Actual source code: tfqmr.c

  1: #define PETSCKSP_DLL

 3:  #include include/private/kspimpl.h

  7: static PetscErrorCode KSPSetUp_TFQMR(KSP ksp)
  8: {

 12:   if (ksp->pc_side == PC_SYMMETRIC){
 13:     SETERRQ(PETSC_ERR_SUP,"no symmetric preconditioning for KSPTFQMR");
 14:   }
 15:   KSPDefaultGetWork(ksp,9);
 16:   return(0);
 17: }

 21: static PetscErrorCode  KSPSolve_TFQMR(KSP ksp)
 22: {
 24:   PetscInt       i,m;
 25:   PetscScalar    rho,rhoold,a,s,b,eta,etaold,psiold,cf;
 26:   PetscReal      dp,dpold,w,dpest,tau,psi,cm;
 27:   Vec            X,B,V,P,R,RP,T,T1,Q,U,D,AUQ;

 30:   X        = ksp->vec_sol;
 31:   B        = ksp->vec_rhs;
 32:   R        = ksp->work[0];
 33:   RP       = ksp->work[1];
 34:   V        = ksp->work[2];
 35:   T        = ksp->work[3];
 36:   Q        = ksp->work[4];
 37:   P        = ksp->work[5];
 38:   U        = ksp->work[6];
 39:   D        = ksp->work[7];
 40:   T1       = ksp->work[8];
 41:   AUQ      = V;

 43:   /* Compute initial preconditioned residual */
 44:   KSPInitialResidual(ksp,X,V,T,R,B);

 46:   /* Test for nothing to do */
 47:   VecNorm(R,NORM_2,&dp);
 48:   PetscObjectTakeAccess(ksp);
 49:   ksp->rnorm  = dp;
 50:   ksp->its    = 0;
 51:   PetscObjectGrantAccess(ksp);
 52:   KSPMonitor(ksp,0,dp);
 53:   (*ksp->converged)(ksp,0,dp,&ksp->reason,ksp->cnvP);
 54:   if (ksp->reason) return(0);

 56:   /* Make the initial Rp == R */
 57:   VecCopy(R,RP);

 59:   /* Set the initial conditions */
 60:   etaold = 0.0;
 61:   psiold = 0.0;
 62:   tau    = dp;
 63:   dpold  = dp;

 65:   VecDot(R,RP,&rhoold);       /* rhoold = (r,rp)     */
 66:   VecCopy(R,U);
 67:   VecCopy(R,P);
 68:   KSP_PCApplyBAorAB(ksp,P,V,T);
 69:   VecSet(D,0.0);

 71:   i=0;
 72:   do {
 73:     PetscObjectTakeAccess(ksp);
 74:     ksp->its++;
 75:     PetscObjectGrantAccess(ksp);
 76:     VecDot(V,RP,&s);          /* s <- (v,rp)          */
 77:     a = rhoold / s;                                 /* a <- rho / s         */
 78:     VecWAXPY(Q,-a,V,U);  /* q <- u - a v         */
 79:     VecWAXPY(T,1.0,U,Q);     /* t <- u + q           */
 80:     KSP_PCApplyBAorAB(ksp,T,AUQ,T1);
 81:     VecAXPY(R,-a,AUQ);      /* r <- r - a K (u + q) */
 82:     VecNorm(R,NORM_2,&dp);
 83:     for (m=0; m<2; m++) {
 84:       if (!m) {
 85:         w = sqrt(dp*dpold);
 86:       } else {
 87:         w = dp;
 88:       }
 89:       psi = w / tau;
 90:       cm  = 1.0 / sqrt(1.0 + psi * psi);
 91:       tau = tau * psi * cm;
 92:       eta = cm * cm * a;
 93:       cf  = psiold * psiold * etaold / a;
 94:       if (!m) {
 95:         VecAYPX(D,cf,U);
 96:       } else {
 97:         VecAYPX(D,cf,Q);
 98:       }
 99:       VecAXPY(X,eta,D);

101:       dpest = sqrt(m + 1.0) * tau;
102:       PetscObjectTakeAccess(ksp);
103:       ksp->rnorm                                    = dpest;
104:       PetscObjectGrantAccess(ksp);
105:       KSPLogResidualHistory(ksp,dpest);
106:       KSPMonitor(ksp,i+1,dpest);
107:       (*ksp->converged)(ksp,i+1,dpest,&ksp->reason,ksp->cnvP);
108:       if (ksp->reason) break;

110:       etaold = eta;
111:       psiold = psi;
112:     }
113:     if (ksp->reason) break;

115:     VecDot(R,RP,&rho);        /* rho <- (r,rp)       */
116:     b = rho / rhoold;                               /* b <- rho / rhoold   */
117:     VecWAXPY(U,b,Q,R);       /* u <- r + b q        */
118:     VecAXPY(Q,b,P);
119:     VecWAXPY(P,b,Q,U);       /* p <- u + b(q + b p) */
120:     KSP_PCApplyBAorAB(ksp,P,V,Q); /* v <- K p  */

122:     rhoold = rho;
123:     dpold  = dp;

125:     i++;
126:   } while (i<ksp->max_it);
127:   if (i >= ksp->max_it) {
128:     ksp->reason = KSP_DIVERGED_ITS;
129:   }

131:   KSPUnwindPreconditioner(ksp,X,T);
132:   return(0);
133: }

135: /*MC
136:      KSPRTFQMR - A transpose free QMR (quasi minimal residual), 

138:    Options Database Keys:
139: .   see KSPSolve()

141:    Level: beginner

143:    Notes: Reference, Freund, 1993

145: .seealso: KSPCreate(), KSPSetType(), KSPType (for list of available types), KSP, KSPTCQMR
146: M*/
150: PetscErrorCode  KSPCreate_TFQMR(KSP ksp)
151: {
153:   ksp->data                      = (void*)0;
154:   ksp->pc_side                   = PC_LEFT;
155:   ksp->ops->setup                = KSPSetUp_TFQMR;
156:   ksp->ops->solve                = KSPSolve_TFQMR;
157:   ksp->ops->destroy              = KSPDefaultDestroy;
158:   ksp->ops->buildsolution        = KSPDefaultBuildSolution;
159:   ksp->ops->buildresidual        = KSPDefaultBuildResidual;
160:   ksp->ops->setfromoptions       = 0;
161:   ksp->ops->view                 = 0;
162:   return(0);
163: }