1 #define PETSCKSP_DLL 2 3 #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) SETERRQ(((PetscObject)ksp)->comm,PETSC_ERR_SUP,"No right preconditioning for KSPSYMMLQ"); 17 else if (ksp->pc_side == PC_SYMMETRIC) SETERRQ(((PetscObject)ksp)->comm,PETSC_ERR_SUP,"No symmetric preconditioning for KSPSYMMLQ"); 18 ierr = KSPDefaultGetWork(ksp,9);CHKERRQ(ierr); 19 PetscFunctionReturn(0); 20 } 21 22 #undef __FUNCT__ 23 #define __FUNCT__ "KSPSolve_SYMMLQ" 24 PetscErrorCode KSPSolve_SYMMLQ(KSP ksp) 25 { 26 PetscErrorCode ierr; 27 PetscInt i; 28 PetscScalar alpha,beta,ibeta,betaold,beta1,ceta = 0,ceta_oold = 0.0, ceta_old = 0.0,ceta_bar; 29 PetscScalar c=1.0,cold=1.0,s=0.0,sold=0.0,coold,soold,rho0,rho1,rho2,rho3; 30 PetscScalar dp = 0.0; 31 PetscReal np,s_prod; 32 Vec X,B,R,Z,U,V,W,UOLD,VOLD,Wbar; 33 Mat Amat,Pmat; 34 MatStructure pflag; 35 KSP_SYMMLQ *symmlq = (KSP_SYMMLQ*)ksp->data; 36 PetscTruth diagonalscale; 37 38 PetscFunctionBegin; 39 ierr = PCGetDiagonalScale(ksp->pc,&diagonalscale);CHKERRQ(ierr); 40 if (diagonalscale) SETERRQ1(((PetscObject)ksp)->comm,PETSC_ERR_SUP,"Krylov method %s does not support diagonal scaling",((PetscObject)ksp)->type_name); 41 42 X = ksp->vec_sol; 43 B = ksp->vec_rhs; 44 R = ksp->work[0]; 45 Z = ksp->work[1]; 46 U = ksp->work[2]; 47 V = ksp->work[3]; 48 W = ksp->work[4]; 49 UOLD = ksp->work[5]; 50 VOLD = ksp->work[6]; 51 Wbar = ksp->work[7]; 52 53 ierr = PCGetOperators(ksp->pc,&Amat,&Pmat,&pflag);CHKERRQ(ierr); 54 55 ksp->its = 0; 56 57 ierr = VecSet(UOLD,0.0);CHKERRQ(ierr); /* u_old <- zeros; */ 58 ierr = VecCopy(UOLD,VOLD);CHKERRQ(ierr); /* v_old <- u_old; */ 59 ierr = VecCopy(UOLD,W);CHKERRQ(ierr); /* w <- u_old; */ 60 ierr = VecCopy(UOLD,Wbar);CHKERRQ(ierr); /* w_bar <- u_old; */ 61 if (!ksp->guess_zero) { 62 ierr = KSP_MatMult(ksp,Amat,X,R);CHKERRQ(ierr); /* r <- b - A*x */ 63 ierr = VecAYPX(R,-1.0,B);CHKERRQ(ierr); 64 } else { 65 ierr = VecCopy(B,R);CHKERRQ(ierr); /* r <- b (x is 0) */ 66 } 67 68 ierr = KSP_PCApply(ksp,R,Z);CHKERRQ(ierr); /* z <- B*r */ 69 ierr = VecDot(R,Z,&dp);CHKERRQ(ierr); /* dp = r'*z; */ 70 if (PetscAbsScalar(dp) < symmlq->haptol) { 71 ierr = PetscInfo2(ksp,"Detected happy breakdown %G tolerance %G\n",PetscAbsScalar(dp),symmlq->haptol);CHKERRQ(ierr); 72 ksp->rnorm = 0.0; /* what should we really put here? */ 73 ksp->reason = KSP_CONVERGED_HAPPY_BREAKDOWN; /* bugfix proposed by Lourens (lourens.vanzanen@shell.com) */ 74 PetscFunctionReturn(0); 75 } 76 77 #if !defined(PETSC_USE_COMPLEX) 78 if (dp < 0.0) { 79 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 80 PetscFunctionReturn(0); 81 } 82 #endif 83 dp = PetscSqrtScalar(dp); 84 beta = dp; /* beta <- sqrt(r'*z) */ 