[Numpy-discussion] Contiguity of result of astype changed - intentional?

Hi,

We hit a subtle behavior change for the ``astype`` array method between 1.6.1 and 1.7.0 beta.

In 1.6.1:

In [18]: a = np.arange(24).reshape((2, 3, 4)).transpose((1, 2, 0))

In [19]: a.flags Out[19]: C_CONTIGUOUS : False F_CONTIGUOUS : False OWNDATA : False WRITEABLE : True ALIGNED : True UPDATEIFCOPY : False

In [20]: b = a.astype(float)

In [21]: b.flags Out[21]: C_CONTIGUOUS : True F_CONTIGUOUS : False OWNDATA : True WRITEABLE : True ALIGNED : True UPDATEIFCOPY : False

In [22]: b.strides Out[22]: (64, 16, 8)

So - ``a.astype(float)`` here has made a new C-contiguous array, somewhat as implied by the 'copy' explanation in the docstring. In 1.7.0 beta, ``a`` is the same but:

In [22]: b.flags Out[22]: C_CONTIGUOUS : False F_CONTIGUOUS : False OWNDATA : True WRITEABLE : True ALIGNED : True UPDATEIFCOPY : False

In [23]: b.strides Out[23]: (32, 8, 96)

Is this intended? Is there a performance reason to keep the same strides in 1.7.0?

Thanks for any pointers,

Matthew