Actual source code: bdf.c
1: /*
2: Code for timestepping with BDF methods
3: */
4: #include <petsc/private/tsimpl.h>
5: #include <petscdm.h>
7: static PetscBool cited = PETSC_FALSE;
8: static const char citation[] = "@book{Brenan1995,\n"
9: " title = {Numerical Solution of Initial-Value Problems in Differential-Algebraic Equations},\n"
10: " author = {Brenan, K. and Campbell, S. and Petzold, L.},\n"
11: " publisher = {Society for Industrial and Applied Mathematics},\n"
12: " year = {1995},\n"
13: " doi = {10.1137/1.9781611971224},\n}\n";
15: typedef struct {
16: PetscInt k, n;
17: PetscReal time[6 + 2];
18: Vec work[6 + 2];
19: Vec tvwork[6 + 2];
20: PetscReal shift;
21: Vec vec_dot; /* Xdot when !transientvar, else Cdot where C(X) is the transient variable. */
22: Vec vec_wrk;
23: Vec vec_lte;
25: PetscBool transientvar;
26: PetscBool extrapolate;
27: PetscInt order;
28: TSStepStatus status;
29: } TS_BDF;
31: /* Compute Lagrange polynomials on T[:n] evaluated at t.
32: * If one has data (T[i], Y[i]), then the interpolation/extrapolation is f(t) = \sum_i L[i]*Y[i].
33: */
34: static inline void LagrangeBasisVals(PetscInt n, PetscReal t, const PetscReal T[], PetscScalar L[])
35: {
36: PetscInt k, j;
37: for (k = 0; k < n; k++)
38: for (L[k] = 1, j = 0; j < n; j++)
39: if (j != k) L[k] *= (t - T[j]) / (T[k] - T[j]);
40: }
42: static inline void LagrangeBasisDers(PetscInt n, PetscReal t, const PetscReal T[], PetscScalar dL[])
43: {
44: PetscInt k, j, i;
45: for (k = 0; k < n; k++)
46: for (dL[k] = 0, j = 0; j < n; j++)
47: if (j != k) {
48: PetscReal L = 1 / (T[k] - T[j]);
49: for (i = 0; i < n; i++)
50: if (i != j && i != k) L *= (t - T[i]) / (T[k] - T[i]);
51: dL[k] += L;
52: }
53: }
55: static PetscErrorCode TSBDF_GetVecs(TS ts, DM dm, Vec *Xdot, Vec *Ydot)
56: {
57: TS_BDF *bdf = (TS_BDF *)ts->data;
59: PetscFunctionBegin;
60: if (dm && dm != ts->dm) {
61: PetscCall(DMGetNamedGlobalVector(dm, "TSBDF_Vec_Xdot", Xdot));
62: PetscCall(DMGetNamedGlobalVector(dm, "TSBDF_Vec_Ydot", Ydot));
63: } else {
64: *Xdot = bdf->vec_dot;
65: *Ydot = bdf->vec_wrk;
66: }
67: PetscFunctionReturn(PETSC_SUCCESS);
68: }
70: static PetscErrorCode TSBDF_RestoreVecs(TS ts, DM dm, Vec *Xdot, Vec *Ydot)
71: {
72: TS_BDF *bdf = (TS_BDF *)ts->data;
74: PetscFunctionBegin;
75: if (dm && dm != ts->dm) {
76: PetscCall(DMRestoreNamedGlobalVector(dm, "TSBDF_Vec_Xdot", Xdot));
77: PetscCall(DMRestoreNamedGlobalVector(dm, "TSBDF_Vec_Ydot", Ydot));
78: } else {
79: PetscCheck(*Xdot == bdf->vec_dot, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_INCOMP, "Vec does not match the cache");
80: PetscCheck(*Ydot == bdf->vec_wrk, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_INCOMP, "Vec does not match the cache");
81: *Xdot = NULL;
82: *Ydot = NULL;
83: }
84: PetscFunctionReturn(PETSC_SUCCESS);
85: }
87: static PetscErrorCode DMCoarsenHook_TSBDF(DM fine, DM coarse, void *ctx)
88: {
89: PetscFunctionBegin;
