Actual source code: ex150.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, N3 = 3, N4 = 3, N = N0 * N1 * N2 * N3;
11: PetscRandom rdm;
12: PetscReal enorm;
13: Vec x, y, z, input, output;
14: Mat A;
15: PetscInt DIM, dim[5], vsize;
16: PetscReal fac;
17: PetscScalar one = 1;
19: PetscFunctionBeginUser;
20: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
21: #if defined(PETSC_USE_COMPLEX)
22: SETERRQ(PETSC_COMM_WORLD, PETSC_ERR_SUP, "This example requires real numbers");
23: #endif
25: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
26: PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
28: PetscCall(PetscRandomCreate(PETSC_COMM_WORLD, &rdm));
29: 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(VecAssemblyBegin(input));
35: PetscCall(VecAssemblyEnd(input));
36: /* PetscCall(VecView(input,PETSC_VIEWER_STDOUT_WORLD)); */
37: PetscCall(VecDuplicate(input, &output));
39: DIM = 4;
40: dim[0] = N0;
41: dim[1] = N1;
42: dim[2] = N2;
43: dim[3] = N3;
44: dim[4] = N4;
46: PetscCall(MatCreateFFT(PETSC_COMM_WORLD, DIM, dim, MATFFTW, &A));
47: PetscCall(MatCreateVecs(A, &x, &y));
48: PetscCall(MatCreateVecs(A, &z, NULL));
49: PetscCall(VecGetSize(x, &vsize));
50: printf("The vector size from the main routine is %d\n", vsize);
52: PetscCall(InputTransformFFT(A, input, x));
54: PetscCall(MatMult(A, x, y));
55: PetscCall(VecAssemblyBegin(y));
56: PetscCall(VecAssemblyEnd(y));
57: PetscCall(VecView(y, PETSC_VIEWER_STDOUT_WORLD));
58: PetscCall(MatMultTranspose(A, y, z));
59: PetscCall(VecGetSize(z, &vsize));
60: printf("The vector size of zfrom the main routine is %d\n", vsize);
62: PetscCall(OutputTransformFFT(A, z, output));
64: fac = 1.0 / (PetscReal)N;
65: PetscCall(VecScale(output, fac));
67: PetscCall(VecAssemblyBegin(input));
68: PetscCall(VecAssemblyEnd(input));
69: PetscCall(VecAssemblyBegin(output));
70: PetscCall(VecAssemblyEnd(output));
72: PetscCall(VecView(input, PETSC_VIEWER_STDOUT_WORLD));
73: PetscCall(VecView(output, PETSC_VIEWER_STDOUT_WORLD));
75: PetscCall(VecAXPY(output, -1.0, input));
76: PetscCall(VecNorm(output, NORM_1, &enorm));
77: /* if (enorm > 1.e-14) { */
78: if (rank == 0) PetscCall(PetscPrintf(PETSC_COMM_SELF, " Error norm of |x - z| %e\n", enorm));
79: /* } */
81: /* PetscCall(MatCreateVecs(A,&z,NULL)); */
82: /* printf("Vector size from ex148 %d\n",vsize); */
83: /* PetscCall(PetscObjectSetName((PetscObject) x, "Real space vector")); */
84: /* PetscCall(PetscObjectSetName((PetscObject) y, "Frequency space vector")); */
85: /* PetscCall(PetscObjectSetName((PetscObject) z, "Reconstructed vector")); */
87: PetscCall(VecDestroy(&output));
88: PetscCall(VecDestroy(&input));
89: PetscCall(VecDestroy(&x));
90: PetscCall(VecDestroy(&y));
91: PetscCall(VecDestroy(&z));
92: PetscCall(MatDestroy(&A));
93: PetscCall(PetscRandomDestroy(&rdm));
94: PetscCall(PetscFinalize());
95: return 0;
96: }