Actual source code: snesmfj.c

petsc-3.10.4 2019-02-26
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  2:  #include <petsc/private/snesimpl.h>
  3:  #include <petscdm.h>
  4:  #include <../src/mat/impls/mffd/mffdimpl.h>
  5:  #include <petsc/private/matimpl.h>

  7: /*@C
  8:    MatMFFDComputeJacobian - Tells the matrix-free Jacobian object the new location at which
  9:        Jacobian matrix vector products will be computed at, i.e. J(x) * a. The x is obtained
 10:        from the SNES object (using SNESGetSolution()).

 12:    Logically Collective on SNES

 14:    Input Parameters:
 15: +   snes - the nonlinear solver context
 16: .   x - the point at which the Jacobian vector products will be performed
 17: .   jac - the matrix-free Jacobian object
 18: .   B - either the same as jac or another matrix type (ignored)
 19: .   flag - not relevent for matrix-free form
 20: -   dummy - the user context (ignored)

 22:    Level: developer

 24:    Warning:
 25:       If MatMFFDSetBase() is ever called on jac then this routine will NO longer get
 26:     the x from the SNES object and MatMFFDSetBase() must from that point on be used to
 27:     change the base vector x.

 29:    Notes:
 30:      This can be passed into SNESSetJacobian() as the Jacobian evaluation function argument
 31:      when using a completely matrix-free solver,
 32:      that is the B matrix is also the same matrix operator. This is used when you select
 33:      -snes_mf but rarely used directly by users. (All this routine does is call MatAssemblyBegin/End() on
 34:      the Mat jac.)

 36: .seealso: MatMFFDGetH(), MatCreateSNESMF(), MatCreateMFFD(), MATMFFD,
 37:           MatMFFDSetHHistory(), MatMFFDSetFunctionError(), MatCreateMFFD(), SNESSetJacobian()

 39: @*/
 40: PetscErrorCode  MatMFFDComputeJacobian(SNES snes,Vec x,Mat jac,Mat B,void *dummy)
 41: {

 45:   MatAssemblyBegin(jac,MAT_FINAL_ASSEMBLY);
 46:   MatAssemblyEnd(jac,MAT_FINAL_ASSEMBLY);
 47:   return(0);
 48: }

 50: PETSC_EXTERN PetscErrorCode MatAssemblyEnd_MFFD(Mat,MatAssemblyType);
 51: PETSC_EXTERN PetscErrorCode MatMFFDSetBase_MFFD(Mat,Vec,Vec);

 53: /*@
 54:     MatSNESMFGetSNES - returns the SNES associated with a matrix created with MatCreateSNESMF()

 56:     Not collective

 58:     Input Parameter:
 59: .   J - the matrix

 61:     Output Parameter:
 62: .   snes - the SNES object

 64:     Level: advanced

 66: .seealso: MatCreateSNESMF()
 67: @*/
 68: PetscErrorCode MatSNESMFGetSNES(Mat J,SNES *snes)
 69: {
 70:   MatMFFD        j    = (MatMFFD)J->data;

 73:   *snes = (SNES)j->ctx;
 74:   return(0);
 75: }

 77: /*
 78:    MatAssemblyEnd_SNESMF - Calls MatAssemblyEnd_MFFD() and then sets the
 79:     base from the SNES context

 81: */
 82: static PetscErrorCode MatAssemblyEnd_SNESMF(Mat J,MatAssemblyType mt)
 83: {
 85:   MatMFFD        j    = (MatMFFD)J->data;
 86:   SNES           snes = (SNES)j->ctx;
 87:   Vec            u,f;

 90:   MatAssemblyEnd_MFFD(J,mt);

 92:   SNESGetSolution(snes,&u);
 93:   if (j->func == (PetscErrorCode (*)(void*,Vec,Vec))SNESComputeFunction) {
 94:     SNESGetFunction(snes,&f,NULL,NULL);
 95:     MatMFFDSetBase_MFFD(J,u,f);
 96:   } else {
 97:     /* f value known by SNES is not correct for other differencing function */
 98:     MatMFFDSetBase_MFFD(J,u,NULL);
 99:   }
100:   return(0);
101: }

