1: static char help[] = "This program illustrates the use of PETSc-fftw interface for parallel real DFT\n";
  2: #include <petscmat.h>
  3: #include <fftw3-mpi.h>
  4: /*extern PetscErrorCode MatCreateVecsFFT(Mat,Vec *,Vec *,Vec *);*/
  5: int main(int argc, char **args)
  6: {
  7:   PetscMPIInt rank, size;
  8:   PetscInt    N0 = 4096, N1 = 4096, N2 = 256, N3 = 10, N4 = 10, N = N0 * N1;
  9:   PetscRandom rdm;
 10:   PetscReal   enorm;
 11:   Vec         x, y, z, input, output;
 12:   Mat         A;
 13:   PetscInt    DIM, dim[5], vsize, row, col;
 14:   PetscReal   fac;

 16:   PetscFunctionBeginUser;
 17:   PetscCall(PetscInitialize(&argc, &args, NULL, help));
 18:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
 19:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));

 21:   PetscCheck(!PetscDefined(USE_COMPLEX), PETSC_COMM_WORLD, PETSC_ERR_SUP, "Example for Real DFT. Your current data type is complex!");
 22:   PetscCall(PetscRandomCreate(PETSC_COMM_WORLD, &rdm));
 23:   PetscCall(PetscRandomSetFromOptions(rdm));
 24:   PetscCall(VecCreate(PETSC_COMM_WORLD, &input));
 25:   PetscCall(VecSetSizes(input, PETSC_DECIDE, N));
 26:   PetscCall(VecSetFromOptions(input));
 27:   PetscCall(VecSetRandom(input, rdm));
 28:   PetscCall(VecDuplicate(input, &output));

 30:   DIM    = 2;
 31:   dim[0] = N0;
 32:   dim[1] = N1;
 33:   dim[2] = N2;
 34:   dim[3] = N3;
 35:   dim[4] = N4;
 36:   PetscCall(MatCreateFFT(PETSC_COMM_WORLD, DIM, dim, MATFFTW, &A));
 37:   PetscCall(MatGetLocalSize(A, &row, &col));
 38:   printf("The Matrix size  is %d and %d from process %d\n", row, col, rank);
 39:   PetscCall(MatCreateVecsFFTW(A, &x, &y, &z));

 41:   PetscCall(VecGetSize(x, &vsize));

 43:   PetscCall(VecGetSize(z, &vsize));
 44:   printf("The vector size of output from the main routine is %d\n", vsize);

 46:   PetscCall(VecScatterPetscToFFTW(A, input, x));
 47:   /*PetscCall(VecDestroy(&input));*/
 48:   PetscCall(MatMult(A, x, y));
 49:   PetscCall(MatMultTranspose(A, y, z));
 50:   PetscCall(VecScatterFFTWToPetsc(A, z, output));
 51:   /*PetscCall(VecDestroy(&z));*/
 52:   fac = 1.0 / (PetscReal)N;
 53:   PetscCall(VecScale(output, fac));

 55:   PetscCall(VecAssemblyBegin(input));
 56:   PetscCall(VecAssemblyEnd(input));
 57:   PetscCall(VecAssemblyBegin(output));
 58:   PetscCall(VecAssemblyEnd(output));

 60:   /*  PetscCall(VecView(input,PETSC_VIEWER_STDOUT_WORLD));*/
 61:   /*  PetscCall(VecView(output,PETSC_VIEWER_STDOUT_WORLD));*/

 63:   PetscCall(VecAXPY(output, -1.0, input));
 64:   PetscCall(VecNorm(output, NORM_1, &enorm));
 65:   if (enorm > 1.e-14) PetscCall(PetscPrintf(PETSC_COMM_SELF, "  Error norm of |x - z| %e\n", enorm));

 67:   PetscCall(VecDestroy(&x));
 68:   PetscCall(VecDestroy(&y));
 69:   PetscCall(VecDestroy(&z));
 70:   PetscCall(VecDestroy(&output));
 71:   PetscCall(VecDestroy(&input));
 72:   PetscCall(MatDestroy(&A));
 73:   PetscCall(PetscRandomDestroy(&rdm));
 74:   PetscCall(PetscFinalize());
 75:   return 0;
 76: }