Actual source code: tseig.c
petsc-3.5.4 2015-05-23
1: #define PETSC_DESIRE_COMPLEX
2: #include <petsc-private/tsimpl.h> /*I "petscts.h" I*/
3: #include <petscdraw.h>
5: /* ------------------------------------------------------------------------*/
6: struct _n_TSMonitorSPEigCtx {
7: PetscDrawSP drawsp;
8: KSP ksp;
9: PetscInt howoften; /* when > 0 uses step % howoften, when negative only final solution plotted */
10: PetscBool computeexplicitly;
11: MPI_Comm comm;
12: PetscRandom rand;
13: PetscReal xmin,xmax,ymin,ymax;
14: };
19: /*@C
20: TSMonitorSPEigCtxCreate - Creates a context for use with TS to monitor the eigenvalues of the linearized operator
22: Collective on TS
24: Input Parameters:
25: + host - the X display to open, or null for the local machine
26: . label - the title to put in the title bar
27: . x, y - the screen coordinates of the upper left coordinate of the window
28: . m, n - the screen width and height in pixels
29: - howoften - if positive then determines the frequency of the plotting, if -1 then only at the final time
31: Output Parameter:
32: . ctx - the context
34: Options Database Key:
35: . -ts_monitor_sp_eig - plot egienvalues of linearized right hand side
37: Notes:
38: Use TSMonitorSPEigCtxDestroy() to destroy.
40: Currently only works if the Jacobian is provided explicitly.
42: Currently only works for ODEs u_t - F(t,u) = 0; that is with no mass matrix.
44: Level: intermediate
46: .keywords: TS, monitor, line graph, residual, seealso
48: .seealso: TSMonitorSPEigTimeStep(), TSMonitorSet(), TSMonitorLGSolution(), TSMonitorLGError()
50: @*/
51: PetscErrorCode TSMonitorSPEigCtxCreate(MPI_Comm comm,const char host[],const char label[],int x,int y,int m,int n,PetscInt howoften,TSMonitorSPEigCtx *ctx)
52: {
53: PetscDraw win;
55: PC pc;
58: PetscNew(ctx);
59: PetscRandomCreate(comm,&(*ctx)->rand);
60: PetscRandomSetFromOptions((*ctx)->rand);
61: PetscDrawCreate(comm,host,label,x,y,m,n,&win);
62: PetscDrawSetFromOptions(win);
63: PetscDrawSPCreate(win,1,&(*ctx)->drawsp);
64: KSPCreate(comm,&(*ctx)->ksp);
65: KSPSetOptionsPrefix((*ctx)->ksp,"ts_monitor_sp_eig_"); /* this is wrong, used use also prefix from the TS */
66: KSPSetType((*ctx)->ksp,KSPGMRES);
67: KSPGMRESSetRestart((*ctx)->ksp,200);
68: KSPSetTolerances((*ctx)->ksp,1.e-10,PETSC_DEFAULT,PETSC_DEFAULT,200);
69: KSPSetComputeSingularValues((*ctx)->ksp,PETSC_TRUE);
70: KSPSetFromOptions((*ctx)->ksp);
71: KSPGetPC((*ctx)->ksp,&pc);
72: PCSetType(pc,PCNONE);
74: (*ctx)->howoften = howoften;
75: (*ctx)->computeexplicitly = PETSC_FALSE;
77: PetscOptionsGetBool(NULL,"-ts_monitor_sp_eig_explicitly",&(*ctx)->computeexplicitly,NULL);
79: (*ctx)->comm = comm;
80: (*ctx)->xmin = -2.1;
81: (*ctx)->xmax = 1.1;
82: (*ctx)->ymin = -1.1;
83: (*ctx)->ymax = 1.1;
84: return(0);
85: }
89: static PetscErrorCode TSLinearStabilityIndicator(TS ts, PetscReal xr,PetscReal xi,PetscBool *flg)
90: {
92: PetscReal yr,yi;
95: TSComputeLinearStability(ts,xr,xi,&yr,&yi);
96: if ((yr*yr + yi*yi) <= 1.0) *flg = PETSC_TRUE;
97: else *flg = PETSC_FALSE;
98: return(0);
99: }
103: PetscErrorCode TSMonitorSPEig(TS ts,PetscInt step,PetscReal ptime,Vec v,void *monctx)
104: {
105: TSMonitorSPEigCtx ctx = (TSMonitorSPEigCtx) monctx;
106: PetscErrorCode ierr;
107: KSP ksp = ctx->ksp;
108: PetscInt n,N,nits,neig,i,its = 200;
109: PetscReal *r,*c,time_step_save;
110: PetscDrawSP drawsp = ctx->drawsp;
111: Mat A,B;
112: Vec xdot;
113: SNES snes;
116: if (!step) return(0);
117: if (((ctx->howoften > 0) && (!(step % ctx->howoften))) || ((ctx->howoften == -1) && ts->reason)) {
118: VecDuplicate(v,&xdot);
119: TSGetSNES(ts,&snes);
120: SNESGetJacobian(snes,&A,&B,NULL,NULL);
121: MatDuplicate(A,MAT_DO_NOT_COPY_VALUES,&B);
122: /*
123: This doesn't work because methods keep and use internal information about the shift so it
124: seems we would need code for each method to trick the correct Jacobian in being computed.