103: /*
104:    MatAssemblyEnd_SNESMF_UseBase - Calls MatAssemblyEnd_MFFD() and then sets the
105:     base from the SNES context. This version will cause the base to be used for differencing
106:     even if the func is not SNESComputeFunction. See: MatSNESMFUseBase()


109: */
110: static PetscErrorCode MatAssemblyEnd_SNESMF_UseBase(Mat J,MatAssemblyType mt)
111: {
113:   MatMFFD        j    = (MatMFFD)J->data;
114:   SNES           snes = (SNES)j->ctx;
115:   Vec            u,f;

118:   MatAssemblyEnd_MFFD(J,mt);

120:   SNESGetSolution(snes,&u);
121:   SNESGetFunction(snes,&f,NULL,NULL);
122:   MatMFFDSetBase_MFFD(J,u,f);
123:   return(0);
124: }

126: /*
127:     This routine resets the MatAssemblyEnd() for the MatMFFD created from MatCreateSNESMF() so that it NO longer
128:   uses the solution in the SNES object to update the base. See the warning in MatCreateSNESMF().
129: */
130: static PetscErrorCode  MatMFFDSetBase_SNESMF(Mat J,Vec U,Vec F)
131: {

135:   MatMFFDSetBase_MFFD(J,U,F);
136:   J->ops->assemblyend = MatAssemblyEnd_MFFD;
137:   return(0);
138: }

140: static PetscErrorCode  MatSNESMFSetReuseBase_SNESMF(Mat J,PetscBool use)
141: {
143:   if (use) {
144:     J->ops->assemblyend = MatAssemblyEnd_SNESMF_UseBase;
145:   } else {
146:     J->ops->assemblyend = MatAssemblyEnd_SNESMF;
147:   }
148:   return(0);
149: }

151: /*@
152:     MatSNESMFSetReuseBase - Causes the base vector to be used for differencing even if the function provided to SNESSetFunction() is not the
153:                        same as that provided to MatMFFDSetFunction().

155:     Logically Collective on Mat

157:     Input Parameters:
158: +   J - the MatMFFD matrix
159: -   use - if true always reuse the base vector instead of recomputing f(u) even if the function in the MatSNESMF is 
160:           not SNESComputeFunction()

162:     Notes:
163:     Care must be taken when using this routine to insure that the function provided to MatMFFDSetFunction(), call it F_MF() is compatible with
164:            with that provided to SNESSetFunction(), call it F_SNES(). That is, (F_MF(u + h*d) - F_SNES(u))/h has to approximate the derivative

166:     Developer Notes:
167:     This was provided for the MOOSE team who desired to have a SNESSetFunction() function that could change configurations due
168:                      to contacts while the function provided to MatMFFDSetFunction() cannot. Except for the possibility of changing the configuration
169:                      both functions compute the same mathematical function so the differencing makes sense.

171:     Level: advanced

173: .seealso: MatCreateSNESMF(), MatSNESMFGetReuseBase()
174: @*/
175: PetscErrorCode  MatSNESMFSetReuseBase(Mat J,PetscBool use)
176: {

181:   PetscTryMethod(J,"MatSNESMFSetReuseBase_C",(Mat,PetscBool),(J,use));
182:   return(0);
183: }

185: static PetscErrorCode  MatSNESMFGetReuseBase_SNESMF(Mat J,PetscBool *use)
186: {
188:   if (J->ops->assemblyend == MatAssemblyEnd_SNESMF_UseBase) *use = PETSC_TRUE;
189:   else *use = PETSC_FALSE;
190:   return(0);
191: }

193: /*@
194:     MatSNESMFGetReuseBase - Determines if the base vector is to be used for differencing even if the function provided to SNESSetFunction() is not the
195:                        same as that provided to MatMFFDSetFunction().

197:     Logically Collective on Mat

199:     Input Parameter:
200: .   J - the MatMFFD matrix

202:     Output Parameter:
203: .   use - if true always reuse the base vector instead of recomputing f(u) even if the function in the MatSNESMF is 
204:           not SNESComputeFunction()

206:     Notes:
207:     Care must be taken when using this routine to insure that the function provided to MatMFFDSetFunction(), call it F_MF() is compatible with
208:            with that provided to SNESSetFunction(), call it F_SNES(). That is, (F_MF(u + h*d) - F_SNES(u))/h has to approximate the derivative

210:     Developer Notes:
211:     This was provided for the MOOSE team who desired to have a SNESSetFunction() function that could change configurations due
212:                      to contacts while the function provided to MatMFFDSetFunction() cannot. Except for the possibility of changing the configuration
213:                      both functions compute the same mathematical function so the differencing makes sense.

