Actual source code: sor.c
petsc-3.4.5 2014-06-29
2: /*
3: Defines a (S)SOR preconditioner for any Mat implementation
4: */
5: #include <petsc-private/pcimpl.h> /*I "petscpc.h" I*/
7: typedef struct {
8: PetscInt its; /* inner iterations, number of sweeps */
9: PetscInt lits; /* local inner iterations, number of sweeps applied by the local matrix mat->A */
10: MatSORType sym; /* forward, reverse, symmetric etc. */
11: PetscReal omega;
12: PetscReal fshift;
13: } PC_SOR;
17: static PetscErrorCode PCDestroy_SOR(PC pc)
18: {
22: PetscFree(pc->data);
23: return(0);
24: }
28: static PetscErrorCode PCApply_SOR(PC pc,Vec x,Vec y)
29: {
30: PC_SOR *jac = (PC_SOR*)pc->data;
32: PetscInt flag = jac->sym | SOR_ZERO_INITIAL_GUESS;
35: MatSOR(pc->pmat,x,jac->omega,(MatSORType)flag,jac->fshift,jac->its,jac->lits,y);
36: return(0);
37: }
41: static PetscErrorCode PCApplyRichardson_SOR(PC pc,Vec b,Vec y,Vec w,PetscReal rtol,PetscReal abstol, PetscReal dtol,PetscInt its,PetscBool guesszero,PetscInt *outits,PCRichardsonConvergedReason *reason)
42: {
43: PC_SOR *jac = (PC_SOR*)pc->data;
45: MatSORType stype = jac->sym;
48: PetscInfo1(pc,"Warning, convergence critera ignored, using %D iterations\n",its);
49: if (guesszero) stype = (MatSORType) (stype | SOR_ZERO_INITIAL_GUESS);
50: MatSOR(pc->pmat,b,jac->omega,stype,jac->fshift,its*jac->its,jac->lits,y);
51: *outits = its;
52: *reason = PCRICHARDSON_CONVERGED_ITS;
53: return(0);
54: }
58: PetscErrorCode PCSetFromOptions_SOR(PC pc)
59: {
60: PC_SOR *jac = (PC_SOR*)pc->data;
62: PetscBool flg;
65: PetscOptionsHead("(S)SOR options");
66: PetscOptionsReal("-pc_sor_omega","relaxation factor (0 < omega < 2)","PCSORSetOmega",jac->omega,&jac->omega,0);
67: PetscOptionsReal("-pc_sor_diagonal_shift","Add to the diagonal entries","",jac->fshift,&jac->fshift,0);
68: PetscOptionsInt("-pc_sor_its","number of inner SOR iterations","PCSORSetIterations",jac->its,&jac->its,0);
69: PetscOptionsInt("-pc_sor_lits","number of local inner SOR iterations","PCSORSetIterations",jac->lits,&jac->lits,0);
70: PetscOptionsBoolGroupBegin("-pc_sor_symmetric","SSOR, not SOR","PCSORSetSymmetric",&flg);
71: if (flg) {PCSORSetSymmetric(pc,SOR_SYMMETRIC_SWEEP);}
72: PetscOptionsBoolGroup("-pc_sor_backward","use backward sweep instead of forward","PCSORSetSymmetric",&flg);
73: if (flg) {PCSORSetSymmetric(pc,SOR_BACKWARD_SWEEP);}
74: PetscOptionsBoolGroup("-pc_sor_forward","use forward sweep","PCSORSetSymmetric",&flg);
75: if (flg) {PCSORSetSymmetric(pc,SOR_FORWARD_SWEEP);}
76: PetscOptionsBoolGroup("-pc_sor_local_symmetric","use SSOR separately on each processor","PCSORSetSymmetric",&flg);
77: if (flg) {PCSORSetSymmetric(pc,SOR_LOCAL_SYMMETRIC_SWEEP);}
78: PetscOptionsBoolGroup("-pc_sor_local_backward","use backward sweep locally","PCSORSetSymmetric",&flg);
79: if (flg) {PCSORSetSymmetric(pc,SOR_LOCAL_BACKWARD_SWEEP);}
80: PetscOptionsBoolGroupEnd("-pc_sor_local_forward","use forward sweep locally","PCSORSetSymmetric",&flg);
81: if (flg) {PCSORSetSymmetric(pc,SOR_LOCAL_FORWARD_SWEEP);}
82: PetscOptionsTail();
83: return(0);
84: }
88: PetscErrorCode PCView_SOR(PC pc,PetscViewer viewer)
89: {
90: PC_SOR *jac = (PC_SOR*)pc->data;
91: MatSORType sym = jac->sym;
92: const char *sortype;
94: PetscBool iascii;
97: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
98: if (iascii) {
