1 #include <../src/snes/impls/ngmres/snesngmres.h> /*I "petscsnes.h" I*/ 2 3 extern PetscErrorCode SNESDestroy_NGMRES(SNES); 4 extern PetscErrorCode SNESReset_NGMRES(SNES); 5 extern PetscErrorCode SNESSetUp_NGMRES(SNES); 6 extern PetscErrorCode SNESView_NGMRES(SNES,PetscViewer); 7 8 PETSC_EXTERN const char *const SNESNGMRESRestartTypes[]; 9 10 #undef __FUNCT__ 11 #define __FUNCT__ "SNESSetFromOptions_Anderson" 12 PetscErrorCode SNESSetFromOptions_Anderson(SNES snes) 13 { 14 SNES_NGMRES *ngmres = (SNES_NGMRES*) snes->data; 15 PetscErrorCode ierr; 16 PetscBool debug; 17 SNESLineSearch linesearch; 18 19 PetscFunctionBegin; 20 ierr = PetscOptionsHead("SNES NGMRES options");CHKERRQ(ierr); 21 ierr = PetscOptionsInt("-snes_anderson_m", "Number of directions","SNES",ngmres->msize,&ngmres->msize,NULL);CHKERRQ(ierr); 22 ierr = PetscOptionsReal("-snes_anderson_beta", "Mixing parameter","SNES",ngmres->andersonBeta,&ngmres->andersonBeta,NULL);CHKERRQ(ierr); 23 ierr = PetscOptionsBool("-snes_anderson_monitor", "Monitor steps of Anderson Mixing","SNES",ngmres->monitor ? PETSC_TRUE : PETSC_FALSE,&debug,NULL);CHKERRQ(ierr); 24 ierr = PetscOptionsInt("-snes_anderson_restart", "Iterations before forced restart", "SNES",ngmres->restart_periodic,&ngmres->restart_periodic,NULL);CHKERRQ(ierr); 25 ierr = PetscOptionsInt("-snes_anderson_restart_it", "Tolerance iterations before restart","SNES",ngmres->restart_it,&ngmres->restart_it,NULL);CHKERRQ(ierr); 26 ierr = PetscOptionsEnum("-snes_anderson_restart_type","Restart type","SNESNGMRESSetRestartType",SNESNGMRESRestartTypes, 27 (PetscEnum)ngmres->restart_type,(PetscEnum*)&ngmres->restart_type,NULL);CHKERRQ(ierr); 28 if (debug) { 29 ngmres->monitor = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes));CHKERRQ(ierr); 30 } 31 ierr = PetscOptionsTail();CHKERRQ(ierr); 32 /* set the default type of the line search if the user hasn't already. */ 33 if (!snes->linesearch) { 34 ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr); 35 ierr = SNESLineSearchSetType(linesearch,SNESLINESEARCHBASIC);CHKERRQ(ierr); 36 } 37 PetscFunctionReturn(0); 38 } 39 40 #undef __FUNCT__ 41 #define __FUNCT__ "SNESSolve_Anderson" 42 PetscErrorCode SNESSolve_Anderson(SNES snes) 43 { 44 SNES_NGMRES *ngmres = (SNES_NGMRES*) snes->data; 45 /* present solution, residual, and preconditioned residual */ 46 Vec X,F,B,D; 47 48 /* candidate linear combination answers */ 49 Vec XA,FA,XM,FM,FPC; 50 51 /* coefficients and RHS to the minimization problem */ 52 PetscReal fnorm,fMnorm; 53 PetscReal dnorm,dminnorm=0.0,fminnorm; 54 PetscInt restart_count=0; 55 PetscInt k,k_restart,l,ivec; 56 57 PetscBool selectRestart; 58 59 SNESConvergedReason reason; 60 PetscErrorCode ierr; 61 62 PetscFunctionBegin; 63 /* variable initialization */ 64 snes->reason = SNES_CONVERGED_ITERATING; 65 X = snes->vec_sol; 66 F = snes->vec_func; 67 B = snes->vec_rhs; 68 XA = snes->vec_sol_update; 69 FA = snes->work[0]; 70 D = snes->work[1]; 71 72 /* work for the line search */ 73 XM = snes->work[3]; 74 FM = snes->work[4]; 75 76 ierr = PetscObjectAMSTakeAccess((PetscObject)snes);CHKERRQ(ierr); 77 snes->iter = 0; 78 snes->norm = 0.; 79 ierr = PetscObjectAMSGrantAccess((PetscObject)snes);CHKERRQ(ierr); 80 81 /* initialization */ 82 83 /* r = F(x) */ 84 