int MakeBoxDomains(const Box &box,int nproc, int nx, int ny, int nz, inp_it result){
int ndir[3]={nx,ny,nz}, nspl[3]={nx,ny,nz};
int np=(nproc>0 ? nproc : -nproc);
int startdir=2;
int dd, curdir=-1;
// getting minimal splits
int nauto=0, autod[3]={-1, -1, -1}, ndef=0;
for(dd=0;dd<3;dd++){
int dir=(dd+startdir)%3;
if(ndir[dir]>0 && ndir[dir]>curdir)curdir=dir;
else if(ndir[dir]<0){
autod[nauto++]=dir;
}
if(ndir[dir]==0)ndef++;
}
if(curdir<0 && nauto>0){
if(nauto==1){
ndir[autod[0]]=np;
curdir=autod[0];
}
else{ // auto-finding direction and number of slices to split
int i;
vec_type lprod=1.;
for(i=0;i<nauto;i++){
lprod*=box.GetSize()[autod[i]];
}
vec_type k=pow((vec_type)np/lprod,vec_type(1)/vec_type(nauto));
int mnp=0, mdir=0;
for(i=0;i<nauto;i++){
int tnp=(int)(box.GetSize()[autod[i]]*k);
if(mnp<tnp){
mnp=tnp;
mdir=i;
}
}
if(mnp>0){
ndir[autod[mdir]]=mnp;
curdir=autod[mdir];
}
}
}
if(curdir>=0){ // splitting by minimal dir, auto split is ignored
// number of domains
int ndom=0;
// determining sub-nps
// THIS IS NP SWITCH : !!!
if(np<ndir[curdir])ndir[curdir]=np;
if(np>ndir[curdir] && ndef==2){ // the last axis
ndir[curdir]=np;
}
int snp=(np>ndir[curdir] ? np : ndir[curdir]);
int mnp=snp/ndir[curdir]; // minimal np
int dntot=snp%ndir[curdir]; // difference
vec_type c0=(vec_type)mnp/snp, c1=(vec_type)(mnp+1)/snp;
Vector_3 p1=box.get_p1();
Vector_3 p2=box.get_p2();
vec_type l=box.GetSize()[curdir];
int i;
for(i=0;i<ndir[curdir];i++){
vec_type dl=(dntot>0 ? l*c1 : l*c0);
int cnp=(dntot>0 ? mnp+1 : mnp);
if(cnp<=0)break;
dntot--;
p2[curdir]=p1[curdir]+dl;
Box subdiv(p1,p2);
nspl[curdir]=0; // this direction is processed
int ddom=MakeBoxDomains(subdiv,(nproc>0 ? cnp: -cnp),nspl[0],nspl[1],nspl[2],result);
if(nproc>0)result+=ddom;
ndom+=ddom;
p1[curdir]=p2[curdir];
}
return ndom;
}
/// called with (0,0,0) split: put this box into the set
if(nproc>0)
*result=box;
return 1;
}
vec_type normal() const
{
vec_type _d = p_[1] - p_[0];
return vec_type(-_d.y(),_d.x());
}
