exponential_pdf

Evaluates the exponential probability density function (PDF).

Synopsis

#include<imsls.h>

floatimsls_f_exponential_pdf(floatx, floatb)

The type double function is imsls_d_exponential_pdf.

Required Arguments

floatx (Input)
Argument for which the exponential PDF is to be evaluated. x must be non-negative.

floatb (Input)
Scale parameter of the exponential PDF.   b must be positive.

Return Value

The value of the exponential probability density function with argument x and scale parameter b. A value of NaN is returned if an input value is in error.

Description

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

 

Example

In this example, we evaluate the exponential PDF at x = 2.0, b = 1.0.

 

#include <imsls.h>

#include <stdio.h>

 

int main()

{

float x = 2.0;

float b = 1.0;

float p;

 

p = imsls_f_exponential_pdf(x,b);

printf("The probability density of exponential ");

printf("random variable X\nwith scale parameter b = ");

printf("%3.1f and value x = %3.1f is %6.4f\n\n", b, x, p);

}

Output

The probability density of exponential random variable X

with scale parameter b = 1.0 and value x = 2.0 is 0.1353