215:     Level: advanced

217: .seealso: MatCreateSNESMF(), MatSNESMFSetReuseBase()
218: @*/
219: PetscErrorCode  MatSNESMFGetReuseBase(Mat J,PetscBool *use)
220: {

225:   PetscUseMethod(J,"MatSNESMFGetReuseBase_C",(Mat,PetscBool*),(J,use));
226:   return(0);
227: }

229: /*@
230:    MatCreateSNESMF - Creates a matrix-free matrix context for use with
231:    a SNES solver.  This matrix can be used as the Jacobian argument for
232:    the routine SNESSetJacobian(). See MatCreateMFFD() for details on how
233:    the finite difference computation is done.

235:    Collective on SNES and Vec

237:    Input Parameters:
238: .  snes - the SNES context

240:    Output Parameter:
241: .  J - the matrix-free matrix

243:    Level: advanced


246:    Notes:
247:      You can call SNESSetJacobian() with MatMFFDComputeJacobian() if you are using matrix and not a different
248:      preconditioner matrix

250:      If you wish to provide a different function to do differencing on to compute the matrix-free operator than
251:      that provided to SNESSetFunction() then call MatMFFDSetFunction() with your function after this call.

253:      The difference between this routine and MatCreateMFFD() is that this matrix
254:      automatically gets the current base vector from the SNES object and not from an
255:      explicit call to MatMFFDSetBase().

257:    Warning:
258:      If MatMFFDSetBase() is ever called on jac then this routine will NO longer get
259:      the x from the SNES object and MatMFFDSetBase() must from that point on be used to
260:      change the base vector x.

262:    Warning:
263:      Using a different function for the differencing will not work if you are using non-linear left preconditioning.


266: .seealso: MatDestroy(), MatMFFDSetFunction(), MatMFFDSetFunctionError(), MatMFFDDSSetUmin()
267:           MatMFFDSetHHistory(), MatMFFDResetHHistory(), MatCreateMFFD(),
268:           MatMFFDGetH(), MatMFFDRegister(), MatMFFDComputeJacobian(), MatSNESMFSetReuseBase(), MatSNESMFGetReuseBase()

270: @*/
271: PetscErrorCode  MatCreateSNESMF(SNES snes,Mat *J)
272: {
274:   PetscInt       n,N;
275:   MatMFFD        mf;

278:   if (snes->vec_func) {
279:     VecGetLocalSize(snes->vec_func,&n);
280:     VecGetSize(snes->vec_func,&N);
281:   } else if (snes->dm) {
282:     Vec tmp;
283:     DMGetGlobalVector(snes->dm,&tmp);
284:     VecGetLocalSize(tmp,&n);
285:     VecGetSize(tmp,&N);
286:     DMRestoreGlobalVector(snes->dm,&tmp);
287:   } else SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"Must call SNESSetFunction() or SNESSetDM() first");
288:   MatCreateMFFD(PetscObjectComm((PetscObject)snes),n,n,N,N,J);

290:   mf      = (MatMFFD)(*J)->data;
291:   mf->ctx = snes;

293:   if (snes->npc && snes->npcside== PC_LEFT) {
294:     MatMFFDSetFunction(*J,(PetscErrorCode (*)(void*,Vec,Vec))SNESComputeFunctionDefaultNPC,snes);
295:   } else {
296:     MatMFFDSetFunction(*J,(PetscErrorCode (*)(void*,Vec,Vec))SNESComputeFunction,snes);
297:   }

299:   (*J)->ops->assemblyend = MatAssemblyEnd_SNESMF;

301:   PetscObjectComposeFunction((PetscObject)*J,"MatMFFDSetBase_C",MatMFFDSetBase_SNESMF);
302:   PetscObjectComposeFunction((PetscObject)*J,"MatSNESMFSetReuseBase_C",MatSNESMFSetReuseBase_SNESMF);
303:   PetscObjectComposeFunction((PetscObject)*J,"MatSNESMFGetReuseBase_C",MatSNESMFGetReuseBase_SNESMF);
304:   return(0);
305: }