| Re: [eigen] conservative resize ... |
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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] conservative resize ...
- From: Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>
- Date: Mon, 7 Sep 2009 13:52:46 +0200
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On Mon, Sep 7, 2009 at 1:34 PM, Márton Danóczy<marton78@xxxxxxxxx> wrote:
> You're right, initializing a matrix after resizing should suffice, if
> it is not slower than doing both in one step.
It is possible and would probably be even faster - if done correctly.
I am just saying this because you would need to take care of
initializing only those parts of the matrix which are yet
uninitialized. At the moment, when pre-initializing with zeros, the
parts of the old and resized matrices that overlap are accessed twice.
Once for initializing with zeros and a second time to copy the old
values.
@Benoit, ExtendByZero is fine. I am just wondering, was there a
particular reason for making NoChange_t a struct? Should we follow the
same strategy to ExtendByZero?
- Hauke