Re: [eigen] return type of inner product

[Robert Bocquier <robert.bocquier@xxxxxxxxxxx>]

Benoit Jacob a écrit :

2009/10/1 Gael Guennebaud <gael.guennebaud@xxxxxxxxx>:
  

hi,

I still have a FIXME in the Product.h file that I'd like to discuss:

// FIXME : maybe the "inner product" could return a Scalar
// instead of a 1x1 matrix ??
// Pro: more natural for the user
// Cons: this could be a problem if in a meta unrolled algorithm a matrix-matrix
// product ends up to a row-vector times col-vector product...

any opinion ?

note that here "inner product" denotes any row-vector times col-vector
products, and not the .dot() function which of course returns a
scalar.
    

Hm, I really can't make myself an opinion either way!

I don't think that the problem for meta-unrolled algorithms is very
important, as that's a very rare use case and these could well handle
a special case with a specialization.

So i'm 63.7% in favor of your proposal to make it return a Scalar.

Benoit



  

Hi,

What about using a (not existing yet I suppose) Matlab => C++/Eigen translator ?
I am thinking about such a beast, and surely 1x1 Matrix would be more convenient in such cases.

But we should discuss that in another thread.

--
Robert Bocquier


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