      SUBROUTINE EV1CDF(X,CDF)
C
C     PURPOSE--THIS SUBROUTINE COMPUTES THE CUMULATIVE DISTRIBUTION
C              FUNCTION VALUE FOR THE EXTREME VALUE TYPE 1
C              DISTRIBUTION.
C              THE EXTREME VALUE TYPE 1 DISTRIBUTION USED
C              HEREIN HAS MEAN = EULER'S NUMBER = 0.57721566
C              AND STANDARD DEVIATION = PI/SQRT(6) = 1.28254983.
C              THIS DISTRIBUTION IS DEFINED FOR ALL X
C              AND HAS THE PROBABILITY DENSITY FUNCTION
C              F(X) = (EXP(-X)) * (EXP(-(EXP(-X))))
C     INPUT  ARGUMENTS--X      = THE SINGLE PRECISION VALUE 
C                                AT WHICH THE CUMULATIVE DISTRIBUTION 
C                                FUNCTION IS TO BE EVALUATED.
C     OUTPUT ARGUMENTS--CDF    = THE SINGLE PRECISION CUMULATIVE
C                                DISTRIBUTION FUNCTION VALUE.
C     OUTPUT--THE SINGLE PRECISION CUMULATIVE DISTRIBUTION
C             FUNCTION VALUE CDF FOR THE EXTREME VALUE TYPE 1
C             DISTRIBUTION WITH MEAN = EULER'S NUMBER = 0.57721566
C             AND STANDARD DEVIATION = PI/SQRT(6) = 1.28254983.
C     PRINTING--NONE UNLESS AN INPUT ARGUMENT ERROR CONDITION EXISTS. 
C     RESTRICTIONS--NONE.
C     OTHER DATAPAC   SUBROUTINES NEEDED--NONE.
C     FORTRAN LIBRARY SUBROUTINES NEEDED--EXP.
C     MODE OF INTERNAL OPERATIONS--SINGLE PRECISION.
C     LANGUAGE--ANSI FORTRAN. 
C     REFERENCES--JOHNSON AND KOTZ, CONTINUOUS UNIVARIATE
C                 DISTRIBUTIONS--1, 1970, PAGES 272-295.
C     WRITTEN BY--JAMES J. FILLIBEN
C                 STATISTICAL ENGINEERING LABORATORY (205.03)
C                 NATIONAL BUREAU OF STANDARDS
C                 WASHINGTON, D. C. 20234
C                 PHONE:  301-921-2315
C     ORIGINAL VERSION--NOVEMBER  1975. 
C
C---------------------------------------------------------------------
C
      IPR=6
C
C     CHECK THE INPUT ARGUMENTS FOR ERRORS.
C     NO INPUT ARGUMENT ERRORS POSSIBLE 
C     FOR THIS DISTRIBUTION.
C
C-----START POINT-----------------------------------------------------
C
      CDF=1.0-EXP(-(EXP(-X))) 
C
      RETURN
      END 
