Re: [eigen] Matrix - Scalar CwiseUnaryOps |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] Matrix - Scalar CwiseUnaryOps*From*: Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>*Date*: Wed, 4 May 2011 15:00:29 +0200*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type:content-transfer-encoding; bh=Fkbcm6aRj9YAAxc0raP32gXag3bCbTqBYZCV6VZKVts=; b=JuZMcjQXf8dUVmeyq0Z6FBhIcGS2GvEH75AkEAz+zcAPP+Skc21UVRjZPK5DUMrJKJ 0rIBTHAopQ5k2YCghQCGswgKC5zI2KPJnmJdNeSZc3OAhNogGGZd/+cQb4Zhfs/mmg1d TP4+7QfrQlkZiNwUgStlRENltQ1ODGrd1CiuM=*Domainkey-signature*: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=GLgLQKkOIUFnJgBKgNlMrw7Ul+HrXtXHOICK19jeA9A0PkLhUvcSUUFm5reFqZmIlw iccrXvSeldkKRslauhj6JaEcNjoT/qypkqoUUjuczPCP1htZi+Bko7IQYdF5C7sem4IK lBAPAyDIrvHczvKXlqYsmmeLrdq+RRXpqeCjc=

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:*Benoit Jacob

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

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

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

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