90: PetscFunctionReturn(PETSC_SUCCESS);
91: }
93: static PetscErrorCode DMRestrictHook_TSBDF(DM fine, Mat restrct, Vec rscale, Mat inject, DM coarse, void *ctx)
94: {
95: TS ts = (TS)ctx;
96: Vec Ydot, Ydot_c;
97: Vec Xdot, Xdot_c;
99: PetscFunctionBegin;
100: PetscCall(TSBDF_GetVecs(ts, fine, &Xdot, &Ydot));
101: PetscCall(TSBDF_GetVecs(ts, coarse, &Xdot_c, &Ydot_c));
103: PetscCall(MatRestrict(restrct, Ydot, Ydot_c));
104: PetscCall(VecPointwiseMult(Ydot_c, rscale, Ydot_c));
106: PetscCall(TSBDF_RestoreVecs(ts, fine, &Xdot, &Ydot));
107: PetscCall(TSBDF_RestoreVecs(ts, coarse, &Xdot_c, &Ydot_c));
108: PetscFunctionReturn(PETSC_SUCCESS);
109: }
111: static PetscErrorCode TSBDF_Advance(TS ts, PetscReal t, Vec X)
112: {
113: TS_BDF *bdf = (TS_BDF *)ts->data;
114: PetscInt i, n = PETSC_STATIC_ARRAY_LENGTH(bdf->work);
115: Vec tail = bdf->work[n - 1], tvtail = bdf->tvwork[n - 1];
117: PetscFunctionBegin;
118: for (i = n - 1; i >= 2; i--) {
119: bdf->time[i] = bdf->time[i - 1];
120: bdf->work[i] = bdf->work[i - 1];
121: bdf->tvwork[i] = bdf->tvwork[i - 1];
122: }
123: bdf->n = PetscMin(bdf->n + 1, n - 1);
124: bdf->time[1] = t;
125: bdf->work[1] = tail;
126: bdf->tvwork[1] = tvtail;
127: PetscCall(VecCopy(X, tail));
128: PetscCall(TSComputeTransientVariable(ts, tail, tvtail));
129: PetscFunctionReturn(PETSC_SUCCESS);
130: }
132: static PetscErrorCode TSBDF_VecLTE(TS ts, PetscInt order, Vec lte)
133: {
134: TS_BDF *bdf = (TS_BDF *)ts->data;
135: PetscInt i, n = order + 1;
136: PetscReal *time = bdf->time;
137: Vec *vecs = bdf->work;
138: PetscScalar a[8], b[8], alpha[8];
140: PetscFunctionBegin;
141: LagrangeBasisDers(n + 0, time[0], time, a);
142: a[n] = 0;
143: LagrangeBasisDers(n + 1, time[0], time, b);
144: for (i = 0; i < n + 1; i++) alpha[i] = (a[i] - b[i]) / a[0];
145: PetscCall(VecZeroEntries(lte));
146: PetscCall(VecMAXPY(lte, n + 1, alpha, vecs));
147: PetscFunctionReturn(PETSC_SUCCESS);
148: }
150: static PetscErrorCode TSBDF_Extrapolate(TS ts, PetscInt order, PetscReal t, Vec X)
151: {
152: TS_BDF *bdf = (TS_BDF *)ts->data;
153: PetscInt n = order + 1;
154: PetscReal *time = bdf->time + 1;
155: Vec *vecs = bdf->work + 1;
156: PetscScalar alpha[7];
158: PetscFunctionBegin;
159: n = PetscMin(n, bdf->n);
160: LagrangeBasisVals(n, t, time, alpha);
161: PetscCall(VecZeroEntries(X));
162: PetscCall(VecMAXPY(X, n, alpha, vecs));
163: PetscFunctionReturn(PETSC_SUCCESS);
164: }
166: static PetscErrorCode TSBDF_Interpolate(TS ts, PetscInt order, PetscReal t, Vec X)
167: {
168: TS_BDF *bdf = (TS_BDF *)ts->data;
169: PetscInt n = order + 1;
170: PetscReal *time = bdf->time;
171: Vec *vecs = bdf->work;
172: PetscScalar alpha[7];
174: PetscFunctionBegin;
175: LagrangeBasisVals(n, t, time, alpha);
176: PetscCall(VecZeroEntries(X));
177: PetscCall(VecMAXPY(X, n, alpha, vecs));
178: PetscFunctionReturn(PETSC_SUCCESS);
179: }
181: /* Compute the affine term V0 such that Xdot = shift*X + V0.
