhys, outcoeff);

    for (i = 0; i < order_f; ++i)
    {
        outarray[(*map)[i].index] += (*map)[i].sign * tau * outcoeff[i];
    }
    //================================================================

    //===============================================================
    // Add -\sum_i D_i^T M^{-1} G_i + E_i M^{-1} G_i =
    //                         \sum_i D_i M^{-1} G_i term

    // Three independent direction
    for (n = 0; n < coordim; ++n)
    {
        if (mmf)
        {
            StdRegions::VarCoeffMap Weight;
            Weight[StdRegions::eVarCoeffMass] = GetMFMag(n, varcoeffs);

            MatrixKey invMasskey(StdRegions::eInvMass, DetShapeType(), *this,
                                 StdRegions::NullConstFactorMap, Weight);

            invMass = *GetLocMatrix(invMasskey);

            Array<OneD, NekDouble> ncdotMF_f =
                GetnFacecdotMF(n, face, FaceExp, normals, varcoeffs);

            Vmath::Vmul(nquad_f, ncdotMF_f, 1, facePhys, 1, inval, 1);
        }
        else
        {
            Vmath::Vmul(nquad_f, normals[n], 1, facePhys, 1, inval, 1);
        }

        NekDouble scale       = invMass.Scale();
        const NekDouble *data = invMass.GetRawPtr();

        // @TODO Multiply by variable coefficients
        // @TODO: Document this (probably not needed)
        /*
        StdRegions::VarCoeffMap::const_iterator x;
        if ((x = varcoeffs.find(VarCoeff[n])) != varcoeffs.end())
        {
            GetPhysEdgeVarCoeffsFromElement(edge,FaceExp,x->second,varcoeff_work);
            Vmath::Vmul(nquad_f,varcoeff_work,1,FaceExp->GetPhys(),1,FaceExp->UpdatePhys(),1);
        }
        */

        FaceExp->IProductWRTBase(inval, outcoeff);

        // M^{-1} G
        for (i = 0; i < ncoeffs; ++i)
        {
            tmpcoeff[i] = 0;
            for (j = 0; j < order_f; ++j)
            {
                tmpcoeff[i] += scale * data[i + (*map)[j].index * ncoeffs] *
                               (*map)[j].sign * outcoeff[j];
            }
        }

        if (mmf)
        {
            StdRegions::VarCoeffMap VarCoeffDirDeriv;
            VarCoeffDirDeriv[StdRegions::eVarCoeffMF] =
                GetMF(n, coordim, varcoeffs);
            VarCoeffDirDeriv[StdRegions::eVarCoeffMFDiv] =
                GetMFDiv(n, varcoeffs);

            MatrixKey Dmatkey(StdRegions::eWeakDirectionalDeriv, DetShapeType(),
                              *this, StdRegions::NullConstFactorMap,
                              VarCoeffDirDeriv);

            DNekScalMat &Dmat = *GetLocMatrix(Dmatkey);

            Coeffs = Coeffs + Dmat * Tmpcoeff;
        }
        else
        {
            DNekScalMat &Dmat = *GetLocMatrix(DerivType[n]);
            Coeffs            = Coeffs + Dmat * Tmpcoeff;
        }

        /*
        if(varcoeffs.find(VarCoeff[n]) != varcoeffs.end())
        {
            MatrixKey mkey(DerivType[n], DetExpansionType(), *this,
        StdRegions::NullConstFactorMap, varcoeffs); DNekScalMat &Dmat =
        *GetLocMatrix(mkey); Coeffs = Coeffs  + Dmat*Tmpcoeff;
        }

        else
        {
            DNekScalMat &Dmat = *GetLocMatrix(DerivType[n]);
            Coeffs = Coeffs  + Dmat*Tmpcoeff;
        }
        */
    }
}

void Expansion3D::GetPhysFaceVarCoeffsFromElement(
    const int face, ExpansionSharedPtr &FaceExp,
    const Array<OneD, const NekDouble> &varcoeff,
    Array<OneD, NekDouble> &outarray)
{
    Array<OneD, NekDouble> tmp(GetNcoeffs());
    Array<OneD, NekDouble> facetmp(FaceExp->GetNcoeffs());

    // FwdTrans varcoeffs
    FwdTrans(varcoeff, tmp);

    // Map to edge
    Array<OneD, unsigned int> emap;
    Array<OneD, int> sign;

    GetTraceToElementMap(face, emap, sign, GetTraceOrient(face));

    for (unsigned int i = 0; i < FaceExp->GetNcoeffs(); ++i)
    {
        facetmp[i] = tmp[emap[i]];
    }

    // BwdTrans
    FaceExp->BwdTrans(facetmp, outarray);
}

/**
 * Computes the C matrix entries due to the presence of the identity
 * matrix in Eqn. 32.
 */
void Expansion3D::AddNormTraceInt(const int dir,
                                  Array<OneD, const NekDouble> &inarray,
                                  Array<OneD, ExpansionSharedPtr> &FaceExp,
                                  Array<OneD, NekDouble> &outarray,
                                  const StdRegions::VarCoeffMap &varcoeffs)
{
    int i, f, cnt;
    int order_f, nquad_f;
    int nfaces = GetNtraces();

    cnt = 0;
    for (f = 0; f < nfaces; ++f)
    {
        order_f = FaceExp[f]->GetNcoeffs();
        nquad_f = FaceExp[f]->GetNumPoints(0) * FaceExp[f]->GetNumPoints(1);

        const Array<OneD, const Array<OneD, NekDouble>> &normals =
            GetTraceNormal(f);
        Array<OneD, NekDouble> faceCoeffs(order_f);
        Array<OneD, NekDouble> facePhys(nquad_f);

        for (i = 0; i < order_f; ++i)
        {
            faceCoeffs[i] = inarray[i + cnt];
        }
        cnt += order_f;

        FaceExp[f]->BwdTrans(faceCoeffs, facePhys);

        // Multiply by variable coefficient
        /// @TODO: Document this
        //                StdRegions::VarCoeffType VarCoeff[3] =
        //                {StdRegions::eVarCoeffD00,
        //                                                        StdRegions::eVarCoeffD11,
        //                                                        StdRegions::eVarCoeffD22};
        //                StdRegions::VarCoeffMap::const_iterator x;
        //                Array<OneD, NekDouble> varcoeff_work(nquad_e);

        //                if ((x = varcoeffs.find(VarCoeff[dir])) !=
        //                varcoeffs.end())
        //                {
        //                    GetPhysEdgeVarCoeffsFromElement(e,EdgeExp[e],x->second,varcoeff_work);
        //                    Vmath::Vmul(nquad_e,varcoeff_work,1,EdgeExp[e]->GetPhys(),1,EdgeExp[e]->UpdatePhys(),1);
        //                }
        StdRegions::VarCoeffMap::const_iterator x;
        if ((x = varcoeffs.find(StdRegions::eVarCoeffMF1x)) != varcoeffs.end())
        {
            Array<OneD, NekDouble> ncdotMF_f =
                GetnFacecdotMF(dir, f, FaceExp[f], normals, varcoeffs);

            Vmath::Vmul(nquad_f, ncdotMF_f, 1, facePhys, 1, facePhys, 1);
        }
        else
        {
            Vmath::Vmul(nquad_f, normals[dir], 1, facePhys, 1, facePhys, 1);
        }

        AddFaceBoundaryInt(f, FaceExp[f], facePhys, outarray, varcoeffs);
    }
}

// shorter version of the above (coefficients are already set for faces)
void Expansion3D::AddNormTraceInt(
    const int dir, Array<OneD, ExpansionSharedPtr> &FaceExp,
    Array<OneD, Array<OneD, NekDouble>> &faceCoeffs,
    Array<OneD, NekDouble> &outarray)
{
    int f;
    int nquad_f;
    int nfaces = GetNtraces();

    for (f = 0; f < nfaces; ++f)
    {
        nquad_f = FaceExp[f]->GetNumPoints(0) * FaceExp[f]->GetNumPoints(1);

        const Array<OneD, const Array<OneD, NekDouble>> &normals =
            GetTraceNormal(f);
        Array<OneD, NekDouble> facePhys(nquad_f);

        FaceExp[f]->BwdTrans(faceCoeffs[f], facePhys);

        Vmath::Vmul(nquad_f, normals[dir], 1, facePhys, 1, facePhys, 1);

        AddFaceBoundaryInt(f, FaceExp[f], facePhys, outarray);
    }
}

/**
 * For a given face add the \tilde{F}_1j contributions
 */
void Expansion3D::AddFaceBoundaryInt(
    const int face, ExpansionSharedPtr &FaceExp,
    Array<OneD, NekDouble> &facePhys, Array<OneD, NekDouble> &outarray,
    [[maybe_unused]] const StdRegions::VarCoeffMap &varcoeffs)
{
    int i;
    int order_f = FaceExp->GetNcoeffs();
    Array<OneD, NekDouble> coeff(order_f);

    IndexMapKey ikey(eFaceToElement, DetShapeType(), GetBasisNumModes(0),
                     GetBasisNumModes(1), GetBasisNumModes(2), face,
                     GetTraceOrient(face));
    IndexMapValuesSharedPtr map = GetIndexMap(ikey);

    FaceExp->IProductWRTBase(facePhys, coeff);

    // add data to out array
    for (i = 0; i < order_f; ++i)
    {
        outarray[(*map)[i].index] += (*map)[i].sign * coeff[i];
    }
}

/**
 * @brief Align face orientation with the geometry orientation.
 */
void Expansion3D::SetFaceToGeomOrientation(const int face,
                                           Array<OneD, NekDouble> &inout)
{
    int j, k;
    int nface = GetTraceNcoeffs(face);
    Array<OneD, NekDouble> f_in(nface);
    Vmath::Vcopy(nface, &inout[0], 1, &f_in[0], 1);

    // retreiving face to element map for standard face orientation and
    // for actual face orientation
    IndexMapKey ikey1(eFaceToElement, DetShapeType(), GetBasisNumModes(0),
                      GetBasisNumModes(1), GetBasisNumModes(2), face,
                      StdRegions::eDir1FwdDir1_Dir2FwdDir2);
    IndexMapValuesSharedPtr map1 = GetIndexMap(ikey1);
    IndexMapKey ikey2(eFaceToElement, DetShapeType(), GetBasisNumModes(0),
                      GetBasisNumModes(1), GetBasisNumModes(2), face,
                      GetTraceOrient(face));
    IndexMapValuesSharedPtr map2 = GetIndexMap(ikey2);

    ASSERTL1((*map1).size() == (*map2).size(),
             "There is an error with the GetTraceToElementMap");

    for (j = 0; j < (*map1).size(); ++j)
    {
        // j = index in the standard orientation
        for (k = 0; k < (*map2).size(); ++k)
        {
            // k = index in the actual orientation
            if ((*map1)[j].index == (*map2)[k].index && k != j)
            {
                inout[k] = f_in[j];
                // checking if sign is changing
                if ((*map1)[j].sign != (*map2)[k].sign)
                {
                    inout[k] *= -1.0;
                }
                break;
            }
        }
    }
}

/**
 * @brief Align trace orientation with the geometry orientation.
 */
void Expansion3D::SetTraceToGeomOrientation(Array<OneD, NekDouble> &inout)
{
    int i, cnt = 0;
    int nfaces = GetNtraces();

    Array<OneD, NekDouble> f_tmp;

    for (i = 0; i < nfaces; ++i)
    {
        SetFaceToGeomOrientation(i, f_tmp = inout + cnt);
        cnt += GetTraceNcoeffs(i);
    }
}

DNekScalMatSharedPtr Expansion3D::CreateMatrix(const MatrixKey &mkey)
{
    DNekScalMatSharedPtr returnval;
    LibUtilities::PointsKeyVector ptsKeys = GetPointsKeys();

    ASSERTL2(m_metricinfo->GetGtype() != SpatialDomains::eNoGeomType,
             "Geometric information is not set up");

    switch (mkey.GetMatrixType())
    {
        case StdRegions::eMass:
        {
            if (m_metricinfo->GetGtype() == SpatialDomains::eDeformed ||
                mkey.GetNVarCoeff())
            {
                NekDouble one        = 1.0;
                DNekMatSharedPtr mat = GenMatrix(mkey);
                returnval =
                    MemoryManager<DNekScalMat>::AllocateSharedPtr(one, mat);
            }
            else
            {
                NekDouble jac        = (m_metricinfo->GetJac(ptsKeys))[0];
                DNekMatSharedPtr mat = GetStdMatrix(mkey);
                returnval =
                    MemoryManager<DNekScalMat>::AllocateSharedPtr(jac, mat);
            }
        }
        break;
        case StdRegions::eInvMass:
        {
            if (m_metricinfo->GetGtype() == SpatialDomains::eDeformed)
            {
                NekDouble one = 1.0;
                StdRegions::StdMatrixKey masskey(StdRegions::eMass,
                                                 DetShapeType(), *this);
                DNekMatSharedPtr mat = GenMatrix(masskey);
                mat->Invert();
                returnval =
                    MemoryManager<DNekScalMat>::AllocateSharedPtr(one, mat);
            }
            else
            {
                NekDouble fac        = 1.0 / (m_metricinfo->GetJac(ptsKeys))[0];
                DNekMatSharedPtr mat = GetStdMatrix(mkey);
                returnval =
                    MemoryManager<DNekScalMat>::AllocateSharedPtr(fac, mat);
            }
        }
        break;
        case StdRegions::eWeakDeriv0:
        case StdRegions::eWeakDeriv1:
        case StdRegions::eWeakDeriv2:
        {
            if (m_metricinfo->GetGtype() == SpatialDomains::eDeformed ||
                mkey.GetNVarCoeff())
            {
                NekDouble one        = 1.0;
                DNekMatSharedPtr mat = GenMatrix(mkey);

                returnval =
                    MemoryManager<DNekScalMat>::AllocateSharedPtr(one, mat);
            }
            else
            {
                NekDouble jac = (m_metricinfo->GetJac(ptsKeys))[0];
                Array<TwoD, const NekDouble> df =
                    m_metricinfo->GetDerivFactors(ptsKeys);
                int dir = 0;
                if (mkey.GetMatrixType() == StdRegions::eWeakDeriv0)
                {
                    dir = 0;
                }
                if (mkey.GetMatrixType() == StdRegions::eWeakDeriv1)
                {
                    dir = 1;
                }
                if (mkey.GetMatrixType() == StdRegions::eWeakDeriv2)
                {
                    dir = 2;
                }

