ran0_vec.f90 Source File

! $Header$

SUBROUTINE ran0_vec(npoints, idum, ran0)

  ! $Id: ran0_vec.f90 5268 2024-10-23 17:02:39Z abarral $
  ! Platform independent random number generator from
  ! Numerical Recipies
  ! Mark Webb July 1999

  IMPLICIT NONE

  INTEGER j, npoints, idum(npoints), ia, im, iq, ir, k(npoints)
  REAL ran0(npoints), am

  PARAMETER (ia=16807, im=2147483647, am=1.0/im, iq=127773, ir=2836)

  ! do j=1,npoints
  ! if (idum(j).eq.0) then
  ! write(6,*) 'idum=',idum
  ! write(6,*) 'ZERO seed not allowed'
  ! stop
  ! endif
  ! enddo

  DO j = 1, npoints
    k(j) = idum(j)/iq
    idum(j) = ia*(idum(j)-k(j)*iq) - ir*k(j)
    IF (idum(j)<0) idum(j) = idum(j) + im
    ran0(j) = am*idum(j)
  END DO

END SUBROUTINE ran0_vec