Actual source code: ex143.c
petsc-3.10.5 2019-03-28
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>
16: int main(int argc,char **args)
17: {
19: PetscMPIInt rank,size;
20: PetscInt N0=50,N1=20,N=N0*N1,DIM;
21: PetscRandom rdm;
22: PetscScalar a;
23: PetscReal enorm;
24: Vec x,y,z;
25: PetscBool view=PETSC_FALSE,use_interface=PETSC_TRUE;
27: PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
28: PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "FFTW Options", "ex143");
29: PetscOptionsBool("-vec_view draw", "View the vectors", "ex143", view, &view, NULL);
30: PetscOptionsBool("-use_FFTW_interface", "Use PETSc-FFTW interface", "ex143",use_interface, &use_interface, NULL);
31: PetscOptionsEnd();
33: PetscOptionsGetBool(NULL,NULL,"-use_FFTW_interface",&use_interface,NULL);
34: MPI_Comm_size(PETSC_COMM_WORLD, &size);
35: MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
37: PetscRandomCreate(PETSC_COMM_WORLD, &rdm);
38: PetscRandomSetFromOptions(rdm);
40: if (!use_interface) {
41: /* Use mpi FFTW without PETSc-FFTW interface, 2D case only */
42: /*---------------------------------------------------------*/
43: fftw_plan fplan,bplan;
44: fftw_complex *data_in,*data_out,*data_out2;
45: ptrdiff_t alloc_local,local_n0,local_0_start;
46:
47: DIM = 2;
48: if (!rank) {
49: PetscPrintf(PETSC_COMM_SELF,"Use FFTW without PETSc-FFTW interface, DIM %D\n",DIM);
50: }
51: fftw_mpi_init();
52: N = N0*N1;
53: alloc_local = fftw_mpi_local_size_2d(N0,N1,PETSC_COMM_WORLD,&local_n0,&local_0_start);
55: data_in = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*alloc_local);
56: data_out = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*alloc_local);
57: data_out2 = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*alloc_local);
59: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_in,&x);
60: PetscObjectSetName((PetscObject) x, "Real Space vector");
61: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_out,&y);
62: PetscObjectSetName((PetscObject) y, "Frequency space vector");
63: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_out2,&z);
64: PetscObjectSetName((PetscObject) z, "Reconstructed vector");
66: fplan = fftw_mpi_plan_dft_2d(N0,N1,data_in,data_out,PETSC_COMM_WORLD,FFTW_FORWARD,FFTW_ESTIMATE);
67: bplan = fftw_mpi_plan_dft_2d(N0,N1,data_out,data_out2,PETSC_COMM_WORLD,FFTW_BACKWARD,FFTW_ESTIMATE);
69: VecSetRandom(x, rdm);
70: if (view) {VecView(x,PETSC_VIEWER_STDOUT_WORLD);}
72: fftw_execute(fplan);
73: if (view) {VecView(y,PETSC_VIEWER_STDOUT_WORLD);}
75: fftw_execute(bplan);
77: /* Compare x and z. FFTW computes an unnormalized DFT, thus z = N*x */
78: a = 1.0/(PetscReal)N;
79: VecScale(z,a);
80: if (view) {VecView(z, PETSC_VIEWER_STDOUT_WORLD);}
81: VecAXPY(z,-1.0,x);
82: VecNorm(z,NORM_1,&enorm);
83: if (enorm > 1.e-11 && !rank) {
84: PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %g\n",(double)enorm);
85: }
87: /* Free spaces */
88: fftw_destroy_plan(fplan);
89: fftw_destroy_plan(bplan);
90: fftw_free(data_in); VecDestroy(&x);
91: fftw_free(data_out); VecDestroy(&y);
92: fftw_free(data_out2);VecDestroy(&z);
94: } else {
95: /* Use PETSc-FFTW interface */
96: /*-------------------------------------------*/
97: PetscInt i,*dim,k;
98: Mat A;
100: N=1;
101: for (i=1; i<5; i++) {
102: DIM = i;
103: PetscMalloc1(i,&dim);
104: for (k=0; k<i; k++) {
105: dim[k]=30;
106: }
107: N *= dim[i-1];
110: /* Create FFTW object */
111: if (!rank) printf("Use PETSc-FFTW interface...%d-DIM: %d\n",(int)DIM,(int)N);
113: MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A);
115: /* Create vectors that are compatible with parallel layout of A - must call MatCreateVecs()! */
117: MatCreateVecsFFTW(A,&x,&y,&z);
118: PetscObjectSetName((PetscObject) x, "Real space vector");
119: PetscObjectSetName((PetscObject) y, "Frequency space vector");
120: PetscObjectSetName((PetscObject) z, "Reconstructed vector");
122: /* Set values of space vector x */
123: VecSetRandom(x,rdm);
125: if (view) {VecView(x,PETSC_VIEWER_STDOUT_WORLD);}
127: /* Apply FFTW_FORWARD and FFTW_BACKWARD */
128: MatMult(A,x,y);
129: if (view) {VecView(y,PETSC_VIEWER_STDOUT_WORLD);}
131: MatMultTranspose(A,y,z);
133: /* Compare x and z. FFTW computes an unnormalized DFT, thus z = N*x */
134: a = 1.0/(PetscReal)N;
135: VecScale(z,a);
136: if (view) {VecView(z,PETSC_VIEWER_STDOUT_WORLD);}
137: VecAXPY(z,-1.0,x);
138: VecNorm(z,NORM_1,&enorm);
139: if (enorm > 1.e-9 && !rank) {
140: PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %e\n",enorm);
141: }
143: VecDestroy(&x);
144: VecDestroy(&y);
145: VecDestroy(&z);
146: MatDestroy(&A);
148: PetscFree(dim);
149: }
150: }
152: PetscRandomDestroy(&rdm);
153: PetscFinalize();
154: return ierr;
155: }
158: /*TEST
160: build:
161: requires: fftw complex
163: test:
164: output_file: output/ex143.out
166: test:
167: suffix: 2
168: nsize: 3
169: output_file: output/ex143.out
171: TEST*/