Actual source code: ex27.c
1: static char help[] = "Test sequential USFFT interface on a uniform DMDA and compares the result to FFTW\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: #include <petscmat.h>
11: #include <petscdm.h>
12: #include <petscdmda.h>
13: int main(int argc, char **args)
14: {
15: typedef enum {
16: RANDOM,
17: CONSTANT,
18: TANH,
19: NUM_FUNCS
20: } FuncType;
21: const char *funcNames[NUM_FUNCS] = {"random", "constant", "tanh"};
22: Mat A, AA;
23: PetscMPIInt size;
24: PetscInt N, i, stencil = 1, dof = 1;
25: PetscInt dim[3] = {10, 10, 10}, ndim = 3;
26: Vec coords, x, y, z, xx, yy, zz;
27: PetscReal h[3];
28: PetscScalar s;
29: PetscRandom rdm;
30: PetscReal norm, enorm;
31: PetscInt func;
32: FuncType function = TANH;
33: DM da, coordsda;
34: PetscBool view_x = PETSC_FALSE, view_y = PETSC_FALSE, view_z = PETSC_FALSE;
36: PetscFunctionBeginUser;
37: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
38: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
39: PetscCheck(size == 1, PETSC_COMM_WORLD, PETSC_ERR_SUP, "This is a uniprocessor example only!");
40: PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "USFFT Options", "ex27");
41: PetscCall(PetscOptionsEList("-function", "Function type", "ex27", funcNames, NUM_FUNCS, funcNames[function], &func, NULL));
42: function = (FuncType)func;
43: PetscOptionsEnd();
44: PetscCall(PetscOptionsGetBool(NULL, NULL, "-view_x", &view_x, NULL));
45: PetscCall(PetscOptionsGetBool(NULL, NULL, "-view_y", &view_y, NULL));
46: PetscCall(PetscOptionsGetBool(NULL, NULL, "-view_z", &view_z, NULL));
47: PetscCall(PetscOptionsGetIntArray(NULL, NULL, "-dim", dim, &ndim, NULL));
49: PetscCall(DMDACreate3d(PETSC_COMM_SELF, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DMDA_STENCIL_STAR, dim[0], dim[1], dim[2], PETSC_DECIDE, PETSC_DECIDE, PETSC_DECIDE, dof, stencil, NULL, NULL, NULL, &da));
50: PetscCall(DMSetFromOptions(da));
51: PetscCall(DMSetUp(da));
53: /* Coordinates */
54: PetscCall(DMGetCoordinateDM(da, &coordsda));
55: PetscCall(DMGetGlobalVector(coordsda, &coords));
56: PetscCall(PetscObjectSetName((PetscObject)coords, "Grid coordinates"));
57: for (i = 0, N = 1; i < 3; i++) {
58: h[i] = 1.0 / dim[i];
59: PetscScalar *a;
60: PetscCall(VecGetArray(coords, &a));
61: PetscInt j, k, n = 0;
62: for (i = 0; i < 3; ++i) {
63: for (j = 0; j < dim[i]; ++j) {
64: for (k = 0; k < 3; ++k) {
65: a[n] = j * h[i]; /* coordinate along the j-th point in the i-th dimension */
66: ++n;
67: }
68: }
69: }
70: PetscCall(VecRestoreArray(coords, &a));
71: }
72: PetscCall(DMSetCoordinates(da, coords));
74: /* Work vectors */
75: PetscCall(DMGetGlobalVector(da, &x));
76: PetscCall(PetscObjectSetName((PetscObject)x, "Real space vector"));
77: PetscCall(DMGetGlobalVector(da, &xx));
78: PetscCall(PetscObjectSetName((PetscObject)xx, "Real space vector"));
79: PetscCall(DMGetGlobalVector(da, &y));
80: PetscCall(PetscObjectSetName((PetscObject)y, "USFFT frequency space vector"));
81: PetscCall(DMGetGlobalVector(da, &yy));
82: PetscCall(PetscObjectSetName((PetscObject)yy, "FFTW frequency space vector"));
83: PetscCall(DMGetGlobalVector(da, &z));
84: PetscCall(PetscObjectSetName((PetscObject)z, "USFFT reconstructed vector"));
85: PetscCall(DMGetGlobalVector(da, &zz));
86: PetscCall(PetscObjectSetName((PetscObject)zz, "FFTW reconstructed vector"));
88: PetscCall(PetscPrintf(PETSC_COMM_SELF, "%3-" PetscInt_FMT ": USFFT on vector of "));
89: for (i = 0, N = 1; i < 3; i++) {
90: PetscCall(PetscPrintf(PETSC_COMM_SELF, "dim[%d] = %d ", i, dim[i]));
91: N *= dim[i];
92: }
93: PetscCall(PetscPrintf(PETSC_COMM_SELF, "; total size %d \n", N));
95: if (function == RANDOM) {