                MatrixKey deriv0key(StdRegions::eWeakDeriv0,
                                    mkey.GetShapeType(), *this);
                MatrixKey deriv1key(StdRegions::eWeakDeriv1,
                                    mkey.GetShapeType(), *this);
                MatrixKey deriv2key(StdRegions::eWeakDeriv2,
                                    mkey.GetShapeType(), *this);

                DNekMat &deriv0 = *GetStdMatrix(deriv0key);
                DNekMat &deriv1 = *GetStdMatrix(deriv1key);
                DNekMat &deriv2 = *GetStdMatrix(deriv2key);

                int rows = deriv0.GetRows();
                int cols = deriv1.GetColumns();

                DNekMatSharedPtr WeakDeriv =
                    MemoryManager<DNekMat>::AllocateSharedPtr(rows, cols);
                (*WeakDeriv) = df[3 * dir][0] * deriv0 +
                               df[3 * dir + 1][0] * deriv1 +
                               df[3 * dir + 2][0] * deriv2;

                returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(
                    jac, WeakDeriv);
            }
        }
        break;
        case StdRegions::eLaplacian:
        {
            if (m_metricinfo->GetGtype() == SpatialDomains::eDeformed ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffLaplacian)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD00)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD01)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD10)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD02)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD20)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD11)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD12)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD21)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD22)) ||
                (mkey.ConstFactorExists(StdRegions::eFactorSVVCutoffRatio)))
            {
                NekDouble one        = 1.0;
                DNekMatSharedPtr mat = GenMatrix(mkey);

                returnval =
                    MemoryManager<DNekScalMat>::AllocateSharedPtr(one, mat);
            }
            else
            {
                MatrixKey lap00key(StdRegions::eLaplacian00,
                                   mkey.GetShapeType(), *this);
                MatrixKey lap01key(StdRegions::eLaplacian01,
                                   mkey.GetShapeType(), *this);
                MatrixKey lap02key(StdRegions::eLaplacian02,
                                   mkey.GetShapeType(), *this);
                MatrixKey lap11key(StdRegions::eLaplacian11,
                                   mkey.GetShapeType(), *this);
                MatrixKey lap12key(StdRegions::eLaplacian12,
                                   mkey.GetShapeType(), *this);
                MatrixKey lap22key(StdRegions::eLaplacian22,
                                   mkey.GetShapeType(), *this);

                DNekMat &lap00 = *GetStdMatrix(lap00key);
                DNekMat &lap01 = *GetStdMatrix(lap01key);
                DNekMat &lap02 = *GetStdMatrix(lap02key);
                DNekMat &lap11 = *GetStdMatrix(lap11key);
                DNekMat &lap12 = *GetStdMatrix(lap12key);
                DNekMat &lap22 = *GetStdMatrix(lap22key);

                NekDouble jac = (m_metricinfo->GetJac(ptsKeys))[0];
                Array<TwoD, const NekDouble> gmat =
                    m_metricinfo->GetGmat(ptsKeys);

                int rows = lap00.GetRows();
                int cols = lap00.GetColumns();

                DNekMatSharedPtr lap =
                    MemoryManager<DNekMat>::AllocateSharedPtr(rows, cols);

                (*lap) = gmat[0][0] * lap00 + gmat[4][0] * lap11 +
                         gmat[8][0] * lap22 +
                         gmat[3][0] * (lap01 + Transpose(lap01)) +
                         gmat[6][0] * (lap02 + Transpose(lap02)) +
                         gmat[7][0] * (lap12 + Transpose(lap12));

                returnval =
                    MemoryManager<DNekScalMat>::AllocateSharedPtr(jac, lap);
            }
        }
        break;
        case StdRegions::eHelmholtz:
        {
            NekDouble factor = mkey.GetConstFactor(StdRegions::eFactorLambda);
            MatrixKey masskey(StdRegions::eMass, mkey.GetShapeType(), *this);
            DNekScalMat &MassMat = *GetLocMatrix(masskey);
            MatrixKey lapkey(StdRegions::eLaplacian, mkey.GetShapeType(), *this,
                             mkey.GetConstFactors(), mkey.GetVarCoeffs());
            DNekScalMat &LapMat = *GetLocMatrix(lapkey);

            int rows = LapMat.GetRows();
            int cols = LapMat.GetColumns();

            DNekMatSharedPtr helm =
                MemoryManager<DNekMat>::AllocateSharedPtr(rows, cols);

            NekDouble one = 1.0;
            (*helm)       = LapMat + factor * MassMat;

            returnval =
                MemoryManager<DNekScalMat>::AllocateSharedPtr(one, helm);
        }
        break;
        case StdRegions::eHelmholtzGJP:
        {
            MatrixKey helmkey(mkey, StdRegions::eHelmholtz);
            DNekScalMat &HelmMat = *GetLocMatrix(helmkey);

            // Generate a local copy of traceMat
            MatrixKey key(mkey, StdRegions::eNormDerivOnTrace);
            DNekMatSharedPtr NDTraceMat = Expansion3D::v_GenMatrix(key);

            ASSERTL1(mkey.ConstFactorExists(StdRegions::eFactorGJP),
                     "Need to specify eFactorGJP to construct "
                     "a HelmholtzGJP matrix");

            NekDouble factor = mkey.GetConstFactor(StdRegions::eFactorGJP);

            factor /= HelmMat.Scale();

            int ntot = HelmMat.GetRows() * HelmMat.GetColumns();

            Vmath::Svtvp(ntot, factor, &NDTraceMat->GetPtr()[0], 1,
                         HelmMat.GetRawPtr(), 1, &NDTraceMat->GetPtr()[0], 1);

            returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(
                HelmMat.Scale(), NDTraceMat);
        }
        break;
        case StdRegions::eLinearAdvectionDiffusionReaction:
        {
            NekDouble lambda = mkey.GetConstFactor(StdRegions::eFactorLambda);

            // Construct mass matrix
            // Check for mass-specific varcoeffs to avoid unncessary
            // re-computation of the elemental matrix every time step
            StdRegions::VarCoeffMap massVarcoeffs = StdRegions::NullVarCoeffMap;
            if (mkey.HasVarCoeff(StdRegions::eVarCoeffMass))
            {
                massVarcoeffs[StdRegions::eVarCoeffMass] =
                    mkey.GetVarCoeff(StdRegions::eVarCoeffMass);
            }
            MatrixKey masskey(StdRegions::eMass, mkey.GetShapeType(), *this,
                              mkey.GetConstFactors(), massVarcoeffs);
            DNekScalMat &MassMat = *GetLocMatrix(masskey);

            // Construct laplacian matrix (Check for varcoeffs)
            // Take all varcoeffs if one or more are detected
            // TODO We might want to have a map
            // from MatrixType to Vector of Varcoeffs and vice-versa
            StdRegions::VarCoeffMap lapVarcoeffs = StdRegions::NullVarCoeffMap;
            if ((mkey.HasVarCoeff(StdRegions::eVarCoeffLaplacian)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD00)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD01)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD10)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD02)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD20)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD11)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD12)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD21)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD22)))
            {
                lapVarcoeffs = mkey.GetVarCoeffs();
            }
            MatrixKey lapkey(StdRegions::eLaplacian, mkey.GetShapeType(), *this,
                             mkey.GetConstFactors(), lapVarcoeffs);
            DNekScalMat &LapMat = *GetLocMatrix(lapkey);

            // Construct advection matrix
            // Check for varcoeffs not required;
            // assume advection velocity is always time-dependent
            MatrixKey advkey(mkey, StdRegions::eLinearAdvection);
            DNekScalMat &AdvMat = *GetLocMatrix(advkey);

            int rows = LapMat.GetRows();
            int cols = LapMat.GetColumns();

            DNekMatSharedPtr adr =
                MemoryManager<DNekMat>::AllocateSharedPtr(rows, cols);

            NekDouble one = 1.0;
            (*adr)        = LapMat - lambda * MassMat + AdvMat;

            returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(one, adr);

            // Clear memory for time-dependent matrices
            DropLocMatrix(advkey);
            if (!massVarcoeffs.empty())
            {
                DropLocMatrix(masskey);
            }
            if (!lapVarcoeffs.empty())
            {
                DropLocMatrix(lapkey);
            }
        }
        break;
        case StdRegions::eLinearAdvectionDiffusionReactionGJP:
        {
            // Copied mostly from ADR solve to have fine-grain control
            // over updating only advection matrix, relevant for performance!
            NekDouble lambda = mkey.GetConstFactor(StdRegions::eFactorLambda);

            // Construct mass matrix (Check for varcoeffs)
            StdRegions::VarCoeffMap massVarcoeffs = StdRegions::NullVarCoeffMap;
            if (mkey.HasVarCoeff(StdRegions::eVarCoeffMass))
            {
                massVarcoeffs[StdRegions::eVarCoeffMass] =
                    mkey.GetVarCoeff(StdRegions::eVarCoeffMass);
            }
            MatrixKey masskey(StdRegions::eMass, mkey.GetShapeType(), *this,
                              mkey.GetConstFactors(), massVarcoeffs);
            DNekScalMat &MassMat = *GetLocMatrix(masskey);

            // Construct laplacian matrix (Check for varcoeffs)
            StdRegions::VarCoeffMap lapVarcoeffs = StdRegions::NullVarCoeffMap;
            if ((mkey.HasVarCoeff(StdRegions::eVarCoeffLaplacian)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD00)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD01)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD10)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD02)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD20)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD11)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD12)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD21)) ||
                (mkey.HasVarCoeff(StdRegions::eVarCoeffD22)))
            {
                lapVarcoeffs = mkey.GetVarCoeffs();
            }
            MatrixKey lapkey(StdRegions::eLaplacian, mkey.GetShapeType(), *this,
                             mkey.GetConstFactors(), lapVarcoeffs);
            DNekScalMat &LapMat = *GetLocMatrix(lapkey);

            // Construct advection matrix
            // (assume advection velocity defined and non-zero)
            // Could check L2(AdvectionVelocity) or HasVarCoeff
            MatrixKey advkey(mkey, StdRegions::eLinearAdvection);
            DNekScalMat &AdvMat = *GetLocMatrix(advkey);

            // Generate a local copy of traceMat
            MatrixKey gjpkey(StdRegions::eNormDerivOnTrace, mkey.GetShapeType(),
                             *this, mkey.GetConstFactors());
            DNekScalMat &NDTraceMat = *GetLocMatrix(gjpkey);

            NekDouble gjpfactor = mkey.GetConstFactor(StdRegions::eFactorGJP);
            ASSERTL1(mkey.ConstFactorExists(StdRegions::eFactorGJP),
                     "Need to specify eFactorGJP to construct "
                     "a LinearAdvectionDiffusionReactionGJP matrix");

            int rows = LapMat.GetRows();
            int cols = LapMat.GetColumns();

            DNekMatSharedPtr adr =
                MemoryManager<DNekMat>::AllocateSharedPtr(rows, cols);

            NekDouble one = 1.0;
            (*adr) =
                LapMat - lambda * MassMat + AdvMat + gjpfactor * NDTraceMat;

            returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(one, adr);

            // Clear memory
            DropLocMatrix(advkey);
            DropLocMatrix(masskey);
            DropLocMatrix(lapkey);
            DropLocMatrix(gjpkey);
        }
        break;
        case StdRegions::eNormDerivOnTrace:
        {
            NekDouble one        = 1.0;
            DNekMatSharedPtr mat = Expansion3D::v_GenMatrix(mkey);

            returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(one, mat);
        }
        break;
        case StdRegions::eIProductWRTBase:
        {
            if (m_metricinfo->GetGtype() == SpatialDomains::eDeformed)
            {
                NekDouble one        = 1.0;
                DNekMatSharedPtr mat = GenMatrix(mkey);
                returnval =
                    MemoryManager<DNekScalMat>::AllocateSharedPtr(one, mat);
            }
            else
            {
                NekDouble jac        = (m_metricinfo->GetJac(ptsKeys))[0];
                DNekMatSharedPtr mat = GetStdMatrix(mkey);
                returnval =
                    MemoryManager<DNekScalMat>::AllocateSharedPtr(jac, mat);
            }
        }
        break;
        case StdRegions::eInvHybridDGHelmholtz:
        {
            NekDouble one = 1.0;

