3.5.2.5.9 Bessel_i1

Definition:

i1 = bessel\_i1(x) evaluates an approximation to the modified Bessel function of the first kind,I_1(x).The function is based on Chebyshev expansions.

For more information please review the s17afc function in the NAG document.

Parameters:

x (input, double)
The argument x of the function.
i1 (output, double)
Approximation of to the modified Bessel function of the first kind.