Actual source code: ex28.c
petsc-3.4.2 2013-07-02
1: static char help[] = "Test sequential USFFT interface on a 3-dof field over a uniform DMDA and compares to the result of FFTW acting on a split version of the field\n\n";
3: /*
4: Compiling the code:
5: This code uses the complex numbers version of PETSc and the FFTW package, so configure
6: must be run to enable these.
8: */
10: #define DOF 3
12: #include <petscmat.h>
13: #include <petscdmda.h>
16: PetscInt main(PetscInt argc,char **args)
17: {
18: typedef enum {RANDOM, CONSTANT, TANH, NUM_FUNCS} FuncType;
19: const char *funcNames[NUM_FUNCS] = {"random", "constant", "tanh"};
20: Mat A, AA;
21: PetscMPIInt size;
22: PetscInt N,i, stencil=1,dof=3;
23: PetscInt dim[3] = {10,10,10}, ndim = 3;
24: Vec coords,x,y,z,xx, yy, zz;
25: Vec xxsplit[DOF], yysplit[DOF], zzsplit[DOF];
26: PetscReal h[3];
27: PetscScalar s;
28: PetscRandom rdm;
29: PetscReal norm, enorm;
30: PetscInt func,ii;
31: FuncType function = TANH;
32: DM da, da1, coordsda;
33: PetscBool view_x = PETSC_FALSE, view_y = PETSC_FALSE, view_z = PETSC_FALSE;
36: PetscInitialize(&argc,&args,(char*)0,help);
37: #if !defined(PETSC_USE_COMPLEX)
38: SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP, "This example requires complex numbers");
39: #endif
40: MPI_Comm_size(PETSC_COMM_WORLD, &size);
41: if (size != 1) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP, "This is a uniprocessor example only!");
42: PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "USFFT Options", "ex27");
43: PetscOptionsEList("-function", "Function type", "ex27", funcNames, NUM_FUNCS, funcNames[function], &func, NULL);
44: function = (FuncType) func;
45: PetscOptionsEnd();
46: PetscOptionsGetBool(NULL,"-view_x",&view_x,NULL);
47: PetscOptionsGetBool(NULL,"-view_y",&view_y,NULL);
48: PetscOptionsGetBool(NULL,"-view_z",&view_z,NULL);
49: PetscOptionsGetIntArray(NULL,"-dim",dim,&ndim,NULL);
51: /* DMDA with the correct fiber dimension */
52: DMDACreate3d(PETSC_COMM_SELF,DMDA_BOUNDARY_NONE,DMDA_BOUNDARY_NONE,DMDA_BOUNDARY_NONE,DMDA_STENCIL_STAR,
53: dim[0], dim[1], dim[2],
54: PETSC_DECIDE, PETSC_DECIDE, PETSC_DECIDE,
55: dof, stencil,
56: NULL, NULL, NULL,
57: &da);
58: /* DMDA with fiber dimension 1 for split fields */
59: DMDACreate3d(PETSC_COMM_SELF,DMDA_BOUNDARY_NONE,DMDA_BOUNDARY_NONE,DMDA_BOUNDARY_NONE,DMDA_STENCIL_STAR,
60: dim[0], dim[1], dim[2],
61: PETSC_DECIDE, PETSC_DECIDE, PETSC_DECIDE,
62: 1, stencil,
63: NULL, NULL, NULL,
64: &da1);
66: /* Coordinates */
67: DMGetCoordinateDM(da, &coordsda);
68: DMGetGlobalVector(coordsda, &coords);
69: PetscObjectSetName((PetscObject) coords, "Grid coordinates");
70: for (i = 0, N = 1; i < 3; i++) {
71: h[i] = 1.0/dim[i];
72: PetscScalar *a;
73: VecGetArray(coords, &a);
74: PetscInt j,k,n = 0;
75: for (i = 0; i < 3; ++i) {
76: for (j = 0; j < dim[i]; ++j) {
77: for (k = 0; k < 3; ++k) {
78: a[n] = j*h[i]; /* coordinate along the j-th point in the i-th dimension */
79: ++n;
80: }
81: }
82: }
83: VecRestoreArray(coords, &a);
85: }
86: DMSetCoordinates(da, coords);
87: VecDestroy(&coords);
89: /* Work vectors */
90: DMGetGlobalVector(da, &x);
91: PetscObjectSetName((PetscObject) x, "Real space vector");
92: DMGetGlobalVector(da, &xx);
93: PetscObjectSetName((PetscObject) xx, "Real space vector");
94: DMGetGlobalVector(da, &y);
95: PetscObjectSetName((PetscObject) y, "USFFT frequency space vector");
96: DMGetGlobalVector(da, &yy);
97: PetscObjectSetName((PetscObject) yy, "FFTW frequency space vector");
98: DMGetGlobalVector(da, &z);
99: PetscObjectSetName((PetscObject) z, "USFFT reconstructed vector");
100: DMGetGlobalVector(da, &zz);
101: PetscObjectSetName((PetscObject) zz, "FFTW reconstructed vector");
102: /* Split vectors for FFTW */
103: for (ii = 0; ii < 3; ++ii) {
104: DMGetGlobalVector(da1, &xxsplit[ii]);
105: PetscObjectSetName((PetscObject) xxsplit[ii], "Real space split vector");
106: DMGetGlobalVector(da1, &yysplit[ii]);
