Actual source code: ex150.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, N3 = 3, N4 = 3, N = N0 * N1 * N2 * N3;
 11:   PetscRandom rdm;
 12:   PetscReal   enorm;
 13:   Vec         x, y, z, input, output;
 14:   Mat         A;
 15:   PetscInt    DIM, dim[5], vsize;
 16:   PetscReal   fac;
 17:   PetscScalar one = 1;

 19:   PetscFunctionBeginUser;
 20:   PetscCall(PetscInitialize(&argc, &args, NULL, help));
 21: #if defined(PETSC_USE_COMPLEX)
 22:   SETERRQ(PETSC_COMM_WORLD, PETSC_ERR_SUP, "This example requires real numbers");
 23: #endif

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

 28:   PetscCall(PetscRandomCreate(PETSC_COMM_WORLD, &rdm));
 29:   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(VecAssemblyBegin(input));
 35:   PetscCall(VecAssemblyEnd(input));
 36:   /*  PetscCall(VecView(input,PETSC_VIEWER_STDOUT_WORLD)); */
 37:   PetscCall(VecDuplicate(input, &output));

 39:   DIM    = 4;
 40:   dim[0] = N0;
 41:   dim[1] = N1;
 42:   dim[2] = N2;
 43:   dim[3] = N3;
 44:   dim[4] = N4;

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

 52:   PetscCall(InputTransformFFT(A, input, x));

 54:   PetscCall(MatMult(A, x, y));
 55:   PetscCall(VecAssemblyBegin(y));
 56:   PetscCall(VecAssemblyEnd(y));
 57:   PetscCall(VecView(y, PETSC_VIEWER_STDOUT_WORLD));
 58:   PetscCall(MatMultTranspose(A, y, z));
 59:   PetscCall(VecGetSize(z, &vsize));
 60:   printf("The vector size of zfrom the main routine is %d\n", vsize);

 62:   PetscCall(OutputTransformFFT(A, z, output));

 64:   fac = 1.0 / (PetscReal)N;
 65:   PetscCall(VecScale(output, fac));

 67:   PetscCall(VecAssemblyBegin(input));
 68:   PetscCall(VecAssemblyEnd(input));
 69:   PetscCall(VecAssemblyBegin(output));
 70:   PetscCall(VecAssemblyEnd(output));

 72:   PetscCall(VecView(input, PETSC_VIEWER_STDOUT_WORLD));
 73:   PetscCall(VecView(output, PETSC_VIEWER_STDOUT_WORLD));

 75:   PetscCall(VecAXPY(output, -1.0, input));
 76:   PetscCall(VecNorm(output, NORM_1, &enorm));
 77:   /*  if (enorm > 1.e-14) { */
 78:   if (rank == 0) PetscCall(PetscPrintf(PETSC_COMM_SELF, "  Error norm of |x - z| %e\n", enorm));
 79:   /*      } */

 81:   /* PetscCall(MatCreateVecs(A,&z,NULL)); */
 82:   /*  printf("Vector size from ex148 %d\n",vsize); */
 83:   /*  PetscCall(PetscObjectSetName((PetscObject) x, "Real space vector")); */
 84:   /*      PetscCall(PetscObjectSetName((PetscObject) y, "Frequency space vector")); */
 85:   /*      PetscCall(PetscObjectSetName((PetscObject) z, "Reconstructed vector")); */

 87:   PetscCall(VecDestroy(&output));
 88:   PetscCall(VecDestroy(&input));
 89:   PetscCall(VecDestroy(&x));
 90:   PetscCall(VecDestroy(&y));
 91:   PetscCall(VecDestroy(&z));
 92:   PetscCall(MatDestroy(&A));
 93:   PetscCall(PetscRandomDestroy(&rdm));
 94:   PetscCall(PetscFinalize());
 95:   return 0;
 96: }