Re: [eigen] Matrix - Scalar CwiseUnaryOps |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] Matrix - Scalar CwiseUnaryOps*From*: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>*Date*: Wed, 4 May 2011 09:08:48 -0400*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type:content-transfer-encoding; bh=+jMxbdPJYG84d/OTKq9R5wVtpE3jC9a9UAXvi00Crgs=; b=m34KiUzUtHX7/f3o15LLa0L5YiYq1Hjq5Oiwg+RDdgef7kAEcym3a/lIj9J/5f1wsK 1szeRmx1Pk4CbsalXFqT4daZpPpbw95znNz/Kk3mPrCtDyK9WLNvX8t250RylMo7HqhF 7vnvfIjS3Z5DZ/nOIibf6dfsNQ0WHRScXFWxs=*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=PYlVXYnwTgBdPlP+kVmbB0DZt5/cc7MUQG/R2nSWx1YgJXEDbDcvv87Em9avLNvIBI D3romOfpbJt1M4NDwFEybSqpF2PRggkyFHHoQ4mawtNXwr2gWxy36IAYXevmUocPjZKL 3UI1Tkotar8MW1erVmc/7R8tqh/elqt4JSMCg=

What we could have is a method for doing that. Like, matrix.cwiseSum(scalar) if we don't have such a thing already. Benoit 2011/5/4 Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>: > Ok. fine enough. I just thought we could be a bit less strict here but > I understand your reasoning. > > On Wed, May 4, 2011 at 2:55 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote: >> Yes, the ambiguity is between interpreting a+M as >> 1) aE+M where E is the matrix all of whose coefficients are 1; this >> is what we do for arrays; or >> 2) aI + M where I is the identity matrix; this is definitely what >> mathematicians mean by a+M whenever they use that notation. This is >> required if you want basic matrix arithmetic rules to be self >> consistent, e.g. distributivity: (a+M)*N = aN + M*N >> >> This ambiguity is the primary reason why we leave this undefined in Eigen. >> >> Benoit >> >> 2011/5/4 Thomas Capricelli <orzel@xxxxxxxxxxxxxxx>: >>> >>> Hi, >>> >>> From a mathematical point of view a.M is defined but a+M is not... >>> (a=scalar, M=Matrix). >>> >>> my 2 cents.. >>> >>> Thomas >>> >>> -- >>> >>> Thomas Capricelli <orzel@xxxxxxxxxxxxxxx> >>> >>> http://www.freehackers.org/thomas >>> >>> On Wednesday 04 May 2011 11:39:13 Hauke Heibel wrote: >>> >>>> Hi, >>> >>>> >>> >>>> I know that we have the array functionality for those operations but I >>> >>>> wonder whether we should enable +/- operations between matrices and >>> >>>> scalars. >>> >>>> >>> >>>> We already have * and / and thus I think it might make sense. It's >>> >>>> just for convenience and I have met quite a few occasions where this >>> >>>> feature would lead to shorter code. What do you think? >>> >>>> >>> >>>> - Hauke >>> >>>> >>> >>>> >>> >>>> >>> >> >> >> > > >

**Follow-Ups**:**Re: [eigen] Matrix - Scalar CwiseUnaryOps***From:*Eamon Nerbonne

**References**:**[eigen] Matrix - Scalar CwiseUnaryOps***From:*Hauke Heibel

**Re: [eigen] Matrix - Scalar CwiseUnaryOps***From:*Thomas Capricelli

**Re: [eigen] Matrix - Scalar CwiseUnaryOps***From:*Benoit Jacob

**Re: [eigen] Matrix - Scalar CwiseUnaryOps***From:*Hauke Heibel

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