b45ch1/algopy — pull request #13 by argriffing (2012-10-19 17:17:23+00:00)
Title: added erfi

This is not technically a scipy special function, so I could understand if you do not want to add it, or at least not lump it together with the official scipy special functions. On the other hand it seems likely, in my opinion, that it will eventually be added to scipy. For example, scipy.special has erf, erfc, and their inverses, whereas the Wikipedia page for erf
http://en.wikipedia.org/wiki/Error_function
lists erfi immediately after erf and erfc.

More arguments in favor of adding erfi are related to its connection to imaginary numbers. The straightforward implementation of erfi(x) is as - 1j * erf( 1j * x) , but the hypergeometric identity may get around this issue of using complex numbers. Normally the presence of imaginary numbers would not be such a big deal, but my understanding is that AlgoPy was not explicitly designed to deal with complex numbers, although in some cases they may be handled correctly. Furthermore, the addition of this special function could help test eventual complex number support, through the equation relating erf and erfi.