125: */
126: time_step_save = ts->time_step;
127: ts->time_step = PETSC_MAX_REAL;
129: SNESComputeJacobian(snes,v,A,B);
131: ts->time_step = time_step_save;
133: KSPSetOperators(ksp,B,B);
134: VecGetSize(v,&n);
135: if (n < 200) its = n;
136: KSPSetTolerances(ksp,1.e-10,PETSC_DEFAULT,PETSC_DEFAULT,its);
137: VecSetRandom(xdot,ctx->rand);
138: KSPSolve(ksp,xdot,xdot);
139: VecDestroy(&xdot);
140: KSPGetIterationNumber(ksp,&nits);
141: N = nits+2;
143: if (nits) {
144: PetscDraw draw;
145: PetscReal pause;
146: PetscDrawAxis axis;
147: PetscReal xmin,xmax,ymin,ymax;
149: PetscDrawSPReset(drawsp);
150: PetscDrawSPSetLimits(drawsp,ctx->xmin,ctx->xmax,ctx->ymin,ctx->ymax);
151: PetscMalloc2(PetscMax(n,N),&r,PetscMax(n,N),&c);
152: if (ctx->computeexplicitly) {
153: KSPComputeEigenvaluesExplicitly(ksp,n,r,c);
154: neig = n;
155: } else {
156: KSPComputeEigenvalues(ksp,N,r,c,&neig);
157: }
158: /* We used the positive operator to be able to reuse KSPs that require positive definiteness, now flip the spectrum as is conventional for ODEs */
159: for (i=0; i<neig; i++) r[i] = -r[i];
160: for (i=0; i<neig; i++) {
161: if (ts->ops->linearstability) {
162: PetscReal fr,fi;
163: TSComputeLinearStability(ts,r[i],c[i],&fr,&fi);
164: if ((fr*fr + fi*fi) > 1.0) {
165: PetscPrintf(ctx->comm,"Linearized Eigenvalue %g + %g i linear stability function %g norm indicates unstable scheme \n",(double)r[i],(double)c[i],(double)(fr*fr + fi*fi));
166: }
167: }
168: PetscDrawSPAddPoint(drawsp,r+i,c+i);
169: }
170: PetscFree2(r,c);
171: PetscDrawSPGetDraw(drawsp,&draw);
172: PetscDrawGetPause(draw,&pause);
173: PetscDrawSetPause(draw,0.0);
174: PetscDrawSPDraw(drawsp,PETSC_TRUE);
175: PetscDrawSetPause(draw,pause);
177: if (ts->ops->linearstability) {
178: PetscDrawSPGetAxis(drawsp,&axis);
179: PetscDrawAxisGetLimits(axis,&xmin,&xmax,&ymin,&ymax);
180: PetscDrawIndicatorFunction(draw,xmin,xmax,ymin,ymax,PETSC_DRAW_CYAN,(PetscErrorCode (*)(void*,PetscReal,PetscReal,PetscBool*))TSLinearStabilityIndicator,ts);
181: PetscDrawSPDraw(drawsp,PETSC_FALSE);
182: }
183: }
184: MatDestroy(&B);
185: }
186: return(0);
187: }
191: /*@C
192: TSMonitorSPEigCtxDestroy - Destroys a scatter plot context that was created with TSMonitorSPEigCtxCreate().
194: Collective on TSMonitorSPEigCtx
196: Input Parameter:
197: . ctx - the monitor context
199: Level: intermediate
201: .keywords: TS, monitor, line graph, destroy
203: .seealso: TSMonitorSPEigCtxCreate(), TSMonitorSet(), TSMonitorSPEig();
204: @*/
205: PetscErrorCode TSMonitorSPEigCtxDestroy(TSMonitorSPEigCtx *ctx)
206: {
207: PetscDraw draw;
211: PetscDrawSPGetDraw((*ctx)->drawsp,&draw);
212: PetscDrawDestroy(&draw);
213: PetscDrawSPDestroy(&(*ctx)->drawsp);
214: KSPDestroy(&(*ctx)->ksp);
215: PetscRandomDestroy(&(*ctx)->rand);
216: PetscFree(*ctx);
217: return(0);
218: }