Dieter Kaiser wrote:
> I have finished some further work on the Exponential Integrals and attached the
> files to the feature request on Sourceforge.net.
I don't think it's necessary to attach files to the feature request or
even file a feature request since you have commit access, and everyone
agrees that exponential integrals are nice feature to have.
It's easier for me to just do a cvs update and diff to see what you've
done. :-)
>
> The following features are now implemented:
>
> 1. Numerical evaluation for complex Flonum and Bigfloat numbers
> using an expansion in a power series or continued fractions.
> The numerical support is fully implemented for the E[n](z) function.
> All other functions call E[n](z) for numerical evaluation.
>
> Because we have no support for a Gamma function with complex Bigfloat
> arguments, the numerical evaluation for complex parameters n is not
> implemented for Complex Bigfloats.
There is bffac and cbffac for bigfloat factorials. They're not in Lisp,
though.
> Implementing the Exponential Integrals I have found the following things which
> could be done also:
>
> 1. Gamma function with support for Complex Bigfloats
> 2. More support for the Erf and Erfc functions
Yes, that would be nice. Erf and Erfc are both lacking evaluation for
complex args and for bigfloats. I thought of just using a continued
fraction for both for bigfloats, but never finished.
> 3. More support for the Gammaincomplete function
Yes, that would be nice. Along with all the other special functions
that specint wants to use and produce.
In any case, this is all good stuff.
Ray