1 #include <../src/snes/impls/richardson/snesrichardsonimpl.h> 2 3 4 #undef __FUNCT__ 5 #define __FUNCT__ "SNESReset_NRichardson" 6 PetscErrorCode SNESReset_NRichardson(SNES snes) 7 { 8 9 PetscFunctionBegin; 10 PetscFunctionReturn(0); 11 } 12 13 /* 14 SNESDestroy_NRichardson - Destroys the private SNES_NRichardson context that was created with SNESCreate_NRichardson(). 15 16 Input Parameter: 17 . snes - the SNES context 18 19 Application Interface Routine: SNESDestroy() 20 */ 21 #undef __FUNCT__ 22 #define __FUNCT__ "SNESDestroy_NRichardson" 23 PetscErrorCode SNESDestroy_NRichardson(SNES snes) 24 { 25 PetscErrorCode ierr; 26 27 PetscFunctionBegin; 28 ierr = SNESReset_NRichardson(snes);CHKERRQ(ierr); 29 ierr = PetscFree(snes->data);CHKERRQ(ierr); 30 PetscFunctionReturn(0); 31 } 32 33 /* 34 SNESSetUp_NRichardson - Sets up the internal data structures for the later use 35 of the SNESNRICHARDSON nonlinear solver. 36 37 Input Parameters: 38 + snes - the SNES context 39 - x - the solution vector 40 41 Application Interface Routine: SNESSetUp() 42 */ 43 #undef __FUNCT__ 44 #define __FUNCT__ "SNESSetUp_NRichardson" 45 PetscErrorCode SNESSetUp_NRichardson(SNES snes) 46 { 47 PetscFunctionBegin; 48 PetscFunctionReturn(0); 49 } 50 51 /* 52 SNESSetFromOptions_NRichardson - Sets various parameters for the SNESNEWTONLS method. 53 54 Input Parameter: 55 . snes - the SNES context 56 57 Application Interface Routine: SNESSetFromOptions() 58 */ 59 #undef __FUNCT__ 60 #define __FUNCT__ "SNESSetFromOptions_NRichardson" 61 static PetscErrorCode SNESSetFromOptions_NRichardson(SNES snes) 62 { 63 PetscErrorCode ierr; 64 SNESLineSearch linesearch; 65 PetscFunctionBegin; 66 ierr = PetscOptionsHead("SNES Richardson options");CHKERRQ(ierr); 67 ierr = PetscOptionsTail();CHKERRQ(ierr); 68 if (!snes->linesearch) { 69 ierr = SNESGetSNESLineSearch(snes, &linesearch);CHKERRQ(ierr); 70 ierr = SNESLineSearchSetType(linesearch, SNESLINESEARCHL2);CHKERRQ(ierr); 71 } 72 PetscFunctionReturn(0); 73 } 74 75 /* 76 SNESView_NRichardson - Prints info from the SNESRichardson data structure. 77 78 Input Parameters: 79 + SNES - the SNES context 80 - viewer - visualization context 81 82 Application Interface Routine: SNESView() 83 */ 84 #undef __FUNCT__ 85 #define __FUNCT__ "SNESView_NRichardson" 86 static PetscErrorCode SNESView_NRichardson(SNES snes, PetscViewer viewer) 87 { 88 PetscBool iascii; 89 PetscErrorCode ierr; 90 91 PetscFunctionBegin; 92 ierr = PetscObjectTypeCompare((PetscObject) viewer, PETSCVIEWERASCII, &iascii);CHKERRQ(ierr); 93 if (iascii) { 94 } 95 PetscFunctionReturn(0); 96 } 97 98 /* 99 SNESSolve_NRichardson - Solves a nonlinear system with the Richardson method. 100 101 Input Parameters: 102 . snes - the SNES context 103 104 Output Parameter: 105 . outits - number of iterations until termination 106 107 Application Interface Routine: SNESSolve() 108 */ 109 #undef __FUNCT__ 110 #define __FUNCT__ "SNESSolve_NRichardson" 111 PetscErrorCode SNESSolve_NRichardson(SNES snes) 112 { 113 Vec X, Y, F; 114 PetscReal xnorm, fnorm, ynorm; 115 PetscInt maxits, i; 116 PetscErrorCode ierr; 117 PetscBool lsSuccess; 118 SNESConvergedReason reason; 119 120 PetscFunctionBegin; 121 snes->reason = SNES_CONVERGED_ITERATING; 122 123 maxits = snes->max_its; /* maximum number of iterations */ 124 X = snes->vec_sol; /* X^n */ 125 Y = snes->vec_sol_update; /* \tilde X */ 126 F = snes->vec_func; /* residual vector */ 127 128 ierr = PetscObjectTakeAccess(snes);CHKERRQ(ierr); 129 snes->iter = 0; 130 snes->norm = 0.; 131 ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr); 132 if (!snes->vec_func_init_set) { 133 ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr); 134 if (snes->domainerror) { 135 snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN; 136 PetscFunctionReturn(0); 137 } 138 } else { 139 snes->vec_func_init_set = PETSC_FALSE; 140 } 141 if (!snes->norm_init_set) { 142 ierr = VecNorm(F,NORM_2,&fnorm);CHKERRQ(ierr); /* fnorm <- ||F|| */ 143 if (PetscIsInfOrNanReal(fnorm)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_FP,"Infinite or not-a-number generated in norm"); 144 } else { 145 fnorm = snes->norm_init; 146 snes->norm_init_set = PETSC_FALSE; 147 } 148 149 ierr = PetscObjectTakeAccess(snes);CHKERRQ(ierr); 150 snes->norm = fnorm; 151 ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr); 152 SNESLogConvHistory(snes,fnorm,0); 153 ierr = SNESMonitor(snes,0,fnorm);CHKERRQ(ierr); 154 155 /* set parameter for default relative tolerance convergence