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C Library Functions  - exppdf (3)

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NAME

exppdf(3f) - [M_datapac:PROBABILITY_DENSITY] compute the exponential probability density function

CONTENTS

Synopsis
Description
Input Arguments
Output Arguments
Examples
Author
Maintainer
License
References

SYNOPSIS

SUBROUTINE EXPPDF(X,Pdf)

       REAL(kind=wp),intent(in) :: X
       REAL(kind=wp),intent(out) :: Pdf

DESCRIPTION

EXPPDF(3f) computes the probability density function value for the exponential distribution with mean = 1 and standard deviation = 1.

This distribution is defined for all non-negative X, and has the probability density function

      f(X) = exp(-X)

INPUT ARGUMENTS

X	The value at which the probability density function is to be evaluated. Values should be non-negative.

OUTPUT ARGUMENTS

PDF	The probability density function value.

EXAMPLES

Sample program:

   program demo_exppdf
   !@(#) line plotter graph of probability density function
   use M_datapac, only : exppdf, plott, label
   implicit none
   real,allocatable  :: x(:), y(:)
   integer           :: i
      call label(’exppdf’)
      x=[(real(i),i=0,100,1)]
      if(allocated(y))deallocate(y)
      allocate(y(size(x)))
      do i=1,size(x)
         call exppdf(x(i)/10.0,y(i))
      enddo
      call plott(x,y,size(x))
   end program demo_exppdf

‘‘‘ Results:

    The following is a plot of Y(I) (vertically) versus X(I) (horizontally)
                      I-----------I-----------I-----------I-----------I
     0.1000000E+03 -  X
     0.9583334E+02 I  X
     0.9166666E+02 I  X
     0.8750000E+02 I  X
     0.8333334E+02 I  X
     0.7916667E+02 I  X
     0.7500000E+02 -  X
     0.7083334E+02 I  X
     0.6666667E+02 I  X
     0.6250000E+02 I  X
     0.5833334E+02 I  X
     0.5416667E+02 I  X
     0.5000000E+02 -  X
     0.4583334E+02 I  XX
     0.4166667E+02 I   X
     0.3750000E+02 I   X
     0.3333334E+02 I   XX
     0.2916667E+02 I    XX
     0.2500000E+02 -     XXX
     0.2083334E+02 I       XXX
     0.1666667E+02 I          XXXX
     0.1250000E+02 I              XXX X
     0.8333336E+01 I                    X X X X
     0.4166672E+01 I                            X  X  X   X
     0.0000000E+00 -                                         X   X    X
                      I-----------I-----------I-----------I-----------I
               0.4540E-04  0.2500E+00  0.5000E+00  0.7500E+00  0.1000E+01

AUTHOR

The original DATAPAC library was written by James Filliben of the Statistical Engineering Division, National Institute of Standards and Technology.

MAINTAINER

John Urban, 2022.05.31

LICENSE

CC0-1.0

REFERENCES

o	Johnson and Kotz, Continuous Univariate Distributions--1, 1970, pages 207-232.

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Nemo Release 3.1

exppdf (3)

February 23, 2025

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