Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!uakari.primate.wisc.edu!unmvax!pprg.unm.edu!topgun.dspo.gov!lanl!ttw
From: ttw@lanl.gov (Tony Warnock)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Stuck on pc random number generation : help
Summary: portable random number generator source
Keywords: beta testing
Message-ID: <14039@lanl.gov>
Date: 6 Sep 89 21:52:49 GMT
References: <7561@microsoft.UUCP> <1991@leah.Albany.Edu> <6474@columbia.edu>
Distribution: usa
Organization: Los Alamos National Laboratory
Lines: 33




   Here is a portable random number generator. It gives the same
sequence of numbers on PC's, VAX's, CRAY's, etc.

      FUNCTION fran ()
c
c...portable random number generator
c
c   A..........temporary partial product
c   B..........temporary partial product
c   GL.........left hand part of multiplier
c   GR.........right hand part of multiplier
c   P..........2**24
c   Q..........2**(-24)
c   SEED.......random number internal value
c   SMALL......2**(-49)
c
      DOUBLE PRECISION p, q, a, b, seed, gl, gr, small
      PARAMETER (p=2.**24, q=2.**(-24), gl=1136868.d0, gr=6328637.d0)
      PARAMETER (small=2.**(-49))
      REAL fran
      SAVE /rhyzome/
      COMMON /rhyzome/ seed(2)
c
      a=gr*seed(2)+1.0d0
      b=gl*seed(2)+gr*seed(1)+dint(a*q)
      seed(1)=b-DINT(b*q)*p
      seed(2)=a-DINT(a*q)*p
      fran=((seed(1)*p+seed(2))*q*q)+small
      RETURN
      END