EV1PPF
      SUBROUTINE EV1PPF(P,PPF)
  
PURPOSE--This subroutine computes the percent point function
         value for the extreme value type 1 distribution.  The
         extreme value type 1 distribution used herein has MEAN
         = EULER'S NUMBER = 0.57721566 and STANDARD DEVIATION =
         PI/SQRT(6) = 1.28254983.  This distribution is defined
         for all x and has the probability density function
         F(X) = (EXP(-X)) * (EXP(-(EXP(-X)))).  Note that the
         percent function of a distribution is identically the
         the same as the inverse cumulative distribution function of
         the distribution.
INPUT  ARGUMENTS--P      = The single precision value (between
                           0.0 and 1.0 (exclusively) at which
                           the percent point function is to be
                           evaluated.
OUTPUT ARGUMENTS--PPF    = The single precision percent point
                           function value.
OUTPUT--The single precision percent point function value PPF
        for the extreme value type 1 distribution with
        MEAN = EULER'S NUMBER = 0.57721566 and
        STANDARD DEVIATION = PI/SQRT(6) = 1.28254983.
PRINTING--None unless an input argument error condition exists.
RESTRICTIONS--P should be between 0.0 and 1.0 (exclusively).
OTHER DATAPAC   SUBROUTINES NEEDED--None.
FORTRAN LIBRARY SUBROUTINES NEEDED--ALOG.
MODE OF INTERNAL OPERATIONS--Single precision.
LANGUAGE--ANSI FORTRAN.
REFERENCES--Johnson and Kotz, Continuous Univariate
            Distributions--1, 1970, Pages 272-295.
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.