Re: [eigen] const Static Vector/Matrix howto |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] const Static Vector/Matrix howto*From*: Gael Guennebaud <gael.guennebaud@xxxxxxxxx>*Date*: Thu, 4 Feb 2010 23:55:02 +0100*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :from:date:message-id:subject:to:content-type :content-transfer-encoding; bh=3GAw9gFhF1F94pGwoECwIBJ9iTS0nnsuI65BvLHEkc4=; b=g17hyj0Y63yVjDO53pcL/3N6e6aAIGs0JgQkcO8T+huaz1ncccQNS4hoBPutW8GRt0 4s4QBnkJFBJYCaexnTmiDyEVzXwnTyu4ycJeDMsaqaFDFTgFzRSw5Q+YQXrR9LjIODhz 7gGPnGXoZISpDLJkR8TWK2/gNxk8CVoTt906c=*Domainkey-signature*: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type:content-transfer-encoding; b=gjdRDPUm88kFFpEAPg8VeO7uGZaNhIUKZkbHkhsZ7J90H0xIaqPIniyFNlW3qG2hpC 9u9veCV14pQtskn+to7zscPriglQ4+2rtpP7huzL39MR8OA1En+9rq1qhWTZr0tp0t4F TJaFhVc7ipN3WS83PcgXzHZp3ZInI+snCLxWk=

On Thu, Feb 4, 2010 at 11:32 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote: > If it makes your life easier to allow the Matrix contructor taking > x,y,z,w for 2x2 matrices, then I'm OK with that and that is a very > simple change in Matrix.h : remember that matrix.coeffRef(int index) > is allowed for all matrices, not just vectors. I was going to propose the same :) However, note that the order of the coefficients should be row major: mat(1,2, 3,4); like the coma initializer. So we cannot simply call coeffRef(int index). gael > > Benoit > > 2010/2/4 Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>: >> I think you can do this: >> >> EIGEN_ALIGN16 double matrix_data[] = { 1., 2., 3. ,4. }; >> Matrix2d::AlignedMapType m(matrix_data); >> >> There are no copies involved and the matrix m is aligned. >> >> - Hauke >> >> On Thu, Feb 4, 2010 at 3:40 PM, Thomas Capricelli <orzel@xxxxxxxxxxxxxxx> wrote: >>> >>> Hi, >>> >>> I'd like to ask about a problem i often encounter. I need to allocate a static const Vector or matrix. That is, i already know the coefficients. >>> >>> I currently do something like this: >>> >>> static double matrix_data[] = { 1., 2., 3. ,4. }; >>> static Eigen::Matrix< double, 2, 2 > m(matrix_data); >>> >>> Which is far from perfect because i guess the data is copied, so we have both an allocation and a copy that are not really needed. >>> >>> I thought about using ::map: >>> >>> Map<Eigen::Matrix< double, 2, 2 > > m(matrix_data); >>> >>> but i'm not sure how efficient this is.. i guess in my first try the constructor of ::Matrix ensure alignement while in the second case, the data is where matrix_data is, which has no guaranty of being aligned, is it ? >>> >>> So what would you suggest ? Should i ensure (how?) that matrix_data is aligned and use the Map stuff ? Any other idea? >>> >>> ++ >>> Thomas >>> -- >>> Thomas Capricelli <orzel@xxxxxxxxxxxxxxx> >>> http://www.freehackers.org/thomas >>> >>> >>> >> >> >> > > >

**Follow-Ups**:**Re: [eigen] const Static Vector/Matrix howto***From:*Benoit Jacob

**References**:**[eigen] const Static Vector/Matrix howto***From:*Thomas Capricelli

**Re: [eigen] const Static Vector/Matrix howto***From:*Hauke Heibel

**Re: [eigen] const Static Vector/Matrix howto***From:*Benoit Jacob

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