[pythran] Re: Matrix multiplication in Pythran
- From: serge guelton <sguelton@xxxxxxxxxxxxx>
- To: pythran@xxxxxxxxxxxxx
- Date: Thu, 26 Mar 2015 19:41:07 +0100
On Thu, Mar 26, 2015 at 04:13:17PM +0000, Valerio De Carolis wrote:
> On 25/03/15 18:31, Pierrick Brunet wrote:
> >Hi Valerio,
> >
> >It is great to see Pythran used that way and thanks for these kind of
> >feed back.
> >
> >About numpy.dot, only the vec * vec implementation exists for now but it
> >is planned to add this with the numpy.linalg package.
> >
> >To get around this problem, we will be really happy if you want to add
> >this implementation in Pythran :-)
> >Otherwise, I may have a look at this tomorrow for, at least, a "slow"
> >implementation for compatibility.
> >If you want to test it now. I suggest you to implement this function in
> >you Python module (using Python) and Pythran will convert it for you.
> >
> >Cheers,
> >Pierrick
>
>
> Hi Pierrick,
>
> yes I gave it a quick try with a double for approach:
>
> >#pythran export mat_vec_mult(float[][], float[])
> >def mat_vec_mult(A, b):
> > c = np.zeros_like(b)
> >
> > for i in xrange(A.shape[0]):
> > for j in xrange(A.shape[1]):
> > c[i] += A[i,j] * b[j]
> >
> > return c
>
> This is working well in Pythran and even for a small matrix if the code is
> using the non-optimized version. I haven't benchmarked it too much though.
>
> I'm not sure what is the best approach for the implementation of such
> feature in Pythran. Numpy internally defaults to BLAS's GEMV and GEMM style
> functions. So I think the use of BLAS primitives is the natural translation
> from numpy-ish code to the lower-level C++.
Yes, that's the on-going direction. Pierrick explored this today.
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