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;
20: 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: MPI_Comm_size(PETSC_COMM_WORLD, &size);
26: MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
28: PetscRandomCreate(PETSC_COMM_WORLD, &rdm);
29: PetscRandomSetFromOptions(rdm);
31: VecCreate(PETSC_COMM_WORLD,&input);
32: VecSetSizes(input,PETSC_DECIDE,N);
33: VecSetFromOptions(input);
34: VecSetRandom(input,rdm);
35: VecDuplicate(input,&output);
36: /* VecGetSize(input,&vsize); */
37: /* printf("Size of the input Vector is %d\n",vsize); */
39: DIM = 3;
40: dim[0] = N0; dim[1] = N1; dim[2] = N2;
42: MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A);
43: MatCreateVecs(A,&x,&y);
44: MatCreateVecs(A,&z,NULL);
45: VecGetSize(y,&vsize);
46: printf("The vector size from the main routine is %d\n",vsize);
48: InputTransformFFT(A,input,x);
49: MatMult(A,x,y);
50: MatMultTranspose(A,y,z);
51: OutputTransformFFT(A,z,output);
53: fac = 1.0/(PetscReal)N;
54: VecScale(output,fac);
56: VecAssemblyBegin(input);
57: VecAssemblyEnd(input);
58: VecAssemblyBegin(output);
59: VecAssemblyEnd(output);
61: VecView(input,PETSC_VIEWER_STDOUT_WORLD);
62: VecView(output,PETSC_VIEWER_STDOUT_WORLD);
64: VecAXPY(output,-1.0,input);
65: VecNorm(output,NORM_1,&enorm);
66: /* if (enorm > 1.e-14) { */
67: if (rank == 0) {
68: PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %e\n",enorm);
69: }
70: /* } */
72: /* MatCreateVecs(A,&z,NULL); */
73: /* printf("Vector size from ex148 %d\n",vsize); */
74: /* PetscObjectSetName((PetscObject) x, "Real space vector"); */
75: /* PetscObjectSetName((PetscObject) y, "Frequency space vector"); */
76: /* PetscObjectSetName((PetscObject) z, "Reconstructed vector"); */
78: PetscFinalize();
79: return 0;
81: }