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: }