# Bessel_k_nu

Bessel-k-nu-func

## Definition:

evaluates an approximation to the modified Bessel function of the second kind , where the order =-3, -2, -1, 1, 2 or 3 and x is real and positive. For negative orders the formula

is used.
For more information please review the s18efc function in the NAG document.

## Parameters:

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

x>0.0.

- (input, int)
- The argument of the function.
- Constraints:

- (output, double)
- Approximation of the modified Bessel function of the second kind.