PetscErrorCode FormFunction(SNES snes,Vec X,Vec F,void *ctx)
{
PetscErrorCode ierr;
DMMG dmmg = (DMMG)ctx;
AppCtx *user = (AppCtx*)dmmg->user;
DA da2 = (DA)dmmg->dm;
DALocalInfo info2;
Field2 **x2,**f2;
Vec X2;
PetscFunctionBegin;
ierr = DAGetLocalInfo(da2,&info2);CHKERRQ(ierr);
/* Get local vectors to hold ghosted parts of X */
ierr = DAGetLocalVector(da2,&X2);CHKERRQ(ierr);
ierr = DAGlobalToLocalBegin(da2,X,INSERT_VALUES,X2);CHKERRQ(ierr);
ierr = DAGlobalToLocalEnd(da2,X,INSERT_VALUES,X2);CHKERRQ(ierr);
/* Access the array inside of X1 */
ierr = DAVecGetArray(da2,X2,(void**)&x2);CHKERRQ(ierr);
/* Access the subvectors in F.
These are not ghosted so directly access the memory locations in F */
ierr = DAVecGetArray(da2,F,(void**)&f2);CHKERRQ(ierr);
/* Evaluate local user provided function */
ierr = FormFunctionLocal2(&info2,0,x2,f2,(void**)user);CHKERRQ(ierr);
ierr = DAVecRestoreArray(da2,F,(void**)&f2);CHKERRQ(ierr);
ierr = DAVecRestoreArray(da2,X2,(void**)&x2);CHKERRQ(ierr);
ierr = DARestoreLocalVector(da2,&X2);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
/*
FormFunctionComp - Unwraps the input vector and passes its local ghosted pieces into the user function
*/
PetscErrorCode FormFunctionComp(SNES snes,Vec X,Vec F,void *ctx)
{
PetscErrorCode ierr;
DMMG dmmg = (DMMG)ctx;
AppCtx *user = (AppCtx*)dmmg->user;
DMComposite dm = (DMComposite)dmmg->dm;
DALocalInfo info1,info2;
DA da1,da2;
Field1 **x1,**f1;
Field2 **x2,**f2;
Vec X1,X2,F1,F2;
PetscFunctionBegin;
ierr = DMCompositeGetEntries(dm,&da1,&da2);CHKERRQ(ierr);
ierr = DAGetLocalInfo(da1,&info1);CHKERRQ(ierr);
ierr = DAGetLocalInfo(da2,&info2);CHKERRQ(ierr);
/* Get local vectors to hold ghosted parts of X */
ierr = DMCompositeGetLocalVectors(dm,&X1,&X2);CHKERRQ(ierr);
ierr = DMCompositeScatter(dm,X,X1,X2);CHKERRQ(ierr);
/* Access the arrays inside the subvectors of X */
ierr = DAVecGetArray(da1,X1,(void**)&x1);CHKERRQ(ierr);
ierr = DAVecGetArray(da2,X2,(void**)&x2);CHKERRQ(ierr);
/* Access the subvectors in F.
These are not ghosted and directly access the memory locations in F */
ierr = DMCompositeGetAccess(dm,F,&F1,&F2);CHKERRQ(ierr);
/* Access the arrays inside the subvectors of F */
ierr = DAVecGetArray(da1,F1,(void**)&f1);CHKERRQ(ierr);
ierr = DAVecGetArray(da2,F2,(void**)&f2);CHKERRQ(ierr);
/* Evaluate local user provided function */
user->x2 = x2; /* used by FormFunctionLocal1() */
ierr = FormFunctionLocal1(&info1,x1,f1,(void**)user);CHKERRQ(ierr);
user->x1 = x1; /* used by FormFunctionLocal2() */
ierr = FormFunctionLocal2(&info2,x2,f2,(void**)user);CHKERRQ(ierr);
ierr = DAVecRestoreArray(da1,F1,(void**)&f1);CHKERRQ(ierr);
ierr = DAVecRestoreArray(da2,F2,(void**)&f2);CHKERRQ(ierr);
ierr = DMCompositeRestoreAccess(dm,F,&F1,&F2);CHKERRQ(ierr);
ierr = DAVecRestoreArray(da1,X1,(void**)&x1);CHKERRQ(ierr);
ierr = DAVecRestoreArray(da2,X2,(void**)&x2);CHKERRQ(ierr);
ierr = DMCompositeRestoreLocalVectors(dm,&X1,&X2);CHKERRQ(ierr);
PetscFunctionReturn(0);
}