# bessel_i_nu

Bessel-i-nu-func

## Definition:

evaluates an approximation to the modified Bessel function of the first kind I/4 (x), where the order v=-3, -2, -1, 1, 2 or 3 and x is real and positive. For positive orders it may also be called with x=0, since I/4 (0)=0 when v>0. For negative orders the formula
is used.

For more information please review the s18eec function in the NAG document.

## Parameters:

- x (input,double)
- The argument x of the function.
- Constraints:
- when ,
- when .

- nu (input,int)
- The argument v of the function.
- Constraints:
- .
- bessel_i_nu (output,double)
- Approximation of the modified Bessel function of the first kind.