bessel_I0

Evaluates the real modified Bessel function of the first kind of order zero I0(x).

Synopsis

#include <imsl.h>

float imsl_f_bessel_I0 (float x)

The type double function is imsl_d_bessel_I0.

Required Arguments

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

Return Value

The value of the Bessel function

 

If no solution can be computed, NaN is returned.

Description

For large ∣x∣, imsl_f_bessel_I0 will overflow.

 

Figure 1,  Plot of I0(x) and I1(x)

Example

The Bessel function I0(1.5) is evaluated.

 

#include <imsl.h>

#include <stdio.h>

 

int main()

{

float x = 1.5;

float ans;

 

ans = imsl_f_bessel_I0(x);

printf("I0(%f) = %f\n", x, ans);

}

Output

 

I0(1.500000) = 1.646723

Fatal Errors

IMSL_LARGE_ABS_ARG_FATAL

The absolute value of x must not be so large that e|x| overflows.