1 2 #include <petsc/private/kspimpl.h> 3 4 typedef struct { 5 PetscReal haptol; 6 } KSP_SYMMLQ; 7 8 PetscErrorCode KSPSetUp_SYMMLQ(KSP ksp) 9 { 10 PetscFunctionBegin; 11 CHKERRQ(KSPSetWorkVecs(ksp,9)); 12 PetscFunctionReturn(0); 13 } 14 15 PetscErrorCode KSPSolve_SYMMLQ(KSP ksp) 16 { 17 PetscInt i; 18 PetscScalar alpha,beta,ibeta,betaold,beta1,ceta = 0,ceta_oold = 0.0, ceta_old = 0.0,ceta_bar; 19 PetscScalar c = 1.0,cold=1.0,s=0.0,sold=0.0,coold,soold,rho0,rho1,rho2,rho3; 20 PetscScalar dp = 0.0; 21 PetscReal np = 0.0,s_prod; 22 Vec X,B,R,Z,U,V,W,UOLD,VOLD,Wbar; 23 Mat Amat,Pmat; 24 KSP_SYMMLQ *symmlq = (KSP_SYMMLQ*)ksp->data; 25 PetscBool diagonalscale; 26 27 PetscFunctionBegin; 28 CHKERRQ(PCGetDiagonalScale(ksp->pc,&diagonalscale)); 29 PetscCheck(!diagonalscale,PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"Krylov method %s does not support diagonal scaling",((PetscObject)ksp)->type_name); 30 31 X = ksp->vec_sol; 32 B = ksp->vec_rhs; 33 R = ksp->work[0]; 34 Z = ksp->work[1]; 35 U = ksp->work[2]; 36 V = ksp->work[3]; 37 W = ksp->work[4]; 38 UOLD = ksp->work[5]; 39 VOLD = ksp->work[6]; 40 Wbar = ksp->work[7]; 41 42 CHKERRQ(PCGetOperators(ksp->pc,&Amat,&Pmat)); 43 44 ksp->its = 0; 45 46 CHKERRQ(VecSet(UOLD,0.0)); /* u_old <- zeros; */ 47 CHKERRQ(VecCopy(UOLD,VOLD)); /* v_old <- u_old; */ 48 CHKERRQ(VecCopy(UOLD,W)); /* w <- u_old; */ 49 CHKERRQ(VecCopy(UOLD,Wbar)); /* w_bar <- u_old; */ 50 if (!ksp->guess_zero) { 51 CHKERRQ(KSP_MatMult(ksp,Amat,X,R)); /* r <- b - A*x */ 52 CHKERRQ(VecAYPX(R,-1.0,B)); 53 } else { 54 CHKERRQ(VecCopy(B,R)); /* r <- b (x is 0) */ 55 } 56 57 CHKERRQ(KSP_PCApply(ksp,R,Z)); /* z <- B*r */ 58 CHKERRQ(VecDot(R,Z,&dp)); /* dp = r'*z; */ 59 KSPCheckDot(ksp,dp); 60 if (PetscAbsScalar(dp) < symmlq->haptol) { 61 CHKERRQ(PetscInfo(ksp,"Detected happy breakdown %g tolerance %g\n",(double)PetscAbsScalar(dp),(double)symmlq->haptol)); 62 ksp->rnorm = 0.0; /* what should we really put here? */ 63 ksp->reason = KSP_CONVERGED_HAPPY_BREAKDOWN; /* bugfix proposed by Lourens (lourens.vanzanen@shell.com) */ 64 PetscFunctionReturn(0); 65 } 66 67 #if !defined(PETSC_USE_COMPLEX) 68 if (dp < 0.0) { 69 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 70 PetscFunctionReturn(0); 71 } 72 #endif 73 dp = PetscSqrtScalar(dp); 74 beta = dp; /* beta <- sqrt(r'*z) */ 75 beta1 = beta; 76 s_prod = PetscAbsScalar(beta1); 77 78 CHKERRQ(VecCopy(R,V)); /* v <- r; */ 79 