[Numpy-discussion] Polynomial silent breakage with 1.13
matthew.brett at gmail.com
Fri Jul 7 12:26:56 EDT 2017
Our (nipy's) test suite just failed with the upgrade to numpy 1.13,
and the cause boiled down to this:
import numpy as np
poly = np.poly1d()
poly.c *= 2
Numpy 1.12 gives (to me) expected output:
Numpy 1.13 gives (to me) unexpected output:
The problem is caused by the fact that the coefficients are now a
*copy* of the actual coefficient array - I think in an attempt to stop
us modifying the coefficients directly.
I can't see any deprecation warnings with `-W always`.
The pain point here is that code that used to give the right answer
has now (I believe silently) switched to giving the wrong answer.
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