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>
9: PetscInt main(PetscInt argc,char **args)
10: {
11: PetscErrorCode ierr;
12: PetscMPIInt rank,size;
13: PetscInt N0=3,N1=3,N2=3,N=N0*N1*N2;
14: PetscRandom rdm;
15: PetscScalar a;
16: PetscReal enorm;
17: Vec x,y,z,input,output;
18: PetscBool view=PETSC_FALSE,use_interface=PETSC_TRUE;
19: Mat A;
20: PetscInt DIM, dim[3],vsize;
21: PetscReal fac;
23: 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");
26: #endif
28: MPI_Comm_size(PETSC_COMM_WORLD, &size);
29: MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
32: PetscRandomCreate(PETSC_COMM_WORLD, &rdm);
33: PetscRandomSetFromOptions(rdm);
35: VecCreate(PETSC_COMM_WORLD,&input);
36: VecSetSizes(input,PETSC_DECIDE,N);
37: VecSetFromOptions(input);
38: VecSetRandom(input,rdm);
39: VecDuplicate(input,&output);
40: // VecGetSize(input,&vsize);
41: // printf("Size of the input Vector is %d\n",vsize);
42:
43: DIM = 3;
44: dim[0] = N0; dim[1] = N1; dim[2] = N2;
46: MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A);
47: MatGetVecs(A,&x,&y);
48: MatGetVecs(A,&z,PETSC_NULL);
49: VecGetSize(y,&vsize);
50: printf("The vector size from the main routine is %d\n",vsize);
52: InputTransformFFT(A,input,x);
53: MatMult(A,x,y);
54: MatMultTranspose(A,y,z);
55: OutputTransformFFT(A,z,output);
57: fac = 1.0/(PetscReal)N;
58: VecScale(output,fac);
60: VecAssemblyBegin(input);
61: VecAssemblyEnd(input);
62: VecAssemblyBegin(output);
63: VecAssemblyEnd(output);
65: VecView(input,PETSC_VIEWER_STDOUT_WORLD);
66: VecView(output,PETSC_VIEWER_STDOUT_WORLD);
68: VecAXPY(output,-1.0,input);
69: VecNorm(output,NORM_1,&enorm);
70: // if (enorm > 1.e-14){
71: if (!rank)
72: PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %e\n",enorm);
73: // }
76:
77:
78: // MatGetVecs(A,&z,PETSC_NULL);
79: // printf("Vector size from ex148 %d\n",vsize);
80: // PetscObjectSetName((PetscObject) x, "Real space vector");
81: // PetscObjectSetName((PetscObject) y, "Frequency space vector");
82: // PetscObjectSetName((PetscObject) z, "Reconstructed vector");
84: PetscFinalize();
85: return 0;
86:
87: }