This function evaluates the exponential probability density function.

Function Return Value

EXPPR — Function value, the value of the probability density function.   (Output)

Required Arguments

X — Argument for which the exponential probability density function is to be evaluated.   (Input)

B — Scale parameter of the exponential probability density function.   (Input)

FORTRAN 90 Interface

Generic:                              EXPPR (X, B)

Specific:                             The specific interface names are S_EXPPR and D_EXPPR.

FORTRAN 77 Interface

Single:                                EXPPR (X, B)

Double:                              The double precision name is DEXPPR.

Description

The function EXPPR evaluates the exponential probability density function.  The exponential distribution is a special case of the gamma distribution and is defined as

 

.

This relationship is used in the computation of.

Example

In this example, we evaluate the probability function at X = 2.0, B = 1.0.

 

      USE UMACH_INT
      USE EXPPR_INT
      IMPLICIT NONE

      INTEGER NOUT

      REAL X, B, PR

      CALL UMACH(2, NOUT)

      X = 2.0

      B = 1.0

      PR = EXPPR(X, B)

      WRITE (NOUT, 99999) X, B, PR

99999 FORMAT (' EXPPR(', F4.2, ', ', F4.2, ') = ', F6.4)

      END

Output

 

 EXPPR(2.00, 1.00) = 0.1353

http://www.vni.com/ PHONE: 713.784.3131 FAX:713.781.9260