| Re: [eigen] How to squeeze in place a vector matrix |
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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] How to squeeze in place a vector matrix
- From: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>
- Date: Wed, 25 Aug 2010 11:35:40 -0400
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2010/8/25 Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>:
> On Wed, Aug 25, 2010 at 5:21 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:
>> Use conservativeResize().
>
> IIRC, conservative resize copies. So there is pretty much no reason in
> avoiding the aliasing since you will anyways introduce a temporary -
> if not more, when "punching out" multiple rows/cols.
>
> I would suggest to write a new function that creates a single target
> temporary and assembles the blocks between the rows/cols you want to
> kick out. It might be a little bit ugly regarding the indexing but is
> probably the most efficient you can do for now.
This is similar to what the Minor expression was doing in eigen2
(still available in EIGEN2_SUPPORT).
But as an expression, it was slow because of the branching (or at
least comparison) needed in every coeff() call.
Benoit
>
> - Hauke
>
>
>