3.5.1.3.10 Bessel_i1_scaled

Definition:

\(i1\_scaled = bessel\_i1\_scaled(x)\) evaluates an approximation to \(e^{-|x|}I_1(x)\), where \(I_1(x)\) is a modified Bessel function of the first kind. The scanling factor \(e^{-|x|}\) removes most of the variation in \(I_1(x)\).

For more information please review the s18cfc function in the NAG document.

Parameters:

x (input, double)

The argument x of the function.

i1_scaled (output, double)

Approximation of \(e^{-|x|}I_1(x)\).