WEICDF
      SUBROUTINE WEICDF(X,GAMMA,CDF)
  
PURPOSE--This subroutine computes the cumulative distribution
         function value for the weibull distribution with single
         precision tail length parameter = GAMMA.  The weibull
         distribution used herein is defined for all positive X,
         and has the probability density function
         F(X) = GAMMA * (X**(GAMMA-1)) * EXP(-(X**GAMMA)).
INPUT  ARGUMENTS--X      = The single precision value at which
                           the cumulative distribution function
                           is to be evaluated.  X should be
                           positive
                --GAMMA  = THhe sngle precision Vvalue of the
                           tail length parameter.  GAMMA should
                           be positive.
OUTPUT ARGUMENTS--CDF    = The single precision cumulative
                           distribution function value.
OUTPUT--The single precision cumulative distribution function
        value CDF for the weibull distribution with tail length
        parameter value = GAMMA.
PRINTING--None unless an input argument error condition exists.
RESTRICTIONS--GAMMA should be positive.
            --X should be positive.
OTHER DATAPAC   SUBROUTINES NEEDED--None.
FORTRAN LIBRARY SUBROUTINES NEEDED--EXP.
MODE OF INTERNAL OPERATIONS--Single precision.
LANGUAGE--ANSI FORTRAN.
REFERENCES--Johnson and Kotz, Continuous Univariate
            Distributions--1, 1970, Pages 250-271.
          --Hasting and Peacock, Statistical Distributions--A
            Handbook for Students and Practitioners, 1975,
            Page 124.
WRITTEN BY--James J. Filliben
            Statistical Engineering Laboratory (205.03)
            National Bureau of Standards
            Gaithersburg, MD  20899
            Phone--  301-921-2315
ORIGINAL VERSION--November  1975.