Re: [eigen] GeneralizedEigenSolver eigenvalues different from lapack dggev |

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*To*: eigen <eigen@xxxxxxxxxxxxxxxxxxx>*Subject*: Re: [eigen] GeneralizedEigenSolver eigenvalues different from lapack dggev*From*: Gael Guennebaud <gael.guennebaud@xxxxxxxxx>*Date*: Thu, 4 Aug 2016 17:17:24 +0200*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=z0ps/xGoHnaDfEelBg0WwKDIeGjF3IrP6Kd/NRlL4h4=; b=sOOllzbXDWH/O/UXVkqJIiZTbtolW5rPBGiQThmOwHFhBYQYT1IJVwsxBpdDJwIt4Z amEswLU0ndFI0dOaUaSieWQp819wkDRsC3HBYS/IQAuO+u4IxAY32tmEvPB8bCJGUSUI SvLz0ok5aqVP3SBFON3pdvaQ85ikSt0nz4NqsFhqcN2YZ2lp/jcyyiX38YjDWtIolyLE X/qtdV7wMUoVt+mf9rugy3TxlF8n5oaqYZOUFtB4AM19vbA1oR7lrwIvLKot8kgf2btL Q2O5Q3GZ0zimgaWwU+/JRJyDDeG7WW2gGinLij+9KG5BDmwPH/3iP8rArXUy3ZYV+29J B2TQ==

I've recently applied some changes in GeneralizedEigenSolver, so it might be worth trying 3.3-beta2. Then, it could also be the case that your pair of matrices is not diagonalizable, in which case both implementation returns garbage. Finally, sharing your matrices would help to identify the issue.

gael

On Thu, Aug 4, 2016 at 3:36 PM, Bill Greene <w.h.greene@xxxxxxxxx> wrote:

I have a simple test case with n=9 where alpha(i) and beta(i) for five eigenvaluesagree but four do not. Only one pair of three of the complex conjugate pairs agree.For the two pair that do not agree, the alpha values are very large (i..e. 10^61).I took a look at bug 645 and it is unclear to me if the problem I'm seeing is relatedto that issue.. I'm using Eigen 3.2.9 but could certainly try 3.3-beta if appropriate..Thanks.Bill Greene

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**References**:**[eigen] GeneralizedEigenSolver eigenvalues different from lapack dggev***From:*Bill Greene

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