nag_bessel_i0_scaled (s18cec) returns a value of the scaled modified Bessel function .

nag_bessel_i0_scaled (s18cec) evaluates an approximation to , where  is a modified Bessel function of the first kind. The scaling factor  removes most of the variation in .

The function uses the same Chebyshev expansions as s18aec (nag_bessel_i0), which returns the unscaled value of .

Relative errors in the argument are attenuated when propagated into the function value. When the accuracy of the argument is essentially limited by the machine precision, the accuracy of the function value will be similarly limited by at most a small multiple of the machine precision.

None.