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 $e^{-|x|}I_1(x)$ .