1 #define PETSCKSP_DLL 2 3 #include "include/private/kspimpl.h" 4 5 typedef struct { 6 PetscReal haptol; 7 } KSP_SYMMLQ; 8 9 #undef __FUNCT__ 10 #define __FUNCT__ "KSPSetUp_SYMMLQ" 11 PetscErrorCode KSPSetUp_SYMMLQ(KSP ksp) 12 { 13 PetscErrorCode ierr; 14 15 PetscFunctionBegin; 16 if (ksp->pc_side == PC_RIGHT) { 17 SETERRQ(PETSC_ERR_SUP,"No right preconditioning for KSPSYMMLQ"); 18 } else if (ksp->pc_side == PC_SYMMETRIC) { 19 SETERRQ(PETSC_ERR_SUP,"No symmetric preconditioning for KSPSYMMLQ"); 20 } 21 ierr = KSPDefaultGetWork(ksp,9);CHKERRQ(ierr); 22 PetscFunctionReturn(0); 23 } 24 25 #undef __FUNCT__ 26 #define __FUNCT__ "KSPSolve_SYMMLQ" 27 PetscErrorCode KSPSolve_SYMMLQ(KSP ksp) 28 { 29 PetscErrorCode ierr; 30 PetscInt i; 31 PetscScalar alpha,beta,ibeta,betaold,beta1,ceta = 0,ceta_oold = 0.0, ceta_old = 0.0,ceta_bar; 32 PetscScalar c=1.0,cold=1.0,s=0.0,sold=0.0,coold,soold,rho0,rho1,rho2,rho3; 33 PetscScalar dp = 0.0; 34 PetscReal np,s_prod; 35 Vec X,B,R,Z,U,V,W,UOLD,VOLD,Wbar; 36 Mat Amat,Pmat; 37 MatStructure pflag; 38 KSP_SYMMLQ *symmlq = (KSP_SYMMLQ*)ksp->data; 39 PetscTruth diagonalscale; 40 41 PetscFunctionBegin; 42 ierr = PCDiagonalScale(ksp->pc,&diagonalscale);CHKERRQ(ierr); 43 if (diagonalscale) SETERRQ1(PETSC_ERR_SUP,"Krylov method %s does not support diagonal scaling",((PetscObject)ksp)->type_name); 44 45 X = ksp->vec_sol; 46 B = ksp->vec_rhs; 47 R = ksp->work[0]; 48 Z = ksp->work[1]; 49 U = ksp->work[2]; 50 V = ksp->work[3]; 51 W = ksp->work[4]; 52 UOLD = ksp->work[5]; 53 VOLD = ksp->work[6]; 54 Wbar = ksp->work[7]; 55 56 ierr = PCGetOperators(ksp->pc,&Amat,&Pmat,&pflag);CHKERRQ(ierr); 57 58 ksp->its = 0; 59 60 ierr = VecSet(UOLD,0.0);CHKERRQ(ierr); /* u_old <- zeros; */ 61 ierr = VecCopy(UOLD,VOLD);CHKERRQ(ierr); /* v_old <- u_old; */ 62 ierr = VecCopy(UOLD,W);CHKERRQ(ierr); /* w <- u_old; */ 63 ierr = VecCopy(UOLD,Wbar);CHKERRQ(ierr); /* w_bar <- u_old; */ 64 if (!ksp->guess_zero) { 65 ierr = KSP_MatMult(ksp,Amat,X,R);CHKERRQ(ierr); /* r <- b - A*x */ 66 ierr = VecAYPX(R,-1.0,B);CHKERRQ(ierr); 67 } else { 68 ierr = VecCopy(B,R);CHKERRQ(ierr); /* r <- b (x is 0) */ 69 } 70 71 ierr = KSP_PCApply(ksp,R,Z);CHKERRQ(ierr); /* z <- B*r */ 72 ierr = VecDot(R,Z,&dp);CHKERRQ(ierr); /* dp = r'*z; */ 73 if (PetscAbsScalar(dp) < symmlq->haptol) { 74 ierr = PetscInfo2(ksp,"Detected happy breakdown %G tolerance %G\n",PetscAbsScalar(dp),symmlq->haptol);CHKERRQ(ierr); 75 ksp->rnorm = 0.0; /* what should we really put here? */ 76 ksp->reason = KSP_CONVERGED_HAPPY_BREAKDOWN; /* bugfix proposed by Lourens (lourens.vanzanen@shell.com) */ 77 PetscFunctionReturn(0); 78 } 79 80 #if !defined(PETSC_USE_COMPLEX) 81 if (dp < 