Actual source code: ex1.c
1: /*$Id: ex1.c,v 1.50 2001/09/07 20:12:09 bsmith Exp $*/
2: /*
3: Formatted test for TS routines.
5: Solves U_t = U_xx
6: F(t,u) = (u_i+1 - 2u_i + u_i-1)/h^2
7: using several different schemes.
8: */
10: static char help[] = "Solves 1D heat equation.\n\n";
12: #include petscda.h
13: #include petscsys.h
14: #include petscts.h
16: #define PETSC_NEAR(a,b,c) (!(PetscAbsReal((a)-(b)) > (c)*PetscMax(PetscAbsReal(a),PetscAbsReal(b))))
18: typedef struct {
19: Vec global,local,localwork,solution; /* location for local work (with ghost points) vector */
20: DA da; /* manages ghost point communication */
21: PetscViewer viewer1,viewer2;
22: int M; /* total number of grid points */
23: PetscReal h; /* mesh width h = 1/(M-1) */
24: PetscReal norm_2,norm_max;
25: int nox; /* indicates problem is to be run without graphics */
26: } AppCtx;
28: extern int Monitor(TS,int,PetscReal,Vec,void *);
29: extern int RHSFunctionHeat(TS,PetscReal,Vec,Vec,void*);
30: extern int RHSMatrixFree(Mat,Vec,Vec);
31: extern int Initial(Vec,void*);
32: extern int RHSMatrixHeat(TS,PetscReal,Mat *,Mat *,MatStructure *,void *);
33: extern int RHSJacobianHeat(TS,PetscReal,Vec,Mat*,Mat*,MatStructure *,void*);
35: #define linear_no_matrix 0
36: #define linear_no_time 1
37: #define linear 2
38: #define nonlinear_no_jacobian 3
39: #define nonlinear 4
43: int main(int argc,char **argv)
44: {
45: int ierr,time_steps = 100,steps,size,m;
46: int problem = linear_no_matrix;
47: PetscTruth flg;
48: AppCtx appctx;
49: PetscReal dt,ftime;
50: TS ts;
51: Mat A = 0;
52: MatStructure A_structure;
53: TSProblemType tsproblem = TS_LINEAR;
54: PetscDraw draw;
55: PetscViewer viewer;
56: char tsinfo[120];
57:
58: PetscInitialize(&argc,&argv,(char*)0,help);
59: MPI_Comm_size(PETSC_COMM_WORLD,&size);
61: appctx.M = 60;
62: PetscOptionsGetInt(PETSC_NULL,"-M",&appctx.M,PETSC_NULL);
63: PetscOptionsGetInt(PETSC_NULL,"-time",&time_steps,PETSC_NULL);
64:
65: PetscOptionsHasName(PETSC_NULL,"-nox",&flg);
66: if (flg) appctx.nox = 1; else appctx.nox = 0;
67: appctx.norm_2 = 0.0; appctx.norm_max = 0.0;
69: /* Set up the ghost point communication pattern */
70: DACreate1d(PETSC_COMM_WORLD,DA_NONPERIODIC,appctx.M,1,1,PETSC_NULL,&appctx.da);
71: DACreateGlobalVector(appctx.da,&appctx.global);
72: VecGetLocalSize(appctx.global,&m);
73: DACreateLocalVector(appctx.da,&appctx.local);
75: /* Set up display to show wave graph */
77: PetscViewerDrawOpen(PETSC_COMM_WORLD,0,"",80,380,400,160,&appctx.viewer1);
78: PetscViewerDrawGetDraw(appctx.viewer1,0,&draw);
79: PetscDrawSetDoubleBuffer(draw);
80: PetscViewerDrawOpen(PETSC_COMM_WORLD,0,"",80,0,400,160,&appctx.viewer2);
81: PetscViewerDrawGetDraw(appctx.viewer2,0,&draw);
82: PetscDrawSetDoubleBuffer(draw);
85: /* make work array for evaluating right hand side function */
86: VecDuplicate(appctx.local,&appctx.localwork);
88: /* make work array for storing exact solution */
89: VecDuplicate(appctx.global,&appctx.solution);
91: appctx.h = 1.0/(appctx.M-1.0);
93: /* set initial conditions */
