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;
21: PetscInitialize(&argc, &args, (char *)0, help);
22: #if defined(PETSC_USE_COMPLEX)
23: SETERRQ(PETSC_COMM_WORLD, PETSC_ERR_SUP, "This example requires real numbers");
24: #endif
26: MPI_Comm_size(PETSC_COMM_WORLD, &size);
27: MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
29: PetscRandomCreate(PETSC_COMM_WORLD, &rdm);
30: PetscRandomSetFromOptions(rdm);
32: VecCreate(PETSC_COMM_WORLD, &input);
33: VecSetSizes(input, PETSC_DECIDE, N);
34: VecSetFromOptions(input);
35: VecSetRandom(input, rdm);
36: VecDuplicate(input, &output);
37: /* VecGetSize(input,&vsize); */
38: /* printf("Size of the input Vector is %d\n",vsize); */
40: DIM = 3;
41: dim[0] = N0;
42: dim[1] = N1;
43: dim[2] = N2;
45: MatCreateFFT(PETSC_COMM_WORLD, DIM, dim, MATFFTW, &A);
46: MatCreateVecs(A, &x, &y);
47: MatCreateVecs(A, &z, NULL);
48: VecGetSize(y, &vsize);
49: printf("The vector size from the main routine is %d\n", vsize);
51: InputTransformFFT(A, input, x);
52: MatMult(A, x, y);
53: MatMultTranspose(A, y, z);
54: OutputTransformFFT(A, z, output);
56: fac = 1.0 / (PetscReal)N;
57: VecScale(output, fac);
59: VecAssemblyBegin(input);
60: VecAssemblyEnd(input);
61: VecAssemblyBegin(output);
62: VecAssemblyEnd(output);
64: VecView(input, PETSC_VIEWER_STDOUT_WORLD);
65: VecView(output, PETSC_VIEWER_STDOUT_WORLD);
67: VecAXPY(output, -1.0, input);
68: VecNorm(output, NORM_1, &enorm);
69: /* if (enorm > 1.e-14) { */
70: if (rank == 0) PetscPrintf(PETSC_COMM_SELF, " Error norm of |x - z| %e\n", enorm);
71: /* } */
73: /* MatCreateVecs(A,&z,NULL); */
74: /* printf("Vector size from ex148 %d\n",vsize); */
75: /* PetscObjectSetName((PetscObject) x, "Real space vector"); */
76: /* PetscObjectSetName((PetscObject) y, "Frequency space vector"); */
77: /* PetscObjectSetName((PetscObject) z, "Reconstructed vector"); */
79: PetscFinalize();
80: return 0;
81: }