            MatrixKey hkey(StdRegions::eHybridDGHelmholtz, DetShapeType(),
                           *this, mkey.GetConstFactors(), mkey.GetVarCoeffs());
            DNekMatSharedPtr mat = GenMatrix(hkey);

            mat->Invert();
            returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(one, mat);
        }
        break;
        case StdRegions::ePreconLinearSpace:
        {
            NekDouble one = 1.0;
            MatrixKey helmkey(StdRegions::eHelmholtz, mkey.GetShapeType(),
                              *this, mkey.GetConstFactors(),
                              mkey.GetVarCoeffs());
            DNekScalBlkMatSharedPtr helmStatCond =
                GetLocStaticCondMatrix(helmkey);
            DNekScalMatSharedPtr A = helmStatCond->GetBlock(0, 0);
            DNekMatSharedPtr R     = BuildVertexMatrix(A);

            returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(one, R);
        }
        break;
        case StdRegions::ePreconLinearSpaceMass:
        {
            NekDouble one = 1.0;
            MatrixKey masskey(StdRegions::eMass, mkey.GetShapeType(), *this);
            DNekScalBlkMatSharedPtr massStatCond =
                GetLocStaticCondMatrix(masskey);
            DNekScalMatSharedPtr A = massStatCond->GetBlock(0, 0);
            DNekMatSharedPtr R     = BuildVertexMatrix(A);

            returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(one, R);
        }
        break;
        case StdRegions::ePreconR:
        {
            NekDouble one = 1.0;
            MatrixKey helmkey(StdRegions::eHelmholtz, mkey.GetShapeType(),
                              *this, mkey.GetConstFactors(),
                              mkey.GetVarCoeffs());
            DNekScalBlkMatSharedPtr helmStatCond =
                GetLocStaticCondMatrix(helmkey);

            DNekScalMatSharedPtr A = helmStatCond->GetBlock(0, 0);

            DNekScalMatSharedPtr Atmp;

            DNekMatSharedPtr R =
                BuildTransformationMatrix(A, mkey.GetMatrixType());

            returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(one, R);

            // Free memory,
            // need to build keys to delete Mass and Laplacian
            MatrixKey masskey(StdRegions::eMass, mkey.GetShapeType(), *this);
            MatrixKey lapkey(StdRegions::eLaplacian, mkey.GetShapeType(), *this,
                             mkey.GetConstFactors(), mkey.GetVarCoeffs());
            DropLocStaticCondMatrix(helmkey);
            DropLocMatrix(helmkey);
            DropLocMatrix(lapkey);
            DropLocMatrix(masskey);
        }
        break;
        case StdRegions::ePreconRMass:
        {
            NekDouble one = 1.0;
            MatrixKey masskey(StdRegions::eMass, mkey.GetShapeType(), *this);
            DNekScalBlkMatSharedPtr StatCond = GetLocStaticCondMatrix(masskey);
            DNekScalMatSharedPtr A           = StatCond->GetBlock(0, 0);

            DNekScalMatSharedPtr Atmp;
            DNekMatSharedPtr R =
                BuildTransformationMatrix(A, mkey.GetMatrixType());

            returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(one, R);
        }
        break;
        default:
        {
            NekDouble one        = 1.0;
            DNekMatSharedPtr mat = GenMatrix(mkey);

            returnval = MemoryManager<DNekScalMat>::AllocateSharedPtr(one, mat);
        }
        break;
    }

    return returnval;
}

/**
 * Computes matrices needed for the HDG formulation. References to
 * equations relate to the following paper (with a suitable changes in
 * formulation to adapt to 3D):
 *   R. M. Kirby, S. J. Sherwin, B. Cockburn, To CG or to HDG: A
 *   Comparative Study, J. Sci. Comp P1-30
 *   DOI 10.1007/s10915-011-9501-7
 *   NOTE: VARIABLE COEFFICIENTS CASE IS NOT IMPLEMENTED
 */
DNekMatSharedPtr Expansion3D::v_GenMatrix(const StdRegions::StdMatrixKey &mkey)
{
    // Variable coefficients are not implemented/////////
    ASSERTL1(!mkey.HasVarCoeff(StdRegions::eVarCoeffD00),
             "Matrix construction is not implemented for variable "
             "coefficients at the moment");
    ////////////////////////////////////////////////////

    DNekMatSharedPtr returnval;

    switch (mkey.GetMatrixType())
    {
        // (Z^e)^{-1} (Eqn. 33, P22)
        case StdRegions::eHybridDGHelmholtz:
        {
            ASSERTL1(IsBoundaryInteriorExpansion(),
                     "HybridDGHelmholtz matrix not set up "
                     "for non boundary-interior expansions");

            int i, j, k;
            NekDouble lambdaval =
                mkey.GetConstFactor(StdRegions::eFactorLambda);
            NekDouble tau = mkey.GetConstFactor(StdRegions::eFactorTau);
            int ncoeffs   = GetNcoeffs();
            int nfaces    = GetNtraces();

            Array<OneD, unsigned int> fmap;
            Array<OneD, int> sign;
            ExpansionSharedPtr FaceExp;
            ExpansionSharedPtr FaceExp2;

            int order_f, coordim = GetCoordim();
            DNekScalMat &invMass = *GetLocMatrix(StdRegions::eInvMass);
            StdRegions::MatrixType DerivType[3] = {StdRegions::eWeakDeriv0,
                                                   StdRegions::eWeakDeriv1,
                                                   StdRegions::eWeakDeriv2};

            returnval =
                MemoryManager<DNekMat>::AllocateSharedPtr(ncoeffs, ncoeffs);
            DNekMat &Mat = *returnval;
            Vmath::Zero(ncoeffs * ncoeffs, Mat.GetPtr(), 1);

            // StdRegions::VarCoeffType Coeffs[3] = {StdRegions::eVarCoeffD00,
            //                                       StdRegions::eVarCoeffD11,
            //                                       StdRegions::eVarCoeffD22};
            StdRegions::VarCoeffMap::const_iterator x;
            const StdRegions::VarCoeffMap &varcoeffs = mkey.GetVarCoeffs();

            for (i = 0; i < coordim; ++i)
            {
                if ((x = varcoeffs.find(StdRegions::eVarCoeffMF1x)) !=
                    varcoeffs.end())
                {
                    StdRegions::VarCoeffMap VarCoeffDirDeriv;
                    VarCoeffDirDeriv[StdRegions::eVarCoeffMF] =
                        GetMF(i, coordim, varcoeffs);
                    VarCoeffDirDeriv[StdRegions::eVarCoeffMFDiv] =
                        GetMFDiv(i, varcoeffs);

                    MatrixKey Dmatkey(StdRegions::eWeakDirectionalDeriv,
                                      DetShapeType(), *this,
                                      StdRegions::NullConstFactorMap,
                                      VarCoeffDirDeriv);

                    DNekScalMat &Dmat = *GetLocMatrix(Dmatkey);

                    StdRegions::VarCoeffMap Weight;
                    Weight[StdRegions::eVarCoeffMass] =
                        GetMFMag(i, mkey.GetVarCoeffs());

                    MatrixKey invMasskey(StdRegions::eInvMass, DetShapeType(),
                                         *this, StdRegions::NullConstFactorMap,
                                         Weight);

                    DNekScalMat &invMass = *GetLocMatrix(invMasskey);

                    Mat = Mat + Dmat * invMass * Transpose(Dmat);
                }
                else
                {
                    DNekScalMat &Dmat = *GetLocMatrix(DerivType[i]);
                    Mat               = Mat + Dmat * invMass * Transpose(Dmat);
                }

                /*
                if(mkey.HasVarCoeff(Coeffs[i]))
                {
                    MatrixKey DmatkeyL(DerivType[i], DetExpansionType(), *this,
                                       StdRegions::NullConstFactorMap,
                                       mkey.GetVarCoeffAsMap(Coeffs[i]));
                    MatrixKey DmatkeyR(DerivType[i], DetExpansionType(), *this);

                    DNekScalMat &DmatL = *GetLocMatrix(DmatkeyL);
                    DNekScalMat &DmatR = *GetLocMatrix(DmatkeyR);
                    Mat = Mat + DmatL*invMass*Transpose(DmatR);
                }
                else
                {
                    DNekScalMat &Dmat = *GetLocMatrix(DerivType[i]);
                    Mat = Mat + Dmat*invMass*Transpose(Dmat);
                }
                */
            }

            // Add Mass Matrix Contribution for Helmholtz problem
            DNekScalMat &Mass = *GetLocMatrix(StdRegions::eMass);
            Mat               = Mat + lambdaval * Mass;

            // Add tau*E_l using elemental mass matrices on each edge
            for (i = 0; i < nfaces; ++i)
            {
                FaceExp = GetTraceExp(i);
                order_f = FaceExp->GetNcoeffs();

                IndexMapKey ikey(eFaceToElement, DetShapeType(),
                                 GetBasisNumModes(0), GetBasisNumModes(1),
                                 GetBasisNumModes(2), i, GetTraceOrient(i));
                IndexMapValuesSharedPtr map = GetIndexMap(ikey);
                ASSERTL0(order_f == (*map).size(),
                         "HDGHelmholtz needs setting up for variable P");

                // @TODO: Document
                /*
                StdRegions::VarCoeffMap edgeVarCoeffs;
                if (mkey.HasVarCoeff(StdRegions::eVarCoeffD00))
                {
                    Array<OneD, NekDouble> mu(nq);
                    GetPhysEdgeVarCoeffsFromElement(
                        i, EdgeExp2,
                        mkey.GetVarCoeff(StdRegions::eVarCoeffD00), mu);
                    edgeVarCoeffs[StdRegions::eVarCoeffMass] = mu;
                }
                DNekScalMat &eMass = *EdgeExp->GetLocMatrix(
                    StdRegions::eMass,
                    StdRegions::NullConstFactorMap, edgeVarCoeffs);
                */

                DNekScalMat &eMass = *FaceExp->GetLocMatrix(StdRegions::eMass);

                for (j = 0; j < order_f; ++j)
                {
                    for (k = 0; k < order_f; ++k)
                    {
                        Mat((*map)[j].index, (*map)[k].index) +=
                            tau * (*map)[j].sign * (*map)[k].sign * eMass(j, k);
                    }
                }
            }
            break;
        }

        // U^e (P22)
        case StdRegions::eHybridDGLamToU:
        {
            int i, j, k;
            int nbndry    = NumDGBndryCoeffs();
            int ncoeffs   = GetNcoeffs();
            int nfaces    = GetNtraces();
            NekDouble tau = mkey.GetConstFactor(StdRegions::eFactorTau);

            Array<OneD, NekDouble> lambda(nbndry);
            DNekVec Lambda(nbndry, lambda, eWrapper);
            Array<OneD, NekDouble> ulam(ncoeffs);
            DNekVec Ulam(ncoeffs, ulam, eWrapper);
            Array<OneD, NekDouble> f(ncoeffs);
            DNekVec F(ncoeffs, f, eWrapper);

            ExpansionSharedPtr FaceExp;
            // declare matrix space
            returnval =
                MemoryManager<DNekMat>::AllocateSharedPtr(ncoeffs, nbndry);
            DNekMat &Umat = *returnval;

            // Z^e matrix
            MatrixKey newkey(StdRegions::eInvHybridDGHelmholtz, DetShapeType(),
                             *this, mkey.GetConstFactors(),
                             mkey.GetVarCoeffs());
            DNekScalMat &invHmat = *GetLocMatrix(newkey);

            Array<OneD, unsigned int> fmap;
            Array<OneD, int> sign;

            // alternative way to add boundary terms contribution
            int bndry_cnt = 0;
            for (i = 0; i < nfaces; ++i)
            {
                FaceExp = GetTraceExp(
                    i); // temporary, need to rewrite AddHDGHelmholtzFaceTerms
                int nface = GetTraceNcoeffs(i);
                Array<OneD, NekDouble> face_lambda(nface);

                const Array<OneD, const Array<OneD, NekDouble>> normals =
                    GetTraceNormal(i);

                for (j = 0; j < nface; ++j)
                {
                    Vmath::Zero(nface, &face_lambda[0], 1);
                    Vmath::Zero(ncoeffs, &f[0], 1);
                    face_lambda[j] = 1.0;

                    SetFaceToGeomOrientation(i, face_lambda);

                    Array<OneD, NekDouble> tmp(FaceExp->GetTotPoints());
                    FaceExp->BwdTrans(face_lambda, tmp);
                    AddHDGHelmholtzFaceTerms(tau, i, tmp, mkey.GetVarCoeffs(),
                                             f);

                    Ulam = invHmat * F; // generate Ulam from lambda

                    // fill column of matrix
                    for (k = 0; k < ncoeffs; ++k)
                    {
                        Umat(k, bndry_cnt) = Ulam[k];
                    }

                    ++bndry_cnt;
                }
            }

            //// Set up face expansions from local geom info
            // for(i = 0; i < nfaces; ++i)
            //{
            //    FaceExp[i] = GetTraceExp(i);
            //}
            //
            //// for each degree of freedom of the lambda space
            //// calculate Umat entry
            //// Generate Lambda to U_lambda matrix
            // for(j = 0; j < nbndry; ++j)
            //{
            //    // standard basis vectors e_j
            //    Vmath::Zero(nbndry,&lambda[0],1);
            //    Vmath::Zero(ncoeffs,&f[0],1);
            //    lambda[j] = 1.0;
            //
            //	//cout << Lambda;
            //    SetTraceToGeomOrientation(lambda);
            //	//cout << Lambda << endl;
            //
            //    // Compute F = [I   D_1 M^{-1}   D_2 M^{-1}] C e_j
            //    AddHDGHelmholtzTraceTerms(tau, lambda, FaceExp,
            //    mkey.GetVarCoeffs(), f);
            //
            //    // Compute U^e_j
            //    Ulam = invHmat*F; // generate Ulam from lambda
            //
            //    // fill column of matrix
            //    for(k = 0; k < ncoeffs; ++k)
            //    {
            //        Umat(k,j) = Ulam[k];
            //    }
            //}
        }
        break;
        // Q_0, Q_1, Q_2 matrices (P23)
        // Each are a product of a row of Eqn 32 with the C matrix.
        // Rather than explicitly computing all of Eqn 32, we note each
        // row is almost a multiple of U^e, so use that as our starting
        // point.
        case StdRegions::eHybridDGLamToQ0:
        case StdRegions::eHybridDGLamToQ1:
        case StdRegions::eHybridDGLamToQ2:
        {
            int i       = 0;
            int j       = 0;
            int k       = 0;
            int dir     = 0;
            int nbndry  = NumDGBndryCoeffs();
            int coordim = GetCoordim();
            int ncoeffs = GetNcoeffs();
            int nfaces  = GetNtraces();

