EXPPR

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 f(xb).

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