Actual source code: ex147.c
1: /* This program illustrates use of parallel real FFT */
2: static char help[] = "This program illustrates the use of parallel real multi-dimensional fftw (without PETSc interface)";
3: #include <petscmat.h>
4: #include <fftw3.h>
5: #include <fftw3-mpi.h>
7: int main(int argc, char **args)
8: {
9: ptrdiff_t N0 = 2, N1 = 2, N2 = 2, N3 = 2, dim[4], N, D;
10: fftw_plan bplan, fplan;
11: fftw_complex *out;
12: double *in1, *in2;
13: ptrdiff_t alloc_local, local_n0, local_0_start;
14: ptrdiff_t local_n1, local_1_start;
15: PetscInt i, j, indx[100], n1;
16: PetscInt size, rank, n, *in, N_factor;
17: PetscScalar *data_fin, value1, one = 1.0, zero = 0.0;
18: PetscScalar a, *x_arr, *y_arr, *z_arr, enorm;
19: Vec fin, fout, fout1, x, y;
20: PetscRandom rnd;
22: PetscFunctionBeginUser;
23: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
24: #if defined(PETSC_USE_COMPLEX)
25: SETERRQ(PETSC_COMM_WORLD, PETSC_ERR_SUP, "This example requires real numbers. Your current scalar type is complex");
26: #endif
27: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
28: PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
30: PetscRandomCreate(PETSC_COMM_WORLD, &rnd);
31: D = 4;
32: dim[0] = N0;
33: dim[1] = N1;
34: dim[2] = N2;
35: dim[3] = N3 / 2 + 1;
37: alloc_local = fftw_mpi_local_size_transposed(D, dim, PETSC_COMM_WORLD, &local_n0, &local_0_start, &local_n1, &local_1_start);
39: printf("The value alloc_local is %ld from process %d\n", alloc_local, rank);
40: printf("The value local_n0 is %ld from process %d\n", local_n0, rank);
41: printf("The value local_0_start is %ld from process %d\n", local_0_start, rank);
42: printf("The value local_n1 is %ld from process %d\n", local_n1, rank);
43: printf("The value local_1_start is %ld from process %d\n", local_1_start, rank);
45: /* Allocate space for input and output arrays */
47: in1 = (double *)fftw_malloc(sizeof(double) * alloc_local * 2);
48: in2 = (double *)fftw_malloc(sizeof(double) * alloc_local * 2);
49: out = (fftw_complex *)fftw_malloc(sizeof(fftw_complex) * alloc_local);
51: N = 2 * N0 * N1 * N2 * (N3 / 2 + 1);
52: N_factor = N0 * N1 * N2 * N3;
53: n = 2 * local_n0 * N1 * N2 * (N3 / 2 + 1);
54: n1 = local_n1 * N0 * 2 * N1 * N2;
56: /* printf("The value N is %d from process %d\n",N,rank); */
57: /* printf("The value n is %d from process %d\n",n,rank); */
58: /* printf("The value n1 is %d from process %d\n",n1,rank); */
59: /* Creating data vector and accompanying array with VeccreateMPIWithArray */
60: PetscCall(VecCreateMPIWithArray(PETSC_COMM_WORLD, 1, n, N, (PetscScalar *)in1, &fin));
61: PetscCall(VecCreateMPIWithArray(PETSC_COMM_WORLD, 1, n, N, (PetscScalar *)out, &fout));
62: PetscCall(VecCreateMPIWithArray(PETSC_COMM_WORLD, 1, n, N, (PetscScalar *)in2, &fout1));
64: /* VecGetSize(fin,&size); */
65: /* printf("The size is %d\n",size); */
67: VecSet(fin, one);
68: /* VecAssemblyBegin(fin); */
69: /* VecAssemblyEnd(fin); */
70: /* VecView(fin,PETSC_VIEWER_STDOUT_WORLD); */
72: VecGetArray(fin, &x_arr);
73: VecGetArray(fout1, &z_arr);
74: VecGetArray(fout, &y_arr);
76: dim[3] = N3;
78: fplan = fftw_mpi_plan_dft_r2c(D, dim, (double *)x_arr, (fftw_complex *)y_arr, PETSC_COMM_WORLD, FFTW_ESTIMATE);
79: bplan = fftw_mpi_plan_dft_c2r(D, dim, (fftw_complex *)y_arr, (double *)z_arr, PETSC_COMM_WORLD, FFTW_ESTIMATE);
81: fftw_execute(fplan);
82: fftw_execute(bplan);
84: VecRestoreArray(fin, &x_arr);
85: VecRestoreArray(fout1, &z_arr);
86: VecRestoreArray(fout, &y_arr);
88: /* a = 1.0/(PetscReal)N_factor; */
89: /* PetscCall(VecScale(fout1,a)); */
91: VecAssemblyBegin(fout1);
92: VecAssemblyEnd(fout1);
94: VecView(fout1, PETSC_VIEWER_STDOUT_WORLD);
96: fftw_destroy_plan(fplan);
97: fftw_destroy_plan(bplan);
98: fftw_free(in1);
99: PetscCall(VecDestroy(&fin));
100: fftw_free(out);
101: PetscCall(VecDestroy(&fout));
102: fftw_free(in2);
103: PetscCall(VecDestroy(&fout1));
105: PetscCall(PetscFinalize());
106: return 0;
107: }