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From: klassen@sol.UVic.CA (Melvin Klassen)
Newsgroups: comp.lang.fortran
Subject: Re: randu?
Summary: A history lesson
Message-ID: <1991Mar1.010946.16149@sol.UVic.CA>
Date: 1 Mar 91 01:09:46 GMT
References: <62349@eerie.acsu.Buffalo.EDU>
Organization: University of Victoria, Victoria B.C. CANADA
Lines: 18

haozhou@acsu.buffalo.edu (Hao Zhou) writes:
>I am trying to port some fortran source code from vax/vms to sun/unix.
>The source code compiles on unix but doesn't link since randu couldn't
>be found. I checked the code and found randu is referred as follows:
>
>	call randu(i1,i2,u)
>
>where i1,i2,and u weren't initialized before the call. I guess this
>routine returns a random number in u and i1 and i2 are two seeds.
>
RANDU originated in the IBM SSP (Scientific Subroutine Package)
in the early 1970's.  It has three arguments:
 - IX, which is the "seed" for the (pseudo-) random-number generator,
   (set IX to some positive, odd, number before the very-first CALL),
 - IY, which is returned as the value which the caller should store
   into IX before calling RANDU again,
 - Z, which is returned as a floating-point number *uniformly* (hence
   the U-suffix) distributed in the 0.0 to 1.0 range.