if (!snes->vec_func_init_set) { 85 ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr); 86 if (snes->domainerror) { 87 snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN; 88 PetscFunctionReturn(0); 89 } 90 } else snes->vec_func_init_set = PETSC_FALSE; 91 92 if (!snes->norm_init_set) { 93 ierr = VecNorm(F,NORM_2,&fnorm);CHKERRQ(ierr); 94 if (PetscIsInfOrNanReal(fnorm)) { 95 snes->reason = SNES_DIVERGED_FNORM_NAN; 96 PetscFunctionReturn(0); 97 } 98 } else { 99 fnorm = snes->norm_init; 100 snes->norm_init_set = PETSC_FALSE; 101 } 102 fminnorm = fnorm; 103 104 ierr = PetscObjectAMSTakeAccess((PetscObject)snes);CHKERRQ(ierr); 105 snes->norm = fnorm; 106 ierr = PetscObjectAMSGrantAccess((PetscObject)snes);CHKERRQ(ierr); 107 ierr = SNESLogConvergenceHistory(snes,fnorm,0);CHKERRQ(ierr); 108 ierr = SNESMonitor(snes,0,fnorm);CHKERRQ(ierr); 109 ierr = (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr); 110 if (snes->reason) PetscFunctionReturn(0); 111 112 k_restart = 0; 113 l = 0; 114 for (k=1; k < snes->max_its+1; k++) { 115 /* select which vector of the stored subspace will be updated */ 116 ivec = k_restart % ngmres->msize; 117 if (snes->pc && snes->pcside == PC_RIGHT) { 118 ierr = VecCopy(X,XM);CHKERRQ(ierr); 119 ierr = SNESSetInitialFunction(snes->pc,F);CHKERRQ(ierr); 120 ierr = SNESSetInitialFunctionNorm(snes->pc,fnorm);CHKERRQ(ierr); 121 122 ierr = PetscLogEventBegin(SNES_NPCSolve,snes->pc,XM,B,0);CHKERRQ(ierr); 123 ierr = SNESSolve(snes->pc,B,XM);CHKERRQ(ierr); 124 ierr = PetscLogEventEnd(SNES_NPCSolve,snes->pc,XM,B,0);CHKERRQ(ierr); 125 126 ierr = SNESGetConvergedReason(snes->pc,&reason);CHKERRQ(ierr); 127 if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) { 128 snes->reason = SNES_DIVERGED_INNER; 129 PetscFunctionReturn(0); 130 } 131 ierr = SNESGetFunction(snes->pc,&FPC,NULL,NULL);CHKERRQ(ierr); 132 ierr = VecCopy(FPC,FM);CHKERRQ(ierr); 133 ierr = SNESGetFunctionNorm(snes->pc,&fMnorm);CHKERRQ(ierr); 134 if (ngmres->andersonBeta != 1.0) { 135 VecAXPBY(XM,(1.0 - ngmres->andersonBeta),ngmres->andersonBeta,X);CHKERRQ(ierr); 136 } 137 } else { 138 ierr = VecCopy(F,FM);CHKERRQ(ierr); 139 ierr = VecCopy(X,XM);CHKERRQ(ierr); 140 ierr = VecAXPY(XM,-ngmres->andersonBeta,FM);CHKERRQ(ierr); 141 fMnorm = fnorm; 142 } 143 144 ierr = SNESNGMRESFormCombinedSolution_Private(snes,l,XM,FM,fMnorm,X,XA,FA);CHKERRQ(ierr); 145 if (ngmres->restart_type == SNES_NGMRES_RESTART_DIFFERENCE) { 146 ierr = SNESNGMRESCalculateDifferences_Private(snes,l,X,F,XM,FM,XA,FA,D,&dnorm,&dminnorm,NULL);CHKERRQ(ierr); 147 ierr = SNESNGMRESSelectRestart_Private(snes,l,fnorm,dnorm,fminnorm,dminnorm,&selectRestart);CHKERRQ(ierr); 148 /* if the restart conditions persist for more than restart_it iterations, restart. */ 149 if (selectRestart) restart_count++; 150 else restart_count = 0; 151 } else if (ngmres->restart_type == SNES_NGMRES_RESTART_PERIODIC) { 152 if (k_restart > ngmres->restart_periodic) { 153 if (ngmres->monitor) ierr = PetscViewerASCIIPrintf(ngmres->monitor,"periodic restart after %D iterations\n",k_restart);CHKERRQ(ierr); 154 restart_count = ngmres->restart_it; 155 } 156 } 157 /* restart after restart conditions have persisted for a fixed number of iterations */ 158 if (restart_count >= ngmres->restart_it) { 159 if (ngmres->monitor) { 160 ierr = PetscViewerASCIIPrintf(ngmres->monitor,"Restarted at iteration %d\n",k_restart);CHKERRQ(ierr); 161 } 162 restart_count = 0; 163 k_restart = 0; 164 l = 0; 165 } else { 166 if (l < ngmres->msize) l++; 167 k_restart++; 168 ierr = SNESNGMRESUpdateSubspace_Private(snes,ivec,l,FM,fnorm,XM);CHKERRQ(ierr); 169 } 170 171 ierr = VecNorm(FA,NORM_2,&fnorm);CHKERRQ(ierr); 172 if (fminnorm > fnorm) fminnorm = fnorm; 173 174 ierr = VecCopy(XA,X);CHKERRQ(ierr); 175 ierr = VecCopy(FA,F);CHKERRQ(ierr); 176 177 ierr = PetscObjectAMSTakeAccess((PetscObject)snes);CHKERRQ(ierr); 178 snes->iter = k; 179 snes->norm = fnorm; 180 ierr = PetscObjectAMSGrantAccess((PetscObject)snes);CHKERRQ(ierr); 181 ierr = SNESLogConvergenceHistory(snes,snes->norm,snes->iter);CHKERRQ(ierr); 182 ierr = SNESMonitor(snes,snes->iter,snes->norm);CHKERRQ(ierr); 183 ierr = (*snes->ops->converged)(snes,snes->iter,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr); 184 if (snes->reason) PetscFunctionReturn(0); 185 } 186 snes->reason = SNES_DIVERGED_MAX_IT; 187 PetscFunctionReturn(0); 188 } 189 190 /*MC 191 SNESAnderson - Anderson Mixing method. 192 193 Level: beginner 194 195 Options Database: 196 + -snes_anderson_m - Number of stored previous solutions and residuals 197 . -snes_anderson_beta - Relaxation parameter; X_{update} = X + \beta F 198 . -snes_anderson_restart_type - Type of restart (see SNESNGMRES) 199 . -snes_anderson_restart_it - Number of iterations of restart conditions before restart 200 . -snes_anderson_restart - Number of iterations before periodic restart 201 - -snes_anderson_monitor - Prints relevant information about the ngmres iteration 202 203 Notes: 204 205 The Anderson Mixing method combines m previous solutions into a minimum-residual solution by solving a small linearized 206 optimization problem at each iteration. 207 208 References: 209 210 "D. G. Anderson. Iterative procedures for nonlinear integral equations. 211 J. Assoc. Comput. Mach., 12:547–560, 1965." 212 213 .seealso: SNESNGMRES, SNESCreate(), SNES, SNESSetType(), SNESType (for list of available types) 214 M*/ 215 216 #undef __FUNCT__ 217 #define __FUNCT__ "SNESCreate_Anderson" 218 PETSC_EXTERN PetscErrorCode SNESCreate_Anderson(SNES snes) 219 { 220 SNES_NGMRES *ngmres; 221 PetscErrorCode ierr; 222 223 PetscFunctionBegin; 224 snes->ops->destroy = SNESDestroy_NGMRES; 225 snes->ops->setup = SNESSetUp_NGMRES; 226 snes->ops->setfromoptions = SNESSetFromOptions_Anderson; 227 snes->ops->view = SNESView_NGMRES; 228 snes->ops->solve = SNESSolve_Anderson; 229 snes->ops->reset = SNESReset_NGMRES; 230 231 snes->usespc = PETSC_TRUE; 232 snes->usesksp = PETSC_FALSE; 233 234 ierr = PetscNewLog(snes,SNES_NGMRES,&ngmres);CHKERRQ(ierr); 235 snes->data = (void*) ngmres; 236 ngmres->msize = 30; 237 238 if (!snes->tolerancesset) { 239 snes->max_funcs = 30000; 240 snes->max_its = 10000; 241 } 242 243 ngmres->additive_linesearch = NULL; 244 ngmres->approxfunc = PETSC_FALSE; 245 ngmres->restart_type = SNES_NGMRES_RESTART_NONE; 246 ngmres->restart_it = 2; 247 ngmres->restart_periodic = 30; 248 ngmres->gammaA = 2.0; 249 ngmres->gammaC = 2.0; 250 ngmres->deltaB = 0.9; 251 ngmres->epsilonB = 0.1; 252 253 ngmres->andersonBeta = 1.0; 254 PetscFunctionReturn(0); 255 } 256 257