182: *
183: * When using transient variables, we're computing Cdot = shift*C(X) + V0, and thus choose a linear combination of tvwork.
184: */
185: static PetscErrorCode TSBDF_PreSolve(TS ts)
186: {
187: TS_BDF *bdf = (TS_BDF *)ts->data;
188: PetscInt i, n = PetscMax(bdf->k, 1) + 1;
189: Vec V, V0;
190: Vec vecs[7];
191: PetscScalar alpha[7];
193: PetscFunctionBegin;
194: PetscCall(TSBDF_GetVecs(ts, NULL, &V, &V0));
195: LagrangeBasisDers(n, bdf->time[0], bdf->time, alpha);
196: for (i = 1; i < n; i++) vecs[i] = bdf->transientvar ? bdf->tvwork[i] : bdf->work[i];
197: PetscCall(VecZeroEntries(V0));
198: PetscCall(VecMAXPY(V0, n - 1, alpha + 1, vecs + 1));
199: bdf->shift = PetscRealPart(alpha[0]);
200: PetscCall(TSBDF_RestoreVecs(ts, NULL, &V, &V0));
201: PetscFunctionReturn(PETSC_SUCCESS);
202: }
204: static PetscErrorCode TSBDF_SNESSolve(TS ts, Vec b, Vec x)
205: {
206: PetscInt nits, lits;
208: PetscFunctionBegin;
209: PetscCall(TSBDF_PreSolve(ts));
210: PetscCall(SNESSolve(ts->snes, b, x));
211: PetscCall(SNESGetIterationNumber(ts->snes, &nits));
212: PetscCall(SNESGetLinearSolveIterations(ts->snes, &lits));
213: ts->snes_its += nits;
214: ts->ksp_its += lits;
215: PetscFunctionReturn(PETSC_SUCCESS);
216: }
218: static PetscErrorCode TSBDF_Restart(TS ts, PetscBool *accept)
219: {
220: TS_BDF *bdf = (TS_BDF *)ts->data;
222: PetscFunctionBegin;
223: bdf->k = 1;
224: bdf->n = 0;
225: PetscCall(TSBDF_Advance(ts, ts->ptime, ts->vec_sol));
226: if (bdf->order == 1) {
227: *accept = PETSC_TRUE;
228: PetscFunctionReturn(PETSC_SUCCESS);
229: }
230: bdf->time[0] = ts->ptime + ts->time_step / 2;
231: PetscCall(VecCopy(bdf->work[1], bdf->work[0]));
232: PetscCall(TSPreStage(ts, bdf->time[0]));
233: PetscCall(TSBDF_SNESSolve(ts, NULL, bdf->work[0]));
234: PetscCall(TSPostStage(ts, bdf->time[0], 0, &bdf->work[0]));
235: PetscCall(TSAdaptCheckStage(ts->adapt, ts, bdf->time[0], bdf->work[0], accept));
236: if (!*accept) PetscFunctionReturn(PETSC_SUCCESS);
238: bdf->k = PetscMin(2, bdf->order);
239: bdf->n++;
240: PetscCall(VecCopy(bdf->work[0], bdf->work[2]));
241: bdf->time[2] = bdf->time[0];
242: PetscCall(TSComputeTransientVariable(ts, bdf->work[2], bdf->tvwork[2]));
243: PetscFunctionReturn(PETSC_SUCCESS);
244: }
246: static const char *const BDF_SchemeName[] = {"", "1", "2", "3", "4", "5", "6"};
248: static PetscErrorCode TSStep_BDF(TS ts)
249: {
250: TS_BDF *bdf = (TS_BDF *)ts->data;
251: PetscInt rejections = 0;
252: PetscBool stageok, accept = PETSC_TRUE;
253: PetscReal next_time_step = ts->time_step;
255: PetscFunctionBegin;
256: PetscCall(PetscCitationsRegister(citation, &cited));
258: if (!ts->steprollback && !ts->steprestart) {
259: bdf->k = PetscMin(bdf->k + 1, bdf->order);
260: PetscCall(TSBDF_Advance(ts, ts->ptime, ts->vec_sol));
261: }
263: bdf->status = TS_STEP_INCOMPLETE;
264: while (!ts->reason && bdf->status != TS_STEP_COMPLETE) {
