[SciPy-Dev] scipy.io.loadmat and matvec multiply

[Stephan Hoyer]

On Sat, Aug 26, 2017 at 12:09 AM, Jonathan Taylor <
jonathan.taylor at stanford.edu> wrote:

> So, matvec is just slower because of strides and where numpy retrieves
> data? Is there a simple way to do this besides a copy? I can easily afford
> the copy, just wondering.
>

No, the only way to change the strides of an array with the same data is to
make a copy.

Array operations will always be fastest when the smallest strides are along
the axis iterated over in the inner-most (summed) loop. So this existing
strides of your matrix are not sub-optimal in general, just for this
specific operation. They would be suitable, for example, in a vector-matrix
multiply.
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