      SUBROUTINE UNIPDF(X,PDF)
C
C     PURPOSE--THIS SUBROUTINE COMPUTES THE PROBABILITY DENSITY
C              FUNCTION VALUE FOR THE UNIFORM (RECTANGULAR) 
C              DISTRIBUTION ON THE UNIT INTERVAL (0,1).
C              THIS DISTRIBUTION HAS MEAN = 0.5
C              AND STANDARD DEVIATION = SQRT(1/12) = 0.28867513.
C              THIS DISTRIBUTION HAS THE PROBABILITY
C              DENSITY FUNCTION F(X) = 1.
C     INPUT  ARGUMENTS--X      = THE SINGLE PRECISION VALUE AT
C                                WHICH THE PROBABILITY DENSITY
C                                FUNCTION IS TO BE EVALUATED.
C     OUTPUT ARGUMENTS--PDF    = THE SINGLE PRECISION PROBABILITY
C                                DENSITY FUNCTION VALUE.
C     OUTPUT--THE SINGLE PRECISION PROBABILITY DENSITY
C             FUNCTION VALUE PDF.
C     PRINTING--NONE UNLESS AN INPUT ARGUMENT ERROR CONDITION EXISTS. 
C     RESTRICTIONS--X SHOULD BE BETWEEN 0 AND 1, INCLUSIVELY.
C     OTHER DATAPAC   SUBROUTINES NEEDED--NONE.
C     FORTRAN LIBRARY SUBROUTINES NEEDED--NONE.
C     MODE OF INTERNAL OPERATIONS--SINGLE PRECISION.
C     LANGUAGE--ANSI FORTRAN. 
C     REFERENCES--JOHNSON AND KOTZ, CONTINUOUS UNIVARIATE
C                 DISTRIBUTIONS--2, 1970, PAGES 57-74.
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--JUNE      1972. 
C     UPDATED         --SEPTEMBER 1975. 
C     UPDATED         --NOVEMBER  1975. 
C
C---------------------------------------------------------------------
C
      IPR=6
C
C     CHECK THE INPUT ARGUMENTS FOR ERRORS
C
      IF(X.LT.0.0.OR.X.GT.1.0)GOTO50
      GOTO90
   50 WRITE(IPR,2)
      WRITE(IPR,46)X
      PDF=0.0
      RETURN
   90 CONTINUE
    2 FORMAT(1H ,120H***** NON-FATAL DIAGNOSTIC--THE FIRST  INPUT ARGUME
     1NT TO THE UNIPDF SUBROUTINE IS OUTSIDE THE USUAL (0,1) INTERVAL **
     1***)
   46 FORMAT(1H , 35H***** THE VALUE OF THE ARGUMENT IS ,E15.8,6H *****)
C
C-----START POINT-----------------------------------------------------
C
      PDF=1.0
C
      RETURN
      END 
