1 #include <../src/snes/impls/gs/gsimpl.h> /*I "petscsnes.h" I*/ 2 3 #undef __FUNCT__ 4 #define __FUNCT__ "SNESNGSSetTolerances" 5 /*@ 6 SNESNGSSetTolerances - Sets various parameters used in convergence tests. 7 8 Logically Collective on SNES 9 10 Input Parameters: 11 + snes - the SNES context 12 . abstol - absolute convergence tolerance 13 . rtol - relative convergence tolerance 14 . stol - convergence tolerance in terms of the norm of the change in the solution between steps, || delta x || < stol*|| x || 15 - maxit - maximum number of iterations 16 17 18 Options Database Keys: 19 + -snes_ngs_atol <abstol> - Sets abstol 20 . -snes_ngs_rtol <rtol> - Sets rtol 21 . -snes_ngs_stol <stol> - Sets stol 22 - -snes_max_it <maxit> - Sets maxit 23 24 Level: intermediate 25 26 .keywords: SNES, nonlinear, gauss-seidel, set, convergence, tolerances 27 28 .seealso: SNESSetTrustRegionTolerance() 29 @*/ 30 PetscErrorCode SNESNGSSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit) 31 { 32 SNES_NGS *gs = (SNES_NGS*)snes->data; 33 34 PetscFunctionBegin; 35 PetscValidHeaderSpecific(snes,SNES_CLASSID,1); 36 37 if (abstol != PETSC_DEFAULT) { 38 if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol); 39 gs->abstol = abstol; 40 } 41 if (rtol != PETSC_DEFAULT) { 42 if (rtol < 0.0 || 1.0 <= rtol) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Relative tolerance %g must be non-negative and less than 1.0",(double)rtol); 43 gs->rtol = rtol; 44 } 45 if (stol != PETSC_DEFAULT) { 46 if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol); 47 gs->stol = stol; 48 } 49 if (maxit != PETSC_DEFAULT) { 50 if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit); 51 gs->max_its = maxit; 52 } 53 PetscFunctionReturn(0); 54 } 55 56 #undef __FUNCT__ 57 #define __FUNCT__ "SNESNGSGetTolerances" 58 /*@ 59 SNESNGSGetTolerances - Gets various parameters used in convergence tests. 60 61 Not Collective 62 63 Input Parameters: 64 + snes - the SNES context 65 . atol - absolute convergence tolerance 66 . rtol - relative convergence tolerance 67 . stol - convergence tolerance in terms of the norm 68 of the change in the solution between steps 69 - maxit - maximum number of iterations 70 71 Notes: 72 The user can specify NULL for any parameter that is not needed. 73 74 Level: intermediate 75 76 .keywords: SNES, nonlinear, get, convergence, tolerances 77 78 .seealso: SNESSetTolerances() 79 @*/ 80 PetscErrorCode SNESNGSGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit) 81 { 82 SNES_NGS *gs = (SNES_NGS*)snes->data; 83 84 PetscFunctionBegin; 85 PetscValidHeaderSpecific(snes,SNES_CLASSID,1); 86 if (atol) *atol = gs->abstol; 87 if (rtol) *rtol = gs->rtol; 88 if (stol) *stol = gs->stol; 89 if (maxit) *maxit = gs->max_its; 90 PetscFunctionReturn(0); 91 } 92 93 #undef __FUNCT__ 94 #define __FUNCT__ "SNESNGSSetSweeps" 95 /*@ 96 SNESNGSSetSweeps - Sets the number of sweeps of GS to use. 97 98 Input Parameters: 99 + snes - the SNES context 100 - sweeps - the number of sweeps of GS to perform. 