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