Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0 |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0*From*: Aron Ahmadia <aja2111@xxxxxxxxxxxx>*Date*: Sat, 17 Jul 2010 19:08:18 +0300*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:sender:received :in-reply-to:references:date:x-google-sender-auth:message-id:subject :from:to:content-type:content-transfer-encoding; bh=6jon+oMnqcnxKDAVgqwKi269fUaX2Xr2Njcn8YJQ65M=; b=jb29+XotprM1ghxqTKUEFtoT/ZSjdNJsqsP6DebASU3wTDT8TVGnTFBrrn8Ttbeh48 ZLiIkd9NNk5VsxSvWQnSyGPr382Ys64o7d4/m3fTHhgZUjjFxm4+8kp2nbkFfKztL4iX vBCQ1eA+w24K2xa3wXRX2iVYs7Pbld6w/6svw=*Domainkey-signature*: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type :content-transfer-encoding; b=EWJaCIonRGwhv8koce25b6UkO0TB3ae+Vp6iG08tcQSyA8DuvGa+tzoSQJCRCbVOlj EIuXd05Agiyk/9w57D8eLydhwOIzbyb69hHhBt4b4+sTrgLQeVaOhn5xYJYAzM21MiI8 v0RO/qyGNMMVAOtac1c7LUL1xTFj3oebJSb98=

I admit that pointing to LAPACK was a bad example (I am least familiar with that package of those mentioned), however, MATLAB and NumPy are far more common these days as computational interfaces than LAPACK (even if they are built on top of its routines). A On Sat, Jul 17, 2010 at 6:55 PM, Aron Ahmadia <aja2111@xxxxxxxxxxxx> wrote: > Hi Benoit, > > Sorry, I meant the inverse in this sense, this is something that > arises when solving the two problems: > > Ab = x > Ax = b > > Where I leave the unknown as x, and the fixed as b. Both problems can > be bound by a condition number that depends on the perturbations of x > > \kappa = ||A||*||b||/||x|| <= ||A||*||A^-1|| (forward) > \kappa = ||A^-1||*||b||/||x|| <= ||A||*||A^-1|| (backward) > > The term ||A||*||A^-1||, since it arises in both forward and backward > problems, is called the condition number of A. This is pretty solidly > in the literature, and you wouldn't confuse anybody if you had a > general "calculate the condition number of a matrix" function and more > specialized ones for calculating the condition numbers of other > specific operations. > > A >

**Follow-Ups**:**Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0***From:*Benoit Jacob

**References**:**[eigen] Problem inverting a Matrix4f with Eigen 2.0.0***From:*Robert Lupton the Good

**Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0***From:*Christoph Hertzberg

**Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0***From:*Gael Guennebaud

**Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0***From:*Robert Lupton the Good

**Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0***From:*Benoit Jacob

**Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0***From:*Aron Ahmadia

**Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0***From:*Benoit Jacob

**Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0***From:*Benoit Jacob

**Re: [eigen] Problem inverting a Matrix4f with Eigen 2.0.0***From:*Aron Ahmadia

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