Actual source code: tseig.c
1: #include <petsc/private/tsimpl.h>
2: #include <petscdraw.h>
4: /* ------------------------------------------------------------------------*/
5: struct _n_TSMonitorSPEigCtx {
6: PetscDrawSP drawsp;
7: KSP ksp;
8: PetscInt howoften; /* when > 0 uses step % howoften, when negative only final solution plotted */
9: PetscBool computeexplicitly;
10: MPI_Comm comm;
11: PetscRandom rand;
12: PetscReal xmin, xmax, ymin, ymax;
13: };
15: /*@C
16: TSMonitorSPEigCtxCreate - Creates a context for use with `TS` to monitor the eigenvalues of the linearized operator
18: Collective
20: Input Parameters:
21: + comm - the communicator to share the monitor
22: . host - the X display to open, or `NULL` for the local machine
23: . label - the title to put in the title bar
24: . x - the horizontal screen coordinates of the upper left coordinate of the window
25: . y - the vertical coordinates of the upper left coordinate of the window
26: . m - the screen width in pixels
27: . n - the screen height in pixels
28: - howoften - if positive then determines the frequency of the plotting, if -1 then only at the final time
30: Output Parameter:
31: . ctx - the context
33: Options Database Key:
34: . -ts_monitor_sp_eig - plot egienvalues of linearized right-hand side
36: Level: intermediate
38: Notes:
39: Use `TSMonitorSPEigCtxDestroy()` to destroy the context
41: Currently only works if the Jacobian is provided explicitly.
43: Currently only works for ODEs u_t - F(t,u) = 0; that is with no mass matrix.
45: .seealso: [](ch_ts), `TSMonitorSPEigTimeStep()`, `TSMonitorSet()`, `TSMonitorLGSolution()`, `TSMonitorLGError()`
46: @*/
47: PetscErrorCode TSMonitorSPEigCtxCreate(MPI_Comm comm, const char host[], const char label[], int x, int y, int m, int n, PetscInt howoften, TSMonitorSPEigCtx *ctx)
48: {
49: PetscDraw win;
50: PC pc;
52: PetscFunctionBegin;
53: PetscCall(PetscNew(ctx));
54: PetscCall(PetscRandomCreate(comm, &(*ctx)->rand));
55: PetscCall(PetscRandomSetFromOptions((*ctx)->rand));
56: PetscCall(PetscDrawCreate(comm, host, label, x, y, m, n, &win));
57: PetscCall(PetscDrawSetFromOptions(win));
58: PetscCall(PetscDrawSPCreate(win, 1, &(*ctx)->drawsp));
59: PetscCall(KSPCreate(comm, &(*ctx)->ksp));
60: PetscCall(KSPSetOptionsPrefix((*ctx)->ksp, "ts_monitor_sp_eig_")); /* this is wrong, used use also prefix from the TS */
61: PetscCall(KSPSetType((*ctx)->ksp, KSPGMRES));
62: PetscCall(KSPGMRESSetRestart((*ctx)->ksp, 200));
63: PetscCall(KSPSetTolerances((*ctx)->ksp, 1.e-10, PETSC_CURRENT, PETSC_CURRENT, 200));
64: PetscCall(KSPSetComputeSingularValues((*ctx)->ksp, PETSC_TRUE));
65: PetscCall(KSPSetFromOptions((*ctx)->ksp));
66: PetscCall(KSPGetPC((*ctx)->ksp, &pc));
67: PetscCall(PCSetType(pc, PCNONE));
69: (*ctx)->howoften = howoften;
70: (*ctx)->computeexplicitly = PETSC_FALSE;
72: PetscCall(PetscOptionsGetBool(NULL, NULL, "-ts_monitor_sp_eig_explicitly", &(*ctx)->computeexplicitly, NULL));
74: (*ctx)->comm = comm;
75: (*ctx)->xmin = -2.1;
76: (*ctx)->xmax = 1.1;
77: (*ctx)->ymin = -1.1;
78: (*ctx)->ymax = 1.1;
79: PetscFunctionReturn(PETSC_SUCCESS);
80: }
82: static PetscErrorCode TSLinearStabilityIndicator(TS ts, PetscReal xr, PetscReal xi, PetscBool *flg)
83: {
84: PetscReal yr, yi;
86: PetscFunctionBegin;
87: PetscCall(TSComputeLinearStability(ts, xr, xi, &yr, &yi));
88: if ((yr * yr + yi * yi) <= 1.0) *flg = PETSC_TRUE;
89: else *flg = PETSC_FALSE;
90: PetscFunctionReturn(PETSC_SUCCESS);
91: }
93: PetscErrorCode TSMonitorSPEig(TS ts, PetscInt step, PetscReal ptime, Vec v, void *monctx)
94: {
95: TSMonitorSPEigCtx ctx = (TSMonitorSPEigCtx)monctx;
96: KSP ksp = ctx->ksp;
97: PetscInt n, N, nits, neig, i, its = 200;
98: PetscReal *r, *c, time_step_save;
99: PetscDrawSP drawsp = ctx->drawsp;
100: Mat A, B;
101: Vec xdot;
102: SNES snes;
104: PetscFunctionBegin;
105: if (step < 0) PetscFunctionReturn(PETSC_SUCCESS); /* -1 indicates interpolated solution */
106: if (!step) PetscFunctionReturn(PETSC_SUCCESS);
107: if (((ctx->howoften > 0) && (!(step % ctx->howoften))) || ((ctx->howoften == -1) && ts->reason)) {
108: PetscCall(VecDuplicate(v, &xdot));
109: PetscCall(TSGetSNES(ts, &snes));
110: PetscCall(SNESGetJacobian(snes, &A, &B, NULL, NULL));
111: PetscCall(MatDuplicate(A, MAT_DO_NOT_COPY_VALUES, &B));
112: /*
113: This doesn't work because methods keep and use internal information about the shift so it
114: seems we would need code for each method to trick the correct Jacobian in being computed.
