1 #define PETSCKSP_DLL 2 3 #include "src/ksp/ksp/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",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 dp = 0.0; 76 } 77 78 #if !defined(PETSC_USE_COMPLEX) 79 if (dp < 0.0) { 80 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 81 PetscFunctionReturn(0); 82 } 83 #endif 84 dp = PetscSqrtScalar(dp); 85 beta = dp; /* beta <- sqrt(r'*z) */ 86 beta1 = beta; 87 s_prod = PetscAbsScalar(beta1); 88 89 ierr = VecCopy(R,V);CHKERRQ(ierr); /* v <- r; */ 90 ierr = VecCopy(Z,U);CHKERRQ(ierr); /* u <- z; */ 91 ibeta = 1.0 / beta; 92 ierr = VecScale(V,ibeta);CHKERRQ(ierr); /* v <- ibeta*v; */ 93 ierr = VecScale(U,ibeta);CHKERRQ(ierr); /* u <- ibeta*u; */ 94 ierr = VecCopy(U,Wbar);CHKERRQ(ierr); /* w_bar <- u; */ 95 ierr = VecNorm(Z,NORM_2,&np);CHKERRQ(ierr); /* np <- ||z|| */ 96 KSPLogResidualHistory(ksp,np); 97 KSPMonitor(ksp,0,np); /* call any registered monitor routines */ 98 ksp->rnorm = np; 99 ierr = (*ksp->converged)(ksp,0,np,&ksp->reason,ksp->cnvP);CHKERRQ(ierr); /* test for convergence */ 100 if (ksp->reason) PetscFunctionReturn(0); 101 102 i = 0; ceta = 0.; 103 do { 104 ksp->its = i+1; 105 106 /* Update */ 107 if (ksp->its > 1){ 108 ierr = VecCopy(V,VOLD);CHKERRQ(ierr); /* v_old <- v; */ 109 ierr = VecCopy(U,UOLD);CHKERRQ(ierr); /* u_old <- u; */ 110 111 ierr = VecCopy(R,V);CHKERRQ(ierr); 112 ierr = VecScale(V,1.0/beta);CHKERRQ(ierr); /* v <- ibeta*r; */ 113 ierr = VecCopy(Z,U);CHKERRQ(ierr); 114 ierr = VecScale(U,1.0/beta);CHKERRQ(ierr); /* u <- ibeta*z; */ 115 116 ierr = VecCopy(Wbar,W);CHKERRQ(ierr); 117 ierr = VecScale(W,c);CHKERRQ(ierr); 118 ierr = VecAXPY(W,s,U);CHKERRQ(ierr); /* w <- c*w_bar + s*u; (w_k) */ 119 ierr = VecScale(Wbar,-s);CHKERRQ(ierr); 120 ierr = VecAXPY(Wbar,c,U);CHKERRQ(ierr); /* w_bar <- -s*w_bar + c*u; (w_bar_(k+1)) */ 121 ierr = VecAXPY(X,ceta,W);CHKERRQ(ierr); /* x <- x + ceta * w; (xL_k) */ 122 123 ceta_oold = ceta_old; 124 ceta_old = ceta; 125 } 126 127 /* Lanczos */ 128 ierr = KSP_MatMult(ksp,Amat,U,R);CHKERRQ(ierr); /* r <- Amat*u; */ 129 ierr = VecDot(U,R,&alpha);CHKERRQ(ierr); /* alpha <- u'*r; */ 130 ierr = KSP_PCApply(ksp,R,Z);CHKERRQ(ierr); /* z <- B*r; */ 131 132 ierr = VecAXPY(R,-alpha,V);CHKERRQ(ierr); /* r <- r - alpha* v; */ 133 ierr = VecAXPY(Z,-alpha,U);CHKERRQ(ierr); /* z <- z - alpha* u; */ 134 ierr = VecAXPY(R,-beta,VOLD);CHKERRQ(ierr); /* r <- r - beta * v_old; */ 135 ierr = VecAXPY(Z,-beta,UOLD);CHKERRQ(ierr); /* z <- z - beta * u_old; */ 136 betaold = beta; /* beta_k */ 137 ierr = VecDot(R,Z,&dp);CHKERRQ(ierr); /* dp <- r'*z; */ 138 if (PetscAbsScalar(dp) < symmlq->haptol) { 139 ierr = PetscInfo2(ksp,"Detected happy breakdown %G tolerance %G\n",PetscAbsScalar(dp),symmlq->haptol);CHKERRQ(ierr); 140 dp = 0.0; 141 } 142 143 #if !defined(PETSC_USE_COMPLEX) 144 if (dp < 0.0) { 145 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 146 break; 147 } 148 #endif 149 beta = PetscSqrtScalar(dp); /* beta = sqrt(dp); */ 150 151 /* QR factorization */ 152 coold = cold; cold = c; soold = sold; sold = s; 153 rho0 = cold * alpha - coold * sold * betaold; /* gamma_bar */ 154 rho1 = PetscSqrtScalar(rho0*rho0 + beta*beta); /* gamma */ 155 rho2 = sold * alpha + coold * cold * betaold; /* delta */ 156 rho3 = soold * betaold; /* epsilon */ 157 158 /* Givens rotation: [c -s; s c] (different from the Reference!) */ 159 c = rho0 / rho1; s = beta / rho1; 160 161 if (ksp->its==1){ 162 ceta = beta1/rho1; 163 } else { 164 ceta = -(rho2*ceta_old + rho3*ceta_oold)/rho1; 165 } 166 167 s_prod = s_prod*PetscAbsScalar(s); 168 if (c == 0.0){ 169 np = s_prod*1.e16; 170 } else { 171 np = s_prod/PetscAbsScalar(c); /* residual norm for xc_k (CGNORM) */ 172 } 173 ksp->rnorm = np; 174 KSPLogResidualHistory(ksp,np); 175 KSPMonitor(ksp,i+1,np); 176 ierr = (*ksp->converged)(ksp,i+1,np,&ksp->reason,ksp->cnvP);CHKERRQ(ierr); /* test for convergence */ 177 if (ksp->reason) break; 178 i++; 179 } while (i<ksp->max_it); 180 181 /* move to the CG point: xc_(k+1) */ 182 if (c == 0.0){ 183 ceta_bar = ceta*1.e15; 184 } else { 185 ceta_bar = ceta/c; 186 } 187 ierr = VecAXPY(X,ceta_bar,Wbar);CHKERRQ(ierr); /* x <- x + ceta_bar*w_bar */ 188 189 if (i >= ksp->max_it) { 190 ksp->reason = KSP_DIVERGED_ITS; 191 } 192 PetscFunctionReturn(0); 193 } 194 195 /*MC 196 KSPSYMMLQ - This code implements the SYMMLQ method. 197 198 Options Database Keys: 199 . see KSPSolve() 200 201 Level: beginner 202 203 Notes: Reference: Paige & Saunders, 1975. 204 205 .seealso: KSPCreate(), KSPSetType(), KSPType (for list of available types), KSP 206 M*/ 207 EXTERN_C_BEGIN 208 #undef __FUNCT__ 209 #define __FUNCT__ "KSPCreate_SYMMLQ" 210 PetscErrorCode PETSCKSP_DLLEXPORT KSPCreate_SYMMLQ(KSP ksp) 211 { 212 KSP_SYMMLQ *symmlq; 213 PetscErrorCode ierr; 214 215 PetscFunctionBegin; 216 ksp->pc_side = PC_LEFT; 217 218 ierr = PetscNew(KSP_SYMMLQ,&symmlq);CHKERRQ(ierr); 219 symmlq->haptol = 1.e-18; 220 ksp->data = (void*)symmlq; 221 222 /* 223 Sets the functions that are associated with this data structure 224 (in C++ this is the same as defining virtual functions) 225 */ 226 ksp->ops->setup = KSPSetUp_SYMMLQ; 227 ksp->ops->solve = KSPSolve_SYMMLQ; 228 ksp->ops->destroy = KSPDefaultDestroy; 229 ksp->ops->setfromoptions = 0; 230 ksp->ops->buildsolution = KSPDefaultBuildSolution; 231 ksp->ops->buildresidual = KSPDefaultBuildResidual; 232 PetscFunctionReturn(0); 233 } 234 EXTERN_C_END 235 236 237 238 239 240