Actual source code: ex143.c
petsc-3.3-p6 2013-02-11
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: {
20: PetscErrorCode ierr;
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, PETSC_NULL, "FFTW Options", "ex143");
35: PetscOptionsBool("-vec_view_draw", "View the vectors", "ex143", view, &view, PETSC_NULL);
36: PetscOptionsBool("-use_FFTW_interface", "Use PETSc-FFTW interface", "ex143",use_interface, &use_interface, PETSC_NULL);
37: PetscOptionsEnd();
39: PetscOptionsGetBool(PETSC_NULL,"-use_FFTW_interface",&use_interface,PETSC_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);
61: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_in,&x);
62: PetscObjectSetName((PetscObject) x, "Real Space vector");
63: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_out,&y);
64: PetscObjectSetName((PetscObject) y, "Frequency space vector");
65: VecCreateMPIWithArray(PETSC_COMM_WORLD,1,(PetscInt)local_n0*N1,(PetscInt)N,(const PetscScalar*)data_out2,&z);
66: PetscObjectSetName((PetscObject) z, "Reconstructed vector");
68: fplan = fftw_mpi_plan_dft_2d(N0,N1,data_in,data_out,PETSC_COMM_WORLD,FFTW_FORWARD,FFTW_ESTIMATE);
69: bplan = fftw_mpi_plan_dft_2d(N0,N1,data_out,data_out2,PETSC_COMM_WORLD,FFTW_BACKWARD,FFTW_ESTIMATE);
71: VecSetRandom(x, rdm);
72: if (view){VecView(x,PETSC_VIEWER_STDOUT_WORLD);}
74: fftw_execute(fplan);
75: if (view){VecView(y,PETSC_VIEWER_STDOUT_WORLD);}
77: fftw_execute(bplan);
79: /* Compare x and z. FFTW computes an unnormalized DFT, thus z = N*x */
80: a = 1.0/(PetscReal)N;
81: VecScale(z,a);
82: if (view){VecView(z, PETSC_VIEWER_STDOUT_WORLD);}
83: VecAXPY(z,-1.0,x);
84: VecNorm(z,NORM_1,&enorm);
85: if (enorm > 1.e-11){
86: PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %G\n",enorm);
87: }
89: /* Free spaces */
90: fftw_destroy_plan(fplan);
91: fftw_destroy_plan(bplan);
92: fftw_free(data_in); VecDestroy(&x);
93: fftw_free(data_out); VecDestroy(&y);
94: fftw_free(data_out2);VecDestroy(&z);
96: } else {
97: /* Use PETSc-FFTW interface */
98: /*-------------------------------------------*/
99: PetscInt i,*dim,k,DIM;
100: Mat A;
102: N=1;
103: for (i=1; i<5; i++){
104: DIM = i;
105: PetscMalloc(i*sizeof(PetscInt),&dim);
106: for(k=0;k<i;k++){
107: dim[k]=30;
108: }
109: N *= dim[i-1];
111:
112: /* Create FFTW object */
113: if (!rank) printf("Use PETSc-FFTW interface...%d-DIM:%d \n",DIM,N);
115: MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A);
117: /* Create vectors that are compatible with parallel layout of A - must call MatGetVecs()! */
118:
119: MatGetVecsFFTW(A,&x,&y,&z);
120: PetscObjectSetName((PetscObject) x, "Real space vector");
121: PetscObjectSetName((PetscObject) y, "Frequency space vector");
122: PetscObjectSetName((PetscObject) z, "Reconstructed vector");
124: /* Set values of space vector x */
125: VecSetRandom(x,rdm);
127: if (view){VecView(x,PETSC_VIEWER_STDOUT_WORLD);}
129: // Apply FFTW_FORWARD and FFTW_BACKWARD
130: MatMult(A,x,y);
131: if (view){VecView(y,PETSC_VIEWER_STDOUT_WORLD);}
133: MatMultTranspose(A,y,z);
135: // Compare x and z. FFTW computes an unnormalized DFT, thus z = N*x
136: a = 1.0/(PetscReal)N;
137: VecScale(z,a);
138: if (view){VecView(z,PETSC_VIEWER_STDOUT_WORLD);}
139: VecAXPY(z,-1.0,x);
140: VecNorm(z,NORM_1,&enorm);
141: if (enorm > 1.e-9 && !rank){
142: PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %e\n",enorm);
143: }
144:
145: VecDestroy(&x);
146: VecDestroy(&y);
147: VecDestroy(&z);
148: MatDestroy(&A);
150: PetscFree(dim);
151: }
152: }
153:
154: PetscRandomDestroy(&rdm);
155: PetscFinalize();
156: return 0;
157: }