sympy/sympy — pull request #944 by raoulb (2012-01-08 17:19:35+00:00)
Title: Improvements on the erf function

Some smaller improvements on the error function `erf(x)`.

Note that this breaks `limit(erf(x),x,oo)` but I could not
figure out the reason.

The rewrite to `uppergamma` has little effect as `uppergamma(1/2, ...)`
autosimplifies.