            Array<OneD, NekDouble> lambda(nbndry);
            DNekVec Lambda(nbndry, lambda, eWrapper);
            Array<OneD, ExpansionSharedPtr> FaceExp(nfaces);

            Array<OneD, NekDouble> ulam(ncoeffs);
            DNekVec Ulam(ncoeffs, ulam, eWrapper);
            Array<OneD, NekDouble> f(ncoeffs);
            DNekVec F(ncoeffs, f, eWrapper);

            // declare matrix space
            returnval =
                MemoryManager<DNekMat>::AllocateSharedPtr(ncoeffs, nbndry);
            DNekMat &Qmat = *returnval;

            // Lambda to U matrix
            MatrixKey lamToUkey(StdRegions::eHybridDGLamToU, DetShapeType(),
                                *this, mkey.GetConstFactors(),
                                mkey.GetVarCoeffs());
            DNekScalMat &lamToU = *GetLocMatrix(lamToUkey);

            // Inverse mass matrix
            DNekScalMat &invMass = *GetLocMatrix(StdRegions::eInvMass);

            for (i = 0; i < nfaces; ++i)
            {
                FaceExp[i] = GetTraceExp(i);
            }

            // Weak Derivative matrix
            DNekScalMatSharedPtr Dmat;
            switch (mkey.GetMatrixType())
            {
                case StdRegions::eHybridDGLamToQ0:
                    dir  = 0;
                    Dmat = GetLocMatrix(StdRegions::eWeakDeriv0);
                    break;
                case StdRegions::eHybridDGLamToQ1:
                    dir  = 1;
                    Dmat = GetLocMatrix(StdRegions::eWeakDeriv1);
                    break;
                case StdRegions::eHybridDGLamToQ2:
                    dir  = 2;
                    Dmat = GetLocMatrix(StdRegions::eWeakDeriv2);
                    break;
                default:
                    ASSERTL0(false, "Direction not known");
                    break;
            }

            // DNekScalMatSharedPtr Dmat;
            // DNekScalMatSharedPtr &invMass;
            StdRegions::VarCoeffMap::const_iterator x;
            const StdRegions::VarCoeffMap &varcoeffs = mkey.GetVarCoeffs();
            if ((x = varcoeffs.find(StdRegions::eVarCoeffMF1x)) !=
                varcoeffs.end())
            {
                StdRegions::VarCoeffMap VarCoeffDirDeriv;
                VarCoeffDirDeriv[StdRegions::eVarCoeffMF] =
                    GetMF(dir, coordim, varcoeffs);
                VarCoeffDirDeriv[StdRegions::eVarCoeffMFDiv] =
                    GetMFDiv(dir, varcoeffs);

                MatrixKey Dmatkey(
                    StdRegions::eWeakDirectionalDeriv, DetShapeType(), *this,
                    StdRegions::NullConstFactorMap, VarCoeffDirDeriv);

                Dmat = GetLocMatrix(Dmatkey);

                StdRegions::VarCoeffMap Weight;
                Weight[StdRegions::eVarCoeffMass] =
                    GetMFMag(dir, mkey.GetVarCoeffs());

                MatrixKey invMasskey(StdRegions::eInvMass, DetShapeType(),
                                     *this, StdRegions::NullConstFactorMap,
                                     Weight);

                invMass = *GetLocMatrix(invMasskey);
            }
            else
            {
                // Inverse mass matrix
                invMass = *GetLocMatrix(StdRegions::eInvMass);
            }

            // for each degree of freedom of the lambda space
            // calculate Qmat entry
            // Generate Lambda to Q_lambda matrix
            for (j = 0; j < nbndry; ++j)
            {
                Vmath::Zero(nbndry, &lambda[0], 1);
                lambda[j] = 1.0;

                // for lambda[j] = 1 this is the solution to ulam
                for (k = 0; k < ncoeffs; ++k)
                {
                    Ulam[k] = lamToU(k, j);
                }

                // -D^T ulam
                Vmath::Neg(ncoeffs, &ulam[0], 1);
                F = Transpose(*Dmat) * Ulam;

                SetTraceToGeomOrientation(lambda);

                // Add the C terms resulting from the I's on the
                // diagonals of Eqn 32
                AddNormTraceInt(dir, lambda, FaceExp, f, mkey.GetVarCoeffs());

                // finally multiply by inverse mass matrix
                Ulam = invMass * F;

                // fill column of matrix (Qmat is in column major format)
                Vmath::Vcopy(ncoeffs, &ulam[0], 1,
                             &(Qmat.GetPtr())[0] + j * ncoeffs, 1);
            }
        }
        break;
        // Matrix K (P23)
        case StdRegions::eHybridDGHelmBndLam:
        {
            int i, j, f, cnt;
            int order_f, nquad_f;
            int nbndry    = NumDGBndryCoeffs();
            int nfaces    = GetNtraces();
            NekDouble tau = mkey.GetConstFactor(StdRegions::eFactorTau);

            Array<OneD, NekDouble> work, varcoeff_work;
            Array<OneD, const Array<OneD, NekDouble>> normals;
            Array<OneD, ExpansionSharedPtr> FaceExp(nfaces);
            Array<OneD, NekDouble> lam(nbndry);

            Array<OneD, unsigned int> fmap;
            Array<OneD, int> sign;

            // declare matrix space
            returnval =
                MemoryManager<DNekMat>::AllocateSharedPtr(nbndry, nbndry);
            DNekMat &BndMat = *returnval;

            DNekScalMatSharedPtr LamToQ[3];

            // Matrix to map Lambda to U
            MatrixKey LamToUkey(StdRegions::eHybridDGLamToU, DetShapeType(),
                                *this, mkey.GetConstFactors(),
                                mkey.GetVarCoeffs());
            DNekScalMat &LamToU = *GetLocMatrix(LamToUkey);

            // Matrix to map Lambda to Q0
            MatrixKey LamToQ0key(StdRegions::eHybridDGLamToQ0, DetShapeType(),
                                 *this, mkey.GetConstFactors(),
                                 mkey.GetVarCoeffs());
            LamToQ[0] = GetLocMatrix(LamToQ0key);

            // Matrix to map Lambda to Q1
            MatrixKey LamToQ1key(StdRegions::eHybridDGLamToQ1, DetShapeType(),
                                 *this, mkey.GetConstFactors(),
                                 mkey.GetVarCoeffs());
            LamToQ[1] = GetLocMatrix(LamToQ1key);

            // Matrix to map Lambda to Q2
            MatrixKey LamToQ2key(StdRegions::eHybridDGLamToQ2, DetShapeType(),
                                 *this, mkey.GetConstFactors(),
                                 mkey.GetVarCoeffs());
            LamToQ[2] = GetLocMatrix(LamToQ2key);

            // Set up edge segment expansions from local geom info
            const StdRegions::VarCoeffMap &varcoeffs = mkey.GetVarCoeffs();
            for (i = 0; i < nfaces; ++i)
            {
                FaceExp[i] = GetTraceExp(i);
            }

            // Set up matrix derived from <mu, Q_lam.n - \tau (U_lam - Lam) >
            for (i = 0; i < nbndry; ++i)
            {
                cnt = 0;

                Vmath::Zero(nbndry, lam, 1);
                lam[i] = 1.0;
                SetTraceToGeomOrientation(lam);

                for (f = 0; f < nfaces; ++f)
                {
                    order_f = FaceExp[f]->GetNcoeffs();
                    nquad_f = FaceExp[f]->GetNumPoints(0) *
                              FaceExp[f]->GetNumPoints(1);
                    normals = GetTraceNormal(f);

                    work          = Array<OneD, NekDouble>(nquad_f);
                    varcoeff_work = Array<OneD, NekDouble>(nquad_f);

                    IndexMapKey ikey(eFaceToElement, DetShapeType(),
                                     GetBasisNumModes(0), GetBasisNumModes(1),
                                     GetBasisNumModes(2), f, GetTraceOrient(f));
                    IndexMapValuesSharedPtr map = GetIndexMap(ikey);

                    // @TODO Variable coefficients
                    /*
                    StdRegions::VarCoeffType VarCoeff[3] =
                    {StdRegions::eVarCoeffD00, StdRegions::eVarCoeffD11,
                                                            StdRegions::eVarCoeffD22};
                    const StdRegions::VarCoeffMap &varcoeffs =
                    mkey.GetVarCoeffs(); StdRegions::VarCoeffMap::const_iterator
                    x;
                    */

                    // Q0 * n0 (BQ_0 terms)
                    Array<OneD, NekDouble> faceCoeffs(order_f);
                    Array<OneD, NekDouble> facePhys(nquad_f);
                    for (j = 0; j < order_f; ++j)
                    {
                        faceCoeffs[j] =
                            (*map)[j].sign * (*LamToQ[0])((*map)[j].index, i);
                    }

                    FaceExp[f]->BwdTrans(faceCoeffs, facePhys);

                    // @TODO Variable coefficients
                    // Multiply by variable coefficient
                    /*
                    if ((x = varcoeffs.find(VarCoeff[0])) != varcoeffs.end())
                    {
                        GetPhysEdgeVarCoeffsFromElement(e,EdgeExp[e],x->second,varcoeff_work);
                        Vmath::Vmul(nquad_e,varcoeff_work,1,EdgeExp[e]->GetPhys(),1,EdgeExp[e]->UpdatePhys(),1);
                    }
                    */

                    if (varcoeffs.find(StdRegions::eVarCoeffMF1x) !=
                        varcoeffs.end())
                    {
                        Array<OneD, NekDouble> ncdotMF = GetnFacecdotMF(
                            0, f, FaceExp[f], normals, varcoeffs);

                        Vmath::Vmul(nquad_f, ncdotMF, 1, facePhys, 1, work, 1);
                    }
                    else
                    {
                        Vmath::Vmul(nquad_f, normals[0], 1, facePhys, 1, work,
                                    1);
                    }

                    // Q1 * n1 (BQ_1 terms)
                    for (j = 0; j < order_f; ++j)
                    {
                        faceCoeffs[j] =
                            (*map)[j].sign * (*LamToQ[1])((*map)[j].index, i);
                    }

                    FaceExp[f]->BwdTrans(faceCoeffs, facePhys);

                    // @TODO Variable coefficients
                    // Multiply by variable coefficients
                    /*
                    if ((x = varcoeffs.find(VarCoeff[1])) != varcoeffs.end())
                    {
                        GetPhysEdgeVarCoeffsFromElement(e,EdgeExp[e],x->second,varcoeff_work);
                        Vmath::Vmul(nquad_e,varcoeff_work,1,EdgeExp[e]->GetPhys(),1,EdgeExp[e]->UpdatePhys(),1);
                    }
                    */

                    if ((varcoeffs.find(StdRegions::eVarCoeffMF1x)) !=
                        varcoeffs.end())
                    {
                        Array<OneD, NekDouble> ncdotMF = GetnFacecdotMF(
                            1, f, FaceExp[f], normals, varcoeffs);

                        Vmath::Vvtvp(nquad_f, ncdotMF, 1, facePhys, 1, work, 1,
                                     work, 1);
                    }
                    else
                    {
                        Vmath::Vvtvp(nquad_f, normals[1], 1, facePhys, 1, work,
                                     1, work, 1);
                    }

                    // Q2 * n2 (BQ_2 terms)
                    for (j = 0; j < order_f; ++j)
                    {
                        faceCoeffs[j] =
                            (*map)[j].sign * (*LamToQ[2])((*map)[j].index, i);
                    }

                    FaceExp[f]->BwdTrans(faceCoeffs, facePhys);

                    // @TODO Variable coefficients
                    // Multiply by variable coefficients
                    /*
                    if ((x = varcoeffs.find(VarCoeff[2])) != varcoeffs.end())
                    {
                        GetPhysEdgeVarCoeffsFromElement(e,EdgeExp[e],x->second,varcoeff_work);
                        Vmath::Vmul(nquad_e,varcoeff_work,1,EdgeExp[e]->GetPhys(),1,EdgeExp[e]->UpdatePhys(),1);
                    }
                    */

                    if (varcoeffs.find(StdRegions::eVarCoeffMF1x) !=
                        varcoeffs.end())
                    {
                        Array<OneD, NekDouble> ncdotMF = GetnFacecdotMF(
                            2, f, FaceExp[f], normals, varcoeffs);

                        Vmath::Vvtvp(nquad_f, ncdotMF, 1, facePhys, 1, work, 1,
                                     work, 1);
                    }
                    else
                    {
                        Vmath::Vvtvp(nquad_f, normals[2], 1, facePhys, 1, work,
                                     1, work, 1);
                    }

                    // - tau (ulam - lam)
                    // Corresponds to the G and BU terms.
                    for (j = 0; j < order_f; ++j)
                    {
                        faceCoeffs[j] =
                            (*map)[j].sign * LamToU((*map)[j].index, i) -
                            lam[cnt + j];
                    }

                    FaceExp[f]->BwdTrans(faceCoeffs, facePhys);

                    // @TODO Variable coefficients
                    // Multiply by variable coefficients
                    /*
                    if ((x = varcoeffs.find(VarCoeff[0])) != varcoeffs.end())
                    {
                        GetPhysEdgeVarCoeffsFromElement(e,FaceExp[f],x->second,varcoeff_work);
                        Vmath::Vmul(nquad_f,varcoeff_work,1,FaceExp[f]->GetPhys(),1,FaceExp[f]->UpdatePhys(),1);
                    }
                    */

                    Vmath::Svtvp(nquad_f, -tau, facePhys, 1, work, 1, work, 1);

