xref: /libCEED/tests/t321-basis.c (revision 2b730f8b5a9c809740a0b3b302db43a719c636b1)

/// @file
/// Test interpolation with a 2D Simplex non-tensor H1 basis
/// \test Test interpolaton with a 2D Simplex non-tensor H1 basis
#include <ceed.h>
#include <math.h>

#include "t320-basis.h"

// polynomial eval helper
static CeedScalar feval(CeedScalar x1, CeedScalar x2) { return x1 * x1 + x2 * x2 + x1 * x2 + 1; }

// main test
int main(int argc, char **argv) {
  Ceed              ceed;
  CeedVector        In, Out;
  const CeedInt     P = 6, Q = 4, dim = 2;
  CeedBasis         b;
  CeedScalar        q_ref[dim * Q], q_weight[Q];
  CeedScalar        interp[P * Q], grad[dim * P * Q];
  CeedScalar        xq[] = {0.2, 0.6, 1. / 3., 0.2, 0.2, 0.2, 1. / 3., 0.6};
  CeedScalar        xr[] = {0., 0.5, 1., 0., 0.5, 0., 0., 0., 0., 0.5, 0.5, 1.};
  const CeedScalar *out;
  CeedScalar        in[P], value;

  buildmats(q_ref, q_weight, interp, grad);

  CeedInit(argv[1], &ceed);

  CeedBasisCreateH1(ceed, CEED_TOPOLOGY_TRIANGLE, 1, P, Q, interp, grad, q_ref, q_weight, &b);

  // Interpolate function to quadrature points
  for (int i = 0; i < P; i++) in[i] = feval(xr[0 * P + i], xr[1 * P + i]);

  CeedVectorCreate(ceed, P, &In);
  CeedVectorSetArray(In, CEED_MEM_HOST, CEED_USE_POINTER, in);
  CeedVectorCreate(ceed, Q, &Out);
  CeedVectorSetValue(Out, 0);

  CeedBasisApply(b, 1, CEED_NOTRANSPOSE, CEED_EVAL_INTERP, In, Out);

  // Check values at quadrature points
  CeedVectorGetArrayRead(Out, CEED_MEM_HOST, &out);
  for (int i = 0; i < Q; i++) {
    value = feval(xq[0 * Q + i], xq[1 * Q + i]);
    if (fabs(out[i] - value) > 100. * CEED_EPSILON) printf("[%" CeedInt_FMT "] %f != %f\n", i, out[i], value);
  }
  CeedVectorRestoreArrayRead(Out, &out);

  CeedVectorDestroy(&In);
  CeedVectorDestroy(&Out);
  CeedBasisDestroy(&b);
  CeedDestroy(&ceed);
  return 0;
}