test */ 156 snes->ttol = fnorm*snes->rtol; 157 /* test convergence */ 158 ierr = (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr); 159 if (snes->reason) PetscFunctionReturn(0); 160 161 for (i = 0; i < maxits; i++) { 162 lsSuccess = PETSC_TRUE; 163 /* Call general purpose update function */ 164 if (snes->ops->update) { 165 ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr); 166 } 167 if (snes->pc && snes->pcside == PC_RIGHT) { 168 ierr = VecCopy(X,Y);CHKERRQ(ierr); 169 ierr = SNESSetInitialFunction(snes->pc, F);CHKERRQ(ierr); 170 ierr = SNESSetInitialFunctionNorm(snes->pc, fnorm);CHKERRQ(ierr); 171 ierr = SNESSolve(snes->pc, snes->vec_rhs, Y);CHKERRQ(ierr); 172 ierr = SNESGetConvergedReason(snes->pc,&reason);CHKERRQ(ierr); 173 if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) { 174 snes->reason = SNES_DIVERGED_INNER; 175 PetscFunctionReturn(0); 176 } 177 ierr = VecAYPX(Y,-1.0,X);CHKERRQ(ierr); 178 } else { 179 ierr = VecCopy(F,Y);CHKERRQ(ierr); 180 } 181 ierr = SNESLineSearchApply(snes->linesearch, X, F, &fnorm, Y);CHKERRQ(ierr); 182 ierr = SNESLineSearchGetNorms(snes->linesearch, &xnorm, &fnorm, &ynorm);CHKERRQ(ierr); 183 ierr = SNESLineSearchGetSuccess(snes->linesearch, &lsSuccess);CHKERRQ(ierr); 184 if (!lsSuccess) { 185 if (++snes->numFailures >= snes->maxFailures) { 186 snes->reason = SNES_DIVERGED_LINE_SEARCH; 187 break; 188 } 189 } 190 if (snes->nfuncs >= snes->max_funcs) { 191 snes->reason = SNES_DIVERGED_FUNCTION_COUNT; 192 break; 193 } 194 if (snes->domainerror) { 195 snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN; 196 PetscFunctionReturn(0); 197 } 198 /* Monitor convergence */ 199 ierr = PetscObjectTakeAccess(snes);CHKERRQ(ierr); 200 snes->iter = i+1; 201 snes->norm = fnorm; 202 ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr); 203 SNESLogConvHistory(snes,snes->norm,0); 204 ierr = SNESMonitor(snes,snes->iter,snes->norm);CHKERRQ(ierr); 205 /* Test for convergence */ 206 ierr = (*snes->ops->converged)(snes,snes->iter,xnorm,ynorm,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr); 207 if (snes->reason) break; 208 } 209 if (i == maxits) { 210 ierr = PetscInfo1(snes, "Maximum number of iterations has been reached: %D\n", maxits);CHKERRQ(ierr); 211 if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT; 212 } 213 PetscFunctionReturn(0); 214 } 215 216 /*MC 217 SNESNRICHARDSON - Richardson nonlinear solver that uses successive substitutions, also sometimes known as Picard iteration. 218 219 Level: beginner 220 221 Options Database: 222 + -snes_linesearch_type <l2,cp,basic> Line search type. 223 - -snes_linesearch_damping<1.0> Damping for the line search. 224 225 Notes: If no inner nonlinear preconditioner is provided then solves F(x) - b = 0 using x^{n+1} = x^{n} - lambda 226 (F(x^n) - b) where lambda is obtained either SNESLineSearchSetDamping(), -snes_damping or a line search. If 227 an inner nonlinear preconditioner is provided (either with -npc_snes_type or SNESSetPC()) then the inner 228 solver is called an initial solution x^n and the nonlinear Richardson uses x^{n+1} = x^{n} + lambda d^{n} 229 where d^{n} = \hat{x}^{n} - x^{n} where \hat{x}^{n} is the solution returned from the inner solver. 230 231 The update, especially without inner nonlinear preconditioner, may be ill-scaled. If using the basic 232 linesearch, one may have to scale the update with -snes_linesearch_damping 233 234 This uses no derivative information thus will be much slower then Newton's method obtained with -snes_type ls 235 236 .seealso: SNESCreate(), SNES, SNESSetType(), SNESNEWTONLS, SNESNEWTONTR, SNESNGMRES, SNESQN, SNESNCG 237 M*/ 238 EXTERN_C_BEGIN 239 #undef __FUNCT__ 240 #define __FUNCT__ "SNESCreate_NRichardson" 241 PetscErrorCode SNESCreate_NRichardson(SNES snes) 242 { 243 PetscErrorCode ierr; 244 SNES_NRichardson *neP; 245 PetscFunctionBegin; 246 snes->ops->destroy = SNESDestroy_NRichardson; 247 snes->ops->setup = SNESSetUp_NRichardson; 248 snes->ops->setfromoptions = SNESSetFromOptions_NRichardson; 249 snes->ops->view = SNESView_NRichardson; 250 snes->ops->solve = SNESSolve_NRichardson; 251 snes->ops->reset = SNESReset_NRichardson; 252 253 snes->usesksp = PETSC_FALSE; 254 snes->usespc = PETSC_TRUE; 255 256 ierr = PetscNewLog(snes, SNES_NRichardson, &neP);CHKERRQ(ierr); 257 snes->data = (void*) neP; 258 259 if (!snes->tolerancesset) { 260 snes->max_funcs = 30000; 261 snes->max_its = 10000; 262 snes->stol = 1e-20; 263 } 264 265 PetscFunctionReturn(0); 266 } 267 EXTERN_C_END 268