1 2 #include <petsc/private/kspimpl.h> 3 4 typedef struct { 5 PetscReal haptol; 6 } KSP_SYMMLQ; 7 8 #undef __FUNCT__ 9 #define __FUNCT__ "KSPSetUp_SYMMLQ" 10 PetscErrorCode KSPSetUp_SYMMLQ(KSP ksp) 11 { 12 PetscErrorCode ierr; 13 14 PetscFunctionBegin; 15 ierr = KSPSetWorkVecs(ksp,9);CHKERRQ(ierr); 16 PetscFunctionReturn(0); 17 } 18 19 #undef __FUNCT__ 20 #define __FUNCT__ "KSPSolve_SYMMLQ" 21 PetscErrorCode KSPSolve_SYMMLQ(KSP ksp) 22 { 23 PetscErrorCode ierr; 24 PetscInt i; 25 PetscScalar alpha,beta,ibeta,betaold,beta1,ceta = 0,ceta_oold = 0.0, ceta_old = 0.0,ceta_bar; 26 PetscScalar c = 1.0,cold=1.0,s=0.0,sold=0.0,coold,soold,rho0,rho1,rho2,rho3; 27 PetscScalar dp = 0.0; 28 PetscReal np,s_prod; 29 Vec X,B,R,Z,U,V,W,UOLD,VOLD,Wbar; 30 Mat Amat,Pmat; 31 KSP_SYMMLQ *symmlq = (KSP_SYMMLQ*)ksp->data; 32 PetscBool diagonalscale; 33 34 PetscFunctionBegin; 35 ierr = PCGetDiagonalScale(ksp->pc,&diagonalscale);CHKERRQ(ierr); 36 if (diagonalscale) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"Krylov method %s does not support diagonal scaling",((PetscObject)ksp)->type_name); 37 38 X = ksp->vec_sol; 39 B = ksp->vec_rhs; 40 R = ksp->work[0]; 41 Z = ksp->work[1]; 42 U = ksp->work[2]; 43 V = ksp->work[3]; 44 W = ksp->work[4]; 45 UOLD = ksp->work[5]; 46 VOLD = ksp->work[6]; 47 Wbar = ksp->work[7]; 48 49 ierr = PCGetOperators(ksp->pc,&Amat,&Pmat);CHKERRQ(ierr); 50 51 ksp->its = 0; 52 53 ierr = VecSet(UOLD,0.0);CHKERRQ(ierr); /* u_old <- zeros; */ 54 ierr = VecCopy(UOLD,VOLD);CHKERRQ(ierr); /* v_old <- u_old; */ 55 ierr = VecCopy(UOLD,W);CHKERRQ(ierr); /* w <- u_old; */ 56 ierr = VecCopy(UOLD,Wbar);CHKERRQ(ierr); /* w_bar <- u_old; */ 57 if (!ksp->guess_zero) { 58 ierr = KSP_MatMult(ksp,Amat,X,R);CHKERRQ(ierr); /* r <- b - A*x */ 59 ierr = VecAYPX(R,-1.0,B);CHKERRQ(ierr); 60 } else { 61 ierr = VecCopy(B,R);CHKERRQ(ierr); /* r <- b (x is 0) */ 62 } 63 64 ierr = KSP_PCApply(ksp,R,Z);CHKERRQ(ierr); /* z <- B*r */ 65 ierr = VecDot(R,Z,&dp);CHKERRQ(ierr); /* dp = r'*z; */ 66 if (PetscAbsScalar(dp) < symmlq->haptol) { 67 ierr = PetscInfo2(ksp,"Detected happy breakdown %g tolerance %g\n",(double)PetscAbsScalar(dp),(double)symmlq->haptol);CHKERRQ(ierr); 68 ksp->rnorm = 0.0; /* what should we really put here? */ 69 ksp->reason = KSP_CONVERGED_HAPPY_BREAKDOWN; /* bugfix proposed by Lourens (lourens.vanzanen@shell.com) */ 70 PetscFunctionReturn(0); 71 } 72 73 #if !defined(PETSC_USE_COMPLEX) 74 if (dp < 0.0) { 75 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 76 PetscFunctionReturn(0); 