RAN (seed)

  Class:  Nonelemental function - Specific

  Generates a general random number of the multiplicative
  congruential type.  This function returns a different REAL*4 number
  between 0.0 (inclusive) and 1.0 (exclusive) each time it is
  invoked.  The argument must be an INTEGER*4 variable or array
  element.

  For best results, you should initialize the argument to a large,
  odd value before invoking RAN the first time.  To generate
  different sets of random values, initialize the seed to a different
  value on each run.  Do not modify the seed during a run.

  This function cannot be passed as an actual argument.