115: */
116: time_step_save = ts->time_step;
117: ts->time_step = PETSC_MAX_REAL;
119: PetscCall(SNESComputeJacobian(snes, v, A, B));
121: ts->time_step = time_step_save;
123: PetscCall(KSPSetOperators(ksp, B, B));
124: PetscCall(VecGetSize(v, &n));
125: if (n < 200) its = n;
126: PetscCall(KSPSetTolerances(ksp, 1.e-10, PETSC_CURRENT, PETSC_CURRENT, its));
127: PetscCall(VecSetRandom(xdot, ctx->rand));
128: PetscCall(KSPSolve(ksp, xdot, xdot));
129: PetscCall(VecDestroy(&xdot));
130: PetscCall(KSPGetIterationNumber(ksp, &nits));
131: N = nits + 2;
133: if (nits) {
134: PetscDraw draw;
135: PetscReal pause;
136: PetscDrawAxis axis;
137: PetscReal xmin, xmax, ymin, ymax;
139: PetscCall(PetscDrawSPReset(drawsp));
140: PetscCall(PetscDrawSPSetLimits(drawsp, ctx->xmin, ctx->xmax, ctx->ymin, ctx->ymax));
141: PetscCall(PetscMalloc2(PetscMax(n, N), &r, PetscMax(n, N), &c));
142: if (ctx->computeexplicitly) {
143: PetscCall(KSPComputeEigenvaluesExplicitly(ksp, n, r, c));
144: neig = n;
145: } else {
146: PetscCall(KSPComputeEigenvalues(ksp, N, r, c, &neig));
147: }
148: /* We used the positive operator to be able to reuse KSPs that require positive definiteness, now flip the spectrum as is conventional for ODEs */
149: for (i = 0; i < neig; i++) r[i] = -r[i];
150: for (i = 0; i < neig; i++) {
151: if (ts->ops->linearstability) {
152: PetscReal fr, fi;
153: PetscCall(TSComputeLinearStability(ts, r[i], c[i], &fr, &fi));
154: if ((fr * fr + fi * fi) > 1.0) PetscCall(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)));
155: }
156: PetscCall(PetscDrawSPAddPoint(drawsp, r + i, c + i));
157: }
158: PetscCall(PetscFree2(r, c));
159: PetscCall(PetscDrawSPGetDraw(drawsp, &draw));
160: PetscCall(PetscDrawGetPause(draw, &pause));
161: PetscCall(PetscDrawSetPause(draw, 0.0));
162: PetscCall(PetscDrawSPDraw(drawsp, PETSC_TRUE));
163: PetscCall(PetscDrawSetPause(draw, pause));
164: if (ts->ops->linearstability) {
165: PetscCall(PetscDrawSPGetAxis(drawsp, &axis));
166: PetscCall(PetscDrawAxisGetLimits(axis, &xmin, &xmax, &ymin, &ymax));
167: PetscCall(PetscDrawIndicatorFunction(draw, xmin, xmax, ymin, ymax, PETSC_DRAW_CYAN, (PetscErrorCode (*)(void *, PetscReal, PetscReal, PetscBool *))TSLinearStabilityIndicator, ts));
168: PetscCall(PetscDrawSPDraw(drawsp, PETSC_FALSE));
169: }
170: PetscCall(PetscDrawSPSave(drawsp));
171: }
172: PetscCall(MatDestroy(&B));
173: }
174: PetscFunctionReturn(PETSC_SUCCESS);
175: }
177: /*@C
178: TSMonitorSPEigCtxDestroy - Destroys a scatter plot context that was created with `TSMonitorSPEigCtxCreate()`.
180: Collective
182: Input Parameter:
183: . ctx - the monitor context
185: Level: intermediate
187: Note:
188: Should be passed to `TSMonitorSet()` along with `TSMonitorSPEig()` an the context created with `TSMonitorSPEigCtxCreate()`
190: .seealso: [](ch_ts), `TSMonitorSPEigCtxCreate()`, `TSMonitorSet()`, `TSMonitorSPEig()`
191: @*/
192: PetscErrorCode TSMonitorSPEigCtxDestroy(TSMonitorSPEigCtx *ctx)
193: {
194: PetscDraw draw;
196: PetscFunctionBegin;
197: PetscCall(PetscDrawSPGetDraw((*ctx)->drawsp, &draw));
198: PetscCall(PetscDrawDestroy(&draw));
199: PetscCall(PetscDrawSPDestroy(&(*ctx)->drawsp));
200: PetscCall(KSPDestroy(&(*ctx)->ksp));
201: PetscCall(PetscRandomDestroy(&(*ctx)->rand));
202: PetscCall(PetscFree(*ctx));
203: PetscFunctionReturn(PETSC_SUCCESS);
204: }