                    // @TODO Add variable coefficients
                    FaceExp[f]->IProductWRTBase(work, faceCoeffs);

                    SetFaceToGeomOrientation(f, faceCoeffs);

                    for (j = 0; j < order_f; ++j)
                    {
                        BndMat(cnt + j, i) = faceCoeffs[j];
                    }

                    cnt += order_f;
                }
            }
        }
        break;
        // HDG postprocessing
        case StdRegions::eInvLaplacianWithUnityMean:
        {
            MatrixKey lapkey(StdRegions::eLaplacian, DetShapeType(), *this,
                             mkey.GetConstFactors(), mkey.GetVarCoeffs());
            DNekScalMat &LapMat = *GetLocMatrix(lapkey);

            returnval = MemoryManager<DNekMat>::AllocateSharedPtr(
                LapMat.GetRows(), LapMat.GetColumns());
            DNekMatSharedPtr lmat = returnval;

            (*lmat) = LapMat;

            // replace first column with inner product wrt 1
            int nq = GetTotPoints();
            Array<OneD, NekDouble> tmp(nq);
            Array<OneD, NekDouble> outarray(m_ncoeffs);
            Vmath::Fill(nq, 1.0, tmp, 1);
            IProductWRTBase(tmp, outarray);

            Vmath::Vcopy(m_ncoeffs, &outarray[0], 1, &(lmat->GetPtr())[0], 1);

            lmat->Invert();
        }
        break;
        case StdRegions::eNormDerivOnTrace:
        {
            int ntraces = GetNtraces();
            int ncoords = GetCoordim();
            int nphys   = GetTotPoints();
            Array<OneD, const Array<OneD, NekDouble>> normals;
            Array<OneD, NekDouble> phys(nphys);
            returnval =
                MemoryManager<DNekMat>::AllocateSharedPtr(m_ncoeffs, m_ncoeffs);
            DNekMat &Mat = *returnval;
            Vmath::Zero(m_ncoeffs * m_ncoeffs, Mat.GetPtr(), 1);

            Array<OneD, Array<OneD, NekDouble>> Deriv(3, NullNekDouble1DArray);

            for (int d = 0; d < ncoords; ++d)
            {
                Deriv[d] = Array<OneD, NekDouble>(nphys);
            }

            Array<OneD, int> tracepts(ntraces);
            Array<OneD, ExpansionSharedPtr> traceExp(ntraces);
            int maxtpts = 0;
            for (int t = 0; t < ntraces; ++t)
            {
                traceExp[t] = GetTraceExp(t);
                tracepts[t] = traceExp[t]->GetTotPoints();
                maxtpts     = (maxtpts > tracepts[t]) ? maxtpts : tracepts[t];
            }

            Array<OneD, NekDouble> val(maxtpts), tmp, tmp1;

            Array<OneD, Array<OneD, NekDouble>> dphidn(ntraces);
            for (int t = 0; t < ntraces; ++t)
            {
                dphidn[t] =
                    Array<OneD, NekDouble>(m_ncoeffs * tracepts[t], 0.0);
            }

            for (int i = 0; i < m_ncoeffs; ++i)
            {
                FillMode(i, phys);
                PhysDeriv(phys, Deriv[0], Deriv[1], Deriv[2]);

                for (int t = 0; t < ntraces; ++t)
                {
                    const NormalVector norm = GetTraceNormal(t);

                    LibUtilities::BasisKey fromkey0 = GetTraceBasisKey(t, 0);
                    LibUtilities::BasisKey fromkey1 = GetTraceBasisKey(t, 1);
                    LibUtilities::BasisKey tokey0 =
                        traceExp[t]->GetBasis(0)->GetBasisKey();
                    LibUtilities::BasisKey tokey1 =
                        traceExp[t]->GetBasis(1)->GetBasisKey();
                    bool DoInterp =
                        (fromkey0 != tokey0) || (fromkey1 != tokey1);

                    // for variable p need add check and
                    // interpolation here.

                    Array<OneD, NekDouble> n(tracepts[t]);
                    ;
                    for (int d = 0; d < ncoords; ++d)
                    {
                        // if variable p may need to interpolate
                        if (DoInterp)
                        {
                            LibUtilities::Interp2D(fromkey0, fromkey1, norm[d],
                                                   tokey0, tokey1, n);
                        }
                        else
                        {
                            n = norm[d];
                        }

                        GetTracePhysVals(t, traceExp[t], Deriv[d], val,
                                         v_GetTraceOrient(t));

                        Vmath::Vvtvp(tracepts[t], n, 1, val, 1,
                                     tmp  = dphidn[t] + i * tracepts[t], 1,
                                     tmp1 = dphidn[t] + i * tracepts[t], 1);
                    }
                }
            }

            for (int t = 0; t < ntraces; ++t)
            {
                int nt = tracepts[t];
                NekDouble h, p;
                TraceNormLen(t, h, p);

                // scaling from GJP paper
                NekDouble scale =
                    (p == 1) ? 0.02 * h * h : 0.8 * pow(p + 1, -4.0) * h * h;

                for (int i = 0; i < m_ncoeffs; ++i)
                {
                    for (int j = i; j < m_ncoeffs; ++j)
                    {
                        Vmath::Vmul(nt, dphidn[t] + i * nt, 1,
                                    dphidn[t] + j * nt, 1, val, 1);
                        Mat(i, j) =
                            Mat(i, j) + scale * traceExp[t]->Integral(val);
                    }
                }
            }

            // fill in symmetric components.
            for (int i = 0; i < m_ncoeffs; ++i)
            {
                for (int j = 0; j < i; ++j)
                {
                    Mat(i, j) = Mat(j, i);
                }
            }
        }
        break;
        default:
            ASSERTL0(false,
                     "This matrix type cannot be generated from this class");
            break;
    }

    return returnval;
}

void Expansion3D::v_AddFaceNormBoundaryInt(
    const int face, const ExpansionSharedPtr &FaceExp,
    const Array<OneD, const NekDouble> &Fn, Array<OneD, NekDouble> &outarray)
{
    int i, j;

    /*
     * Coming into this routine, the velocity V will have been
     * multiplied by the trace normals to give the input vector Vn. By
     * convention, these normals are inwards facing for elements which
     * have FaceExp as their right-adjacent face.  This conditional
     * statement therefore determines whether the normals must be
     * negated, since the integral being performed here requires an
     * outwards facing normal.
     */
    if (m_requireNeg.size() == 0)
    {
        m_requireNeg.resize(GetNtraces());

        for (i = 0; i < GetNtraces(); ++i)
        {
            m_requireNeg[i] = false;

            ExpansionSharedPtr faceExp = m_traceExp[i].lock();

            if (faceExp->GetRightAdjacentElementExp())
            {
                if (faceExp->GetRightAdjacentElementExp()
                        ->GetGeom()
                        ->GetGlobalID() == GetGeom()->GetGlobalID())
                {
                    m_requireNeg[i] = true;
                }
            }
        }
    }

    IndexMapKey ikey(eFaceToElement, DetShapeType(), GetBasisNumModes(0),
                     GetBasisNumModes(1), GetBasisNumModes(2), face,
                     GetTraceOrient(face));
    IndexMapValuesSharedPtr map = GetIndexMap(ikey);

    int order_e  = (*map).size(); // Order of the element
    int n_coeffs = FaceExp->GetNcoeffs();

    Array<OneD, NekDouble> faceCoeffs(n_coeffs);

    if (n_coeffs != order_e) // Going to orthogonal space
    {
        FaceExp->FwdTrans(Fn, faceCoeffs);

        int NumModesElementMax = FaceExp->GetBasis(0)->GetNumModes();
        int NumModesElementMin = m_base[0]->GetNumModes();

        FaceExp->ReduceOrderCoeffs(NumModesElementMin, faceCoeffs, faceCoeffs);

        StdRegions::StdMatrixKey masskey(StdRegions::eMass,
                                         FaceExp->DetShapeType(), *FaceExp);
        FaceExp->MassMatrixOp(faceCoeffs, faceCoeffs, masskey);

        // Reorder coefficients for the lower degree face.
        int offset1 = 0, offset2 = 0;

        if (FaceExp->DetShapeType() == LibUtilities::eQuadrilateral)
        {
            for (i = 0; i < NumModesElementMin; ++i)
            {
                for (j = 0; j < NumModesElementMin; ++j)
                {
                    faceCoeffs[offset1 + j] = faceCoeffs[offset2 + j];
                }
                offset1 += NumModesElementMin;
                offset2 += NumModesElementMax;
            }

            // Extract lower degree modes. TODO: Check this is correct.
            for (i = NumModesElementMin; i < NumModesElementMax; ++i)
            {
                for (j = NumModesElementMin; j < NumModesElementMax; ++j)
                {
                    faceCoeffs[i * NumModesElementMax + j] = 0.0;
                }
            }
        }

        if (FaceExp->DetShapeType() == LibUtilities::eTriangle)
        {

            // Reorder coefficients for the lower degree face.
            int offset1 = 0, offset2 = 0;

            for (i = 0; i < NumModesElementMin; ++i)
            {
                for (j = 0; j < NumModesElementMin - i; ++j)
                {
                    faceCoeffs[offset1 + j] = faceCoeffs[offset2 + j];
                }
                offset1 += NumModesElementMin - i;
                offset2 += NumModesElementMax - i;
            }
        }
    }
    else
    {
        FaceExp->IProductWRTBase(Fn, faceCoeffs);
    }

    if (m_requireNeg[face])
    {
        for (i = 0; i < order_e; ++i)
        {
            outarray[(*map)[i].index] -= (*map)[i].sign * faceCoeffs[i];
        }
    }
    else
    {
        for (i = 0; i < order_e; ++i)
        {
            outarray[(*map)[i].index] += (*map)[i].sign * faceCoeffs[i];
        }
    }
}

/**
 * @brief Evaluate coefficients of weak deriviative in the direction dir
 * given the input coefficicents incoeffs and the imposed boundary
 * values in EdgeExp (which will have its phys space updated).
 */
void Expansion3D::v_DGDeriv(int dir,
                            const Array<OneD, const NekDouble> &incoeffs,
                            Array<OneD, ExpansionSharedPtr> &FaceExp,
                            Array<OneD, Array<OneD, NekDouble>> &faceCoeffs,
                            Array<OneD, NekDouble> &out_d)
{
    int ncoeffs                         = GetNcoeffs();
    StdRegions::MatrixType DerivType[3] = {StdRegions::eWeakDeriv0,
                                           StdRegions::eWeakDeriv1,
                                           StdRegions::eWeakDeriv2};

    DNekScalMat &InvMass = *GetLocMatrix(StdRegions::eInvMass);
    DNekScalMat &Dmat    = *GetLocMatrix(DerivType[dir]);

    Array<OneD, NekDouble> coeffs = incoeffs;
    DNekVec Coeffs(ncoeffs, coeffs, eWrapper);

    Coeffs = Transpose(Dmat) * Coeffs;
    Vmath::Neg(ncoeffs, coeffs, 1);

    // Add the boundary integral including the relevant part of
    // the normal
    AddNormTraceInt(dir, FaceExp, faceCoeffs, coeffs);

    DNekVec Out_d(ncoeffs, out_d, eWrapper);

    Out_d = InvMass * Coeffs;
}

void Expansion3D::v_AddRobinMassMatrix(
    const int face, const Array<OneD, const NekDouble> &primCoeffs,
    DNekMatSharedPtr &inoutmat)
{
    ASSERTL1(IsBoundaryInteriorExpansion(),
             "Not set up for non boundary-interior expansions");
    ASSERTL1(inoutmat->GetRows() == inoutmat->GetColumns(),
             "Assuming that input matrix was square");

    int i, j;
    int id1, id2;
    ExpansionSharedPtr faceExp = m_traceExp[face].lock();
    int order_f                = faceExp->GetNcoeffs();

    Array<OneD, unsigned int> map;
    Array<OneD, int> sign;

    StdRegions::VarCoeffMap varcoeffs;
    varcoeffs[StdRegions::eVarCoeffMass] = primCoeffs;

    LibUtilities::ShapeType shapeType = faceExp->DetShapeType();

    LocalRegions::MatrixKey mkey(StdRegions::eMass, shapeType, *faceExp,
                                 StdRegions::NullConstFactorMap, varcoeffs);

    DNekScalMat &facemat = *faceExp->GetLocMatrix(mkey);

    // Now need to identify a map which takes the local face
    // mass matrix to the matrix stored in inoutmat;
    // This can currently be deduced from the size of the matrix

    // - if inoutmat.m_rows() == v_NCoeffs() it is a full
    //   matrix system

    // - if inoutmat.m_rows() == v_GetNverts() it is a vertex space
    //  preconditioner.

