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,malpha,beta,mbeta,ibeta,betaold,beta1,ceta,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,ms,rho0,rho1,rho2,rho3; 33 PetscScalar mone = -1.0,zero = 0.0,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(&zero,UOLD);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(&mone,B,R);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 = PetscLogInfo((ksp,"KSPSolve_SYMMLQ: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(&ibeta,V);CHKERRQ(ierr); /* v <- ibeta*v; */ 93 ierr = VecScale(&ibeta,U);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; 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 ibeta = 1.0 / beta; 112 ierr = VecCopy(R,V);CHKERRQ(ierr); 113 ierr = VecScale(&ibeta,V);CHKERRQ(ierr); /* v <- ibeta*r; */ 114 ierr = VecCopy(Z,U);CHKERRQ(ierr); 115 ierr = VecScale(&ibeta,U);CHKERRQ(ierr); /* u <- ibeta*z; */ 116 117 ierr = VecCopy(Wbar,W);CHKERRQ(ierr); 118 ierr = VecScale(&c,W);CHKERRQ(ierr); 119 ierr = VecAXPY(&s,U,W);CHKERRQ(ierr); /* w <- c*w_bar + s*u; (w_k) */ 120 ms = -s; 121 ierr = VecScale(&ms,Wbar);CHKERRQ(ierr); 122 ierr = VecAXPY(&c,U,Wbar);CHKERRQ(ierr); /* w_bar <- -s*w_bar + c*u; (w_bar_(k+1)) */ 123 ierr = VecAXPY(&ceta,W,X);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 malpha = - alpha; 135 ierr = VecAXPY(&malpha,V,R);CHKERRQ(ierr); /* r <- r - alpha* v; */ 136 ierr = VecAXPY(&malpha,U,Z);CHKERRQ(ierr); /* z <- z - alpha* u; */ 137 mbeta = - beta; 138 ierr = VecAXPY(&mbeta,VOLD,R);CHKERRQ(ierr); /* r <- r - beta * v_old; */ 139 ierr = VecAXPY(&mbeta,UOLD,Z);CHKERRQ(ierr); /* z <- z - beta * u_old; */ 140 betaold = beta; /* beta_k */ 141 ierr = VecDot(R,Z,&dp);CHKERRQ(ierr); /* dp <- r'*z; */ 142 if (PetscAbsScalar(dp) < symmlq->haptol) { 143 ierr = PetscLogInfo((ksp,"KSPSolve_SYMMLQ:Detected happy breakdown %g tolerance %g\n",PetscAbsScalar(dp),symmlq->haptol));CHKERRQ(ierr); 144 dp = 0.0; 145 } 146 147 #if !defined(PETSC_USE_COMPLEX) 148 if (dp < 0.0) { 149 ksp->reason = KSP_DIVERGED_INDEFINITE_PC; 150 break; 151 } 152 #endif 153 beta = PetscSqrtScalar(dp); /* beta = sqrt(dp); */ 154 155 /* QR factorization */ 156 coold = cold; cold = c; soold = sold; sold = s; 157 rho0 = cold * alpha - coold * sold * betaold; /* gamma_bar */ 158 rho1 = PetscSqrtScalar(rho0*rho0 + beta*beta); /* gamma */ 159 rho2 = sold * alpha + coold * cold * betaold; /* delta */ 160 rho3 = soold * betaold; /* epsilon */ 161 162 /* Givens rotation: [c -s; s c] (different from the Reference!) */ 163 c = rho0 / rho1; s = beta / rho1; 164 165 if (ksp->its==1){ 166 ceta = beta1/rho1; 167 } else { 168 ceta = -(rho2*ceta_old + rho3*ceta_oold)/rho1; 169 } 170 171 s_prod = s_prod*PetscAbsScalar(s); 172 if (c == 0.0){ 173 np = s_prod*1.e16; 174 } else { 175 np = s_prod/PetscAbsScalar(c); /* residual norm for xc_k (CGNORM) */ 176 } 177 ksp->rnorm = np; 178 KSPLogResidualHistory(ksp,np); 179 KSPMonitor(ksp,i+1,np); 180 ierr = (*ksp->converged)(ksp,i+1,np,&ksp->reason,ksp->cnvP);CHKERRQ(ierr); /* test for convergence */ 181 if (ksp->reason) break; 182 i++; 183 } while (i<ksp->max_it); 184 185 /* move to the CG point: xc_(k+1) */ 186 if (c == 0.0){ 187 ceta_bar = ceta*1.e15; 188 } else { 189 ceta_bar = ceta/c; 190 } 191 ierr = VecAXPY(&ceta_bar,Wbar,X);CHKERRQ(ierr); /* x <- x + ceta_bar*w_bar */ 192 193 if (i >= ksp->max_it) { 194 ksp->reason = KSP_DIVERGED_ITS; 195 } 196 PetscFunctionReturn(0); 197 } 198 199 /*MC 200 KSPSYMMLQ - This code implements the SYMMLQ method. 201 202 Options Database Keys: 203 . see KSPSolve() 204 205 Level: beginner 206 207 Notes: 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 ksp->pc_side = PC_LEFT; 221 222 ierr = PetscNew(KSP_SYMMLQ,&symmlq);CHKERRQ(ierr); 223 symmlq->haptol = 1.e-18; 224 ksp->data = (void*)symmlq; 225 226 /* 227 Sets the functions that are associated with this data structure 228 (in C++ this is the same as defining virtual functions) 229 */ 230 ksp->ops->setup = KSPSetUp_SYMMLQ; 231 ksp->ops->solve = KSPSolve_SYMMLQ; 232 ksp->ops->destroy = KSPDefaultDestroy; 233 ksp->ops->setfromoptions = 0; 234 ksp->ops->buildsolution = KSPDefaultBuildSolution; 235 ksp->ops->buildresidual = KSPDefaultBuildResidual; 236 PetscFunctionReturn(0); 237 } 238 EXTERN_C_END 239 240 241 242 243 244