Actual source code: ex153.c
1: static char help[] = "This program illustrates the use of PETSc-fftw interface for sequential real DFT\n";
2: #include <petscmat.h>
3: #include <fftw3-mpi.h>
4: int main(int argc, char **args)
5: {
6: PetscMPIInt rank, size;
7: PetscInt N0 = 10, N1 = 10, N2 = 10, N3 = 10, N4 = 10, N = N0 * N1 * N2 * N3 * N4;
8: PetscRandom rdm;
9: PetscReal enorm;
10: Vec x, y, z, input, output;
11: Mat A;
12: PetscInt DIM, dim[5], vsize;
13: PetscReal fac;
16: PetscInitialize(&argc, &args, (char *)0, help);
17: #if defined(PETSC_USE_COMPLEX)
18: SETERRQ(PETSC_COMM_WORLD, PETSC_ERR_SUP, "This example requires real numbers");
19: #endif
20: MPI_Comm_size(PETSC_COMM_WORLD, &size);
21: MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
24: PetscRandomCreate(PETSC_COMM_SELF, &rdm);
25: PetscRandomSetFromOptions(rdm);
26: VecCreate(PETSC_COMM_SELF, &input);
27: VecSetSizes(input, N, N);
28: VecSetFromOptions(input);
29: VecSetRandom(input, rdm);
30: VecDuplicate(input, &output);
32: DIM = 5;
33: dim[0] = N0;
34: dim[1] = N1;
35: dim[2] = N2;
36: dim[3] = N3;
37: dim[4] = N4;
38: MatCreateFFT(PETSC_COMM_SELF, DIM, dim, MATFFTW, &A);
39: MatCreateVecs(A, &x, &y);
40: MatCreateVecs(A, &z, NULL);
42: VecGetSize(x, &vsize);
43: printf("The vector size of input from the main routine is %d\n", vsize);
45: VecGetSize(z, &vsize);
46: printf("The vector size of output from the main routine is %d\n", vsize);
48: InputTransformFFT(A, input, x);
50: MatMult(A, x, y);
51: MatMultTranspose(A, y, z);
53: OutputTransformFFT(A, z, output);
54: fac = 1.0 / (PetscReal)N;
55: VecScale(output, fac);
56: /*
57: VecAssemblyBegin(input);
58: VecAssemblyEnd(input);
59: VecAssemblyBegin(output);
60: VecAssemblyEnd(output);
62: VecView(input,PETSC_VIEWER_STDOUT_WORLD);
63: VecView(output,PETSC_VIEWER_STDOUT_WORLD);
64: */
65: VecAXPY(output, -1.0, input);
66: VecNorm(output, NORM_1, &enorm);
67: /* if (enorm > 1.e-14) { */
68: PetscPrintf(PETSC_COMM_SELF, " Error norm of |x - z| %e\n", enorm);
69: /* } */
71: VecDestroy(&output);
72: VecDestroy(&input);
73: VecDestroy(&x);
74: VecDestroy(&y);
75: VecDestroy(&z);
76: MatDestroy(&A);
77: PetscRandomDestroy(&rdm);
78: PetscFinalize();
79: return 0;
80: }