94: Initial(appctx.global,&appctx);
95:
96: /*
97: This example is written to allow one to easily test parts
98: of TS, we do not expect users to generally need to use more
99: then a single TSProblemType
100: */
101: PetscOptionsHasName(PETSC_NULL,"-linear_no_matrix",&flg);
102: if (flg) {
103: tsproblem = TS_LINEAR;
104: problem = linear_no_matrix;
105: }
106: PetscOptionsHasName(PETSC_NULL,"-linear_constant_matrix",&flg);
107: if (flg) {
108: tsproblem = TS_LINEAR;
109: problem = linear_no_time;
110: }
111: PetscOptionsHasName(PETSC_NULL,"-linear_variable_matrix",&flg);
112: if (flg) {
113: tsproblem = TS_LINEAR;
114: problem = linear;
115: }
116: PetscOptionsHasName(PETSC_NULL,"-nonlinear_no_jacobian",&flg);
117: if (flg) {
118: tsproblem = TS_NONLINEAR;
119: problem = nonlinear_no_jacobian;
120: }
121: PetscOptionsHasName(PETSC_NULL,"-nonlinear_jacobian",&flg);
122: if (flg) {
123: tsproblem = TS_NONLINEAR;
124: problem = nonlinear;
125: }
126:
127: /* make timestep context */
128: TSCreate(PETSC_COMM_WORLD,&ts);
129: TSSetProblemType(ts,tsproblem);
130: TSSetMonitor(ts,Monitor,&appctx,PETSC_NULL);
132: dt = appctx.h*appctx.h/2.01;
134: if (problem == linear_no_matrix) {
135: /*
136: The user provides the RHS as a Shell matrix.
137: */
138: MatCreateShell(PETSC_COMM_WORLD,m,appctx.M,appctx.M,appctx.M,&appctx,&A);
139: MatShellSetOperation(A,MATOP_MULT,(void(*)(void))RHSMatrixFree);
140: TSSetRHSMatrix(ts,A,A,PETSC_NULL,&appctx);
141: } else if (problem == linear_no_time) {
142: /*
143: The user provides the RHS as a matrix
144: */
145: MatCreate(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,appctx.M,appctx.M,&A);
146: MatSetFromOptions(A);
147: RHSMatrixHeat(ts,0.0,&A,&A,&A_structure,&appctx);
148: TSSetRHSMatrix(ts,A,A,PETSC_NULL,&appctx);
149: } else if (problem == linear) {
150: /*
151: The user provides the RHS as a time dependent matrix
152: */
153: MatCreate(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,appctx.M,appctx.M,&A);
154: MatSetFromOptions(A);
155: RHSMatrixHeat(ts,0.0,&A,&A,&A_structure,&appctx);
156: TSSetRHSMatrix(ts,A,A,RHSMatrixHeat,&appctx);
157: } else if (problem == nonlinear_no_jacobian) {
158: /*
159: The user provides the RHS and a Shell Jacobian
160: */
161: TSSetRHSFunction(ts,RHSFunctionHeat,&appctx);
162: MatCreateShell(PETSC_COMM_WORLD,m,appctx.M,appctx.M,appctx.M,&appctx,&A);
163: MatShellSetOperation(A,MATOP_MULT,(void(*)(void))RHSMatrixFree);
164: TSSetRHSJacobian(ts,A,A,PETSC_NULL,&appctx);
165: } else if (problem == nonlinear) {
166: /*
167: The user provides the RHS and Jacobian
168: */
169: TSSetRHSFunction(ts,RHSFunctionHeat,&appctx);
170: MatCreate(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,appctx.M,appctx.M,&A);
171: MatSetFromOptions(A);
172: RHSMatrixHeat(ts,0.0,&A,&A,&A_structure,&appctx);
173: TSSetRHSJacobian(ts,A,A,RHSJacobianHeat,&appctx);
174: }
176: TSSetFromOptions(ts);
178: TSSetInitialTimeStep(ts,0.0,dt);
179: TSSetDuration(ts,time_steps,100.);
180: TSSetSolution(ts,appctx.global);