    // - if inoutmat.m_rows() == v_NumBndCoeffs() it is a
    //  boundary CG system

    // - if inoutmat.m_rows() == v_NumDGBndCoeffs() it is a
    //  trace DG system; still needs implementing.
    int rows = inoutmat->GetRows();

    if (rows == GetNcoeffs())
    {
        GetTraceToElementMap(face, map, sign, GetTraceOrient(face));
    }
    else if (rows == GetNverts())
    {
        int nfvert = faceExp->GetNverts();

        // Need to find where linear vertices are in facemat
        Array<OneD, unsigned int> linmap;
        Array<OneD, int> linsign;

        // Use a linear expansion to get correct mapping
        GetLinStdExp()->GetTraceToElementMap(face, linmap, linsign,
                                             GetTraceOrient(face));

        // zero out sign map to remove all other modes
        sign = Array<OneD, int>(order_f, 0);
        map  = Array<OneD, unsigned int>(order_f, (unsigned int)0);

        int fmap;
        // Reset sign map to only have contribution from vertices
        for (i = 0; i < nfvert; ++i)
        {
            fmap       = faceExp->GetVertexMap(i, true);
            sign[fmap] = 1;

            // need to reset map
            map[fmap] = linmap[i];
        }
    }
    else if (rows == NumBndryCoeffs())
    {
        int nbndry = NumBndryCoeffs();
        Array<OneD, unsigned int> bmap(nbndry);

        GetTraceToElementMap(face, map, sign, GetTraceOrient(face));
        GetBoundaryMap(bmap);

        for (i = 0; i < order_f; ++i)
        {
            for (j = 0; j < nbndry; ++j)
            {
                if (map[i] == bmap[j])
                {
                    map[i] = j;
                    break;
                }
            }
            ASSERTL1(j != nbndry, "Did not find number in map");
        }
    }
    else if (rows == NumDGBndryCoeffs())
    {
        // possibly this should be a separate method
        int cnt = 0;
        map     = Array<OneD, unsigned int>(order_f);
        sign    = Array<OneD, int>(order_f, 1);

        IndexMapKey ikey1(eFaceToElement, DetShapeType(), GetBasisNumModes(0),
                          GetBasisNumModes(1), GetBasisNumModes(2), face,
                          GetTraceOrient(face));
        IndexMapValuesSharedPtr map1 = GetIndexMap(ikey1);
        IndexMapKey ikey2(eFaceToElement, DetShapeType(), GetBasisNumModes(0),
                          GetBasisNumModes(1), GetBasisNumModes(2), face,
                          StdRegions::eDir1FwdDir1_Dir2FwdDir2);
        IndexMapValuesSharedPtr map2 = GetIndexMap(ikey2);

        ASSERTL1((*map1).size() == (*map2).size(),
                 "There is an error with the GetTraceToElementMap");

        for (i = 0; i < face; ++i)
        {
            cnt += GetTraceNcoeffs(i);
        }

        for (i = 0; i < (*map1).size(); ++i)
        {
            int idx = -1;

            for (j = 0; j < (*map2).size(); ++j)
            {
                if ((*map1)[i].index == (*map2)[j].index)
                {
                    idx = j;
                    break;
                }
            }

            ASSERTL2(idx >= 0, "Index not found");
            map[i]  = idx + cnt;
            sign[i] = (*map2)[idx].sign;
        }
    }
    else
    {
        ASSERTL0(false, "Could not identify matrix type from dimension");
    }

    for (i = 0; i < order_f; ++i)
    {
        id1 = map[i];
        for (j = 0; j < order_f; ++j)
        {
            id2 = map[j];
            (*inoutmat)(id1, id2) += facemat(i, j) * sign[i] * sign[j];
        }
    }
}

DNekMatSharedPtr Expansion3D::v_BuildVertexMatrix(
    const DNekScalMatSharedPtr &r_bnd)
{
    MatrixStorage storage = eFULL;
    DNekMatSharedPtr vertexmatrix;

    int nVerts, vid1, vid2, vMap1, vMap2;
    NekDouble VertexValue;

    nVerts = GetNverts();

    vertexmatrix =
        MemoryManager<DNekMat>::AllocateSharedPtr(nVerts, nVerts, 0.0, storage);
    DNekMat &VertexMat = (*vertexmatrix);

    for (vid1 = 0; vid1 < nVerts; ++vid1)
    {
        vMap1 = GetVertexMap(vid1, true);

        for (vid2 = 0; vid2 < nVerts; ++vid2)
        {
            vMap2       = GetVertexMap(vid2, true);
            VertexValue = (*r_bnd)(vMap1, vMap2);
            VertexMat.SetValue(vid1, vid2, VertexValue);
        }
    }

    return vertexmatrix;
}

DNekMatSharedPtr Expansion3D::v_BuildTransformationMatrix(
    const DNekScalMatSharedPtr &r_bnd, const StdRegions::MatrixType matrixType)
{
    int nVerts, nEdges;
    int eid, fid, vid, n, i;

    int nBndCoeffs = NumBndryCoeffs();

    const SpatialDomains::Geometry3DSharedPtr &geom = GetGeom3D();

    // Get geometric information about this element
    nVerts = GetNverts();
    nEdges = GetNedges();

    /*************************************/
    /* Vetex-edge & vertex-face matrices */
    /*************************************/

    /**
     * The matrix component of \f$\mathbf{R}\f$ is given by \f[
     * \mathbf{R^{T}_{v}}=
     * -\mathbf{S}^{-1}_{ef,ef}\mathbf{S}^{T}_{v,ef}\f]
     *
     * For every vertex mode we extract the submatrices from statically
     * condensed matrix \f$\mathbf{S}\f$ corresponding to the coupling
     * between the attached edges and faces of a vertex
     * (\f$\mathbf{S_{ef,ef}}\f$). This matrix is then inverted and
     * multiplied by the submatrix representing the coupling between a
     * vertex and the attached edges and faces
     * (\f$\mathbf{S_{v,ef}}\f$).
     */

    int nmodes;
    int m;
    NekDouble VertexEdgeFaceValue;

    // The number of connected edges/faces is 3 (for all elements)
    int nConnectedEdges = 3;
    int nConnectedFaces = 3;

    // Location in the matrix
    Array<OneD, Array<OneD, unsigned int>> MatEdgeLocation(nConnectedEdges);
    Array<OneD, Array<OneD, unsigned int>> MatFaceLocation(nConnectedFaces);

    // Define storage for vertex transpose matrix and zero all entries
    MatrixStorage storage = eFULL;
    DNekMatSharedPtr transformationmatrix;

    transformationmatrix = MemoryManager<DNekMat>::AllocateSharedPtr(
        nBndCoeffs, nBndCoeffs, 0.0, storage);

    DNekMat &R = (*transformationmatrix);

    // Build the vertex-edge/face transform matrix: This matrix is
    // constructed from the submatrices corresponding to the couping
    // between each vertex and the attached edges/faces
    for (vid = 0; vid < nVerts; ++vid)
    {
        // Row and column size of the vertex-edge/face matrix
        int efRow = GetEdgeNcoeffs(geom->GetVertexEdgeMap(vid, 0)) +
                    GetEdgeNcoeffs(geom->GetVertexEdgeMap(vid, 1)) +
                    GetEdgeNcoeffs(geom->GetVertexEdgeMap(vid, 2)) +
                    GetTraceIntNcoeffs(geom->GetVertexFaceMap(vid, 0)) +
                    GetTraceIntNcoeffs(geom->GetVertexFaceMap(vid, 1)) +
                    GetTraceIntNcoeffs(geom->GetVertexFaceMap(vid, 2)) - 6;

        int nedgemodesconnected =
            GetEdgeNcoeffs(geom->GetVertexEdgeMap(vid, 0)) +
            GetEdgeNcoeffs(geom->GetVertexEdgeMap(vid, 1)) +
            GetEdgeNcoeffs(geom->GetVertexEdgeMap(vid, 2)) - 6;
        Array<OneD, unsigned int> edgemodearray(nedgemodesconnected);

        int nfacemodesconnected =
            GetTraceIntNcoeffs(geom->GetVertexFaceMap(vid, 0)) +
            GetTraceIntNcoeffs(geom->GetVertexFaceMap(vid, 1)) +
            GetTraceIntNcoeffs(geom->GetVertexFaceMap(vid, 2));
        Array<OneD, unsigned int> facemodearray(nfacemodesconnected);

        int offset = 0;

        // Create array of edge modes
        for (eid = 0; eid < nConnectedEdges; ++eid)
        {
            MatEdgeLocation[eid] =
                GetEdgeInverseBoundaryMap(geom->GetVertexEdgeMap(vid, eid));
            nmodes = MatEdgeLocation[eid].size();

            if (nmodes)
            {
                Vmath::Vcopy(nmodes, &MatEdgeLocation[eid][0], 1,
                             &edgemodearray[offset], 1);
            }

            offset += nmodes;
        }

        offset = 0;

        // Create array of face modes
        for (fid = 0; fid < nConnectedFaces; ++fid)
        {
            MatFaceLocation[fid] =
                GetTraceInverseBoundaryMap(geom->GetVertexFaceMap(vid, fid));
            nmodes = MatFaceLocation[fid].size();

            if (nmodes)
            {
                Vmath::Vcopy(nmodes, &MatFaceLocation[fid][0], 1,
                             &facemodearray[offset], 1);
            }
            offset += nmodes;
        }

        DNekMatSharedPtr vertexedgefacetransformmatrix =
            MemoryManager<DNekMat>::AllocateSharedPtr(1, efRow, 0.0, storage);
        DNekMat &Sveft = (*vertexedgefacetransformmatrix);

        DNekMatSharedPtr vertexedgefacecoupling =
            MemoryManager<DNekMat>::AllocateSharedPtr(1, efRow, 0.0, storage);
        DNekMat &Svef = (*vertexedgefacecoupling);

        // Vertex-edge coupling
        for (n = 0; n < nedgemodesconnected; ++n)
        {
            // Matrix value for each coefficient location
            VertexEdgeFaceValue = (*r_bnd)(GetVertexMap(vid), edgemodearray[n]);

            // Set the value in the vertex edge/face matrix
            Svef.SetValue(0, n, VertexEdgeFaceValue);
        }

        // Vertex-face coupling
        for (n = 0; n < nfacemodesconnected; ++n)
        {
            // Matrix value for each coefficient location
            VertexEdgeFaceValue = (*r_bnd)(GetVertexMap(vid), facemodearray[n]);

            // Set the value in the vertex edge/face matrix
            Svef.SetValue(0, n + nedgemodesconnected, VertexEdgeFaceValue);
        }

        /*
         * Build the edge-face transform matrix: This matrix is
         * constructed from the submatrices corresponding to the couping
         * between the edges and faces on the attached faces/edges of a
         * vertex.
         */

        // Allocation of matrix to store edge/face-edge/face coupling
        DNekMatSharedPtr edgefacecoupling =
            MemoryManager<DNekMat>::AllocateSharedPtr(efRow, efRow, 0.0,
                                                      storage);
        DNekMat &Sefef = (*edgefacecoupling);

        NekDouble EdgeEdgeValue, FaceFaceValue;

        // Edge-edge coupling (S_{ee})
        for (m = 0; m < nedgemodesconnected; ++m)
        {
            for (n = 0; n < nedgemodesconnected; ++n)
            {
                // Matrix value for each coefficient location
                EdgeEdgeValue = (*r_bnd)(edgemodearray[n], edgemodearray[m]);

                // Set the value in the vertex edge/face matrix
                Sefef.SetValue(n, m, EdgeEdgeValue);
            }
        }

        // Face-face coupling (S_{ff})
        for (n = 0; n < nfacemodesconnected; ++n)
        {
            for (m = 0; m < nfacemodesconnected; ++m)
            {
                // Matrix value for each coefficient location
                FaceFaceValue = (*r_bnd)(facemodearray[n], facemodearray[m]);
                // Set the value in the vertex edge/face matrix
                Sefef.SetValue(nedgemodesconnected + n, nedgemodesconnected + m,
                               FaceFaceValue);
            }
        }

        // Edge-face coupling (S_{ef} and trans(S_{ef}))
        for (n = 0; n < nedgemodesconnected; ++n)
        {
            for (m = 0; m < nfacemodesconnected; ++m)
            {
                // Matrix value for each coefficient location
                FaceFaceValue = (*r_bnd)(edgemodearray[n], facemodearray[m]);

                // Set the value in the vertex edge/face matrix
                Sefef.SetValue(n, nedgemodesconnected + m, FaceFaceValue);

                FaceFaceValue = (*r_bnd)(facemodearray[m], edgemodearray[n]);

                // and transpose
                Sefef.SetValue(nedgemodesconnected + m, n, FaceFaceValue);
            }
        }

        // Invert edge-face coupling matrix
        if (efRow)
        {
            Sefef.Invert();

            // R_{v}=-S_{v,ef}inv(S_{ef,ef})
            Sveft = -Svef * Sefef;
        }

        // Populate R with R_{ve} components
        for (n = 0; n < edgemodearray.size(); ++n)
        {
            R.SetValue(GetVertexMap(vid), edgemodearray[n], Sveft(0, n));
        }

        // Populate R with R_{vf} components
        for (n = 0; n < facemodearray.size(); ++n)
        {
            R.SetValue(GetVertexMap(vid), facemodearray[n],
                       Sveft(0, n + nedgemodesconnected));
        }
    }

    /********************/
    /* edge-face matrix */
    /********************/

    /*
     * The matrix component of \f$\mathbf{R}\f$ is given by \f[
     * \mathbf{R^{T}_{ef}}=-\mathbf{S}^{-1}_{ff}\mathbf{S}^{T}_{ef}\f]
     *
     * For each edge extract the submatrices from statically condensed
     * matrix \f$\mathbf{S}\f$ corresponding to inner products of modes
     * on the two attached faces within themselves as well as the
     * coupling matrix between the two faces
     * (\f$\mathbf{S}_{ff}\f$). This matrix of face coupling is then
     * inverted and multiplied by the submatrices of corresponding to
     * the coupling between the edge and attached faces
     * (\f$\mathbf{S}_{ef}\f$).
     */

    NekDouble EdgeFaceValue, FaceFaceValue;
    int efCol, efRow, nedgemodes;

    // Number of attached faces is always 2
    nConnectedFaces = 2;

    // Location in the matrix
    MatEdgeLocation = Array<OneD, Array<OneD, unsigned int>>(nEdges);
    MatFaceLocation = Array<OneD, Array<OneD, unsigned int>>(nConnectedFaces);

    // Build the edge/face transform matrix: This matrix is constructed
    // from the submatrices corresponding to the couping between a
    // specific edge and the two attached faces.
    for (eid = 0; eid < nEdges; ++eid)
    {
        // Row and column size of the vertex-edge/face matrix
        efCol = GetTraceIntNcoeffs(geom->GetEdgeFaceMap(eid, 0)) +
                GetTraceIntNcoeffs(geom->GetEdgeFaceMap(eid, 1));
        efRow = GetEdgeNcoeffs(eid) - 2;

