Actual source code: tfqmr.c
2: #include <petsc/private/kspimpl.h>
4: static PetscErrorCode KSPSetUp_TFQMR(KSP ksp)
5: {
7: KSPSetWorkVecs(ksp,9);
8: return 0;
9: }
11: static PetscErrorCode KSPSolve_TFQMR(KSP ksp)
12: {
13: PetscInt i,m;
14: PetscScalar rho,rhoold,a,s,b,eta,etaold,psiold,cf;
15: PetscReal dp,dpold,w,dpest,tau,psi,cm;
16: Vec X,B,V,P,R,RP,T,T1,Q,U,D,AUQ;
18: X = ksp->vec_sol;
19: B = ksp->vec_rhs;
20: R = ksp->work[0];
21: RP = ksp->work[1];
22: V = ksp->work[2];
23: T = ksp->work[3];
24: Q = ksp->work[4];
25: P = ksp->work[5];
26: U = ksp->work[6];
27: D = ksp->work[7];
28: T1 = ksp->work[8];
29: AUQ = V;
31: /* Compute initial preconditioned residual */
32: KSPInitialResidual(ksp,X,V,T,R,B);
34: /* Test for nothing to do */
35: VecNorm(R,NORM_2,&dp);
36: KSPCheckNorm(ksp,dp);
37: PetscObjectSAWsTakeAccess((PetscObject)ksp);
38: if (ksp->normtype != KSP_NORM_NONE) ksp->rnorm = dp;
39: else ksp->rnorm = 0.0;
40: ksp->its = 0;
41: PetscObjectSAWsGrantAccess((PetscObject)ksp);
42: KSPMonitor(ksp,0,ksp->rnorm);
43: (*ksp->converged)(ksp,0,ksp->rnorm,&ksp->reason,ksp->cnvP);
44: if (ksp->reason) return 0;
46: /* Make the initial Rp == R */
47: VecCopy(R,RP);
49: /* Set the initial conditions */
50: etaold = 0.0;
51: psiold = 0.0;
52: tau = dp;
53: dpold = dp;
55: VecDot(R,RP,&rhoold); /* rhoold = (r,rp) */
56: VecCopy(R,U);
57: VecCopy(R,P);
58: KSP_PCApplyBAorAB(ksp,P,V,T);
59: VecSet(D,0.0);
61: i=0;
62: do {
63: PetscObjectSAWsTakeAccess((PetscObject)ksp);
64: ksp->its++;
65: PetscObjectSAWsGrantAccess((PetscObject)ksp);
66: VecDot(V,RP,&s); /* s <- (v,rp) */
67: KSPCheckDot(ksp,s);
68: a = rhoold / s; /* a <- rho / s */
69: VecWAXPY(Q,-a,V,U); /* q <- u - a v */
70: VecWAXPY(T,1.0,U,Q); /* t <- u + q */
71: KSP_PCApplyBAorAB(ksp,T,AUQ,T1);
72: VecAXPY(R,-a,AUQ); /* r <- r - a K (u + q) */
73: VecNorm(R,NORM_2,&dp);
74: KSPCheckNorm(ksp,dp);
75: for (m=0; m<2; m++) {
76: if (!m) w = PetscSqrtReal(dp*dpold);
77: else w = dp;
78: psi = w / tau;
79: cm = 1.0 / PetscSqrtReal(1.0 + psi * psi);
80: tau = tau * psi * cm;
81: eta = cm * cm * a;
82: cf = psiold * psiold * etaold / a;
83: if (!m) {
84: VecAYPX(D,cf,U);
85: } else {
86: VecAYPX(D,cf,Q);
87: }
88: VecAXPY(X,eta,D);
90: dpest = PetscSqrtReal(2*i + m + 2.0) * tau;
91: PetscObjectSAWsTakeAccess((PetscObject)ksp);
92: if (ksp->normtype != KSP_NORM_NONE) ksp->rnorm = dpest;
93: else ksp->rnorm = 0.0;
94: PetscObjectSAWsGrantAccess((PetscObject)ksp);
95: KSPLogResidualHistory(ksp,ksp->rnorm);
96: KSPMonitor(ksp,i+1,ksp->rnorm);
97: (*ksp->converged)(ksp,i+1,ksp->rnorm,&ksp->reason,ksp->cnvP);
98: if (ksp->reason) break;
100: etaold = eta;
101: psiold = psi;
102: }
103: if (ksp->reason) break;
105: VecDot(R,RP,&rho); /* rho <- (r,rp) */
106: b = rho / rhoold; /* b <- rho / rhoold */
107: VecWAXPY(U,b,Q,R); /* u <- r + b q */
108: VecAXPY(Q,b,P);
109: VecWAXPY(P,b,Q,U); /* p <- u + b(q + b p) */
110: KSP_PCApplyBAorAB(ksp,P,V,Q); /* v <- K p */
112: rhoold = rho;
113: dpold = dp;
115: i++;
116: } while (i<ksp->max_it);
117: if (i >= ksp->max_it) ksp->reason = KSP_DIVERGED_ITS;
119: KSPUnwindPreconditioner(ksp,X,T);
120: return 0;
121: }
123: /*MC
124: KSPTFQMR - A transpose free QMR (quasi minimal residual),
126: Options Database Keys:
127: see KSPSolve()
129: Level: beginner
131: Notes:
132: Supports left and right preconditioning, but not symmetric
134: The "residual norm" computed in this algorithm is actually just an upper bound on the actual residual norm.
135: That is for left preconditioning it is a bound on the preconditioned residual and for right preconditioning
136: it is a bound on the true residual.
138: References:
139: . * - Freund, 1993
141: .seealso: KSPCreate(), KSPSetType(), KSPType (for list of available types), KSP, KSPTCQMR
142: M*/
143: PETSC_EXTERN PetscErrorCode KSPCreate_TFQMR(KSP ksp)
144: {
145: KSPSetSupportedNorm(ksp,KSP_NORM_PRECONDITIONED,PC_LEFT,3);
146: KSPSetSupportedNorm(ksp,KSP_NORM_UNPRECONDITIONED,PC_RIGHT,2);
147: KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_LEFT,1);
148: KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_RIGHT,1);
150: ksp->data = (void*)0;
151: ksp->ops->setup = KSPSetUp_TFQMR;
152: ksp->ops->solve = KSPSolve_TFQMR;
153: ksp->ops->destroy = KSPDestroyDefault;
154: ksp->ops->buildsolution = KSPBuildSolutionDefault;
155: ksp->ops->buildresidual = KSPBuildResidualDefault;
156: ksp->ops->setfromoptions = NULL;
157: ksp->ops->view = NULL;
158: return 0;
159: }