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>
main(int argc,char ** args)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;
14
15 PetscFunctionBeginUser;
16 PetscCall(PetscInitialize(&argc, &args, NULL, help));
17 #if defined(PETSC_USE_COMPLEX)
18 SETERRQ(PETSC_COMM_WORLD, PETSC_ERR_SUP, "This example requires real numbers");
19 #endif
20 PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
21 PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
22
23 PetscCheck(size == 1, PETSC_COMM_WORLD, PETSC_ERR_WRONG_MPI_SIZE, "This is a uni-processor example only");
24 PetscCall(PetscRandomCreate(PETSC_COMM_SELF, &rdm));
25 PetscCall(PetscRandomSetFromOptions(rdm));
26 PetscCall(VecCreate(PETSC_COMM_SELF, &input));
27 PetscCall(VecSetSizes(input, N, N));
28 PetscCall(VecSetFromOptions(input));
29 PetscCall(VecSetRandom(input, rdm));
30 PetscCall(VecDuplicate(input, &output));
31
32 DIM = 5;
33 dim[0] = N0;
34 dim[1] = N1;
35 dim[2] = N2;
36 dim[3] = N3;
37 dim[4] = N4;
38 PetscCall(MatCreateFFT(PETSC_COMM_SELF, DIM, dim, MATFFTW, &A));
39 PetscCall(MatCreateVecs(A, &x, &y));
40 PetscCall(MatCreateVecs(A, &z, NULL));
41
42 PetscCall(VecGetSize(x, &vsize));
43 printf("The vector size of input from the main routine is %d\n", vsize);
44
45 PetscCall(VecGetSize(z, &vsize));
46 printf("The vector size of output from the main routine is %d\n", vsize);
47
48 PetscCall(InputTransformFFT(A, input, x));
49
50 PetscCall(MatMult(A, x, y));
51 PetscCall(MatMultTranspose(A, y, z));
52
53 PetscCall(OutputTransformFFT(A, z, output));
54 fac = 1.0 / (PetscReal)N;
55 PetscCall(VecScale(output, fac));
56 /*
57 PetscCall(VecAssemblyBegin(input));
58 PetscCall(VecAssemblyEnd(input));
59 PetscCall(VecAssemblyBegin(output));
60 PetscCall(VecAssemblyEnd(output));
61
62 PetscCall(VecView(input,PETSC_VIEWER_STDOUT_WORLD));
63 PetscCall(VecView(output,PETSC_VIEWER_STDOUT_WORLD));
64 */
65 PetscCall(VecAXPY(output, -1.0, input));
66 PetscCall(VecNorm(output, NORM_1, &enorm));
67 /* if (enorm > 1.e-14) { */
68 PetscCall(PetscPrintf(PETSC_COMM_SELF, " Error norm of |x - z| %e\n", enorm));
69 /* } */
70
71 PetscCall(VecDestroy(&output));
72 PetscCall(VecDestroy(&input));
73 PetscCall(VecDestroy(&x));
74 PetscCall(VecDestroy(&y));
75 PetscCall(VecDestroy(&z));
76 PetscCall(MatDestroy(&A));
77 PetscCall(PetscRandomDestroy(&rdm));
78 PetscCall(PetscFinalize());
79 return 0;
80 }
81