EXPDF
This function evaluates the exponential cumulative distribution function.
Function Return Value
EXPDF — Function value, the probability that an exponential random variable takes a value less than or equal to X. (Output)
Required Arguments
X — Argument for which the exponential cumulative distribution function is to be evaluated. (Input)
B — Scale parameter of the exponential distribution function. (Input)
FORTRAN 90 Interface
Generic: EXPDF (X, B)
Specific: The specific interface names are S_EXPDF and D_EXPDF.
FORTRAN 77 Interface
Single: EXPDF (X, B)
Double: The double precision name is DEXPDF.
Description
The function EXPDF evaluates the exponential cumulative distribution function (CDF), defined:
where
is the exponential probability density function (PDF).
Example
In this example, we evaluate the probability function at X = 2.0, B = 1.0.
USE UMACH_INT
USE EXPDF_INT
IMPLICIT NONE
INTEGER NOUT
REAL X, B, PR
CALL UMACH(2, NOUT)
X = 2.0
B = 1.0
PR = EXPDF(X, B)
WRITE (NOUT, 99999) X, B, PR
99999 FORMAT (' EXPDF(', F4.2, ', ', F4.2, ') = ', F6.4)
END
Output
EXPDF(2.00, 1.00) = 0.8647
