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 17:16:17 +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=lgbXribpHe9DVMUhA+2OjHtoPEGasJgtRafx5SRH0P8=; b=Q3kQttXw+rPO87tQJnAnBmEN754rRnRZGgM17sSt8so5uRIhG4kIe72cze10w1srS7 P73ZKB3lWD2cLPiO3bp6bxYbWlK8+1r7OTElqVSuEDIrIaBVezofAiK2u4h8NMilwk8z RMGeptPNbAQRObiKAuEftPXgum2egmlzxCdfA=*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=ur+Rwj3TwHFayYCye0RdFxxJbEfTnVEAlfKNZMzA2TAMCJb5BOJTA9alKRDvUq6FzB uyTDdtFqKTz9+aJCBCA9a2oEUtCxwwq258lJrhX4l86vjsQgmuO84mk5DsavWr9HmmdV oxA7dakL4gW1mULkQ2guIcew5TfSSKUNEF2Yw=

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 ? Bastien

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

**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

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