        // Edge-face coupling matrix
        DNekMatSharedPtr efedgefacecoupling =
            MemoryManager<DNekMat>::AllocateSharedPtr(efRow, efCol, 0.0,
                                                      storage);
        DNekMat &Mef = (*efedgefacecoupling);

        // Face-face coupling matrix
        DNekMatSharedPtr effacefacecoupling =
            MemoryManager<DNekMat>::AllocateSharedPtr(efCol, efCol, 0.0,
                                                      storage);
        DNekMat &Meff = (*effacefacecoupling);

        // Edge-face transformation matrix
        DNekMatSharedPtr edgefacetransformmatrix =
            MemoryManager<DNekMat>::AllocateSharedPtr(efRow, efCol, 0.0,
                                                      storage);
        DNekMat &Meft = (*edgefacetransformmatrix);

        int nfacemodesconnected =
            GetTraceIntNcoeffs(geom->GetEdgeFaceMap(eid, 0)) +
            GetTraceIntNcoeffs(geom->GetEdgeFaceMap(eid, 1));
        Array<OneD, unsigned int> facemodearray(nfacemodesconnected);

        // Create array of edge modes
        Array<OneD, unsigned int> inedgearray = GetEdgeInverseBoundaryMap(eid);
        nedgemodes                            = GetEdgeNcoeffs(eid) - 2;
        Array<OneD, unsigned int> edgemodearray(nedgemodes);

        if (nedgemodes)
        {
            Vmath::Vcopy(nedgemodes, &inedgearray[0], 1, &edgemodearray[0], 1);
        }

        int offset = 0;

        // Create array of face modes
        for (fid = 0; fid < nConnectedFaces; ++fid)
        {
            MatFaceLocation[fid] =
                GetTraceInverseBoundaryMap(geom->GetEdgeFaceMap(eid, fid));
            nmodes = MatFaceLocation[fid].size();

            if (nmodes)
            {
                Vmath::Vcopy(nmodes, &MatFaceLocation[fid][0], 1,
                             &facemodearray[offset], 1);
            }
            offset += nmodes;
        }

        // Edge-face coupling
        for (n = 0; n < nedgemodes; ++n)
        {
            for (m = 0; m < nfacemodesconnected; ++m)
            {
                // Matrix value for each coefficient location
                EdgeFaceValue = (*r_bnd)(edgemodearray[n], facemodearray[m]);

                // Set the value in the edge/face matrix
                Mef.SetValue(n, m, EdgeFaceValue);
            }
        }

        // Face-face coupling
        for (n = 0; n < nfacemodesconnected; ++n)
        {
            for (m = 0; m < nfacemodesconnected; ++m)
            {
                // Matrix value for each coefficient location
                FaceFaceValue = (*r_bnd)(facemodearray[n], facemodearray[m]);

                // Set the value in the vertex edge/face matrix
                Meff.SetValue(n, m, FaceFaceValue);
            }
        }

        if (efCol)
        {
            // Invert edge-face coupling matrix
            Meff.Invert();

            // trans(R_{ef})=-S_{ef}*(inv(S_{ff})
            Meft = -Mef * Meff;
        }

        // Populate transformation matrix with Meft
        for (n = 0; n < Meft.GetRows(); ++n)
        {
            for (m = 0; m < Meft.GetColumns(); ++m)
            {
                R.SetValue(edgemodearray[n], facemodearray[m], Meft(n, m));
            }
        }
    }

    for (i = 0; i < R.GetRows(); ++i)
    {
        R.SetValue(i, i, 1.0);
    }

    if ((matrixType == StdRegions::ePreconR) ||
        (matrixType == StdRegions::ePreconRMass))
    {
        return transformationmatrix;
    }
    else
    {
        NEKERROR(ErrorUtil::efatal, "unkown matrix type");
        return NullDNekMatSharedPtr;
    }
}

/**
 * \brief Build inverse and inverse transposed transformation matrix:
 * \f$\mathbf{R^{-1}}\f$ and \f$\mathbf{R^{-T}}\f$
 *
 * \f\mathbf{R^{-T}}=[\left[\begin{array}{ccc} \mathbf{I} &
 * -\mathbf{R}_{ef} & -\mathbf{R}_{ve}+\mathbf{R}_{ve}\mathbf{R}_{vf} \\
 *  0 & \mathbf{I} & \mathbf{R}_{ef} \\
 *  0 & 0 & \mathbf{I}} \end{array}\right]\f]
 */
DNekMatSharedPtr Expansion3D::v_BuildInverseTransformationMatrix(
    const DNekScalMatSharedPtr &transformationmatrix)
{
    int i, j, n, eid = 0, fid = 0;
    int nCoeffs = NumBndryCoeffs();
    NekDouble MatrixValue;
    DNekScalMat &R = (*transformationmatrix);

    // Define storage for vertex transpose matrix and zero all entries
    MatrixStorage storage = eFULL;

    // Inverse transformation matrix
    DNekMatSharedPtr inversetransformationmatrix =
        MemoryManager<DNekMat>::AllocateSharedPtr(nCoeffs, nCoeffs, 0.0,
                                                  storage);
    DNekMat &InvR = (*inversetransformationmatrix);

    int nVerts = GetNverts();
    int nEdges = GetNedges();
    int nFaces = GetNtraces();

    int nedgemodes      = 0;
    int nfacemodes      = 0;
    int nedgemodestotal = 0;
    int nfacemodestotal = 0;

    for (eid = 0; eid < nEdges; ++eid)
    {
        nedgemodes = GetEdgeNcoeffs(eid) - 2;
        nedgemodestotal += nedgemodes;
    }

    for (fid = 0; fid < nFaces; ++fid)
    {
        nfacemodes = GetTraceIntNcoeffs(fid);
        nfacemodestotal += nfacemodes;
    }

    Array<OneD, unsigned int> edgemodearray(nedgemodestotal);
    Array<OneD, unsigned int> facemodearray(nfacemodestotal);

    int offset = 0;

    // Create array of edge modes
    for (eid = 0; eid < nEdges; ++eid)
    {
        Array<OneD, unsigned int> edgearray = GetEdgeInverseBoundaryMap(eid);
        nedgemodes                          = GetEdgeNcoeffs(eid) - 2;

        // Only copy if there are edge modes
        if (nedgemodes)
        {
            Vmath::Vcopy(nedgemodes, &edgearray[0], 1, &edgemodearray[offset],
                         1);
        }

        offset += nedgemodes;
    }

    offset = 0;

    // Create array of face modes
    for (fid = 0; fid < nFaces; ++fid)
    {
        Array<OneD, unsigned int> facearray = GetTraceInverseBoundaryMap(fid);
        nfacemodes                          = GetTraceIntNcoeffs(fid);

        // Only copy if there are face modes
        if (nfacemodes)
        {
            Vmath::Vcopy(nfacemodes, &facearray[0], 1, &facemodearray[offset],
                         1);
        }

        offset += nfacemodes;
    }

    // Vertex-edge/face
    for (i = 0; i < nVerts; ++i)
    {
        for (j = 0; j < nedgemodestotal; ++j)
        {
            InvR.SetValue(GetVertexMap(i), edgemodearray[j],
                          -R(GetVertexMap(i), edgemodearray[j]));
        }
        for (j = 0; j < nfacemodestotal; ++j)
        {
            InvR.SetValue(GetVertexMap(i), facemodearray[j],
                          -R(GetVertexMap(i), facemodearray[j]));
            for (n = 0; n < nedgemodestotal; ++n)
            {
                MatrixValue = InvR.GetValue(GetVertexMap(i), facemodearray[j]) +
                              R(GetVertexMap(i), edgemodearray[n]) *
                                  R(edgemodearray[n], facemodearray[j]);
                InvR.SetValue(GetVertexMap(i), facemodearray[j], MatrixValue);
            }
        }
    }

    // Edge-face contributions
    for (i = 0; i < nedgemodestotal; ++i)
    {
        for (j = 0; j < nfacemodestotal; ++j)
        {
            InvR.SetValue(edgemodearray[i], facemodearray[j],
                          -R(edgemodearray[i], facemodearray[j]));
        }
    }

    for (i = 0; i < nCoeffs; ++i)
    {
        InvR.SetValue(i, i, 1.0);
    }

    return inversetransformationmatrix;
}

Array<OneD, unsigned int> Expansion3D::GetEdgeInverseBoundaryMap(int eid)
{
    int n, j;
    int nEdgeCoeffs;
    int nBndCoeffs = NumBndryCoeffs();

    Array<OneD, unsigned int> bmap(nBndCoeffs);
    GetBoundaryMap(bmap);

    // Map from full system to statically condensed system (i.e reverse
    // GetBoundaryMap)
    map<int, int> invmap;
    for (j = 0; j < nBndCoeffs; ++j)
    {
        invmap[bmap[j]] = j;
    }

    // Number of interior edge coefficients
    nEdgeCoeffs = GetEdgeNcoeffs(eid) - 2;

    const SpatialDomains::Geometry3DSharedPtr &geom = GetGeom3D();

    Array<OneD, unsigned int> edgemaparray(nEdgeCoeffs);
    StdRegions::Orientation eOrient    = geom->GetEorient(eid);
    Array<OneD, unsigned int> maparray = Array<OneD, unsigned int>(nEdgeCoeffs);
    Array<OneD, int> signarray         = Array<OneD, int>(nEdgeCoeffs, 1);

    // maparray is the location of the edge within the matrix
    GetEdgeInteriorToElementMap(eid, maparray, signarray, eOrient);

    for (n = 0; n < nEdgeCoeffs; ++n)
    {
        edgemaparray[n] = invmap[maparray[n]];
    }

    return edgemaparray;
}

Array<OneD, unsigned int> Expansion3D::GetTraceInverseBoundaryMap(
    int fid, StdRegions::Orientation faceOrient, int P1, int P2)
{
    int n, j;
    int nFaceCoeffs;

    int nBndCoeffs = NumBndryCoeffs();

    Array<OneD, unsigned int> bmap(nBndCoeffs);
    GetBoundaryMap(bmap);

    // Map from full system to statically condensed system (i.e reverse
    // GetBoundaryMap)
    map<int, int> reversemap;
    for (j = 0; j < bmap.size(); ++j)
    {
        reversemap[bmap[j]] = j;
    }

    // Number of interior face coefficients
    nFaceCoeffs = GetTraceIntNcoeffs(fid);

    StdRegions::Orientation fOrient;
    Array<OneD, unsigned int> maparray = Array<OneD, unsigned int>(nFaceCoeffs);
    Array<OneD, int> signarray         = Array<OneD, int>(nFaceCoeffs, 1);

    if (faceOrient == StdRegions::eNoOrientation)
    {
        fOrient = GetTraceOrient(fid);
    }
    else
    {
        fOrient = faceOrient;
    }

    // maparray is the location of the face within the matrix
    GetTraceInteriorToElementMap(fid, maparray, signarray, fOrient);

    Array<OneD, unsigned int> facemaparray;
    int locP1, locP2;
    GetTraceNumModes(fid, locP1, locP2, fOrient);

    if (P1 == -1)
    {
        P1 = locP1;
    }
    else
    {
        ASSERTL1(P1 <= locP1, "Expect value of passed P1 to "
                              "be lower or equal to face num modes");
    }

    if (P2 == -1)
    {
        P2 = locP2;
    }
    else
    {
        ASSERTL1(P2 <= locP2, "Expect value of passed P2 to "
                              "be lower or equal to face num modes");
    }

    switch (GetGeom3D()->GetFace(fid)->GetShapeType())
    {
        case LibUtilities::eTriangle:
        {
            if (((P1 - 3) > 0) && ((P2 - 3) > 0))
            {
                facemaparray = Array<OneD, unsigned int>(
                    LibUtilities::StdTriData::getNumberOfCoefficients(P1 - 3,
                                                                      P2 - 3));
                int cnt  = 0;
                int cnt1 = 0;
                for (n = 0; n < P1 - 3; ++n)
                {
                    for (int m = 0; m < P2 - 3 - n; ++m, ++cnt)
                    {
                        facemaparray[cnt] = reversemap[maparray[cnt1 + m]];
                    }
                    cnt1 += locP2 - 3 - n;
                }
            }
        }
        break;
        case LibUtilities::eQuadrilateral:
        {
            if (((P1 - 2) > 0) && ((P2 - 2) > 0))
            {
                facemaparray = Array<OneD, unsigned int>(
                    LibUtilities::StdQuadData::getNumberOfCoefficients(P1 - 2,
                                                                       P2 - 2));
                int cnt  = 0;
                int cnt1 = 0;
                for (n = 0; n < P2 - 2; ++n)
                {
                    for (int m = 0; m < P1 - 2; ++m, ++cnt)
                    {
                        facemaparray[cnt] = reversemap[maparray[cnt1 + m]];
                    }
                    cnt1 += locP1 - 2;
                }
            }
        }
        break;
        default:
        {
            ASSERTL0(false, "Invalid shape type.");
        }
        break;
    }

    return facemaparray;
}

void Expansion3D::GetInverseBoundaryMaps(
    Array<OneD, unsigned int> &vmap,
    Array<OneD, Array<OneD, unsigned int>> &emap,
    Array<OneD, Array<OneD, unsigned int>> &fmap)
{
    int n, j;
    int nEdgeCoeffs;
    int nFaceCoeffs;

    int nBndCoeffs = NumBndryCoeffs();

    Array<OneD, unsigned int> bmap(nBndCoeffs);
    GetBoundaryMap(bmap);

