| Re: [eigen] issue 77: map with stride |
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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] issue 77: map with stride
- From: Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>
- Date: Mon, 18 Jan 2010 09:48:22 +0100
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On Mon, Jan 18, 2010 at 6:25 AM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:
> Then I thought about the example of tiny matrix-matrix products with
> InnerVectorization and how they should specialize to matrix-vector
> product... so you are right, this does matter.
A reference to a code Example within Eigen would be cool. Currently, I
don't really understand the problem.
> But on the other hand, your convention that stride means "outer
> stride" for matrices but suddenly becomes 1 for vectors, is much more
> logical if vectors have innerSize==1, which led to my proposal.
>
> So we have a dilemma.
>
> Let's propose to solve this problem by decoupling the notion of stride
> into two separate notions of stride: "inner stride" and "outer
> stride". Outer stride is what you used to call stride for matrices
> (not vectors). Inner stride is the spacing between two consecutive
> entries within an inner slice, so it is equal to 1 almost always.
Personally, I don't like the notion of inner and outer stride. For 2D
objects, there should only be one stride function. Conversely, the
stride for 1D objects should either not be called at all or it should
be one. But as I said, maybe I am not yet understanding the problem
this causes within Eigen.
- Hauke