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#if HAVE_CONFIG_H
# include "config.fh"
#endif
subroutine factor(p,idx,idy,idz)
implicit none
integer i,j,p,idx,idy,idz,it
integer ip,ifac,pmax,prime(1000)
integer fac(1000)
c
i = 1
ip = p
c
c factor p completely
c first, find all prime numbers less than or equal to p
c
pmax = 0
do i = 2, p
do j = 1, pmax
if (mod(i,prime(j)).eq.0) go to 100
end do
pmax = pmax + 1
prime(pmax) = i
100 continue
end do
c
c find all prime factors of p
c
ifac = 0
do i = 1, pmax
200 if (mod(ip,prime(i)).eq.0) then
ifac = ifac + 1
fac(ifac) = prime(i)
ip = ip/prime(i)
go to 200
endif
end do
c
c determine three factors of p of approximately the
c same size
c
idx = 1
idy = 1
idz = 1
do i = ifac, 1, -1
if (idx.le.idy.and.idx.le.idz) then
idx = fac(i)*idx
elseif (idy.le.idx.and.idy.le.idz) then
idy = fac(i)*idy
elseif (idz.le.idx.and.idz.le.idy) then
idz = fac(i)*idz
endif
end do
c it = idy
c idy = idx
c idx = it
c
c it = idx
c idx = idz
c idz = it
c
c it = idy
c idy = idz
c idz = it
return
end
c
subroutine i_proc_to_xyz(p,ix,iy,iz,idx,idy,idz)
implicit none
integer p,ix,iy,iz,ip,it
integer idx,idy,idz
c
ip = p
c
it = mod(ip,idx)
ix = it
ip = (ip - it)/idx
it = mod(ip,idy)
iy = it
ip = (ip - it)/idy
it = mod(ip,idz)
iz = it
c
return
end
c
subroutine i_xyz_to_proc(p,ix,iy,iz,idx,idy,idz)
implicit none
integer p,ix,iy,iz,idx,idy,idz
c
p = ix + idx*iy + idx*idy*iz
c
return
end
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