    // Map from full system to statically condensed system (i.e reverse
    // GetBoundaryMap)
    map<int, int> reversemap;
    for (j = 0; j < bmap.size(); ++j)
    {
        reversemap[bmap[j]] = j;
    }

    int nverts = GetNverts();
    vmap       = Array<OneD, unsigned int>(nverts);
    for (n = 0; n < nverts; ++n)
    {
        int id  = GetVertexMap(n);
        vmap[n] = reversemap[id]; // not sure what should be true here.
    }

    int nedges = GetNedges();
    emap       = Array<OneD, Array<OneD, unsigned int>>(nedges);

    for (int eid = 0; eid < nedges; ++eid)
    {
        // Number of interior edge coefficients
        nEdgeCoeffs = GetEdgeNcoeffs(eid) - 2;

        Array<OneD, unsigned int> edgemaparray(nEdgeCoeffs);
        Array<OneD, unsigned int> maparray =
            Array<OneD, unsigned int>(nEdgeCoeffs);
        Array<OneD, int> signarray = Array<OneD, int>(nEdgeCoeffs, 1);

        // maparray is the location of the edge within the matrix
        GetEdgeInteriorToElementMap(eid, maparray, signarray,
                                    StdRegions::eForwards);

        for (n = 0; n < nEdgeCoeffs; ++n)
        {
            edgemaparray[n] = reversemap[maparray[n]];
        }
        emap[eid] = edgemaparray;
    }

    int nfaces = GetNtraces();
    fmap       = Array<OneD, Array<OneD, unsigned int>>(nfaces);

    for (int fid = 0; fid < nfaces; ++fid)
    {
        // Number of interior face coefficients
        nFaceCoeffs = GetTraceIntNcoeffs(fid);

        Array<OneD, unsigned int> facemaparray(nFaceCoeffs);
        Array<OneD, unsigned int> maparray =
            Array<OneD, unsigned int>(nFaceCoeffs);
        Array<OneD, int> signarray = Array<OneD, int>(nFaceCoeffs, 1);

        // maparray is the location of the face within the matrix
        GetTraceInteriorToElementMap(fid, maparray, signarray,
                                     StdRegions::eDir1FwdDir1_Dir2FwdDir2);

        for (n = 0; n < nFaceCoeffs; ++n)
        {
            facemaparray[n] = reversemap[maparray[n]];
        }

        fmap[fid] = facemaparray;
    }
}

StdRegions::Orientation Expansion3D::v_GetTraceOrient(int face)
{
    return m_geom->GetForient(face);
}

/**
 * @brief Extract the physical values along face \a face from \a
 * inarray into \a outarray following the local face orientation
 * and point distribution defined by defined in \a FaceExp.
 */
void Expansion3D::v_GetTracePhysVals(
    const int face, const StdRegions::StdExpansionSharedPtr &FaceExp,
    const Array<OneD, const NekDouble> &inarray,
    Array<OneD, NekDouble> &outarray, StdRegions::Orientation orient)
{
    if (orient == StdRegions::eNoOrientation)
    {
        orient = GetTraceOrient(face);
    }

    int nq0 = FaceExp->GetNumPoints(0);
    int nq1 = FaceExp->GetNumPoints(1);

    int nfacepts = GetTraceNumPoints(face);
    int dir0     = GetGeom3D()->GetDir(face, 0);
    int dir1     = GetGeom3D()->GetDir(face, 1);

    Array<OneD, NekDouble> o_tmp(nfacepts);
    Array<OneD, NekDouble> o_tmp2(FaceExp->GetTotPoints());
    Array<OneD, int> faceids;

    // Get local face pts and put into o_tmp
    GetTracePhysMap(face, faceids);
    // The static cast is necessary because faceids should be
    // Array<OneD, size_t> faceids ... or at leaste the same type as
    // faceids.size() ...
    Vmath::Gathr(static_cast<int>(faceids.size()), inarray, faceids, o_tmp);

    int to_id0, to_id1;

    if (orient < StdRegions::eDir1FwdDir2_Dir2FwdDir1)
    {
        to_id0 = 0;
        to_id1 = 1;
    }
    else // transpose points key evaluation
    {
        to_id0 = 1;
        to_id1 = 0;
    }

    // interpolate to points distrbution given in FaceExp
    LibUtilities::Interp2D(
        m_base[dir0]->GetPointsKey(), m_base[dir1]->GetPointsKey(),
        o_tmp.data(), FaceExp->GetBasis(to_id0)->GetPointsKey(),
        FaceExp->GetBasis(to_id1)->GetPointsKey(), o_tmp2.data());

    // Reshuffule points as required and put into outarray.
    v_ReOrientTracePhysMap(orient, faceids, nq0, nq1);
    Vmath::Scatr(nq0 * nq1, o_tmp2, faceids, outarray);
}

void Expansion3D::v_GenTraceExp(const int traceid, ExpansionSharedPtr &exp)
{
    SpatialDomains::GeometrySharedPtr faceGeom = m_geom->GetFace(traceid);
    if (faceGeom->GetNumVerts() == 3)
    {
        exp = MemoryManager<LocalRegions::TriExp>::AllocateSharedPtr(
            GetTraceBasisKey(traceid, 0), GetTraceBasisKey(traceid, 1),
            m_geom->GetFace(traceid));
    }
    else
    {
        exp = MemoryManager<LocalRegions::QuadExp>::AllocateSharedPtr(
            GetTraceBasisKey(traceid, 0), GetTraceBasisKey(traceid, 1),
            m_geom->GetFace(traceid));
    }
}

void Expansion3D::v_ReOrientTracePhysMap(const StdRegions::Orientation orient,
                                         Array<OneD, int> &idmap, const int nq0,
                                         const int nq1)
{

    if (idmap.size() != nq0 * nq1)
    {
        idmap = Array<OneD, int>(nq0 * nq1);
    }

    if (GetNverts() == 3) // Tri face
    {
        switch (orient)
        {
            case StdRegions::eDir1FwdDir1_Dir2FwdDir2:
                // eseentially straight copy
                for (int i = 0; i < nq0 * nq1; ++i)
                {
                    idmap[i] = i;
                }
                break;
            case StdRegions::eDir1BwdDir1_Dir2FwdDir2:
                // reverse
                for (int j = 0; j < nq1; ++j)
                {
                    for (int i = 0; i < nq0; ++i)
                    {
                        idmap[j * nq0 + i] = nq0 - 1 - i + j * nq0;
                    }
                }
                break;
            default:
                ASSERTL0(false,
                         "Case not supposed to be used in this function");
        }
    }
    else
    {
        switch (orient)
        {
            case StdRegions::eDir1FwdDir1_Dir2FwdDir2:
                // eseentially straight copy
                for (int i = 0; i < nq0 * nq1; ++i)
                {
                    idmap[i] = i;
                }
                break;
            case StdRegions::eDir1BwdDir1_Dir2FwdDir2:
            {
                // Direction A negative and B positive
                for (int j = 0; j < nq1; j++)
                {
                    for (int i = 0; i < nq0; ++i)
                    {
                        idmap[j * nq0 + i] = nq0 - 1 - i + j * nq0;
                    }
                }
            }
            break;
            case StdRegions::eDir1FwdDir1_Dir2BwdDir2:
            {
                // Direction A positive and B negative
                for (int j = 0; j < nq1; j++)
                {
                    for (int i = 0; i < nq0; ++i)
                    {
                        idmap[j * nq0 + i] = nq0 * (nq1 - 1 - j) + i;
                    }
                }
            }
            break;
            case StdRegions::eDir1BwdDir1_Dir2BwdDir2:
            {
                // Direction A negative and B negative
                for (int j = 0; j < nq1; j++)
                {
                    for (int i = 0; i < nq0; ++i)
                    {
                        idmap[j * nq0 + i] = nq0 * nq1 - 1 - j * nq0 - i;
                    }
                }
            }
            break;
            case StdRegions::eDir1FwdDir2_Dir2FwdDir1:
            {
                // Transposed, Direction A and B positive
                for (int i = 0; i < nq0; ++i)
                {
                    for (int j = 0; j < nq1; ++j)
                    {
                        idmap[i * nq1 + j] = i + j * nq0;
                    }
                }
            }
            break;
            case StdRegions::eDir1FwdDir2_Dir2BwdDir1:
            {
                // Transposed, Direction A positive and B negative
                for (int i = 0; i < nq0; ++i)
                {
                    for (int j = 0; j < nq1; ++j)
                    {
                        idmap[i * nq1 + j] = nq0 - 1 - i + j * nq0;
                    }
                }
            }
            break;
            case StdRegions::eDir1BwdDir2_Dir2FwdDir1:
            {
                // Transposed, Direction A negative and B positive
                for (int i = 0; i < nq0; ++i)
                {
                    for (int j = 0; j < nq1; ++j)
                    {
                        idmap[i * nq1 + j] = i + nq0 * (nq1 - 1) - j * nq0;
                    }
                }
            }
            break;
            case StdRegions::eDir1BwdDir2_Dir2BwdDir1:
            {
                // Transposed, Direction A and B negative
                for (int i = 0; i < nq0; ++i)
                {
                    for (int j = 0; j < nq1; ++j)
                    {
                        idmap[i * nq1 + j] = nq0 * nq1 - 1 - i - j * nq0;
                    }
                }
            }
            break;
            default:
                ASSERTL0(false, "Unknow orientation");
                break;
        }
    }
}

void Expansion3D::v_NormVectorIProductWRTBase(
    const Array<OneD, const Array<OneD, NekDouble>> &Fvec,
    Array<OneD, NekDouble> &outarray)
{
    NormVectorIProductWRTBase(Fvec[0], Fvec[1], Fvec[2], outarray);
}

// Compute edgenormal \cdot vector
Array<OneD, NekDouble> Expansion3D::GetnFacecdotMF(
    const int dir, const int face, ExpansionSharedPtr &FaceExp_f,
    const Array<OneD, const Array<OneD, NekDouble>> &normals,
    const StdRegions::VarCoeffMap &varcoeffs)
{
    int nquad_f = FaceExp_f->GetNumPoints(0) * FaceExp_f->GetNumPoints(1);
    int coordim = GetCoordim();

    int nquad0 = m_base[0]->GetNumPoints();
    int nquad1 = m_base[1]->GetNumPoints();
    int nquad2 = m_base[2]->GetNumPoints();
    int nqtot  = nquad0 * nquad1 * nquad2;

    StdRegions::VarCoeffType MMFCoeffs[15] = {
        StdRegions::eVarCoeffMF1x,   StdRegions::eVarCoeffMF1y,
        StdRegions::eVarCoeffMF1z,   StdRegions::eVarCoeffMF1Div,
        StdRegions::eVarCoeffMF1Mag, StdRegions::eVarCoeffMF2x,
        StdRegions::eVarCoeffMF2y,   StdRegions::eVarCoeffMF2z,
        StdRegions::eVarCoeffMF2Div, StdRegions::eVarCoeffMF2Mag,
        StdRegions::eVarCoeffMF3x,   StdRegions::eVarCoeffMF3y,
        StdRegions::eVarCoeffMF3z,   StdRegions::eVarCoeffMF3Div,
        StdRegions::eVarCoeffMF3Mag};

    StdRegions::VarCoeffMap::const_iterator MFdir;

    Array<OneD, NekDouble> nFacecdotMF(nqtot, 0.0);
    Array<OneD, NekDouble> tmp(nqtot);
    Array<OneD, NekDouble> tmp_f(nquad_f);
    for (int k = 0; k < coordim; k++)
    {
        MFdir = varcoeffs.find(MMFCoeffs[dir * 5 + k]);
        tmp   = MFdir->second.GetValue();

        GetPhysFaceVarCoeffsFromElement(face, FaceExp_f, tmp, tmp_f);

        Vmath::Vvtvp(nquad_f, &tmp_f[0], 1, &normals[k][0], 1, &nFacecdotMF[0],
                     1, &nFacecdotMF[0], 1);
    }

    return nFacecdotMF;
}

void Expansion3D::v_TraceNormLen(const int traceid, NekDouble &h, NekDouble &p)
{
    SpatialDomains::GeometrySharedPtr geom = GetGeom();

    int nverts = geom->GetFace(traceid)->GetNumVerts();

    SpatialDomains::PointGeom tn1, tn2, normal;
    tn1.Sub(*(geom->GetFace(traceid)->GetVertex(1)),
            *(geom->GetFace(traceid)->GetVertex(0)));

    tn2.Sub(*(geom->GetFace(traceid)->GetVertex(nverts - 1)),
            *(geom->GetFace(traceid)->GetVertex(0)));

    normal.Mult(tn1, tn2);

    // normalise normal
    NekDouble mag = normal.dot(normal);
    mag           = 1.0 / sqrt(mag);
    normal.UpdatePosition(normal.x() * mag, normal.y() * mag, normal.z() * mag);

    SpatialDomains::PointGeom Dx;
    h = 0.0;
    p = 0.0;
    for (int i = 0; i < nverts; ++i)
    {
        // vertices on edges
        int edgid = geom->GetEdgeNormalToFaceVert(traceid, i);

        // vector along noramal edge to each vertex
        Dx.Sub(*(geom->GetEdge(edgid)->GetVertex(0)),
               *(geom->GetEdge(edgid)->GetVertex(1)));

        // calculate perpendicular distance of normal length
        // from first vertex
        h += fabs(normal.dot(Dx));
    }

    h /= static_cast<NekDouble>(nverts);

    // find normal basis direction
    int dir0 = geom->GetDir(traceid, 0);
    int dir1 = geom->GetDir(traceid, 1);
    int dirn;
    for (dirn = 0; dirn < 3; ++dirn)
    {
        if ((dirn != dir0) && (dirn != dir1))
        {
            break;
        }
    }
    p = (NekDouble)(GetBasisNumModes(dirn) - 1);
}
} // namespace Nektar::LocalRegions
