Actual source code: ex143.c
petsc-3.7.3 2016-08-01
1: static char help[] = "Illustrate how to use mpi FFTW and PETSc-FFTW interface \n\n";
3: /*
4: Compiling the code:
5: This code uses the complex numbers version of PETSc, so configure
6: must be run to enable this
8: Usage:
9: mpiexec -n <np> ./ex143 -use_FFTW_interface NO
10: mpiexec -n <np> ./ex143 -use_FFTW_interface YES
11: */
13: #include <petscmat.h>
14: #include <fftw3-mpi.h>
18: int main(int argc,char **args)
19: {
21: PetscMPIInt rank,size;
22: PetscInt N0=50,N1=20,N=N0*N1,DIM;
23: PetscRandom rdm;
24: PetscScalar a;
25: PetscReal enorm;
26: Vec x,y,z;
27: PetscBool view=PETSC_FALSE,use_interface=PETSC_TRUE;
29: PetscInitialize(&argc,&args,(char*)0,help);
30: #if !defined(PETSC_USE_COMPLEX)
31: SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP, "This example requires complex numbers");
32: #endif
34: PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "FFTW Options", "ex143");
35: PetscOptionsBool("-vec_view draw", "View the vectors", "ex143", view, &view, NULL);
36: PetscOptionsBool("-use_FFTW_interface", "Use PETSc-FFTW interface", "ex143",use_interface, &use_interface, NULL);
37: PetscOptionsEnd();
39: PetscOptionsGetBool(NULL,NULL,"-use_FFTW_interface",&use_interface,NULL);
40: MPI_Comm_size(PETSC_COMM_WORLD, &size);
41: MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
43: PetscRandomCreate(PETSC_COMM_WORLD, &rdm);
44: PetscRandomSetFromOptions(rdm);
46: if (!use_interface) {
47: /* Use mpi FFTW without PETSc-FFTW interface, 2D case only */
48: /*---------------------------------------------------------*/
49: fftw_plan fplan,bplan;
50: fftw_complex *data_in,*data_out,*data_out2;
51: ptrdiff_t alloc_local,local_n0,local_0_start;
52:
53: DIM = 2;
54: if (!rank) {
55: PetscPrintf(PETSC_COMM_SELF,"Use FFTW without PETSc-FFTW interface, DIM %D\n",DIM);
56: }
57: fftw_mpi_init();
58: N = N0*N1;
59: alloc_local = fftw_mpi_local_size_2d(N0,N1,PETSC_COMM_WORLD,&local_n0,&local_0_start);
61: data_in = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*alloc_local);
62: data_out = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*alloc_local);
63: data_out2 = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*alloc_local);
65: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_in,&x);
66: PetscObjectSetName((PetscObject) x, "Real Space vector");
67: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_out,&y);
68: PetscObjectSetName((PetscObject) y, "Frequency space vector");
69: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_out2,&z);
70: PetscObjectSetName((PetscObject) z, "Reconstructed vector");
72: fplan = fftw_mpi_plan_dft_2d(N0,N1,data_in,data_out,PETSC_COMM_WORLD,FFTW_FORWARD,FFTW_ESTIMATE);
73: bplan = fftw_mpi_plan_dft_2d(N0,N1,data_out,data_out2,PETSC_COMM_WORLD,FFTW_BACKWARD,FFTW_ESTIMATE);
75: VecSetRandom(x, rdm);
76: if (view) {VecView(x,PETSC_VIEWER_STDOUT_WORLD);}
78: fftw_execute(fplan);
79: if (view) {VecView(y,PETSC_VIEWER_STDOUT_WORLD);}
81: fftw_execute(bplan);
83: /* Compare x and z. FFTW computes an unnormalized DFT, thus z = N*x */
84: a = 1.0/(PetscReal)N;
85: VecScale(z,a);
86: if (view) {VecView(z, PETSC_VIEWER_STDOUT_WORLD);}
87: VecAXPY(z,-1.0,x);
88: VecNorm(z,NORM_1,&enorm);
89: if (enorm > 1.e-11 && !rank) {
90: PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %g\n",(double)enorm);
91: }
93: /* Free spaces */
94: fftw_destroy_plan(fplan);
95: fftw_destroy_plan(bplan);
96: fftw_free(data_in); VecDestroy(&x);
97: fftw_free(data_out); VecDestroy(&y);
98: fftw_free(data_out2);VecDestroy(&z);
100: } else {
101: /* Use PETSc-FFTW interface */
102: /*-------------------------------------------*/
103: PetscInt i,*dim,k;
104: Mat A;
106: N=1;
107: for (i=1; i<5; i++) {
108: DIM = i;
109: PetscMalloc1(i,&dim);
110: for (k=0; k<i; k++) {
111: dim[k]=30;
112: }
113: N *= dim[i-1];
116: /* Create FFTW object */
117: if (!rank) printf("Use PETSc-FFTW interface...%d-DIM: %d\n",(int)DIM,(int)N);
119: MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A);
121: /* Create vectors that are compatible with parallel layout of A - must call MatCreateVecs()! */
123: MatCreateVecsFFTW(A,&x,&y,&z);
124: PetscObjectSetName((PetscObject) x, "Real space vector");
125: PetscObjectSetName((PetscObject) y, "Frequency space vector");
126: PetscObjectSetName((PetscObject) z, "Reconstructed vector");
128: /* Set values of space vector x */
129: VecSetRandom(x,rdm);
131: if (view) {VecView(x,PETSC_VIEWER_STDOUT_WORLD);}
133: /* Apply FFTW_FORWARD and FFTW_BACKWARD */
134: MatMult(A,x,y);
135: if (view) {VecView(y,PETSC_VIEWER_STDOUT_WORLD);}
137: MatMultTranspose(A,y,z);
139: /* Compare x and z. FFTW computes an unnormalized DFT, thus z = N*x */
140: a = 1.0/(PetscReal)N;
141: VecScale(z,a);
142: if (view) {VecView(z,PETSC_VIEWER_STDOUT_WORLD);}
143: VecAXPY(z,-1.0,x);
144: VecNorm(z,NORM_1,&enorm);
145: if (enorm > 1.e-9 && !rank) {
146: PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %e\n",enorm);
147: }
149: VecDestroy(&x);
150: VecDestroy(&y);
151: VecDestroy(&z);
152: MatDestroy(&A);
154: PetscFree(dim);
155: }
156: }
158: PetscRandomDestroy(&rdm);
159: PetscFinalize();
160: return 0;
161: }