Oops, sorry, Keith Goodman kindly pointed out that I had missed out: On Wed, Apr 18, 2012 at 11:03 AM, Matthew Brett <matthew.br...@gmail.com> wrote: > Hi, > > I just wanted to point out a situation where the scalar casting rules > can be a little confusing:
In [110]: a = np.array([-128, 127], dtype=np.int8) > In [113]: a - np.int16(128) > Out[113]: array([-256, -1], dtype=int16) > > In [114]: a + np.int16(-128) > Out[114]: array([ 0, -1], dtype=int8) > > This is predictable from the nice docs here: > > http://docs.scipy.org/doc/numpy/reference/generated/numpy.result_type.html > > but I offer it only as a speedbump I hit. > > On the other hand I didn't find it easy to predict what numpy 1.5.1 > was going to do: > > In [31]: a - np.int16(1) > Out[31]: array([127, 126], dtype=int8) > > In [32]: a + np.int16(-1) > Out[32]: array([-129, 126], dtype=int16) > > As a matter of interest, what was the rule for 1.5.1? Matthew _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