85 beta1 = beta; 86 s_prod = PetscAbsScalar(beta1); 87 88 ierr = VecCopy(R,V);CHKERRQ(ierr); /* v <- r; */ 89 ierr = VecCopy(Z,U);CHKERRQ(ierr); /* u <- z; */ 90 ibeta = 1.0 / beta; 91 ierr = VecScale(V,ibeta);CHKERRQ(ierr); /* v <- ibeta*v; */ 92 ierr = VecScale(U,ibeta);CHKERRQ(ierr); /* u <- ibeta*u; */ 93 ierr = VecCopy(U,Wbar);CHKERRQ(ierr); /* w_bar <- u; */ 94 ierr = VecNorm(Z,NORM_2,&np);CHKERRQ(ierr); /* np <- ||z|| */ 95 KSPLogResidualHistory(ksp,np); 96 KSPMonitor(ksp,0,np); /* call any registered monitor routines */ 97 ksp->rnorm = np; 98 ierr = (*ksp->converged)(ksp,0,np,&ksp->reason,ksp->cnvP);CHKERRQ(ierr); /* test for convergence */ 99 if (ksp->reason) PetscFunctionReturn(0); 100 101 i = 0; ceta = 0.; 102 do { 103 ksp->its = i+1; 104 105 /* Update */ 106 if (ksp->its > 1){ 107 ierr = VecCopy(V,VOLD);CHKERRQ(ierr); /* v_old <- v; */ 108 ierr = VecCopy(U,UOLD);CHKERRQ(ierr); /* u_old <- u; */ 109 110 ierr = VecCopy(R,V);CHKERRQ(ierr); 111 ierr = VecScale(V,1.0/beta);CHKERRQ(ierr); /* v <- ibeta*r; */ 112 ierr = VecCopy(Z,U);CHKERRQ(ierr); 113 ierr = VecScale(U,1.0/beta);CHKERRQ(ierr); /* u <- ibeta*z; */ 114 115 ierr = VecCopy(Wbar,W);CHKERRQ(ierr); 116 ierr = VecScale(W,c);CHKERRQ(ierr); 117 ierr = VecAXPY(W,s,U);CHKERRQ(ierr); /* w <- c*w_bar + s*u; (w_k) */ 118 ierr = VecScale(Wbar,-s);CHKERRQ(ierr); 119 ierr = VecAXPY(Wbar,c,U);CHKERRQ(ierr); /* w_bar <- -s*w_bar + c*u; (w_bar_(k+1)) */ 120 ierr = VecAXPY(X,ceta,W);CHKERRQ(ierr); /* x <- x + ceta * w; (xL_k) */ 121 122 ceta_oold = ceta_old; 123 ceta_old = ceta; 124 } 125 126 /* Lanczos */ 127 ierr = KSP_MatMult(ksp,Amat,U,R);CHKERRQ(ierr); /* r <- Amat*u; */ 128 ierr = VecDot(U,R,&alpha);CHKERRQ(ierr); /* alpha <- u'*r; */ 129 ierr = KSP_PCApply(ksp,R,Z);CHKERRQ(ierr); /* z <- B*r; */ 130 131 ierr = VecAXPY(R,-alpha,V);CHKERRQ(ierr); /* r <- r - alpha* v; */ 132 ierr = VecAXPY(Z,-alpha,U);CHKERRQ(ierr); /* z <- z - alpha* u; */ 133 ierr = VecAXPY(R,-beta,VOLD);CHKERRQ(ierr); /* r <- r - beta * v_old; */ 134 ierr = VecAXPY(Z,-beta,UOLD);CHKERRQ(ierr); /* z <- z - beta * u_old; */ 135 betaold = beta; /* beta_k */ 136 ierr = VecDot(R,Z,&dp);CHKERRQ(ierr); /* dp <- r'*z; */ 137 if (PetscAbsScalar(dp) < symmlq->haptol) { 138 ierr = PetscInfo2(ksp,"Detected happy breakdown %G tolerance %G\n",PetscAbsScalar(dp),symmlq->haptol);CHKERRQ(ierr); 139 dp = 0.0; 140 } 141 142 #if !defined(PETSC_USE_COMPLEX) 143 if (dp < 0.0) { 144 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 145 break; 146 } 147 #endif 148 beta = PetscSqrtScalar(dp); /* beta = sqrt(dp); */ 149 150 /* QR factorization */ 151 coold = cold; cold = c; soold = sold; sold = s; 152 rho0 = cold * alpha - coold * sold * betaold; /* gamma_bar */ 153 rho1 = PetscSqrtScalar(rho0*rho0 + beta*beta); /* gamma */ 154 rho2 = sold * alpha + coold * cold * betaold; /* delta */ 155 rho3 = soold * betaold; /* epsilon */ 156 157 /* Givens rotation: [c -s; s c] (different from the Reference!) */ 158 c = rho0 / rho1; s = beta / rho1; 159 160 if (ksp->its==1){ 161 ceta = beta1/rho1; 162 } else { 163 ceta = -(rho2*ceta_old + rho3*ceta_oold)/rho1; 164 } 165 166 s_prod = s_prod*PetscAbsScalar(s); 167 if (c == 0.0){ 168 np = s_prod*1.e16; 169 } else { 170 np = s_prod/PetscAbsScalar(c); /* residual norm for xc_k (CGNORM) */ 171 } 172 ksp->rnorm = np; 173 KSPLogResidualHistory(ksp,np); 174 KSPMonitor(ksp,i+1,np); 175 ierr = (*ksp->converged)(ksp,i+1,np,&ksp->reason,ksp->cnvP);CHKERRQ(ierr); /* test for convergence */ 176 if (ksp->reason) break; 177 i++; 178 } while (i<ksp->max_it); 179 180 /* move to the CG point: xc_(k+1) */ 181 if (c == 0.0){ 182 ceta_bar = ceta*1.e15; 183 } else { 184 ceta_bar = ceta/c; 185 } 186 ierr = VecAXPY(X,ceta_bar,Wbar);CHKERRQ(ierr); /* x <- x + ceta_bar*w_bar */ 187 188 if (i >= ksp->max_it) { 189 ksp->reason = KSP_DIVERGED_ITS; 190 } 191 PetscFunctionReturn(0); 192 } 193 194 /*MC 195 KSPSYMMLQ - This code implements the SYMMLQ method. 196 197 Options Database Keys: 198 . see KSPSolve() 199 200 Level: beginner 201 202 Notes: The operator and the preconditioner must be symmetric for this method. The 203 preconditioner must be POSITIVE-DEFINITE. 204 205 Supports only left preconditioning. 206 207 Reference: Paige & Saunders, 1975. 208 209 .seealso: KSPCreate(), KSPSetType(), KSPType (for list of available types), KSP 210 M*/ 211 EXTERN_C_BEGIN 212 #undef __FUNCT__ 213 #define __FUNCT__ "KSPCreate_SYMMLQ" 214 PetscErrorCode PETSCKSP_DLLEXPORT KSPCreate_SYMMLQ(KSP ksp) 215 { 216 KSP_SYMMLQ *symmlq; 217 PetscErrorCode ierr; 218 219 PetscFunctionBegin; 220 if (ksp->pc_side != PC_LEFT) { 221 ierr = PetscInfo(ksp,"WARNING! Setting PC_SIDE for SYMMLQ to left!\n");CHKERRQ(ierr); 222 } 223 ksp->pc_side = PC_LEFT; 224 ierr = PetscNewLog(ksp,KSP_SYMMLQ,&symmlq);CHKERRQ(ierr); 225 symmlq->haptol = 1.e-18; 226 ksp->data = (void*)symmlq; 227 228 /* 229 Sets the functions that are associated with this data structure 230 (in C++ this is the same as defining virtual functions) 231 */ 232 ksp->ops->setup = KSPSetUp_SYMMLQ; 233 ksp->ops->solve = KSPSolve_SYMMLQ; 234 ksp->ops->destroy = KSPDefaultDestroy; 235 ksp->ops->setfromoptions = 0; 236 ksp->ops->buildsolution = KSPDefaultBuildSolution; 237 ksp->ops->buildresidual = KSPDefaultBuildResidual; 238 PetscFunctionReturn(0); 239 } 240 EXTERN_C_END 241 242 243 244 245 246