PETSC_EXTERN void PETSC_STDCALL dmdagetnumlocalsubdomains_(DM da,PetscInt *Nsub, int *__ierr ){
*__ierr = DMDAGetNumLocalSubDomains(
(DM)PetscToPointer((da) ),Nsub);
}
PetscErrorCode DMDASubDomainDA_Private(DM dm, PetscInt *nlocal, DM **sdm)
{
DM *da;
PetscInt dim,size,i,j,k,idx;
PetscErrorCode ierr;
DMDALocalInfo info;
PetscInt xsize,ysize,zsize;
PetscInt xo,yo,zo;
PetscInt xs,ys,zs;
PetscInt xm=1,ym=1,zm=1;
PetscInt xol,yol,zol;
PetscInt m=1,n=1,p=1;
PetscInt M,N,P;
PetscInt pm,mtmp;
PetscFunctionBegin;
ierr = DMDAGetLocalInfo(dm,&info);CHKERRQ(ierr);
ierr = DMDAGetOverlap(dm,&xol,&yol,&zol);CHKERRQ(ierr);
ierr = DMDAGetNumLocalSubDomains(dm,&size);CHKERRQ(ierr);
ierr = PetscMalloc1(size,&da);CHKERRQ(ierr);
if (nlocal) *nlocal = size;
dim = info.dim;
M = info.xm;
N = info.ym;
P = info.zm;
if (dim == 1) {
m = size;
} else if (dim == 2) {
m = (PetscInt)(0.5 + PetscSqrtReal(((PetscReal)M)*((PetscReal)size)/((PetscReal)N)));
while (m > 0) {
n = size/m;
if (m*n*p == size) break;
m--;
}
} else if (dim == 3) {
n = (PetscInt)(0.5 + PetscPowReal(((PetscReal)N*N)*((PetscReal)size)/((PetscReal)P*M),(PetscReal)(1./3.))); if (!n) n = 1;
while (n > 0) {
pm = size/n;
if (n*pm == size) break;
n--;
}
if (!n) n = 1;
m = (PetscInt)(0.5 + PetscSqrtReal(((PetscReal)M)*((PetscReal)size)/((PetscReal)P*n)));
if (!m) m = 1;
while (m > 0) {
p = size/(m*n);
if (m*n*p == size) break;
m--;
}
if (M > P && m < p) {mtmp = m; m = p; p = mtmp;}
}
zs = info.zs;
idx = 0;
for (k = 0; k < p; k++) {
ys = info.ys;
for (j = 0; j < n; j++) {
xs = info.xs;
for (i = 0; i < m; i++) {
if (dim == 1) {
xm = M/m + ((M % m) > i);
} else if (dim == 2) {
xm = M/m + ((M % m) > i);
ym = N/n + ((N % n) > j);
} else if (dim == 3) {
xm = M/m + ((M % m) > i);
ym = N/n + ((N % n) > j);
zm = P/p + ((P % p) > k);
}
xsize = xm;
ysize = ym;
zsize = zm;
xo = xs;
yo = ys;
zo = zs;
ierr = DMDACreate(PETSC_COMM_SELF,&(da[idx]));CHKERRQ(ierr);
ierr = DMSetOptionsPrefix(da[idx],"sub_");CHKERRQ(ierr);
ierr = DMSetDimension(da[idx], info.dim);CHKERRQ(ierr);
ierr = DMDASetDof(da[idx], info.dof);CHKERRQ(ierr);
ierr = DMDASetStencilType(da[idx],info.st);CHKERRQ(ierr);
ierr = DMDASetStencilWidth(da[idx],info.sw);CHKERRQ(ierr);
if (info.bx == DM_BOUNDARY_PERIODIC || (xs != 0)) {
xsize += xol;
xo -= xol;
}
if (info.by == DM_BOUNDARY_PERIODIC || (ys != 0)) {
ysize += yol;
yo -= yol;
}
if (info.bz == DM_BOUNDARY_PERIODIC || (zs != 0)) {
zsize += zol;
zo -= zol;
}
if (info.bx == DM_BOUNDARY_PERIODIC || (xs+xm != info.mx)) xsize += xol;
if (info.by == DM_BOUNDARY_PERIODIC || (ys+ym != info.my)) ysize += yol;
if (info.bz == DM_BOUNDARY_PERIODIC || (zs+zm != info.mz)) zsize += zol;
if (info.bx != DM_BOUNDARY_PERIODIC) {
if (xo < 0) {
xsize += xo;
xo = 0;
}
if (xo+xsize > info.mx-1) {
xsize -= xo+xsize - info.mx;
}
}
if (info.by != DM_BOUNDARY_PERIODIC) {
if (yo < 0) {
ysize += yo;
yo = 0;
}
if (yo+ysize > info.my-1) {
ysize -= yo+ysize - info.my;
}
}
if (info.bz != DM_BOUNDARY_PERIODIC) {
if (zo < 0) {
zsize += zo;
zo = 0;
}
if (zo+zsize > info.mz-1) {
zsize -= zo+zsize - info.mz;
}
}
ierr = DMDASetSizes(da[idx], xsize, ysize, zsize);CHKERRQ(ierr);
ierr = DMDASetNumProcs(da[idx], 1, 1, 1);CHKERRQ(ierr);
ierr = DMDASetBoundaryType(da[idx], DM_BOUNDARY_GHOSTED, DM_BOUNDARY_GHOSTED, DM_BOUNDARY_GHOSTED);CHKERRQ(ierr);
/* set up as a block instead */
ierr = DMSetUp(da[idx]);CHKERRQ(ierr);
/* nonoverlapping region */
ierr = DMDASetNonOverlappingRegion(da[idx],xs,ys,zs,xm,ym,zm);CHKERRQ(ierr);
/* this alters the behavior of DMDAGetInfo, DMDAGetLocalInfo, DMDAGetCorners, and DMDAGetGhostedCorners and should be used with care */
ierr = DMDASetOffset(da[idx],xo,yo,zo,info.mx,info.my,info.mz);CHKERRQ(ierr);
xs += xm;
idx++;
}
ys += ym;
}
zs += zm;
}
*sdm = da;
PetscFunctionReturn(0);
}