96: PetscCall(PetscRandomCreate(PETSC_COMM_SELF, &rdm));
97: PetscCall(PetscRandomSetFromOptions(rdm));
98: PetscCall(VecSetRandom(x, rdm));
99: PetscCall(PetscRandomDestroy(&rdm));
100: } else if (function == CONSTANT) {
101: PetscCall(VecSet(x, 1.0));
102: } else if (function == TANH) {
103: PetscScalar *a;
104: PetscCall(VecGetArray(x, &a));
105: PetscInt j, k = 0;
106: for (i = 0; i < 3; ++i) {
107: for (j = 0; j < dim[i]; ++j) {
108: a[k] = tanh((j - dim[i] / 2.0) * (10.0 / dim[i]));
109: ++k;
110: }
111: }
112: PetscCall(VecRestoreArray(x, &a));
113: }
114: if (view_x) PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));
115: PetscCall(VecCopy(x, xx));
117: PetscCall(VecNorm(x, NORM_2, &norm));
118: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|x|_2 = %g\n", norm));
120: /* create USFFT object */
121: PetscCall(MatCreateSeqUSFFT(coords, da, &A));
122: /* create FFTW object */
123: PetscCall(MatCreateSeqFFTW(PETSC_COMM_SELF, 3, dim, &AA));
125: /* apply USFFT and FFTW FORWARD "preemptively", so the fftw_plans can be reused on different vectors */
126: PetscCall(MatMult(A, x, z));
127: PetscCall(MatMult(AA, xx, zz));
128: /* Now apply USFFT and FFTW forward several (3) times */
129: for (i = 0; i < 3; ++i) {
130: PetscCall(MatMult(A, x, y));
131: PetscCall(MatMult(AA, xx, yy));
132: PetscCall(MatMultTranspose(A, y, z));
133: PetscCall(MatMultTranspose(AA, yy, zz));
134: }
136: if (view_y) {
137: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "y = \n"));
138: PetscCall(VecView(y, PETSC_VIEWER_STDOUT_WORLD));
139: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "yy = \n"));
140: PetscCall(VecView(yy, PETSC_VIEWER_STDOUT_WORLD));
141: }
143: if (view_z) {
144: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "z = \n"));
145: PetscCall(VecView(z, PETSC_VIEWER_STDOUT_WORLD));
146: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "zz = \n"));
147: PetscCall(VecView(zz, PETSC_VIEWER_STDOUT_WORLD));
148: }
150: /* compare x and z. USFFT computes an unnormalized DFT, thus z = N*x */
151: s = 1.0 / (PetscReal)N;
152: PetscCall(VecScale(z, s));
153: PetscCall(VecAXPY(x, -1.0, z));
154: PetscCall(VecNorm(x, NORM_1, &enorm));
155: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|x-z| = %g\n", enorm));
157: /* compare xx and zz. FFTW computes an unnormalized DFT, thus zz = N*x */
158: s = 1.0 / (PetscReal)N;
159: PetscCall(VecScale(zz, s));
160: PetscCall(VecAXPY(xx, -1.0, zz));
161: PetscCall(VecNorm(xx, NORM_1, &enorm));
162: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|xx-zz| = %g\n", enorm));
164: /* compare y and yy: USFFT and FFTW results*/
165: PetscCall(VecNorm(y, NORM_2, &norm));
166: PetscCall(VecAXPY(y, -1.0, yy));
167: PetscCall(VecNorm(y, NORM_1, &enorm));
168: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|y|_2 = %g\n", norm));
169: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|y-yy| = %g\n", enorm));
171: /* compare z and zz: USFFT and FFTW results*/
172: PetscCall(VecNorm(z, NORM_2, &norm));
173: PetscCall(VecAXPY(z, -1.0, zz));
174: PetscCall(VecNorm(z, NORM_1, &enorm));
175: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|z|_2 = %g\n", norm));
176: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|z-zz| = %g\n", enorm));
178: /* free spaces */
179: PetscCall(DMRestoreGlobalVector(da, &x));
180: PetscCall(DMRestoreGlobalVector(da, &xx));
181: PetscCall(DMRestoreGlobalVector(da, &y));
182: PetscCall(DMRestoreGlobalVector(da, &yy));
183: PetscCall(DMRestoreGlobalVector(da, &z));
184: PetscCall(DMRestoreGlobalVector(da, &zz));
185: PetscCall(VecDestroy(&coords));
186: PetscCall(DMDestroy(&da));
187: PetscCall(PetscFinalize());
188: return 0;
189: }