107: PetscObjectSetName((PetscObject) yysplit[ii], "FFTW frequency space split vector");
108: DMGetGlobalVector(da1, &zzsplit[ii]);
109: PetscObjectSetName((PetscObject) zzsplit[ii], "FFTW reconstructed split vector");
110: }
113: PetscPrintf(PETSC_COMM_SELF, "%3-D: USFFT on vector of ");
114: for (i = 0, N = 1; i < 3; i++) {
115: PetscPrintf(PETSC_COMM_SELF, "dim[%d] = %d ",i,dim[i]);
116: N *= dim[i];
117: }
118: PetscPrintf(PETSC_COMM_SELF, "; total size %d \n",N);
121: if (function == RANDOM) {
122: PetscRandomCreate(PETSC_COMM_SELF, &rdm);
123: PetscRandomSetFromOptions(rdm);
124: VecSetRandom(x, rdm);
125: PetscRandomDestroy(&rdm);
126: } else if (function == CONSTANT) {
127: VecSet(x, 1.0);
128: } else if (function == TANH) {
129: PetscScalar *a;
130: VecGetArray(x, &a);
131: PetscInt j,k = 0;
132: for (i = 0; i < 3; ++i) {
133: for (j = 0; j < dim[i]; ++j) {
134: a[k] = tanh((j - dim[i]/2.0)*(10.0/dim[i]));
135: ++k;
136: }
137: }
138: VecRestoreArray(x, &a);
139: }
140: if (view_x) {
141: VecView(x, PETSC_VIEWER_STDOUT_WORLD);
142: }
143: VecCopy(x,xx);
144: /* Split xx */
145: VecStrideGatherAll(xx,xxsplit, INSERT_VALUES); /*YES! 'Gather' means 'split' (or maybe 'scatter'?)! */
147: VecNorm(x,NORM_2,&norm);
148: PetscPrintf(PETSC_COMM_SELF, "|x|_2 = %g\n",norm);
150: /* create USFFT object */
151: MatCreateSeqUSFFT(da,da,&A);
152: /* create FFTW object */
153: MatCreateSeqFFTW(PETSC_COMM_SELF,3,dim,&AA);
155: /* apply USFFT and FFTW FORWARD "preemptively", so the fftw_plans can be reused on different vectors */
156: MatMult(A,x,z);
157: for (ii = 0; ii < 3; ++ii) {
158: MatMult(AA,xxsplit[ii],zzsplit[ii]);
159: }
160: /* Now apply USFFT and FFTW forward several (3) times */
161: for (i=0; i<3; ++i) {
162: MatMult(A,x,y);
163: for (ii = 0; ii < 3; ++ii) {
164: MatMult(AA,xxsplit[ii],yysplit[ii]);
165: }
166: MatMultTranspose(A,y,z);
167: for (ii = 0; ii < 3; ++ii) {
168: MatMult(AA,yysplit[ii],zzsplit[ii]);
169: }
170: }
171: /* Unsplit yy */
172: VecStrideScatterAll(yysplit, yy, INSERT_VALUES); /*YES! 'Scatter' means 'collect' (or maybe 'gather'?)! */
173: /* Unsplit zz */
174: VecStrideScatterAll(zzsplit, zz, INSERT_VALUES); /*YES! 'Scatter' means 'collect' (or maybe 'gather'?)! */
176: if (view_y) {
177: PetscPrintf(PETSC_COMM_WORLD, "y = \n");
178: VecView(y, PETSC_VIEWER_STDOUT_WORLD);
179: PetscPrintf(PETSC_COMM_WORLD, "yy = \n");
180: VecView(yy, PETSC_VIEWER_STDOUT_WORLD);
181: }
183: if (view_z) {
184: PetscPrintf(PETSC_COMM_WORLD, "z = \n");
185: VecView(z, PETSC_VIEWER_STDOUT_WORLD);
186: PetscPrintf(PETSC_COMM_WORLD, "zz = \n");
187: VecView(zz, PETSC_VIEWER_STDOUT_WORLD);
188: }
190: /* compare x and z. USFFT computes an unnormalized DFT, thus z = N*x */
191: s = 1.0/(PetscReal)N;
192: VecScale(z,s);
193: VecAXPY(x,-1.0,z);
194: VecNorm(x,NORM_1,&enorm);
195: PetscPrintf(PETSC_COMM_SELF, "|x-z| = %g\n",enorm);
197: /* compare xx and zz. FFTW computes an unnormalized DFT, thus zz = N*x */
198: s = 1.0/(PetscReal)N;
199: VecScale(zz,s);
200: VecAXPY(xx,-1.0,zz);
201: VecNorm(xx,NORM_1,&enorm);
202: PetscPrintf(PETSC_COMM_SELF, "|xx-zz| = %g\n",enorm);
204: /* compare y and yy: USFFT and FFTW results*/
205: VecNorm(y,NORM_2,&norm);
206: VecAXPY(y,-1.0,yy);
207: VecNorm(y,NORM_1,&enorm);
208: PetscPrintf(PETSC_COMM_SELF, "|y|_2 = %g\n",norm);
209: PetscPrintf(PETSC_COMM_SELF, "|y-yy| = %g\n",enorm);
211: /* compare z and zz: USFFT and FFTW results*/
212: VecNorm(z,NORM_2,&norm);
213: VecAXPY(z,-1.0,zz);
214: VecNorm(z,NORM_1,&enorm);
215: PetscPrintf(PETSC_COMM_SELF, "|z|_2 = %g\n",norm);
216: PetscPrintf(PETSC_COMM_SELF, "|z-zz| = %g\n",enorm);
219: /* free spaces */
220: DMRestoreGlobalVector(da,&x);
221: DMRestoreGlobalVector(da,&xx);
222: DMRestoreGlobalVector(da,&y);
223: DMRestoreGlobalVector(da,&yy);
224: DMRestoreGlobalVector(da,&z);
225: DMRestoreGlobalVector(da,&zz);
227: PetscFinalize();
228: return 0;
229: }