!--------------------------------------------------------!
!Random number generator based on algorithm 'mzran' by   !
!Marsiglia and Zaman, Computers in Physics, 8, 107 (1994)!
!--------------------------------------------------------!
!rand() generates a random number in the range [0,1)     !
!initrand(w) reads 4 integer seeds from 'seed.in',       !
!writes new random seeds to the same file if w/=0.       !
!--------------------------------------------------------!

!-----------------------!
 real(8) function rand()
!-----------------------!
 implicit none

 integer :: iir,jjr,kkr,nnr,mzran
 common/brand/iir,jjr,kkr,nnr,mzran

 mzran=iir-kkr
 if (mzran < 0) mzran=mzran+2147483579
 iir=jjr; jjr=kkr; kkr=mzran
 nnr=69069*nnr+1013904243
 mzran=mzran+nnr
 rand=0.5d0+mzran*0.23283064d-9

 end function rand
!-----------------!

!----------------------!
 subroutine initrand(w)
!----------------------!
 implicit none

 integer :: iir,jjr,kkr,nnr,mzran
 common/brand/iir,jjr,kkr,nnr,mzran

 integer :: w
 real(8) :: rand

 open(1,file='seed.in',status='old')
 read(1,*)iir 
 read(1,*)jjr
 read(1,*)kkr
 read(1,*)nnr
 close(1)
 iir=abs(iir)+1; jjr=abs(jjr)+1; kkr=abs(kkr)+1
 if (w /= 0) then
   open(1,file='seed.in',status='replace')
   write(1,*)abs(int((rand()-0.5d0)/0.23283064d-9))
   write(1,*)abs(int((rand()-0.5d0)/0.23283064d-9))
   write(1,*)abs(int((rand()-0.5d0)/0.23283064d-9))
   write(1,*)abs(int((rand()-0.5d0)/0.23283064d-9))
   close(1)
 end if

 end subroutine initrand
!-----------------------!