Re: [eigen] [Review] Pull request 66, Huge Tensor module improvements |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] [Review] Pull request 66, Huge Tensor module improvements*From*: Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx>*Date*: Wed, 11 Jun 2014 22:58:54 +0200

Hi! On 11.06.2014 20:27, Christian Seiler wrote:

Ok, since we're looking for an arbitrary number anyway, why don't we just say 10?

"640 [...] should be enough for everyone" Bonus question: What is the smallest arbitrary integer? ;) (10 is not correct because it is not arbitrary)

however I don't see an equivalent to the Eigen Matrix class in the tensor world.

The downside of the pblend approach is that the then and else expression always have to be evaluated. When using a packet of 4 there is a 12.5% chance that either can be completely skipped, so the non vectorized implementation of select might be faster in some case. Before using the pblend instruction in Eigen Core I'd like to update the evaluation cost model to reflect this.

ArrayXi A, B; // ... ArrayXi C = (B!=0).select(A/B, 0);

The Map code assumes a 2D layout in several places. For example, the notion of inner and outer strides assume there are exactly 2 strides. Similarly, referring to a coefficient can be done by row and column. On the other hands, n dimensional accessors are missing. Long term I'd like to see the Tensor code moved into Eigen core and the TensorMap merged with the Map class, but for the time being I thought it was safer to create a TensorMap class.No, you completely misunderstand me: I don't want to reuse the code of Map<>. It's clear that this won't work. I just want to reuse the name, so that the user has a consistent API.

Generally speaking: just to be on the same page about a future plan: I'd also like to continue working on the Tensor module myself (that's why I started this thread in the first place), so we need to do a couple of things:

Christoph -- ---------------------------------------------- Dipl.-Inf., Dipl.-Math. Christoph Hertzberg Cartesium 0.049 Universität Bremen Enrique-Schmidt-Straße 5 28359 Bremen Tel: +49 (421) 218-64252 ----------------------------------------------

**Follow-Ups**:**Re: [eigen] [Review] Pull request 66, Huge Tensor module improvements***From:*Christian Seiler

**References**:**[eigen] [RFC] Tensor module: class hierarchy***From:*Christian Seiler

**Re: [eigen] [RFC] Tensor module: class hierarchy***From:*Benoit Steiner

**[eigen] [Review] Pull request 66, Huge Tensor module improvements***From:*Christian Seiler

**Re: [eigen] [Review] Pull request 66, Huge Tensor module improvements***From:*Benoit Steiner

**Re: [eigen] [Review] Pull request 66, Huge Tensor module improvements***From:*Christian Seiler

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