Re: [OctDev] complex error function

[Steven G. Johnson]

On 11/20/12 4:33 PM, Jordi Gutiérrez Hermoso wrote:
> I'm still not sure what to do with this code... It sounds useful,
> sure, but you didn't write it for Octave except for a small wrapper.

Not sure why that matters?  Most of the math and linear algebra 
functions in Octave were not written "for Octave".

Presumably, that is how it would remain as well -- the only 
octave-specific portion of the function that is needed would be a thin 
interface layer, similar to what I am providing already.

> Since you're trying to overwrite Octave functions, it should go in
> Octave core but you also want to provide a bunch of other special
> functions, so those should go in the specfun package in OF.
>
> I'm also not sure how committed you are to maintaining this code for
> Octave. If this is a one-time code dump and it's up to us to maintain
> this code in the future, I'm less inclined to accept it into Octave
> core, since it's a relatively rare request. I have never heard of our
> users clamouring for the Faddeeva function or its relatives.

It is up to you, of course, whether you want to support error functions 
of complex arguments.  Note that these are used in a variety of 
applications, not just in wave theory.  But of course you can always 
direct such users to an external package.

One argument would be that, as a general principle, Octave supports 
complex arguments for special functions (trig, bessel, ...) where it 
makes sense and free code is available, so why should erf and erfc be 
any different?

Another argument is the SciPy has found it useful for some time to 
support error functions of complex arguments, including both erf and the 
Faddeeva function, and recently switched over to my implementation:
    https://github.com/scipy/scipy/commit/ed14bf0

Regarding support, I plan to update my code as necessary for the 
foreseeable future, e.g. for bug fixes and new languages.  If specific 
changes are needed for Octave (or SciPy), I am happy to consider them, 
and to work with the Octave maintainers as needed.

--SGJ