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*: Bastien ROUCARIES <roucaries.bastien@xxxxxxxxx>*Date*: Wed, 25 Aug 2010 17:24:48 +0200*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type :content-transfer-encoding; bh=PZ9y6TqiMefIK4xOErPJftS6ny6bgbcponDoJBSamHg=; b=I6L6bYrCyo2S3W0Q+nKNUlPXTHUSnLDAA7MgAMrIYlDZbwDnNScgArtVq0UxUlFoEK iJJXFFRJvyf/mpThWcKCdRFuRafIV5xzdXdF66/Skw3Ggp1g3SS5H8Ntr7lLyf/DboU+ 0JwnDiy2xYaR0S37e/jDdgW/Txiq2AkzuXO7Y=*Domainkey-signature*: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=f/0j6CBiCJeBmDWGs28jWrvxenxp+hy1LdABfXh1aK3imDrae3wo43xmZabrp1HM3v TYztuzRvGEo9LLJn2aXxPzEVzYUt5fyU03UMWYfCicfaiaKOg4ikeiqfKU9Rm+F/CgxY qjr06L57mLnfTxFsTxoGlPANMqh9WgffYYwcI=

On Wed, Aug 25, 2010 at 5:21 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote: > 2010/8/25 Bastien ROUCARIES <roucaries.bastien@xxxxxxxxx>: >> On Wed, Aug 25, 2010 at 4:54 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote: >>> 2010/8/25 Bastien ROUCARIES <roucaries.bastien@xxxxxxxxx>: >>>> On Wed, Aug 25, 2010 at 4:18 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote: >>>>> 2010/8/25 Bastien ROUCARIES <roucaries.bastien@xxxxxxxxx>: >>>>>> Hi, >>>>>> >>>>>> I want to squeeze some line and column of matrix in place, in order to >>>>>> remove the null space. >>>>>> >>>>>> How can I do that? >>>>>> >>>>>> I have tryied block(i,j,k,l).eval() but i think it is suboptimal >>>>> >>>>> Ah, I see, trying to avoid aliasing issues. >>>>> >>>>> In fact, in assignments, we are always traversing matrices >>>>> left-to-right and top-to-bottom. >>>>> >>>>> So you can remove the eval() if you are a little careful. For example, >>>>> this works: >>>>> >>>>> matrix.block(i,j,k,l) = matrix.block(i+1,j,k,l); // squeeze row i >>>>> >>>>> Of course this is relying on undocumented behavior; but I really don't >>>>> see why we'd ever change this. >>>> >>>> Because it is really really useful removing null space on eigenvector >>>> decomposition** ? >>> >>> I wasn't questioning the interest of removing null parts of matrices :-) >>> I was saying that the behavior on why my trick above is relying, >>> though undocumented, is unlikely to change. >>> >> >> BTW this solution using block does not change the size of the matrix. >> Do you know how to change the size ? > > Use conservativeResize(). Thanks And i will welcome a punchout(row i, colum i) method for the next api revision :) Bastien

**References**:**[eigen] How to squeeze in place a vector matrix***From:*Bastien ROUCARIES

**Re: [eigen] How to squeeze in place a vector matrix***From:*Benoit Jacob

**Re: [eigen] How to squeeze in place a vector matrix***From:*Bastien ROUCARIES

**Re: [eigen] How to squeeze in place a vector matrix***From:*Benoit Jacob

**Re: [eigen] How to squeeze in place a vector matrix***From:*Bastien ROUCARIES

**Re: [eigen] How to squeeze in place a vector matrix***From:*Benoit Jacob

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