Actual source code: ex147.c
petsc-3.3-p6 2013-02-11
1: /* This program illustrates use of parallel real FFT */
2: static char help[]="This program illustrates the use of parallel real fftw (without PETSc interface)";
3: #include <petscmat.h>
4: #include <fftw3.h>
5: #include <fftw3-mpi.h>
9: PetscInt main(PetscInt argc,char **args)
10: {
11: ptrdiff_t N0=2,N1=2,N2=2,N3=2,dim[4],N,D;
12: fftw_plan bplan,fplan;
13: fftw_complex *out;
14: double *in1,*in2;
15: ptrdiff_t alloc_local,local_n0,local_0_start;
16: ptrdiff_t local_n1,local_1_start;
17: PetscInt i,j,indx[100],n1;
18: PetscInt size,rank,n,*in,N_factor;
19: PetscScalar *data_fin,value1,one=1.0,zero=0.0;
20: PetscScalar a,*x_arr,*y_arr,*z_arr,enorm;
21: Vec fin,fout,fout1,x,y;
22: PetscRandom rnd;
25: PetscInitialize(&argc,&args,(char *)0,help);
26: MPI_Comm_size(PETSC_COMM_WORLD, &size);
27: MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
29: PetscRandomCreate(PETSC_COMM_WORLD,&rnd);
30: D=4;
31: dim[0]=N0;dim[1]=N1;dim[2]=N2;dim[3]=N3/2+1;
34: alloc_local = fftw_mpi_local_size_transposed(D,dim,PETSC_COMM_WORLD,&local_n0,&local_0_start,&local_n1,&local_1_start);
36: printf("The value alloc_local is %ld from process %d\n",alloc_local,rank);
37: printf("The value local_n0 is %ld from process %d\n",local_n0,rank);
38: printf("The value local_0_start is %ld from process %d\n",local_0_start,rank);
39: printf("The value local_n1 is %ld from process %d\n",local_n1,rank);
40: printf("The value local_1_start is %ld from process %d\n",local_1_start,rank);
42: /* Allocate space for input and output arrays */
44: in1=(double *)fftw_malloc(sizeof(double)*alloc_local*2);
45: in2=(double *)fftw_malloc(sizeof(double)*alloc_local*2);
46: out=(fftw_complex *)fftw_malloc(sizeof(fftw_complex)*alloc_local);
49: N=2*N0*N1*N2*(N3/2+1);N_factor=N0*N1*N2*N3;
50: n=2*local_n0*N1*N2*(N3/2+1);n1=local_n1*N0*2*N1*N2;
52: // printf("The value N is %d from process %d\n",N,rank);
53: // printf("The value n is %d from process %d\n",n,rank);
54: // printf("The value n1 is %d from process %d\n",n1,rank);
55: /* Creating data vector and accompanying array with VeccreateMPIWithArray */
56: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,n,N,(PetscScalar *)in1,&fin);
57: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,n,N,(PetscScalar*)out,&fout);
58: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,n,N,(PetscScalar*)in2,&fout1);
60: // VecGetSize(fin,&size);
61: // printf("The size is %d\n",size);
63: VecSet(fin,one);
64: // VecAssemblyBegin(fin);
65: // VecAssemblyEnd(fin);
66: // VecView(fin,PETSC_VIEWER_STDOUT_WORLD);
69: VecGetArray(fin,&x_arr);
70: VecGetArray(fout1,&z_arr);
71: VecGetArray(fout,&y_arr);
72:
73: dim[3]=N3;
74:
75: fplan=fftw_mpi_plan_dft_r2c(D,dim,(double *)x_arr,(fftw_complex *)y_arr,PETSC_COMM_WORLD,FFTW_ESTIMATE);
76: bplan=fftw_mpi_plan_dft_c2r(D,dim,(fftw_complex *)y_arr,(double *)z_arr,PETSC_COMM_WORLD,FFTW_ESTIMATE);
78: fftw_execute(fplan);
79: fftw_execute(bplan);
81: VecRestoreArray(fin,&x_arr);
82: VecRestoreArray(fout1,&z_arr);
83: VecRestoreArray(fout,&y_arr);
85: // a = 1.0/(PetscReal)N_factor;
86: // VecScale(fout1,a);
88: VecAssemblyBegin(fout1);
89: VecAssemblyEnd(fout1);
91: VecView(fout1,PETSC_VIEWER_STDOUT_WORLD);
93: fftw_destroy_plan(fplan);
94: fftw_destroy_plan(bplan);
95: fftw_free(in1); VecDestroy(&fin) ;
96: fftw_free(out); VecDestroy(&fout);
97: fftw_free(in2); VecDestroy(&fout1);
99: PetscFinalize();
100: return 0;
101: }