/*@
ISLocalToGlobalMappingApplyIS - Creates from an IS in the local numbering
a new index set using the global numbering defined in an ISLocalToGlobalMapping
context.
Not collective
Input Parameters:
+ mapping - mapping between local and global numbering
- is - index set in local numbering
Output Parameters:
. newis - index set in global numbering
Level: advanced
Concepts: mapping^local to global
.seealso: ISLocalToGlobalMappingApply(), ISLocalToGlobalMappingCreate(),
ISLocalToGlobalMappingDestroy(), ISGlobalToLocalMappingApply()
@*/
PetscErrorCode PETSCVEC_DLLEXPORT ISLocalToGlobalMappingApplyIS(ISLocalToGlobalMapping mapping,IS is,IS *newis)
{
PetscErrorCode ierr;
PetscInt n,i,*idxmap,*idxout,Nmax = mapping->n;
const PetscInt *idxin;
PetscFunctionBegin;
PetscValidHeaderSpecific(mapping,IS_LTOGM_COOKIE,1);
PetscValidHeaderSpecific(is,IS_COOKIE,2);
PetscValidPointer(newis,3);
ierr = ISGetLocalSize(is,&n);CHKERRQ(ierr);
ierr = ISGetIndices(is,&idxin);CHKERRQ(ierr);
idxmap = mapping->indices;
ierr = PetscMalloc(n*sizeof(PetscInt),&idxout);CHKERRQ(ierr);
for (i=0; i<n; i++) {
if (idxin[i] >= Nmax) SETERRQ3(PETSC_ERR_ARG_OUTOFRANGE,"Local index %d too large %d (max) at %d",idxin[i],Nmax-1,i);
idxout[i] = idxmap[idxin[i]];
}
ierr = ISRestoreIndices(is,&idxin);CHKERRQ(ierr);
ierr = ISCreateGeneralNC(PETSC_COMM_SELF,n,idxout,newis);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
/*@
ISDifference - Computes the difference between two index sets.
Collective on IS
Input Parameter:
+ is1 - first index, to have items removed from it
- is2 - index values to be removed
Output Parameters:
. isout - is1 - is2
Notes:
Negative values are removed from the lists. is2 may have values
that are not in is1. This requires O(imax-imin) memory and O(imax-imin)
work, where imin and imax are the bounds on the indices in is1.
Level: intermediate
Concepts: index sets^difference
Concepts: IS^difference
.seealso: ISDestroy(), ISView(), ISSum(), ISExpand()
@*/
PetscErrorCode PETSCVEC_DLLEXPORT ISDifference(IS is1,IS is2,IS *isout)
{
PetscErrorCode ierr;
PetscInt i,n1,n2,imin,imax,nout,*iout;
const PetscInt *i1,*i2;
PetscBT mask;
MPI_Comm comm;
PetscFunctionBegin;
PetscValidHeaderSpecific(is1,IS_COOKIE,1);
PetscValidHeaderSpecific(is2,IS_COOKIE,2);
PetscValidPointer(isout,3);
ierr = ISGetIndices(is1,&i1);CHKERRQ(ierr);
ierr = ISGetLocalSize(is1,&n1);CHKERRQ(ierr);
/* Create a bit mask array to contain required values */
if (n1) {
imin = PETSC_MAX_INT;
imax = 0;
for (i=0; i<n1; i++) {
if (i1[i] < 0) continue;
imin = PetscMin(imin,i1[i]);
imax = PetscMax(imax,i1[i]);
}
} else {
imin = imax = 0;
}
ierr = PetscBTCreate(imax-imin,mask);CHKERRQ(ierr);
/* Put the values from is1 */
for (i=0; i<n1; i++) {
if (i1[i] < 0) continue;
ierr = PetscBTSet(mask,i1[i] - imin);CHKERRQ(ierr);
}
ierr = ISRestoreIndices(is1,&i1);CHKERRQ(ierr);
/* Remove the values from is2 */
ierr = ISGetIndices(is2,&i2);CHKERRQ(ierr);
ierr = ISGetLocalSize(is2,&n2);CHKERRQ(ierr);
for (i=0; i<n2; i++) {
if (i2[i] < imin || i2[i] > imax) continue;
ierr = PetscBTClear(mask,i2[i] - imin);CHKERRQ(ierr);
}
ierr = ISRestoreIndices(is2,&i2);CHKERRQ(ierr);
/* Count the number in the difference */
nout = 0;
for (i=0; i<imax-imin+1; i++) {
if (PetscBTLookup(mask,i)) nout++;
}
/* create the new IS containing the difference */
ierr = PetscMalloc(nout*sizeof(PetscInt),&iout);CHKERRQ(ierr);
nout = 0;
for (i=0; i<imax-imin+1; i++) {
if (PetscBTLookup(mask,i)) iout[nout++] = i + imin;
}
ierr = PetscObjectGetComm((PetscObject)is1,&comm);CHKERRQ(ierr);
ierr = ISCreateGeneralNC(comm,nout,iout,isout);CHKERRQ(ierr);
ierr = PetscBTDestroy(mask);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
