bessel_K0

Evaluates the real modified Bessel function of the second kind of order zero K0(x).

Synopsis

#include <imsl.h>

float imsl_f_bessel_K0 (float x)

The type double function is imsl_d_bessel_K0.

Required Arguments

float x (Input)
Point at which the modified Bessel function is to be evaluated. It must be positive.

Return Value

The value of the modified Bessel function

 

If no solution can be computed, then NaN is returned.

Description

Since K0(x) is complex for negative x and is undefined at x = 0, imsl_f_bessel_K0 is defined only for x > 0. For large x, imsl_f_bessel_K0 will underflow.

 

Figure 1,  Plot of K0(x) and K1(x)

Example

The Bessel function K0(1.5) is evaluated.

 

#include <imsl.h>

#include <stdio.h>

 

int main()

{

float x = 1.5;

float ans;

 

ans = imsl_f_bessel_K0(x);

printf("K0(%f) = %f\n", x, ans);

}

Output

 

K0(1.500000) = 0.213806

Alert Errors

IMSL_LARGE_ARG_UNDERFLOW

The argument x must not be so large that the result, approximately equal to ,

underflows.