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: }