Re: [Numpy-discussion] einsum slow vs (tensor)dot

[George Nurser]

On 25 October 2012 22:54, David Warde-Farley warde...@iro.umontreal.cawrote:

 On Wed, Oct 24, 2012 at 7:18 AM, George Nurser gnur...@gmail.com wrote:
  Hi,
 
  I was just looking at the einsum function.
  To me, it's a really elegant and clear way of doing array operations,
 which
  is the core of what numpy is about.
  It removes the need to remember a range of functions, some of which I
 find
  tricky (e.g. tile).
 
  Unfortunately the present implementation seems ~ 4-6x slower than dot or
  tensordot for decent size arrays.
  I suspect it is because the implementation does not use blas/lapack
 calls.
 
  cheers, George Nurser.

 Hi George,

 IIRC (and I haven't dug into it heavily; not a physicist so I don't
 encounter this notation often), einsum implements a superset of what
 dot or tensordot (and the corresponding BLAS calls) can do. So, I
 think that logic is needed to carve out the special cases in which an
 einsum can be performed quickly with BLAS.


Hi David,
Yes, that's my reading of the situation as well.


 Pull requests in this vein would certainly be welcome, but requires
 the attention of someone who really understands how einsum works/can
 work.


...and I guess how to interface w BLAS/LAPACK.

cheers, George.


 David
 ___
 NumPy-Discussion mailing list
 NumPy-Discussion@scipy.org
 http://mail.scipy.org/mailman/listinfo/numpy-discussion

___
NumPy-Discussion mailing list
NumPy-Discussion@scipy.org
http://mail.scipy.org/mailman/listinfo/numpy-discussion

Re: [Numpy-discussion] einsum slow vs (tensor)dot

[David Warde-Farley]

On Wed, Oct 24, 2012 at 7:18 AM, George Nurser gnur...@gmail.com wrote:
 Hi,

 I was just looking at the einsum function.
 To me, it's a really elegant and clear way of doing array operations, which
 is the core of what numpy is about.
 It removes the need to remember a range of functions, some of which I find
 tricky (e.g. tile).

 Unfortunately the present implementation seems ~ 4-6x slower than dot or
 tensordot for decent size arrays.
 I suspect it is because the implementation does not use blas/lapack calls.

 cheers, George Nurser.

Hi George,

IIRC (and I haven't dug into it heavily; not a physicist so I don't
encounter this notation often), einsum implements a superset of what
dot or tensordot (and the corresponding BLAS calls) can do. So, I
think that logic is needed to carve out the special cases in which an
einsum can be performed quickly with BLAS.

Pull requests in this vein would certainly be welcome, but requires
the attention of someone who really understands how einsum works/can
work.

David
___
NumPy-Discussion mailing list
NumPy-Discussion@scipy.org
http://mail.scipy.org/mailman/listinfo/numpy-discussion