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(x∣b).
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
