NAG CL Interface
s18cec returns a value of the scaled modified Bessel function .
The function may be called by the names: s18cec, nag_specfun_bessel_i0_scaled or 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
, which returns the unscaled value of
On entry: the argument of the function.
Error Indicators and Warnings
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.
Parallelism and Performance
Background information to multithreading can be found in the Multithreading
s18cec is not threaded in any implementation.
This example reads values of the argument from a file, evaluates the function at each value of and prints the results.