Function:     RAN

Purpose:      Returns a uniform random deviate between 0.0 and 1.0.

Category:     MATH

Files:        ran.c

Author:       K.G. Begeman

Use:          REAL RAN( SEED )         Input/Output       INTEGER

              RAN       Uniform random deviate between 0.0 and 1.0.
              SEED      A negative value for SEED reintializes the
                        sequence with seed -SEED and on exit SEED
                        will be one.
                        A positive value for SEED has no effect except
                        for the first call to RAN. Then it initializes
                        the sequence with seed SEED and on exit SEED
                        will be one.

Description:  The random numbers are obtained with the subtractive
              method described by Knuth (Knuth, D.E. 1981, Seminumerical
              Algorithms, 2nd ed., vol. 2 of The Art of Computer
              Programming).

Updates:      May  25, 1990: KGB, Document created.