CHKERRQ(VecCopy(Z,U)); /* u <- z; */ 80 ibeta = 1.0 / beta; 81 CHKERRQ(VecScale(V,ibeta)); /* v <- ibeta*v; */ 82 CHKERRQ(VecScale(U,ibeta)); /* u <- ibeta*u; */ 83 CHKERRQ(VecCopy(U,Wbar)); /* w_bar <- u; */ 84 if (ksp->normtype != KSP_NORM_NONE) { 85 CHKERRQ(VecNorm(Z,NORM_2,&np)); /* np <- ||z|| */ 86 KSPCheckNorm(ksp,np); 87 } 88 CHKERRQ(KSPLogResidualHistory(ksp,np)); 89 CHKERRQ(KSPMonitor(ksp,0,np)); 90 ksp->rnorm = np; 91 CHKERRQ((*ksp->converged)(ksp,0,np,&ksp->reason,ksp->cnvP)); /* test for convergence */ 92 if (ksp->reason) PetscFunctionReturn(0); 93 94 i = 0; ceta = 0.; 95 do { 96 ksp->its = i+1; 97 98 /* Update */ 99 if (ksp->its > 1) { 100 CHKERRQ(VecCopy(V,VOLD)); /* v_old <- v; */ 101 CHKERRQ(VecCopy(U,UOLD)); /* u_old <- u; */ 102 103 CHKERRQ(VecCopy(R,V)); 104 CHKERRQ(VecScale(V,1.0/beta)); /* v <- ibeta*r; */ 105 CHKERRQ(VecCopy(Z,U)); 106 CHKERRQ(VecScale(U,1.0/beta)); /* u <- ibeta*z; */ 107 108 CHKERRQ(VecCopy(Wbar,W)); 109 CHKERRQ(VecScale(W,c)); 110 CHKERRQ(VecAXPY(W,s,U)); /* w <- c*w_bar + s*u; (w_k) */ 111 CHKERRQ(VecScale(Wbar,-s)); 112 CHKERRQ(VecAXPY(Wbar,c,U)); /* w_bar <- -s*w_bar + c*u; (w_bar_(k+1)) */ 113 CHKERRQ(VecAXPY(X,ceta,W)); /* x <- x + ceta * w; (xL_k) */ 114 115 ceta_oold = ceta_old; 116 ceta_old = ceta; 117 } 118 119 /* Lanczos */ 120 CHKERRQ(KSP_MatMult(ksp,Amat,U,R)); /* r <- Amat*u; */ 121 CHKERRQ(VecDot(U,R,&alpha)); /* alpha <- u'*r; */ 122 CHKERRQ(KSP_PCApply(ksp,R,Z)); /* z <- B*r; */ 123 124 CHKERRQ(VecAXPY(R,-alpha,V)); /* r <- r - alpha* v; */ 125 CHKERRQ(VecAXPY(Z,-alpha,U)); /* z <- z - alpha* u; */ 126 CHKERRQ(VecAXPY(R,-beta,VOLD)); /* r <- r - beta * v_old; */ 127 CHKERRQ(VecAXPY(Z,-beta,UOLD)); /* z <- z - beta * u_old; */ 128 betaold = beta; /* beta_k */ 129 CHKERRQ(VecDot(R,Z,&dp)); /* dp <- r'*z; */ 130 KSPCheckDot(ksp,dp); 131 if (PetscAbsScalar(dp) < symmlq->haptol) { 132 CHKERRQ(PetscInfo(ksp,"Detected happy breakdown %g tolerance %g\n",(double)PetscAbsScalar(dp),(double)symmlq->haptol)); 133 dp = 0.0; 134 } 135 136 #if !defined(PETSC_USE_COMPLEX) 137 if (dp < 0.0) { 138 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 139 break; 140 } 141 #endif 142 beta = PetscSqrtScalar(dp); /* beta = sqrt(dp); */ 143 144 /* QR factorization */ 145 coold = cold; cold = c; soold = sold; sold = s; 146 rho0 = cold * alpha - coold * sold * betaold; /* gamma_bar */ 147 rho1 = PetscSqrtScalar(rho0*rho0 + beta*beta); /* gamma */ 148 rho2 = sold * alpha + coold * cold * betaold; /* delta */ 149 rho3 = soold * betaold; /* epsilon */ 150 151 /* Givens rotation: [c -s; s c] (different from the Reference!) */ 152 c = rho0 / rho1; s = beta / rho1; 153 154 if (ksp->its==1) ceta = beta1/rho1; 155 else ceta = -(rho2*ceta_old + rho3*ceta_oold)/rho1; 156 157 s_prod = s_prod*PetscAbsScalar(s); 158 if (c == 0.0) np = s_prod*1.e16; 159 else np = s_prod/PetscAbsScalar(c); /* residual norm for xc_k (CGNORM) */ 160 161 if (ksp->normtype != KSP_NORM_NONE) ksp->rnorm = np; 162 else ksp->rnorm = 0.0; 163 CHKERRQ(KSPLogResidualHistory(ksp,ksp->rnorm)); 164 CHKERRQ(KSPMonitor(ksp,i+1,ksp->rnorm)); 165 CHKERRQ((*ksp->converged)(ksp,i+1,ksp->rnorm,&ksp->reason,ksp->cnvP)); /* test for convergence */ 166 if (ksp->reason) break; 167 i++; 168 } while (i<ksp->max_it); 169 170 /* move to the CG point: xc_(k+1) */ 171 if (c == 0.0) ceta_bar = ceta*1.e15; 172 else ceta_bar = ceta/c; 173 174 CHKERRQ(VecAXPY(X,ceta_bar,Wbar)); /* x <- x + ceta_bar*w_bar */ 175 176 if (i >= ksp->max_it) ksp->reason = KSP_DIVERGED_ITS; 177 PetscFunctionReturn(0); 178 } 179 180 /*MC 181 KSPSYMMLQ - This code implements the SYMMLQ method. 182 183 Options Database Keys: 184 see KSPSolve() 185 186 Level: beginner 187 188 Notes: 189 The operator and the preconditioner must be symmetric for this method. The 190 preconditioner must be POSITIVE-DEFINITE. 191 192 Supports only left preconditioning. 193 194 Reference: Paige & Saunders, 1975. 195 196 .seealso: KSPCreate(), KSPSetType(), KSPType (for list of available types), KSP 197 M*/ 198 PETSC_EXTERN PetscErrorCode KSPCreate_SYMMLQ(KSP ksp) 199 { 200 KSP_SYMMLQ *symmlq; 201 202 PetscFunctionBegin; 203 CHKERRQ(KSPSetSupportedNorm(ksp,KSP_NORM_PRECONDITIONED,PC_LEFT,3)); 204 CHKERRQ(KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_LEFT,1)); 205 206 CHKERRQ(PetscNewLog(ksp,&symmlq)); 207 symmlq->haptol = 1.e-18; 208 ksp->data = (void*)symmlq; 209 210 /* 211 Sets the functions that are associated with this data structure 212 (in C++ this is the same as defining virtual functions) 213 */ 214 ksp->ops->setup = KSPSetUp_SYMMLQ; 215 ksp->ops->solve = KSPSolve_SYMMLQ; 216 ksp->ops->destroy = KSPDestroyDefault; 217 ksp->ops->setfromoptions = NULL; 218 ksp->ops->buildsolution = KSPBuildSolutionDefault; 219 ksp->ops->buildresidual = KSPBuildResidualDefault; 220 PetscFunctionReturn(0); 221 } 222