183: TSSetUp(ts);
184: TSStep(ts,&steps,&ftime);
185: PetscViewerStringOpen(PETSC_COMM_WORLD,tsinfo,120,&viewer);
186: TSView(ts,viewer);
188: PetscOptionsHasName(PETSC_NULL,"-test",&flg);
189: if (flg) {
190: PetscTruth iseuler;
191: PetscTypeCompare((PetscObject)ts,"euler",&iseuler);
192: if (iseuler) {
193: if (!PETSC_NEAR(appctx.norm_2/steps,0.00257244,1.e-4)) {
194: fprintf(stdout,"Error in Euler method: 2-norm %g expecting: 0.00257244\n",appctx.norm_2/steps);
195: }
196: } else {
197: if (!PETSC_NEAR(appctx.norm_2/steps,0.00506174,1.e-4)) {
198: fprintf(stdout,"Error in %s method: 2-norm %g expecting: 0.00506174\n",tsinfo,appctx.norm_2/steps);
199: }
200: }
201: } else {
202: PetscPrintf(PETSC_COMM_WORLD,"%d Procs Avg. error 2 norm %g max norm %g %s\n",
203: size,appctx.norm_2/steps,appctx.norm_max/steps,tsinfo);
204: }
206: PetscViewerDestroy(viewer);
207: TSDestroy(ts);
208: PetscViewerDestroy(appctx.viewer1);
209: PetscViewerDestroy(appctx.viewer2);
210: VecDestroy(appctx.localwork);
211: VecDestroy(appctx.solution);
212: VecDestroy(appctx.local);
213: VecDestroy(appctx.global);
214: DADestroy(appctx.da);
215: if (A) {ierr= MatDestroy(A);}
217: PetscFinalize();
218: return 0;
219: }
221: /* -------------------------------------------------------------------*/
224: int Initial(Vec global,void *ctx)
225: {
226: AppCtx *appctx = (AppCtx*) ctx;
227: PetscScalar *localptr,h = appctx->h;
228: int i,mybase,myend,ierr;
230: /* determine starting point of each processor */
231: VecGetOwnershipRange(global,&mybase,&myend);
233: /* Initialize the array */
234: VecGetArray(global,&localptr);
235: for (i=mybase; i<myend; i++) {
236: localptr[i-mybase] = PetscSinScalar(PETSC_PI*i*6.*h) + 3.*PetscSinScalar(PETSC_PI*i*2.*h);
237: }
238: VecRestoreArray(global,&localptr);
239: return 0;
240: }
244: /*
245: Exact solution
246: */
247: int Solution(PetscReal t,Vec solution,void *ctx)
248: {
249: AppCtx *appctx = (AppCtx*) ctx;
250: PetscScalar *localptr,h = appctx->h,ex1,ex2,sc1,sc2;
251: int i,mybase,myend,ierr;
253: /* determine starting point of each processor */
254: VecGetOwnershipRange(solution,&mybase,&myend);
256: ex1 = exp(-36.*PETSC_PI*PETSC_PI*t);
257: ex2 = exp(-4.*PETSC_PI*PETSC_PI*t);
258: sc1 = PETSC_PI*6.*h; sc2 = PETSC_PI*2.*h;
259: VecGetArray(solution,&localptr);
260: for (i=mybase; i<myend; i++) {
261: localptr[i-mybase] = PetscSinScalar(sc1*(PetscReal)i)*ex1 + 3.*PetscSinScalar(sc2*(PetscReal)i)*ex2;
262: }
263: VecRestoreArray(solution,&localptr);
264: return 0;
265: }
269: int Monitor(TS ts,int step,PetscReal ltime,Vec global,void *ctx)
270: {
271: AppCtx *appctx = (AppCtx*) ctx;
272: int ierr;
273: PetscReal norm_2,norm_max;
274: PetscScalar mone = -1.0;
275: MPI_Comm comm;
277: PetscObjectGetComm((PetscObject)ts,&comm);
279: VecView(global,appctx->viewer2);
281: Solution(ltime,appctx->solution,ctx);
282: VecAXPY(&mone,global,appctx->solution);
283: VecNorm(appctx->solution,NORM_2,&norm_2);
284: norm_2 = sqrt(appctx->h)*norm_2;