0.0) { 82 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 83 PetscFunctionReturn(0); 84 } 85 #endif 86 dp = PetscSqrtScalar(dp); 87 beta = dp; /* beta <- sqrt(r'*z) */ 88 beta1 = beta; 89 s_prod = PetscAbsScalar(beta1); 90 91 ierr = VecCopy(R,V);CHKERRQ(ierr); /* v <- r; */ 92 ierr = VecCopy(Z,U);CHKERRQ(ierr); /* u <- z; */ 93 ibeta = 1.0 / beta; 94 ierr = VecScale(V,ibeta);CHKERRQ(ierr); /* v <- ibeta*v; */ 95 ierr = VecScale(U,ibeta);CHKERRQ(ierr); /* u <- ibeta*u; */ 96 ierr = VecCopy(U,Wbar);CHKERRQ(ierr); /* w_bar <- u; */ 97 ierr = VecNorm(Z,NORM_2,&np);CHKERRQ(ierr); /* np <- ||z|| */ 98 KSPLogResidualHistory(ksp,np); 99 KSPMonitor(ksp,0,np); /* call any registered monitor routines */ 100 ksp->rnorm = np; 101 ierr = (*ksp->converged)(ksp,0,np,&ksp->reason,ksp->cnvP);CHKERRQ(ierr); /* test for convergence */ 102 if (ksp->reason) PetscFunctionReturn(0); 103 104 i = 0; ceta = 0.; 105 do { 106 ksp->its = i+1; 107 108 /* Update */ 109 if (ksp->its > 1){ 110 ierr = VecCopy(V,VOLD);CHKERRQ(ierr); /* v_old <- v; */ 111 ierr = VecCopy(U,UOLD);CHKERRQ(ierr); /* u_old <- u; */ 112 113 ierr = VecCopy(R,V);CHKERRQ(ierr); 114 ierr = VecScale(V,1.0/beta);CHKERRQ(ierr); /* v <- ibeta*r; */ 115 ierr = VecCopy(Z,U);CHKERRQ(ierr); 116 ierr = VecScale(U,1.0/beta);CHKERRQ(ierr); /* u <- ibeta*z; */ 117 118 ierr = VecCopy(Wbar,W);CHKERRQ(ierr); 119 ierr = VecScale(W,c);CHKERRQ(ierr); 120 ierr = VecAXPY(W,s,U);CHKERRQ(ierr); /* w <- c*w_bar + s*u; (w_k) */ 121 ierr = VecScale(Wbar,-s);CHKERRQ(ierr); 122 ierr = VecAXPY(Wbar,c,U);CHKERRQ(ierr); /* w_bar <- -s*w_bar + c*u; (w_bar_(k+1)) */ 123 ierr = VecAXPY(X,ceta,W);CHKERRQ(ierr); /* x <- x + ceta * w; (xL_k) */ 124 125 ceta_oold = ceta_old; 126 ceta_old = ceta; 127 } 128 129 /* Lanczos */ 130 ierr = KSP_MatMult(ksp,Amat,U,R);CHKERRQ(ierr); /* r <- Amat*u; */ 131 ierr = VecDot(U,R,&alpha);CHKERRQ(ierr); /* alpha <- u'*r; */ 132 ierr = KSP_PCApply(ksp,R,Z);CHKERRQ(ierr); /* z <- B*r; */ 133 134 ierr = VecAXPY(R,-alpha,V);CHKERRQ(ierr); /* r <- r - alpha* v; */ 135 ierr = VecAXPY(Z,-alpha,U);CHKERRQ(ierr); /* z <- z - alpha* u; */ 136 ierr = VecAXPY(R,-beta,VOLD);CHKERRQ(ierr); /* r <- r - beta * v_old; */ 137 ierr = VecAXPY(Z,-beta,UOLD);CHKERRQ(ierr); /* z <- z - beta * u_old; */ 138 betaold = beta; /* beta_k */ 139 ierr = VecDot(R,Z,&dp);CHKERRQ(ierr); /* dp <- r'*z; */ 140 if (PetscAbsScalar(dp) < symmlq->haptol) { 141 ierr = PetscInfo2(ksp,"Detected happy breakdown %G tolerance %G\n",PetscAbsScalar(dp),symmlq->haptol);CHKERRQ(ierr); 142 dp = 0.0; 143 } 144 145 #if !defined(PETSC_USE_COMPLEX) 146 if (dp < 0.0) { 147 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 148 break; 