Actual source code: ex143.c
petsc-3.4.2 2013-07-02
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: PetscInt main(PetscInt argc,char **args)
19: {
21: PetscMPIInt rank,size;
22: PetscInt N0=50,N1=20,N=N0*N1;
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,"-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;
53: if (!rank) printf("Use FFTW without PETSc-FFTW interface\n");
54: fftw_mpi_init();
55: N = N0*N1;
56: alloc_local = fftw_mpi_local_size_2d(N0,N1,PETSC_COMM_WORLD,&local_n0,&local_0_start);
58: data_in = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*alloc_local);
59: data_out = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*alloc_local);
60: data_out2 = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*alloc_local);
62: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_in,&x);
63: PetscObjectSetName((PetscObject) x, "Real Space vector");
64: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_out,&y);
65: PetscObjectSetName((PetscObject) y, "Frequency space vector");
66: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_out2,&z);
67: PetscObjectSetName((PetscObject) z, "Reconstructed vector");
69: fplan = fftw_mpi_plan_dft_2d(N0,N1,data_in,data_out,PETSC_COMM_WORLD,FFTW_FORWARD,FFTW_ESTIMATE);
70: bplan = fftw_mpi_plan_dft_2d(N0,N1,data_out,data_out2,PETSC_COMM_WORLD,FFTW_BACKWARD,FFTW_ESTIMATE);
72: VecSetRandom(x, rdm);
73: if (view) {VecView(x,PETSC_VIEWER_STDOUT_WORLD);}
75: fftw_execute(fplan);
76: if (view) {VecView(y,PETSC_VIEWER_STDOUT_WORLD);}
78: fftw_execute(bplan);
80: /* Compare x and z. FFTW computes an unnormalized DFT, thus z = N*x */
81: a = 1.0/(PetscReal)N;
82: VecScale(z,a);
83: if (view) {VecView(z, PETSC_VIEWER_STDOUT_WORLD);}
84: VecAXPY(z,-1.0,x);
85: VecNorm(z,NORM_1,&enorm);
86: if (enorm > 1.e-11) {
87: PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %G\n",enorm);
88: }
90: /* Free spaces */
91: fftw_destroy_plan(fplan);
92: fftw_destroy_plan(bplan);
93: fftw_free(data_in); VecDestroy(&x);
94: fftw_free(data_out); VecDestroy(&y);
95: fftw_free(data_out2);VecDestroy(&z);
97: } else {
98: /* Use PETSc-FFTW interface */
99: /*-------------------------------------------*/
100: PetscInt i,*dim,k,DIM;
101: Mat A;
103: N=1;
104: for (i=1; i<5; i++) {
105: DIM = i;
106: PetscMalloc(i*sizeof(PetscInt),&dim);
107: for (k=0; k<i; k++) {
108: dim[k]=30;
109: }
110: N *= dim[i-1];
113: /* Create FFTW object */
114: if (!rank) printf("Use PETSc-FFTW interface...%d-DIM:%d \n",DIM,N);
116: MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A);
118: /* Create vectors that are compatible with parallel layout of A - must call MatGetVecs()! */
120: MatGetVecsFFTW(A,&x,&y,&z);
121: PetscObjectSetName((PetscObject) x, "Real space vector");
122: PetscObjectSetName((PetscObject) y, "Frequency space vector");
123: PetscObjectSetName((PetscObject) z, "Reconstructed vector");
125: /* Set values of space vector x */
126: VecSetRandom(x,rdm);
128: if (view) {VecView(x,PETSC_VIEWER_STDOUT_WORLD);}
130: /* Apply FFTW_FORWARD and FFTW_BACKWARD */
131: MatMult(A,x,y);
132: if (view) {VecView(y,PETSC_VIEWER_STDOUT_WORLD);}
134: MatMultTranspose(A,y,z);
136: /* Compare x and z. FFTW computes an unnormalized DFT, thus z = N*x */
137: a = 1.0/(PetscReal)N;
138: VecScale(z,a);
139: if (view) {VecView(z,PETSC_VIEWER_STDOUT_WORLD);}
140: VecAXPY(z,-1.0,x);
141: VecNorm(z,NORM_1,&enorm);
142: if (enorm > 1.e-9 && !rank) {
143: PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %e\n",enorm);
144: }
146: VecDestroy(&x);
147: VecDestroy(&y);
148: VecDestroy(&z);
149: MatDestroy(&A);
151: PetscFree(dim);
152: }
153: }
155: PetscRandomDestroy(&rdm);
156: PetscFinalize();
157: return 0;
158: }