265: if (ts->steprestart) {
266: PetscCall(TSBDF_Restart(ts, &stageok));
267: if (!stageok) goto reject_step;
268: }
270: bdf->time[0] = ts->ptime + ts->time_step;
271: if (bdf->extrapolate) PetscCall(TSBDF_Extrapolate(ts, bdf->k - (accept ? 0 : 1), bdf->time[0], bdf->work[0]));
272: else if (!accept) PetscCall(VecCopy(ts->vec_sol, bdf->work[0]));
273: PetscCall(TSPreStage(ts, bdf->time[0]));
274: PetscCall(TSBDF_SNESSolve(ts, NULL, bdf->work[0]));
275: PetscCall(TSPostStage(ts, bdf->time[0], 0, &bdf->work[0]));
276: PetscCall(TSAdaptCheckStage(ts->adapt, ts, bdf->time[0], bdf->work[0], &stageok));
277: if (!stageok) goto reject_step;
279: bdf->status = TS_STEP_PENDING;
280: PetscCall(TSAdaptCandidatesClear(ts->adapt));
281: PetscCall(TSAdaptCandidateAdd(ts->adapt, BDF_SchemeName[bdf->k], bdf->k, 1, 1.0, 1.0, PETSC_TRUE));
282: PetscCall(TSAdaptChoose(ts->adapt, ts, ts->time_step, NULL, &next_time_step, &accept));
283: bdf->status = accept ? TS_STEP_COMPLETE : TS_STEP_INCOMPLETE;
284: if (!accept) {
285: ts->time_step = next_time_step;
286: goto reject_step;
287: }
289: PetscCall(VecCopy(bdf->work[0], ts->vec_sol));
290: ts->ptime += ts->time_step;
291: ts->time_step = next_time_step;
292: break;
294: reject_step:
295: ts->reject++;
296: accept = PETSC_FALSE;
297: if (!ts->reason && ++rejections > ts->max_reject && ts->max_reject >= 0) {
298: PetscCall(PetscInfo(ts, "Step=%" PetscInt_FMT ", step rejections %" PetscInt_FMT " greater than current TS allowed, stopping solve\n", ts->steps, rejections));
299: ts->reason = TS_DIVERGED_STEP_REJECTED;
300: }
301: }
302: PetscFunctionReturn(PETSC_SUCCESS);
303: }
305: static PetscErrorCode TSInterpolate_BDF(TS ts, PetscReal t, Vec X)
306: {
307: TS_BDF *bdf = (TS_BDF *)ts->data;
309: PetscFunctionBegin;
310: PetscCall(TSBDF_Interpolate(ts, bdf->k, t, X));
311: PetscFunctionReturn(PETSC_SUCCESS);
312: }
314: static PetscErrorCode TSEvaluateWLTE_BDF(TS ts, NormType wnormtype, PetscInt *order, PetscReal *wlte)
315: {
316: TS_BDF *bdf = (TS_BDF *)ts->data;
317: PetscInt k = bdf->k;
318: PetscReal wltea, wlter;
319: Vec X = bdf->work[0], Y = bdf->vec_lte;
321: PetscFunctionBegin;
322: k = PetscMin(k, bdf->n - 1);
323: if (k == 0) {
324: *wlte = -1;
325: PetscFunctionReturn(PETSC_SUCCESS);
326: }
327: PetscCall(TSBDF_VecLTE(ts, k, Y));
328: PetscCall(VecAXPY(Y, 1, X));
329: PetscCall(TSErrorWeightedNorm(ts, X, Y, wnormtype, wlte, &wltea, &wlter));
330: if (order) *order = k + 1;
331: PetscFunctionReturn(PETSC_SUCCESS);
332: }
334: static PetscErrorCode TSResizeRegister_BDF(TS ts, PetscBool reg)
335: {
336: TS_BDF *bdf = (TS_BDF *)ts->data;
337: const char *names[] = {"", "ts:bdf:1", "ts:bdf:2", "ts:bdf:3", "ts:bdf:4", "ts:bdf:5", "ts:bdf:6", "ts:bdf:7"};
338: PetscInt i, maxn = PETSC_STATIC_ARRAY_LENGTH(bdf->work);
340: PetscFunctionBegin;
