[Numpy-discussion] Ticket #798: `piecewise` exposes raw memory

[Stéfan van der Walt]

Referring to
http://scipy.org/scipy/numpy/ticket/798

`piecewise` uses `empty` to allocate output memory.  If the conditions
do not sufficiently cover the output, then raw memory is returned,
e.g.,

{{{
import numpy as np
np.piecewise([0,1,2],[True,False,False],[1])
}}}

A patch which addresses the issue is available here for review:

http://codereview.appspot.com/1105

Documentation is being updated on the wiki.