3.5.1.3.13 Bessel_k_nu

Definition:

\(k\_nu =bessel\_k\_nu(x,nu)\) evaluates an approximation to the modified Bessel function of the second kind \(K_{\upsilon /4}(x)\), where the order =-3, -2, -1, 1, 2 or 3 and x is real and positive. For negative orders the formula

\[K_{-\upsilon /4}(x)=K_{\upsilon /4}(x)\]

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.

\(nu\) (input, int)

The argument \(\nu\) of the function.

Constraints:

\[1\leq abs(nu)\leq 3\]

\(k\_nu\) (output, double)

Approximation of the modified Bessel function of the second kind.