101 102 Level: intermediate 103 104 .keywords: SNES, nonlinear, set, Gauss-Siedel 105 106 .seealso: SNESSetNGS(), SNESGetNGS(), SNESSetPC(), SNESNGSGetSweeps() 107 @*/ 108 109 PetscErrorCode SNESNGSSetSweeps(SNES snes, PetscInt sweeps) 110 { 111 SNES_NGS *gs = (SNES_NGS*)snes->data; 112 113 PetscFunctionBegin; 114 PetscValidHeaderSpecific(snes,SNES_CLASSID,1); 115 gs->sweeps = sweeps; 116 PetscFunctionReturn(0); 117 } 118 119 #undef __FUNCT__ 120 #define __FUNCT__ "SNESNGSGetSweeps" 121 /*@ 122 SNESNGSGetSweeps - Gets the number of sweeps GS will use. 123 124 Input Parameters: 125 . snes - the SNES context 126 127 Output Parameters: 128 . sweeps - the number of sweeps of GS to perform. 129 130 Level: intermediate 131 132 .keywords: SNES, nonlinear, set, Gauss-Siedel 133 134 .seealso: SNESSetNGS(), SNESGetNGS(), SNESSetPC(), SNESNGSSetSweeps() 135 @*/ 136 PetscErrorCode SNESNGSGetSweeps(SNES snes, PetscInt * sweeps) 137 { 138 SNES_NGS *gs = (SNES_NGS*)snes->data; 139 140 PetscFunctionBegin; 141 PetscValidHeaderSpecific(snes,SNES_CLASSID,1); 142 *sweeps = gs->sweeps; 143 PetscFunctionReturn(0); 144 } 145 146 147 #undef __FUNCT__ 148 #define __FUNCT__ "SNESDefaultApplyNGS" 149 PetscErrorCode SNESDefaultApplyNGS(SNES snes,Vec X,Vec F,void *ctx) 150 { 151 PetscFunctionBegin; 152 /* see if there's a coloring on the DM */ 153 PetscFunctionReturn(0); 154 } 155 156 #undef __FUNCT__ 157 #define __FUNCT__ "SNESReset_NGS" 158 PetscErrorCode SNESReset_NGS(SNES snes) 159 { 160 PetscFunctionBegin; 161 PetscFunctionReturn(0); 162 } 163 164 #undef __FUNCT__ 165 #define __FUNCT__ "SNESDestroy_NGS" 166 PetscErrorCode SNESDestroy_NGS(SNES snes) 167 { 168 PetscErrorCode ierr; 169 170 PetscFunctionBegin; 171 ierr = SNESReset_NGS(snes);CHKERRQ(ierr); 172 ierr = PetscFree(snes->data);CHKERRQ(ierr); 173 PetscFunctionReturn(0); 174 } 175 176 #undef __FUNCT__ 177 #define __FUNCT__ "SNESSetUp_NGS" 178 PetscErrorCode SNESSetUp_NGS(SNES snes) 179 { 180 PetscErrorCode ierr; 181 PetscErrorCode (*f)(SNES,Vec,Vec,void*); 182 183 PetscFunctionBegin; 184 ierr = SNESGetNGS(snes,&f,NULL);CHKERRQ(ierr); 185 if (!f) { 186 ierr = SNESSetNGS(snes,SNESComputeNGSDefaultSecant,NULL);CHKERRQ(ierr); 187 } 188 PetscFunctionReturn(0); 189 } 190 191 #undef __FUNCT__ 192 #define __FUNCT__ "SNESSetFromOptions_NGS" 193 PetscErrorCode SNESSetFromOptions_NGS(PetscOptionItems *PetscOptionsObject,SNES snes) 194 { 195 SNES_NGS *gs = (SNES_NGS*)snes->data; 196 PetscErrorCode ierr; 197 PetscInt sweeps,max_its=PETSC_DEFAULT; 198 PetscReal rtol=PETSC_DEFAULT,atol=PETSC_DEFAULT,stol=PETSC_DEFAULT; 199 PetscBool flg,flg1,flg2,flg3; 200 201 PetscFunctionBegin; 202 ierr = PetscOptionsHead(PetscOptionsObject,"SNES GS options");CHKERRQ(ierr); 203 /* GS Options */ 204 ierr = PetscOptionsInt("-snes_ngs_sweeps","Number of sweeps of GS to apply","SNESComputeGS",gs->sweeps,&sweeps,&flg);CHKERRQ(ierr); 205 if (flg) { 206 ierr = SNESNGSSetSweeps(snes,sweeps);CHKERRQ(ierr); 207 } 208 ierr = PetscOptionsReal("-snes_ngs_atol","Absolute residual tolerance for GS iteration","SNESComputeGS",gs->abstol,&atol,&flg);CHKERRQ(ierr); 209 ierr = PetscOptionsReal("-snes_ngs_rtol","Relative residual tolerance for GS iteration","SNESComputeGS",gs->rtol,&rtol,&flg1);CHKERRQ(ierr); 210 ierr = PetscOptionsReal("-snes_ngs_stol","Absolute update tolerance for GS iteration","SNESComputeGS",gs->stol,&stol,&flg2);CHKERRQ(ierr); 211 ierr = PetscOptionsInt("-snes_ngs_max_it","Maximum number of sweeps of GS to apply","SNESComputeGS",gs->max_its,&max_its,&flg3);CHKERRQ(ierr); 212 if (flg || flg1 || flg2 || flg3) { 213 ierr = SNESNGSSetTolerances(snes,atol,rtol,stol,max_its);CHKERRQ(ierr); 214 } 215 flg = PETSC_FALSE; 216 ierr = PetscOptionsBool("-snes_ngs_secant","Use pointwise secant local Jacobian approximation","",flg,&flg,NULL);CHKERRQ(ierr); 217 if (flg) { 218 ierr = SNESSetNGS(snes,SNESComputeNGSDefaultSecant,NULL);CHKERRQ(ierr); 219 ierr = PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");CHKERRQ(ierr); 220 } 221 ierr = PetscOptionsReal("-snes_ngs_secant_h","Differencing parameter for secant search","",gs->h,&gs->h,NULL);CHKERRQ(ierr); 222 ierr = PetscOptionsBool("-snes_ngs_secant_mat_coloring","Use the Jacobian coloring for the secant GS","",gs->secant_mat,&gs->secant_mat,&flg);CHKERRQ(ierr); 223 224 ierr = PetscOptionsTail();CHKERRQ(ierr); 225 PetscFunctionReturn(0); 226 } 227 228 #undef __FUNCT__ 229 #define __FUNCT__ "SNESView_NGS" 230 PetscErrorCode SNESView_NGS(SNES snes, PetscViewer viewer) 231 { 232 PetscFunctionBegin; 233 PetscFunctionReturn(0); 234 } 235 236 #undef __FUNCT__ 237 #define __FUNCT__ "SNESSolve_NGS" 238 PetscErrorCode SNESSolve_NGS(SNES snes) 239 { 240 Vec F; 241 Vec X; 242 Vec B; 243 PetscInt i; 244 PetscReal fnorm; 245 PetscErrorCode ierr; 246 SNESNormSchedule normschedule; 247 248 PetscFunctionBegin; 249 250 if (snes->xl || snes->xu || snes->ops->computevariablebounds) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE, "SNES solver %s does not support bounds", ((PetscObject)snes)->type_name); 251 252 ierr = PetscCitationsRegister(SNESCitation,&SNEScite);CHKERRQ(ierr); 253 X = snes->vec_sol; 254 F = snes->vec_func; 255 B = snes->vec_rhs; 256 257 ierr = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr); 258 snes->iter = 0; 259 snes->norm = 0.; 260 ierr = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr); 261 snes->reason = SNES_CONVERGED_ITERATING; 262 263 ierr = SNESGetNormSchedule(snes, &normschedule);CHKERRQ(ierr); 264 if (normschedule == SNES_NORM_ALWAYS || normschedule == SNES_NORM_INITIAL_ONLY || normschedule == SNES_NORM_INITIAL_FINAL_ONLY) { 265 /* compute the initial function and preconditioned update delX */ 266 if (!snes->vec_func_init_set) { 267 ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr); 268 } else snes->vec_func_init_set = PETSC_FALSE; 269 270 ierr = VecNorm(F, NORM_2, &fnorm);CHKERRQ(ierr); /* fnorm <- ||F|| */ 271 SNESCheckFunctionNorm(snes,fnorm); 272 ierr = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr); 273 snes->iter = 0; 274 snes->norm = fnorm; 275 ierr = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr); 276 ierr = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr); 277 ierr = SNESMonitor(snes,0,snes->norm);CHKERRQ(ierr); 278 279 /* test convergence */ 280 ierr = (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr); 281 if (snes->reason) PetscFunctionReturn(0); 282 } else { 283 ierr = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr); 284 ierr = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr); 285 } 286 287 /* Call general purpose update function */ 288 if (snes->ops->update) { 289 ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr); 290 } 291 292 for (i = 0; i < snes->max_its; i++) { 293 ierr = SNESComputeNGS(snes, B, X);CHKERRQ(ierr); 294 /* only compute norms if requested or about to exit due to maximum iterations */ 295 if (normschedule == SNES_NORM_ALWAYS || ((i == snes->max_its - 1) && (normschedule == SNES_NORM_INITIAL_FINAL_ONLY || normschedule == SNES_NORM_FINAL_ONLY))) { 296 ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr); 297 ierr = VecNorm(F, NORM_2, &fnorm);CHKERRQ(ierr); /* fnorm <- ||F|| */ 298 SNESCheckFunctionNorm(snes,fnorm); 299 /* Monitor convergence */ 300 ierr = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr); 301 snes->iter = i+1; 302 snes->norm = fnorm; 303 ierr = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr); 304 ierr = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr); 305 ierr = SNESMonitor(snes,snes->iter,snes->norm);CHKERRQ(ierr); 306 } 307 /* Test for convergence */ 308 if (normschedule == SNES_NORM_ALWAYS) ierr = (*snes->ops->converged)(snes,snes->iter,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr); 309 if (snes->reason) PetscFunctionReturn(0); 310 /* Call general purpose update function */ 311 if (snes->ops->update) { 312 ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr); 313 } 314 } 315 if (normschedule == SNES_NORM_ALWAYS) { 316 if (i == snes->max_its) { 317 ierr = PetscInfo1(snes,"Maximum number of iterations has been reached: %D\n",snes->max_its);CHKERRQ(ierr); 318 if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT; 319 } 320 } else if (!snes->reason) snes->reason = SNES_CONVERGED_ITS; /* GS is meant to be used as a preconditioner */ 321 PetscFunctionReturn(0); 322 } 323 324 /*MC 325 SNESNGS - Just calls the user-provided solution routine provided with SNESSetNGS() 326 327 Level: advanced 328 329 Notes: 330 the Gauss-Seidel smoother is inherited through composition. If a solver has been created with SNESGetPC(), it will have 331 its parent's Gauss-Seidel routine associated with it. 332 333 References: 334 . 1. - Peter R. Brune, Matthew G. Knepley, Barry F. Smith, and Xuemin Tu, "Composing Scalable Nonlinear Algebraic Solvers", 335 SIAM Review, 57(4), 2015 336 337 .seealso: SNESCreate(), SNES, SNESSetType(), SNESSetNGS(), SNESType (for list of available types) 338 M*/ 339 340 #undef __FUNCT__ 341 #define __FUNCT__ "SNESCreate_NGS" 342 PETSC_EXTERN PetscErrorCode SNESCreate_NGS(SNES snes) 343 { 344 SNES_NGS *gs; 345 PetscErrorCode ierr; 346 347 PetscFunctionBegin; 348 snes->ops->destroy = SNESDestroy_NGS; 349 snes->ops->setup = SNESSetUp_NGS; 350 snes->ops->setfromoptions = SNESSetFromOptions_NGS; 351 snes->ops->view = SNESView_NGS; 352 snes->ops->solve = SNESSolve_NGS; 353 snes->ops->reset = SNESReset_NGS; 354 355 snes->usesksp = PETSC_FALSE; 356 snes->usespc = PETSC_FALSE; 357 358 if (!snes->tolerancesset) { 359 snes->max_its = 10000; 360 snes->max_funcs = 10000; 361 } 362 363 ierr = PetscNewLog(snes,&gs);CHKERRQ(ierr); 364 365 gs->sweeps = 1; 366 gs->rtol = 1e-5; 367 gs->abstol = 1e-15; 368 gs->stol = 1e-12; 369 gs->max_its = 50; 370 gs->h = 1e-8; 371 372 snes->data = (void*) gs; 373 PetscFunctionReturn(0); 374 } 375