99: if (sym & SOR_ZERO_INITIAL_GUESS) {PetscViewerASCIIPrintf(viewer," SOR: zero initial guess\n");}
100: if (sym == SOR_APPLY_UPPER) sortype = "apply_upper";
101: else if (sym == SOR_APPLY_LOWER) sortype = "apply_lower";
102: else if (sym & SOR_EISENSTAT) sortype = "Eisenstat";
103: else if ((sym & SOR_SYMMETRIC_SWEEP) == SOR_SYMMETRIC_SWEEP) sortype = "symmetric";
104: else if (sym & SOR_BACKWARD_SWEEP) sortype = "backward";
105: else if (sym & SOR_FORWARD_SWEEP) sortype = "forward";
106: else if ((sym & SOR_LOCAL_SYMMETRIC_SWEEP) == SOR_LOCAL_SYMMETRIC_SWEEP) sortype = "local_symmetric";
107: else if (sym & SOR_LOCAL_FORWARD_SWEEP) sortype = "local_forward";
108: else if (sym & SOR_LOCAL_BACKWARD_SWEEP) sortype = "local_backward";
109: else sortype = "unknown";
110: PetscViewerASCIIPrintf(viewer," SOR: type = %s, iterations = %D, local iterations = %D, omega = %G\n",sortype,jac->its,jac->lits,jac->omega);
111: }
112: return(0);
113: }
116: /* ------------------------------------------------------------------------------*/
119: static PetscErrorCode PCSORSetSymmetric_SOR(PC pc,MatSORType flag)
120: {
121: PC_SOR *jac;
124: jac = (PC_SOR*)pc->data;
125: jac->sym = flag;
126: return(0);
127: }
131: static PetscErrorCode PCSORSetOmega_SOR(PC pc,PetscReal omega)
132: {
133: PC_SOR *jac;
136: if (omega >= 2.0 || omega <= 0.0) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_OUTOFRANGE,"Relaxation out of range");
137: jac = (PC_SOR*)pc->data;
138: jac->omega = omega;
139: return(0);
140: }
144: static PetscErrorCode PCSORSetIterations_SOR(PC pc,PetscInt its,PetscInt lits)
145: {
146: PC_SOR *jac;
149: jac = (PC_SOR*)pc->data;
150: jac->its = its;
151: jac->lits = lits;
152: return(0);
153: }
155: /* ------------------------------------------------------------------------------*/
158: /*@
159: PCSORSetSymmetric - Sets the SOR preconditioner to use symmetric (SSOR),
160: backward, or forward relaxation. The local variants perform SOR on
161: each processor. By default forward relaxation is used.
163: Logically Collective on PC
165: Input Parameters:
166: + pc - the preconditioner context
167: - flag - one of the following
168: .vb
169: SOR_FORWARD_SWEEP
170: SOR_BACKWARD_SWEEP
171: SOR_SYMMETRIC_SWEEP
172: SOR_LOCAL_FORWARD_SWEEP
173: SOR_LOCAL_BACKWARD_SWEEP
174: SOR_LOCAL_SYMMETRIC_SWEEP
175: .ve
177: Options Database Keys:
178: + -pc_sor_symmetric - Activates symmetric version
179: . -pc_sor_backward - Activates backward version
180: . -pc_sor_local_forward - Activates local forward version
181: . -pc_sor_local_symmetric - Activates local symmetric version
182: - -pc_sor_local_backward - Activates local backward version
184: Notes:
185: To use the Eisenstat trick with SSOR, employ the PCEISENSTAT preconditioner,
186: which can be chosen with the option
187: . -pc_type eisenstat - Activates Eisenstat trick
189: Level: intermediate
191: .keywords: PC, SOR, SSOR, set, relaxation, sweep, forward, backward, symmetric
193: .seealso: PCEisenstatSetOmega(), PCSORSetIterations(), PCSORSetOmega()
194: @*/
195: PetscErrorCode PCSORSetSymmetric(PC pc,MatSORType flag)
196: {
202: PetscTryMethod(pc,"PCSORSetSymmetric_C",(PC,MatSORType),(pc,flag));
203: return(0);
204: }
208: /*@
209: PCSORSetOmega - Sets the SOR relaxation coefficient, omega
210: (where omega = 1.0 by default).
