Actual source code: ex149.c

  1: static char help[] = "This program illustrates the use of PETSc-fftw interface for real DFT\n";
  2: #include <petscmat.h>
  3: #include <fftw3-mpi.h>

  5: extern PetscErrorCode InputTransformFFT(Mat, Vec, Vec);
  6: extern PetscErrorCode OutputTransformFFT(Mat, Vec, Vec);
  7: int                   main(int argc, char **args)
  8: {
  9:   PetscMPIInt rank, size;
 10:   PetscInt    N0 = 3, N1 = 3, N2 = 3, N = N0 * N1 * N2;
 11:   PetscRandom rdm;
 12:   PetscScalar a;
 13:   PetscReal   enorm;
 14:   Vec         x, y, z, input, output;
 15:   PetscBool   view = PETSC_FALSE, use_interface = PETSC_TRUE;
 16:   Mat         A;
 17:   PetscInt    DIM, dim[3], vsize;
 18:   PetscReal   fac;

 20:   PetscFunctionBeginUser;
 21:   PetscCall(PetscInitialize(&argc, &args, NULL, help));
 22:   PetscCheck(!PetscDefined(USE_COMPLEX), PETSC_COMM_WORLD, PETSC_ERR_SUP, "This example requires real numbers");

 24:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
 25:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));

 27:   PetscCall(PetscRandomCreate(PETSC_COMM_WORLD, &rdm));
 28:   PetscCall(PetscRandomSetFromOptions(rdm));

 30:   PetscCall(VecCreate(PETSC_COMM_WORLD, &input));
 31:   PetscCall(VecSetSizes(input, PETSC_DECIDE, N));
 32:   PetscCall(VecSetFromOptions(input));
 33:   PetscCall(VecSetRandom(input, rdm));
 34:   PetscCall(VecDuplicate(input, &output));
 35:   /*  PetscCall(VecGetSize(input,&vsize)); */
 36:   /*  printf("Size of the input Vector is %d\n",vsize); */

 38:   DIM    = 3;
 39:   dim[0] = N0;
 40:   dim[1] = N1;
 41:   dim[2] = N2;

 43:   PetscCall(MatCreateFFT(PETSC_COMM_WORLD, DIM, dim, MATFFTW, &A));
 44:   PetscCall(MatCreateVecs(A, &x, &y));
 45:   PetscCall(MatCreateVecs(A, &z, NULL));
 46:   PetscCall(VecGetSize(y, &vsize));
 47:   printf("The vector size from the main routine is %d\n", vsize);

 49:   PetscCall(InputTransformFFT(A, input, x));
 50:   PetscCall(MatMult(A, x, y));
 51:   PetscCall(MatMultTranspose(A, y, z));
 52:   PetscCall(OutputTransformFFT(A, z, output));

 54:   fac = 1.0 / (PetscReal)N;
 55:   PetscCall(VecScale(output, fac));

 57:   PetscCall(VecAssemblyBegin(input));
 58:   PetscCall(VecAssemblyEnd(input));
 59:   PetscCall(VecAssemblyBegin(output));
 60:   PetscCall(VecAssemblyEnd(output));

 62:   PetscCall(VecView(input, PETSC_VIEWER_STDOUT_WORLD));
 63:   PetscCall(VecView(output, PETSC_VIEWER_STDOUT_WORLD));

 65:   PetscCall(VecAXPY(output, -1.0, input));
 66:   PetscCall(VecNorm(output, NORM_1, &enorm));
 67:   /*  if (enorm > 1.e-14) { */
 68:   if (rank == 0) PetscCall(PetscPrintf(PETSC_COMM_SELF, "  Error norm of |x - z| %e\n", enorm));
 69:   /*      } */

 71:   /* PetscCall(MatCreateVecs(A,&z,NULL)); */
 72:   /*  printf("Vector size from ex148 %d\n",vsize); */
 73:   /*  PetscCall(PetscObjectSetName((PetscObject) x, "Real space vector")); */
 74:   /*      PetscCall(PetscObjectSetName((PetscObject) y, "Frequency space vector")); */
 75:   /*      PetscCall(PetscObjectSetName((PetscObject) z, "Reconstructed vector")); */

 77:   PetscCall(PetscFinalize());
 78:   return 0;
 79: }