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 11:21:54 -0400*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=1Vu/0q5vtkLcI347Yu5XKQc76UuZuOPKLJjT8NHdBrI=; b=UfoXd/IwyEtCwxTmciYSPNcRu9fz7Hwey2vdUzSzcPMLR7aHgJeF8hf3FOQ2fwY2Ht NhFUaUxm3+xDRTzyLFbWa8sCKXhI0aqn876DC28Uqmd4HPyBQ9Rp+27OvnCwmuU/qGQS xjOFS39LNnUHcr/jbk0mgJy4Wn/g/c+PEMEMY=*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=Bxjceww3gPmQIoRospG42mGTtSPo7q2Z28EywmCSkFdsal7EXOPk3bIiVAQdu6+bvK PZwz+gULkO4LDiHwjkQhh3cMho6Qm4FEB2PV82ayjl8y2vE7Cd65GNzbAvsur3aA9mde 9muAeaBqWbZHnbPRZKThLvmIPX6lM4K9fVBlg=

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(). Benoit > > Bastien > > >

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

**Re: [eigen] How to squeeze in place a vector matrix***From:*Hauke Heibel

**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

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