285: VecNorm(appctx->solution,NORM_MAX,&norm_max);
287: if (!appctx->nox) {
288: PetscPrintf(comm,"timestep %d time %g norm of error %g %g\n",step,ltime,norm_2,norm_max);
289: }
291: appctx->norm_2 += norm_2;
292: appctx->norm_max += norm_max;
294: VecView(appctx->solution,appctx->viewer1);
296: return 0;
297: }
299: /* -----------------------------------------------------------------------*/
302: int RHSMatrixFree(Mat mat,Vec x,Vec y)
303: {
304: int ierr;
305: void *ctx;
307: MatShellGetContext(mat,(void **)&ctx);
308: RHSFunctionHeat(0,0.0,x,y,ctx);
309: return 0;
310: }
314: int RHSFunctionHeat(TS ts,PetscReal t,Vec globalin,Vec globalout,void *ctx)
315: {
316: AppCtx *appctx = (AppCtx*) ctx;
317: DA da = appctx->da;
318: Vec local = appctx->local,localwork = appctx->localwork;
319: int ierr,i,localsize;
320: PetscScalar *copyptr,*localptr,sc;
322: /*Extract local array */
323: DAGlobalToLocalBegin(da,globalin,INSERT_VALUES,local);
324: DAGlobalToLocalEnd(da,globalin,INSERT_VALUES,local);
325: VecGetArray(local,&localptr);
327: /* Extract work vector */
328: VecGetArray(localwork,©ptr);
330: /* Update Locally - Make array of new values */
331: /* Note: For the first and last entry I copy the value */
332: /* if this is an interior node it is irrelevant */
333: sc = 1.0/(appctx->h*appctx->h);
334: VecGetLocalSize(local,&localsize);
335: copyptr[0] = localptr[0];
336: for (i=1; i<localsize-1; i++) {
337: copyptr[i] = sc * (localptr[i+1] + localptr[i-1] - 2.0*localptr[i]);
338: }
339: copyptr[localsize-1] = localptr[localsize-1];
340: VecRestoreArray(local,&localptr);
341: VecRestoreArray(localwork,©ptr);
343: /* Local to Global */
344: DALocalToGlobal(da,localwork,INSERT_VALUES,globalout);
345: return 0;
346: }
348: /* ---------------------------------------------------------------------*/
351: int RHSMatrixHeat(TS ts,PetscReal t,Mat *AA,Mat *BB,MatStructure *str,void *ctx)
352: {
353: Mat A = *AA;
354: AppCtx *appctx = (AppCtx*) ctx;
355: int ierr,i,mstart,mend,rank,size,idx[3];
356: PetscScalar v[3],stwo = -2./(appctx->h*appctx->h),sone = -.5*stwo;
358: *str = SAME_NONZERO_PATTERN;
360: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
361: MPI_Comm_size(PETSC_COMM_WORLD,&size);
363: MatGetOwnershipRange(A,&mstart,&mend);
364: if (mstart == 0) {
365: v[0] = 1.0;
366: MatSetValues(A,1,&mstart,1,&mstart,v,INSERT_VALUES);
367: mstart++;
368: }
369: if (mend == appctx->M) {
370: mend--;
371: v[0] = 1.0;
372: MatSetValues(A,1,&mend,1,&mend,v,INSERT_VALUES);
373: }
375: /*
376: Construct matrice one row at a time
377: */
378: v[0] = sone; v[1] = stwo; v[2] = sone;
379: for (i=mstart; i<mend; i++) {
380: idx[0] = i-1; idx[1] = i; idx[2] = i+1;
381: MatSetValues(A,1,&i,3,idx,v,INSERT_VALUES);
382: }
384: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
385: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
386: return 0;
387: }
391: int RHSJacobianHeat(TS ts,PetscReal t,Vec x,Mat *AA,Mat *BB,MatStructure *str,void *ctx)
392: {
393: return RHSMatrixHeat(ts,t,AA,BB,str,ctx);
394: }