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subroutine lspis(ma,na,nela,inda,i,ni,j,nj,
c Copyright INRIA
$ mb,nb,b,mr,nr,nelr,indr,ierr)
c extract a submatrix from a sparse matrix
c!
integer inda(*),indr(*),i(*),j(*)
integer mb,nb
integer ma,na,ni,nj,mr,nr,nela,nelr,ierr
integer b(mb,*)
logical allrow,allcol
integer findl
external findl
c
nelmx=nelr
ierr=0
mr=ni
nr=nj
allrow=ni.lt.0
allcol=nj.lt.0
if(allrow) then
mr=ma
else
mi=0
do 01 kk=1,ni
mi=max(mi,i(kk))
01 continue
mr=max(ma,mi)
endif
if(allcol) then
nr=na
else
mj=0
do 02 kk=1,nj
mj=max(mj,j(kk))
02 continue
nr=max(na,mj)
endif
if (allrow.and.allcol) then
c a(:,:)=b
if(mb*nb.gt.nelmx) then
ierr=1
return
endif
call iset(mb,0,indr,1)
jr=1
if(mb*nb.ne.0) then
do 04 l=1,mb
do 03 k=1,nb
if(b(l,k).ne.0) then
indr(mb+jr)=k
indr(l)=indr(l)+1
jr=jr+1
endif
03 continue
04 continue
endif
nelr=jr-1
return
elseif(allcol) then
c a(i,:)=b
jr=1
ja=1
do 20 l=1,mr
indr(l)=0
ii=findl(l,i,ni)
if(ii.eq.0) then
c this line is not modified
if(l.le.ma) then
indr(l)=inda(l)
call icopy(indr(l),inda(ma+ja),1,indr(mr+jr),1)
jr=jr+indr(l)
ja=ja+indr(l)
else
indr(l)=0
endif
else
c all this line is replaced by corresponding b line
if(nb.gt.0) then
if(jr+nb.gt.nelmx) then
ierr=1
return
endif
do 19 k1=1,nb
if(b(ii,k1).ne.0) then
indr(mr+jr)=k1
indr(l)=indr(l)+1
jr=jr+1
endif
19 continue
endif
if(l.le.ma) then
ja=ja+inda(l)
endif
endif
20 continue
nelr=jr-1
if(nb.eq.0) mr=mr-ni
elseif(allrow) then
c a(:,j)=b
jr=1
ja=0
do 35 l=1,ma
ja1=1
nal=inda(l)
indr(l)=0
kr=1
do 31 k=1,nr
jj=findl(k,j,nj)
if(jj.eq.0) then
c the a(l,k) element is not modified insert it in r if non zero
if(ja1.le.nal.and.inda(ma+ja+ja1).eq.k) then
c * a(l,k) element is non zero
indr(l)=indr(l)+1
indr(mr+jr)=kr
jr=jr+1
ja1=ja1+1
endif
kr=kr+1
else
c the a(l,k) element is replaced by b(l,jj) element
if(nb.gt.0) then
if(b(l,jj).ne.0) then
if(jr+1.gt.nelmx) then
ierr=1
return
endif
indr(l)=indr(l)+1
indr(mr+jr)=kr
jr=jr+1
endif
kr=kr+1
endif
endif
if(ja1.le.nal.and.inda(ma+ja+ja1).eq.k) ja1=ja1+1
31 continue
ja=ja+nal
35 continue
nelr=jr-1
if(nb.eq.0) nr=nr-nj
return
else
c a(i,j)=b
jr=1
ja=0
do 45 l=1,mr
ja1=1
if(l.le.ma) then
nal=inda(l)
else
nal=0
endif
indr(l)=0
ii=findl(l,i,ni)
if(ii.eq.0) then
c * the a(l,:) is not modified
if(l.le.ma) then
indr(l)=inda(l)
call icopy(indr(l),inda(ma+ja+ja1),1,indr(mr+jr),1)
jr=jr+indr(l)
ja1=ja1+indr(l)
else
indr(l)=0
endif
else
kr=1
do 42 k=1,nr
jj=findl(k,j,nj)
if(jj.eq.0) then
c * insert a(l,k) element in r if non zero
if(ja1.le.nal.and.inda(ma+ja+ja1).eq.k) then
c * a(l,k) element is non zero
indr(l)=indr(l)+1
indr(mr+jr)=kr
jr=jr+1
ja1=ja1+1
endif
kr=kr+1
else
c * replace a(l,k) element by b(ii,jj) element if non zero
if(nb.gt.0) then
if(b(ii,jj).ne.0) then
if(jr+1.gt.nelmx) then
ierr=1
return
endif
indr(l)=indr(l)+1
indr(mr+jr)=kr
jr=jr+1
endif
kr=kr+1
endif
if(ja1.le.nal.and.inda(ma+ja+ja1).eq.k) ja1=ja1+1
endif
42 continue
endif
ja=ja+nal
45 continue
nelr=jr-1
endif
end
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