[Maxima] slatec bessel_k(n, %i*x): lack of precision for large x
toy.raymond at gmail.com
Fri Mar 2 16:31:00 CST 2012
On Fri, Mar 2, 2012 at 11:47 AM, Edwin Woollett <woollett at charter.net>wrote:
> /* this calculation also agrees with Mma, but the zbesk
> error messages clutter up the output, and
> show why it is desireable to have a way to
> surpress the printing of these messages to
> the screen! */
What would you want? No messages so you have no way of knowing that
something potentially bad happened? Signal an (annoying?) error?
> The bottom line here is: are there better bessel function
> routines available which are reasonably accurate for large
> abs(z) args??
Don't know. Maybe you can compute using bfloats and return a float at the
end? (But we don't have a real bfloat implementation of Bessel functions,
so you will have to use Barton's hypergeometric code to compute the Bessel
Maybe bessel_k(v,%i*x) can be computed via
http://www.wolframalpha.com/input/?i=BesselK[v%2Cix]. (See alternate
form). The Bessel J and Y functions don't appear to have problems with the
size of x in your tests. But I have no idea how accurate the result would
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