341: PetscAssert(maxn == 8, PetscObjectComm((PetscObject)ts), PETSC_ERR_PLIB, "names need to be redefined");
342: if (reg) {
343: for (i = 1; i < PetscMin(bdf->n + 1, maxn); i++) PetscCall(TSResizeRegisterVec(ts, names[i], bdf->work[i]));
344: } else {
345: for (i = 1; i < maxn; i++) {
346: PetscCall(TSResizeRetrieveVec(ts, names[i], &bdf->work[i]));
347: if (!bdf->work[i]) break;
348: PetscCall(PetscObjectReference((PetscObject)bdf->work[i]));
349: if (bdf->transientvar) {
350: PetscCall(VecDuplicate(bdf->work[i], &bdf->tvwork[i]));
351: PetscCall(TSComputeTransientVariable(ts, bdf->work[i], bdf->tvwork[i]));
352: }
353: }
354: }
355: PetscFunctionReturn(PETSC_SUCCESS);
356: }
358: static PetscErrorCode SNESTSFormFunction_BDF(SNES snes, Vec X, Vec F, TS ts)
359: {
360: TS_BDF *bdf = (TS_BDF *)ts->data;
361: DM dm, dmsave = ts->dm;
362: PetscReal t = bdf->time[0];
363: PetscReal shift = bdf->shift;
364: Vec V, V0;
366: PetscFunctionBegin;
367: PetscCall(SNESGetDM(snes, &dm));
368: PetscCall(TSBDF_GetVecs(ts, dm, &V, &V0));
369: if (bdf->transientvar) { /* shift*C(X) + V0 */
370: PetscCall(TSComputeTransientVariable(ts, X, V));
371: PetscCall(VecAYPX(V, shift, V0));
372: } else { /* shift*X + V0 */
373: PetscCall(VecWAXPY(V, shift, X, V0));
374: }
376: /* F = Function(t,X,V) */
377: ts->dm = dm;
378: PetscCall(TSComputeIFunction(ts, t, X, V, F, PETSC_FALSE));
379: ts->dm = dmsave;
381: PetscCall(TSBDF_RestoreVecs(ts, dm, &V, &V0));
382: PetscFunctionReturn(PETSC_SUCCESS);
383: }
385: static PetscErrorCode SNESTSFormJacobian_BDF(SNES snes, Vec X, Mat J, Mat P, TS ts)
386: {
387: TS_BDF *bdf = (TS_BDF *)ts->data;
388: DM dm, dmsave = ts->dm;
389: PetscReal t = bdf->time[0];
390: PetscReal shift = bdf->shift;
391: Vec V, V0;
393: PetscFunctionBegin;
394: PetscCall(SNESGetDM(snes, &dm));
395: PetscCall(TSBDF_GetVecs(ts, dm, &V, &V0));
397: /* J,P = Jacobian(t,X,V) */
398: ts->dm = dm;
399: PetscCall(TSComputeIJacobian(ts, t, X, V, shift, J, P, PETSC_FALSE));
400: ts->dm = dmsave;
402: PetscCall(TSBDF_RestoreVecs(ts, dm, &V, &V0));
403: PetscFunctionReturn(PETSC_SUCCESS);
404: }
406: static PetscErrorCode TSReset_BDF(TS ts)
407: {
408: TS_BDF *bdf = (TS_BDF *)ts->data;
409: size_t i, n = PETSC_STATIC_ARRAY_LENGTH(bdf->work);
411: PetscFunctionBegin;
412: for (i = 0; i < n; i++) {
413: PetscCall(VecDestroy(&bdf->work[i]));
414: PetscCall(VecDestroy(&bdf->tvwork[i]));
415: }
416: PetscCall(VecDestroy(&bdf->vec_dot));
417: PetscCall(VecDestroy(&bdf->vec_wrk));
418: PetscCall(VecDestroy(&bdf->vec_lte));
419: if (ts->dm) PetscCall(DMCoarsenHookRemove(ts->dm, DMCoarsenHook_TSBDF, DMRestrictHook_TSBDF, ts));
420: PetscFunctionReturn(PETSC_SUCCESS);
421: }
423: static PetscErrorCode TSDestroy_BDF(TS ts)
424: {
425: PetscFunctionBegin;
426: PetscCall(TSReset_BDF(ts));
427: PetscCall(PetscFree(ts->data));
428: PetscCall(PetscObjectComposeFunction((PetscObject)ts, "TSBDFSetOrder_C", NULL));