149 } 150 #endif 151 beta = PetscSqrtScalar(dp); /* beta = sqrt(dp); */ 152 153 /* QR factorization */ 154 coold = cold; cold = c; soold = sold; sold = s; 155 rho0 = cold * alpha - coold * sold * betaold; /* gamma_bar */ 156 rho1 = PetscSqrtScalar(rho0*rho0 + beta*beta); /* gamma */ 157 rho2 = sold * alpha + coold * cold * betaold; /* delta */ 158 rho3 = soold * betaold; /* epsilon */ 159 160 /* Givens rotation: [c -s; s c] (different from the Reference!) */ 161 c = rho0 / rho1; s = beta / rho1; 162 163 if (ksp->its==1){ 164 ceta = beta1/rho1; 165 } else { 166 ceta = -(rho2*ceta_old + rho3*ceta_oold)/rho1; 167 } 168 169 s_prod = s_prod*PetscAbsScalar(s); 170 if (c == 0.0){ 171 np = s_prod*1.e16; 172 } else { 173 np = s_prod/PetscAbsScalar(c); /* residual norm for xc_k (CGNORM) */ 174 } 175 ksp->rnorm = np; 176 KSPLogResidualHistory(ksp,np); 177 KSPMonitor(ksp,i+1,np); 178 ierr = (*ksp->converged)(ksp,i+1,np,&ksp->reason,ksp->cnvP);CHKERRQ(ierr); /* test for convergence */ 179 if (ksp->reason) break; 180 i++; 181 } while (i<ksp->max_it); 182 183 /* move to the CG point: xc_(k+1) */ 184 if (c == 0.0){ 185 ceta_bar = ceta*1.e15; 186 } else { 187 ceta_bar = ceta/c; 188 } 189 ierr = VecAXPY(X,ceta_bar,Wbar);CHKERRQ(ierr); /* x <- x + ceta_bar*w_bar */ 190 191 if (i >= ksp->max_it) { 192 ksp->reason = KSP_DIVERGED_ITS; 193 } 194 PetscFunctionReturn(0); 195 } 196 197 /*MC 198 KSPSYMMLQ - This code implements the SYMMLQ method. 199 200 Options Database Keys: 201 . see KSPSolve() 202 203 Level: beginner 204 205 Notes: The operator and the preconditioner must be symmetric for this method. The 206 preconditioner must be POSITIVE-DEFINITE. 207 208 Reference: Paige & Saunders, 1975. 209 210 .seealso: KSPCreate(), KSPSetType(), KSPType (for list of available types), KSP 211 M*/ 212 EXTERN_C_BEGIN 213 #undef __FUNCT__ 214 #define __FUNCT__ "KSPCreate_SYMMLQ" 215 PetscErrorCode PETSCKSP_DLLEXPORT KSPCreate_SYMMLQ(KSP ksp) 216 { 217 KSP_SYMMLQ *symmlq; 218 PetscErrorCode ierr; 219 220 PetscFunctionBegin; 221 ksp->pc_side = PC_LEFT; 222 223 ierr = PetscNewLog(ksp,KSP_SYMMLQ,&symmlq);CHKERRQ(ierr); 224 symmlq->haptol = 1.e-18; 225 ksp->data = (void*)symmlq; 226 227 /* 228 Sets the functions that are associated with this data structure 229 (in C++ this is the same as defining virtual functions) 230 */ 231 ksp->ops->setup = KSPSetUp_SYMMLQ; 232 ksp->ops->solve = KSPSolve_SYMMLQ; 233 ksp->ops->destroy = KSPDefaultDestroy; 234 ksp->ops->setfromoptions = 0; 235 ksp->ops->buildsolution = KSPDefaultBuildSolution; 236 ksp->ops->buildresidual = KSPDefaultBuildResidual; 237 PetscFunctionReturn(0); 238 } 239 EXTERN_C_END 240 241 242 243 244 245