212: Logically Collective on PC
214: Input Parameters:
215: + pc - the preconditioner context
216: - omega - relaxation coefficient (0 < omega < 2).
218: Options Database Key:
219: . -pc_sor_omega <omega> - Sets omega
221: Level: intermediate
223: .keywords: PC, SOR, SSOR, set, relaxation, omega
225: .seealso: PCSORSetSymmetric(), PCSORSetIterations(), PCEisenstatSetOmega()
226: @*/
227: PetscErrorCode PCSORSetOmega(PC pc,PetscReal omega)
228: {
234: PetscTryMethod(pc,"PCSORSetOmega_C",(PC,PetscReal),(pc,omega));
235: return(0);
236: }
240: /*@
241: PCSORSetIterations - Sets the number of inner iterations to
242: be used by the SOR preconditioner. The default is 1.
244: Logically Collective on PC
246: Input Parameters:
247: + pc - the preconditioner context
248: . lits - number of local iterations, smoothings over just variables on processor
249: - its - number of parallel iterations to use; each parallel iteration has lits local iterations
251: Options Database Key:
252: + -pc_sor_its <its> - Sets number of iterations
253: - -pc_sor_lits <lits> - Sets number of local iterations
255: Level: intermediate
257: Notes: When run on one processor the number of smoothings is lits*its
259: .keywords: PC, SOR, SSOR, set, iterations
261: .seealso: PCSORSetOmega(), PCSORSetSymmetric()
262: @*/
263: PetscErrorCode PCSORSetIterations(PC pc,PetscInt its,PetscInt lits)
264: {
270: PetscTryMethod(pc,"PCSORSetIterations_C",(PC,PetscInt,PetscInt),(pc,its,lits));
271: return(0);
272: }
274: /*MC
275: PCSOR - (S)SOR (successive over relaxation, Gauss-Seidel) preconditioning
277: Options Database Keys:
278: + -pc_sor_symmetric - Activates symmetric version
279: . -pc_sor_backward - Activates backward version
280: . -pc_sor_forward - Activates forward version
281: . -pc_sor_local_forward - Activates local forward version
282: . -pc_sor_local_symmetric - Activates local symmetric version (default version)
283: . -pc_sor_local_backward - Activates local backward version
284: . -pc_sor_omega <omega> - Sets omega
285: . -pc_sor_its <its> - Sets number of iterations (default 1)
286: - -pc_sor_lits <lits> - Sets number of local iterations (default 1)
288: Level: beginner
290: Concepts: SOR, preconditioners, Gauss-Seidel
292: Notes: Only implemented for the AIJ and SeqBAIJ matrix formats.
293: Not a true parallel SOR, in parallel this implementation corresponds to block
294: Jacobi with SOR on each block.
296: For SeqBAIJ matrices this implements point-block SOR, but the omega, its, lits options are not supported.
298: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PC,
299: PCSORSetIterations(), PCSORSetSymmetric(), PCSORSetOmega(), PCEISENSTAT
300: M*/
304: PETSC_EXTERN PetscErrorCode PCCreate_SOR(PC pc)
305: {
307: PC_SOR *jac;
310: PetscNewLog(pc,PC_SOR,&jac);
312: pc->ops->apply = PCApply_SOR;
313: pc->ops->applyrichardson = PCApplyRichardson_SOR;
314: pc->ops->setfromoptions = PCSetFromOptions_SOR;
315: pc->ops->setup = 0;
316: pc->ops->view = PCView_SOR;
317: pc->ops->destroy = PCDestroy_SOR;
318: pc->data = (void*)jac;
319: jac->sym = SOR_LOCAL_SYMMETRIC_SWEEP;
320: jac->omega = 1.0;
321: jac->fshift = 0.0;
322: jac->its = 1;
323: jac->lits = 1;
325: PetscObjectComposeFunction((PetscObject)pc,"PCSORSetSymmetric_C",PCSORSetSymmetric_SOR);
326: PetscObjectComposeFunction((PetscObject)pc,"PCSORSetOmega_C",PCSORSetOmega_SOR);
327: PetscObjectComposeFunction((PetscObject)pc,"PCSORSetIterations_C",PCSORSetIterations_SOR);
328: return(0);
329: }