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 PetscFunctionBegin; 9 PetscFunctionReturn(0); 10 } 11 12 /* 13 SNESDestroy_NRichardson - Destroys the private SNES_NRichardson context that was created with SNESCreate_NRichardson(). 14 15 Input Parameter: 16 . snes - the SNES context 17 18 Application Interface Routine: SNESDestroy() 19 */ 20 #undef __FUNCT__ 21 #define __FUNCT__ "SNESDestroy_NRichardson" 22 PetscErrorCode SNESDestroy_NRichardson(SNES snes) 23 { 24 PetscErrorCode ierr; 25 26 PetscFunctionBegin; 27 ierr = SNESReset_NRichardson(snes);CHKERRQ(ierr); 28 ierr = PetscFree(snes->data);CHKERRQ(ierr); 29 PetscFunctionReturn(0); 30 } 31 32 /* 33 SNESSetUp_NRichardson - Sets up the internal data structures for the later use 34 of the SNESNRICHARDSON nonlinear solver. 35 36 Input Parameters: 37 + snes - the SNES context 38 - x - the solution vector 39 40 Application Interface Routine: SNESSetUp() 41 */ 42 #undef __FUNCT__ 43 #define __FUNCT__ "SNESSetUp_NRichardson" 44 PetscErrorCode SNESSetUp_NRichardson(SNES snes) 45 { 46 PetscFunctionBegin; 47 PetscFunctionReturn(0); 48 } 49 50 /* 51 SNESSetFromOptions_NRichardson - Sets various parameters for the SNESNEWTONLS method. 52 53 Input Parameter: 54 . snes - the SNES context 55 56 Application Interface Routine: SNESSetFromOptions() 57 */ 58 #undef __FUNCT__ 59 #define __FUNCT__ "SNESSetFromOptions_NRichardson" 60 static PetscErrorCode SNESSetFromOptions_NRichardson(SNES snes) 61 { 62 PetscErrorCode ierr; 63 SNESLineSearch linesearch; 64 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 snes->vec_func_init_set = PETSC_FALSE; 139 140 if (!snes->norm_init_set) { 141 ierr = VecNorm(F,NORM_2,&fnorm);CHKERRQ(ierr); /* fnorm <- ||F|| */ 142 if (PetscIsInfOrNanReal(fnorm)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_FP,"Infinite or not-a-number generated in norm"); 143 } else { 144 fnorm = snes->norm_init; 145 snes->norm_init_set = PETSC_FALSE; 146 } 147 148 ierr = PetscObjectTakeAccess(snes);CHKERRQ(ierr); 149 snes->norm = fnorm; 150 ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr); 151 SNESLogConvHistory(snes,fnorm,0); 152 ierr = SNESMonitor(snes,0,fnorm);CHKERRQ(ierr); 153 154 /* set parameter for default relative tolerance convergence test */ 155 snes->ttol = fnorm*snes->rtol; 156 /* test convergence */ 157 ierr = (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr); 158 if (snes->reason) PetscFunctionReturn(0); 159 160 for (i = 0; i < maxits; i++) { 161 lsSuccess = PETSC_TRUE; 162 /* Call general purpose update function */ 163 if (snes->ops->update) { 164 ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr); 165 } 166 if (snes->pc && snes->pcside == PC_RIGHT) { 167 ierr = VecCopy(X,Y);CHKERRQ(ierr); 168 ierr = SNESSetInitialFunction(snes->pc, F);CHKERRQ(ierr); 169 ierr = SNESSetInitialFunctionNorm(snes->pc, fnorm);CHKERRQ(ierr); 170 ierr = SNESSolve(snes->pc, snes->vec_rhs, Y);CHKERRQ(ierr); 171 ierr = SNESGetConvergedReason(snes->pc,&reason);CHKERRQ(ierr); 172 if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) { 173 snes->reason = SNES_DIVERGED_INNER; 174 PetscFunctionReturn(0); 175 } 176 ierr = VecAYPX(Y,-1.0,X);CHKERRQ(ierr); 177 } else { 178 ierr = VecCopy(F,Y);CHKERRQ(ierr); 179 } 180 ierr = SNESLineSearchApply(snes->linesearch, X, F, &fnorm, Y);CHKERRQ(ierr); 181 ierr = SNESLineSearchGetNorms(snes->linesearch, &xnorm, &fnorm, &ynorm);CHKERRQ(ierr); 182 ierr = SNESLineSearchGetSuccess(snes->linesearch, &lsSuccess);CHKERRQ(ierr); 183 if (!lsSuccess) { 184 if (++snes->numFailures >= snes->maxFailures) { 185 snes->reason = SNES_DIVERGED_LINE_SEARCH; 186 break; 187 } 188 } 189 if (snes->nfuncs >= snes->max_funcs) { 190 snes->reason = SNES_DIVERGED_FUNCTION_COUNT; 191 break; 192 } 193 if (snes->domainerror) { 194 snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN; 195 PetscFunctionReturn(0); 196 } 197 /* Monitor convergence */ 198 ierr = PetscObjectTakeAccess(snes);CHKERRQ(ierr); 199 snes->iter = i+1; 200 snes->norm = fnorm; 201 ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr); 202 SNESLogConvHistory(snes,snes->norm,0); 203 ierr = SNESMonitor(snes,snes->iter,snes->norm);CHKERRQ(ierr); 204 /* Test for convergence */ 205 ierr = (*snes->ops->converged)(snes,snes->iter,xnorm,ynorm,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr); 206 if (snes->reason) break; 207 } 208 if (i == maxits) { 209 ierr = PetscInfo1(snes, "Maximum number of iterations has been reached: %D\n", maxits);CHKERRQ(ierr); 210 if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT; 211 } 212 PetscFunctionReturn(0); 213 } 214 215 /*MC 216 SNESNRICHARDSON - Richardson nonlinear solver that uses successive substitutions, also sometimes known as Picard iteration. 217 218 Level: beginner 219 220 Options Database: 221 + -snes_linesearch_type <l2,cp,basic> Line search type. 222 - -snes_linesearch_damping<1.0> Damping for the line search. 223 224 Notes: If no inner nonlinear preconditioner is provided then solves F(x) - b = 0 using x^{n+1} = x^{n} - lambda 225 (F(x^n) - b) where lambda is obtained either SNESLineSearchSetDamping(), -snes_damping or a line search. If 226 an inner nonlinear preconditioner is provided (either with -npc_snes_type or SNESSetPC()) then the inner 227 solver is called an initial solution x^n and the nonlinear Richardson uses x^{n+1} = x^{n} + lambda d^{n} 228 where d^{n} = \hat{x}^{n} - x^{n} where \hat{x}^{n} is the solution returned from the inner solver. 229 230 The update, especially without inner nonlinear preconditioner, may be ill-scaled. If using the basic 231 linesearch, one may have to scale the update with -snes_linesearch_damping 232 233 This uses no derivative information thus will be much slower then Newton's method obtained with -snes_type ls 234 235 .seealso: SNESCreate(), SNES, SNESSetType(), SNESNEWTONLS, SNESNEWTONTR, SNESNGMRES, SNESQN, SNESNCG 236 M*/ 237 EXTERN_C_BEGIN 238 #undef __FUNCT__ 239 #define __FUNCT__ "SNESCreate_NRichardson" 240 PetscErrorCode SNESCreate_NRichardson(SNES snes) 241 { 242 PetscErrorCode ierr; 243 SNES_NRichardson *neP; 244 245 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 PetscFunctionReturn(0); 265 } 266 EXTERN_C_END 267