429: PetscCall(PetscObjectComposeFunction((PetscObject)ts, "TSBDFGetOrder_C", NULL));
430: PetscFunctionReturn(PETSC_SUCCESS);
431: }
433: static PetscErrorCode TSSetUp_BDF(TS ts)
434: {
435: TS_BDF *bdf = (TS_BDF *)ts->data;
436: size_t n = PETSC_STATIC_ARRAY_LENGTH(bdf->work);
437: PetscReal low, high, two = 2;
438: PetscInt cnt = 0;
440: PetscFunctionBegin;
441: PetscCall(TSHasTransientVariable(ts, &bdf->transientvar));
442: for (size_t i = 0; i < n; i++) {
443: if (!bdf->work[i]) PetscCall(VecDuplicate(ts->vec_sol, &bdf->work[i]));
444: else cnt++;
445: if (i && bdf->transientvar && !bdf->tvwork[i]) PetscCall(VecDuplicate(ts->vec_sol, &bdf->tvwork[i]));
446: }
447: if (!cnt) bdf->k = bdf->n = 0;
448: PetscCall(VecDuplicate(ts->vec_sol, &bdf->vec_dot));
449: PetscCall(VecDuplicate(ts->vec_sol, &bdf->vec_wrk));
450: PetscCall(VecDuplicate(ts->vec_sol, &bdf->vec_lte));
451: PetscCall(TSGetDM(ts, &ts->dm));
452: PetscCall(DMCoarsenHookAdd(ts->dm, DMCoarsenHook_TSBDF, DMRestrictHook_TSBDF, ts));
454: PetscCall(TSGetAdapt(ts, &ts->adapt));
455: PetscCall(TSAdaptCandidatesClear(ts->adapt));
456: PetscCall(TSAdaptGetClip(ts->adapt, &low, &high));
457: PetscCall(TSAdaptSetClip(ts->adapt, low, PetscMin(high, two)));
459: PetscCall(TSGetSNES(ts, &ts->snes));
460: PetscFunctionReturn(PETSC_SUCCESS);
461: }
463: static PetscErrorCode TSSetFromOptions_BDF(TS ts, PetscOptionItems PetscOptionsObject)
464: {
465: TS_BDF *bdf = (TS_BDF *)ts->data;
467: PetscFunctionBegin;
468: PetscOptionsHeadBegin(PetscOptionsObject, "BDF ODE solver options");
469: {
470: PetscBool flg;
471: PetscInt order;
472: PetscCall(TSBDFGetOrder(ts, &order));
473: PetscCall(PetscOptionsInt("-ts_bdf_order", "Order of the BDF method", "TSBDFSetOrder", order, &order, &flg));
474: if (flg) PetscCall(TSBDFSetOrder(ts, order));
475: PetscCall(PetscOptionsBool("-ts_bdf_initial_guess_extrapolate", "Extrapolate the initial guess of the nonlinear solve from previous time steps", "", bdf->extrapolate, &bdf->extrapolate, NULL));
476: }
477: PetscOptionsHeadEnd();
478: PetscFunctionReturn(PETSC_SUCCESS);
479: }
481: static PetscErrorCode TSView_BDF(TS ts, PetscViewer viewer)
482: {
483: TS_BDF *bdf = (TS_BDF *)ts->data;
484: PetscBool isascii;
486: PetscFunctionBegin;
487: PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
488: if (isascii) PetscCall(PetscViewerASCIIPrintf(viewer, " Order=%" PetscInt_FMT "\n", bdf->order));
489: PetscFunctionReturn(PETSC_SUCCESS);
490: }
492: /* ------------------------------------------------------------ */
494: static PetscErrorCode TSBDFSetOrder_BDF(TS ts, PetscInt order)
495: {
496: TS_BDF *bdf = (TS_BDF *)ts->data;
498: PetscFunctionBegin;
499: if (order == bdf->order) PetscFunctionReturn(PETSC_SUCCESS);
500: PetscCheck(order >= 1 && order <= 6, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "BDF Order %" PetscInt_FMT " not implemented", order);
