text: // Copyright (c) 2017-2018, Lawrence Livermore National Security, LLC.
  // Produced at the Lawrence Livermore National Laboratory. LLNL-CODE-734707.
  // All Rights reserved. See files LICENSE and NOTICE for details.
  //
  // This file is part of CEED, a collection of benchmarks, miniapps, software
  // libraries and APIs for efficient high-order finite element and spectral
  // element discretizations for exascale applications. For more information and
  // source code availability see http://github.com/ceed.
  //
  // The CEED research is supported by the Exascale Computing Project 17-SC-20-SC,
  // a collaborative effort of two U.S. Department of Energy organizations (Office
  // of Science and the National Nuclear Security Administration) responsible for
  // the planning and preparation of a capable exascale ecosystem, including
  // software, applications, hardware, advanced system engineering and early
  // testbed platforms, in support of the nation's exascale computing imperative.
  
  /// A structure used to pass additional data to f_build_mass
  struct BuildContext { CeedInt dim, space_dim; };
  
  /// libCEED Q-function for building quadrature data for a mass operator
  CEED_QFUNCTION(f_build_mass)(void *ctx, const CeedInt Q,
                               const CeedScalar *const *in, CeedScalar *const *out) {
    // in[0] is Jacobians with shape [dim, nc=dim, Q]
    // in[1] is quadrature weights, size (Q)
    BuildContext *bc = (BuildContext *)ctx;
    const CeedScalar *J = in[0], *w = in[1];
    CeedScalar *qdata = out[0];
  
    switch (bc->dim + 10*bc->space_dim) {
    case 11:
      // Quadrature Point Loop
      CeedPragmaSIMD
      for (CeedInt i=0; i<Q; i++) {
        qdata[i] = J[i] * w[i];
      }
      break;
    case 22:
      // Quadrature Point Loop
      CeedPragmaSIMD
      for (CeedInt i=0; i<Q; i++) {
        // 0 2
        // 1 3
        qdata[i] = (J[i+Q*0]*J[i+Q*3] - J[i+Q*1]*J[i+Q*2]) * w[i];
      }
      break;
    case 33:
      // Quadrature Point Loop
      CeedPragmaSIMD
      for (CeedInt i=0; i<Q; i++) {
        // 0 3 6
        // 1 4 7
        // 2 5 8
        qdata[i] = (J[i+Q*0]*(J[i+Q*4]*J[i+Q*8] - J[i+Q*5]*J[i+Q*7]) -
                    J[i+Q*1]*(J[i+Q*3]*J[i+Q*8] - J[i+Q*5]*J[i+Q*6]) +
                    J[i+Q*2]*(J[i+Q*3]*J[i+Q*7] - J[i+Q*4]*J[i+Q*6])) * w[i];
      }
      break;
    }
    return 0;
  }
  
  /// libCEED Q-function for applying a mass operator
  CEED_QFUNCTION(f_apply_mass)(void *ctx, const CeedInt Q,
                               const CeedScalar *const *in, CeedScalar *const *out) {
    const CeedScalar *u = in[0], *qdata = in[1];
    CeedScalar *v = out[0];
  
    // Quadrature Point Loop
    CeedPragmaSIMD
    for (CeedInt i=0; i<Q; i++) {
      v[i] = qdata[i] * u[i];
    }
    return 0;
  }
  