77 } 78 #endif 79 dp = PetscSqrtScalar(dp); 80 beta = dp; /* beta <- sqrt(r'*z) */ 81 beta1 = beta; 82 s_prod = PetscAbsScalar(beta1); 83 84 ierr = VecCopy(R,V);CHKERRQ(ierr); /* v <- r; */ 85 ierr = VecCopy(Z,U);CHKERRQ(ierr); /* u <- z; */ 86 ibeta = 1.0 / beta; 87 ierr = VecScale(V,ibeta);CHKERRQ(ierr); /* v <- ibeta*v; */ 88 ierr = VecScale(U,ibeta);CHKERRQ(ierr); /* u <- ibeta*u; */ 89 ierr = VecCopy(U,Wbar);CHKERRQ(ierr); /* w_bar <- u; */ 90 ierr = VecNorm(Z,NORM_2,&np);CHKERRQ(ierr); /* np <- ||z|| */ 91 ierr = KSPLogResidualHistory(ksp,np);CHKERRQ(ierr); 92 ierr = KSPMonitor(ksp,0,np);CHKERRQ(ierr); 93 ksp->rnorm = np; 94 ierr = (*ksp->converged)(ksp,0,np,&ksp->reason,ksp->cnvP);CHKERRQ(ierr); /* test for convergence */ 95 if (ksp->reason) PetscFunctionReturn(0); 96 97 i = 0; ceta = 0.; 98 do { 99 ksp->its = i+1; 100 101 /* Update */ 102 if (ksp->its > 1) { 103 ierr = VecCopy(V,VOLD);CHKERRQ(ierr); /* v_old <- v; */ 104 ierr = VecCopy(U,UOLD);CHKERRQ(ierr); /* u_old <- u; */ 105 106 ierr = VecCopy(R,V);CHKERRQ(ierr); 107 ierr = VecScale(V,1.0/beta);CHKERRQ(ierr); /* v <- ibeta*r; */ 108 ierr = VecCopy(Z,U);CHKERRQ(ierr); 109 ierr = VecScale(U,1.0/beta);CHKERRQ(ierr); /* u <- ibeta*z; */ 110 111 ierr = VecCopy(Wbar,W);CHKERRQ(ierr); 112 ierr = VecScale(W,c);CHKERRQ(ierr); 113 ierr = VecAXPY(W,s,U);CHKERRQ(ierr); /* w <- c*w_bar + s*u; (w_k) */ 114 ierr = VecScale(Wbar,-s);CHKERRQ(ierr); 115 ierr = VecAXPY(Wbar,c,U);CHKERRQ(ierr); /* w_bar <- -s*w_bar + c*u; (w_bar_(k+1)) */ 116 ierr = VecAXPY(X,ceta,W);CHKERRQ(ierr); /* x <- x + ceta * w; (xL_k) */ 117 118 ceta_oold = ceta_old; 119 ceta_old = ceta; 120 } 121 122 /* Lanczos */ 123 ierr = KSP_MatMult(ksp,Amat,U,R);CHKERRQ(ierr); /* r <- Amat*u; */ 124 ierr = VecDot(U,R,&alpha);CHKERRQ(ierr); /* alpha <- u'*r; */ 125 ierr = KSP_PCApply(ksp,R,Z);CHKERRQ(ierr); /* z <- B*r; */ 126 127 ierr = VecAXPY(R,-alpha,V);CHKERRQ(ierr); /* r <- r - alpha* v; */ 128 ierr = VecAXPY(Z,-alpha,U);CHKERRQ(ierr); /* z <- z - alpha* u; */ 129 ierr = VecAXPY(R,-beta,VOLD);CHKERRQ(ierr); /* r <- r - beta * v_old; */ 130 ierr = VecAXPY(Z,-beta,UOLD);CHKERRQ(ierr); /* z <- z - beta * u_old; */ 131 betaold = beta; /* beta_k */ 132 ierr = VecDot(R,Z,&dp);CHKERRQ(ierr); /* dp <- r'*z; */ 133 if (PetscAbsScalar(dp) < symmlq->haptol) { 134 ierr = PetscInfo2(ksp,"Detected happy breakdown %g tolerance %g\n",(double)PetscAbsScalar(dp),(double)symmlq->haptol);CHKERRQ(ierr); 135 dp = 0.0; 136 } 137 138 #if !defined(PETSC_USE_COMPLEX) 139 if (dp < 0.0) { 140 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 141 break; 142 } 143 #endif 144 beta = PetscSqrtScalar(dp); /* beta = sqrt(dp); */ 145 146 /* QR factorization */ 147 coold = cold; cold = c; soold = sold; sold = s; 148 rho0 = cold * alpha - coold * sold * betaold; /* gamma_bar */ 149 rho1 = PetscSqrtScalar(rho0*rho0 + beta*beta); /* gamma */ 150 rho2 = sold * alpha + coold * cold * betaold; /* delta */ 151 rho3 = soold * betaold; /* epsilon */ 152 153 /* Givens rotation: [c -s; s c] (different from the Reference!) */ 154 c = rho0 / rho1; s = beta / rho1; 155 156 if (ksp->its==1) ceta = beta1/rho1; 157 else ceta = -(rho2*ceta_old + rho3*ceta_oold)/rho1; 158 159 s_prod = s_prod*PetscAbsScalar(s); 160 if (c == 0.0) np = s_prod*1.e16; 161 else np = s_prod/PetscAbsScalar(c); /* residual norm for xc_k (CGNORM) */ 162 163 ksp->rnorm = np; 164 ierr = KSPLogResidualHistory(ksp,np);CHKERRQ(ierr); 165 ierr = KSPMonitor(ksp,i+1,np);CHKERRQ(ierr); 166 ierr = (*ksp->converged)(ksp,i+1,np,&ksp->reason,ksp->cnvP);CHKERRQ(ierr); /* test for convergence */ 167 if (ksp->reason) break; 168 i++; 169 } while (i<ksp->max_it); 170 171 /* move to the CG point: xc_(k+1) */ 172 if (c == 0.0) ceta_bar = ceta*1.e15; 173 else ceta_bar = ceta/c; 174 175 ierr = VecAXPY(X,ceta_bar,Wbar);CHKERRQ(ierr); /* x <- x + ceta_bar*w_bar */ 176 177 if (i >= ksp->max_it) ksp->reason = KSP_DIVERGED_ITS; 178 PetscFunctionReturn(0); 179 } 180 181 /*MC 182 KSPSYMMLQ - This code implements the SYMMLQ method. 183 184 Options Database Keys: 185 . see KSPSolve() 186 187 Level: beginner 188 189 Notes: 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 #undef __FUNCT__ 199 #define __FUNCT__ "KSPCreate_SYMMLQ" 200 PETSC_EXTERN PetscErrorCode KSPCreate_SYMMLQ(KSP ksp) 201 { 202 KSP_SYMMLQ *symmlq; 203 PetscErrorCode ierr; 204 205 PetscFunctionBegin; 206 ierr = KSPSetSupportedNorm(ksp,KSP_NORM_PRECONDITIONED,PC_LEFT,3);CHKERRQ(ierr); 207 208 ierr = PetscNewLog(ksp,&symmlq);CHKERRQ(ierr); 209 symmlq->haptol = 1.e-18; 210 ksp->data = (void*)symmlq; 211 212 /* 213 Sets the functions that are associated with this data structure 214 (in C++ this is the same as defining virtual functions) 215 */ 216 ksp->ops->setup = KSPSetUp_SYMMLQ; 217 ksp->ops->solve = KSPSolve_SYMMLQ; 218 ksp->ops->destroy = KSPDestroyDefault; 219 ksp->ops->setfromoptions = 0; 220 ksp->ops->buildsolution = KSPBuildSolutionDefault; 221 ksp->ops->buildresidual = KSPBuildResidualDefault; 222 PetscFunctionReturn(0); 223 } 224 225 226 227 228 229