501: bdf->order = order;
502: PetscFunctionReturn(PETSC_SUCCESS);
503: }
505: static PetscErrorCode TSBDFGetOrder_BDF(TS ts, PetscInt *order)
506: {
507: TS_BDF *bdf = (TS_BDF *)ts->data;
509: PetscFunctionBegin;
510: *order = bdf->order;
511: PetscFunctionReturn(PETSC_SUCCESS);
512: }
514: /* ------------------------------------------------------------ */
516: /*MC
517: TSBDF - DAE solver using BDF methods
519: Level: beginner
521: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetType()`, `TSType`
522: M*/
523: PETSC_EXTERN PetscErrorCode TSCreate_BDF(TS ts)
524: {
525: TS_BDF *bdf;
527: PetscFunctionBegin;
528: ts->ops->reset = TSReset_BDF;
529: ts->ops->destroy = TSDestroy_BDF;
530: ts->ops->view = TSView_BDF;
531: ts->ops->setup = TSSetUp_BDF;
532: ts->ops->setfromoptions = TSSetFromOptions_BDF;
533: ts->ops->step = TSStep_BDF;
534: ts->ops->evaluatewlte = TSEvaluateWLTE_BDF;
535: ts->ops->interpolate = TSInterpolate_BDF;
536: ts->ops->resizeregister = TSResizeRegister_BDF;
537: ts->ops->snesfunction = SNESTSFormFunction_BDF;
538: ts->ops->snesjacobian = SNESTSFormJacobian_BDF;
539: ts->default_adapt_type = TSADAPTBASIC;
541: ts->usessnes = PETSC_TRUE;
543: PetscCall(PetscNew(&bdf));
544: ts->data = (void *)bdf;
546: bdf->extrapolate = PETSC_TRUE;
547: bdf->status = TS_STEP_COMPLETE;
548: for (size_t i = 0; i < PETSC_STATIC_ARRAY_LENGTH(bdf->work); i++) bdf->work[i] = bdf->tvwork[i] = NULL;
550: PetscCall(PetscObjectComposeFunction((PetscObject)ts, "TSBDFSetOrder_C", TSBDFSetOrder_BDF));
551: PetscCall(PetscObjectComposeFunction((PetscObject)ts, "TSBDFGetOrder_C", TSBDFGetOrder_BDF));
552: PetscCall(TSBDFSetOrder(ts, 2));
553: PetscFunctionReturn(PETSC_SUCCESS);
554: }
556: /* ------------------------------------------------------------ */
558: /*@
559: TSBDFSetOrder - Set the order of the `TSBDF` method
561: Logically Collective
563: Input Parameters:
564: + ts - timestepping context
565: - order - order of the method
567: Options Database Key:
568: . -ts_bdf_order <order> - select the order
570: Level: intermediate
572: .seealso: `TSBDFGetOrder()`, `TS`, `TSBDF`
573: @*/
574: PetscErrorCode TSBDFSetOrder(TS ts, PetscInt order)
575: {
576: PetscFunctionBegin;
579: PetscTryMethod(ts, "TSBDFSetOrder_C", (TS, PetscInt), (ts, order));
580: PetscFunctionReturn(PETSC_SUCCESS);
581: }
583: /*@
584: TSBDFGetOrder - Get the order of the `TSBDF` method
586: Not Collective
588: Input Parameter:
589: . ts - timestepping context
591: Output Parameter:
592: . order - order of the method
594: Level: intermediate
596: .seealso: `TSBDFSetOrder()`, `TS`, `TSBDF`
597: @*/
598: PetscErrorCode TSBDFGetOrder(TS ts, PetscInt *order)
599: {
600: PetscFunctionBegin;
602: PetscAssertPointer(order, 2);
603: PetscUseMethod(ts, "TSBDFGetOrder_C", (TS, PetscInt *), (ts, order));
604: PetscFunctionReturn(PETSC_SUCCESS);
605: }