SUBROUTINE para_range(n1,n2,nprocs,irank,ista,iend)
           iwork1=(n2-n1+1)/nprocs
           iwork2=MOD(n2-n1+1,nprocs)
           ista=irank*iwork1+n1+MIN(irank,iwork2)
           iend=ista+iwork1-1
           if(iwork2.gt.irank) iend=iend+1
           RETURN
           END SUBROUTINE para_range