Re: [eigen] inconsistency in fast eigen decomposition |

[ Thread Index | Date Index | More lists.tuxfamily.org/eigen Archives ]

*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] inconsistency in fast eigen decomposition*From*: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>*Date*: Thu, 3 Feb 2011 08:24:58 -0500*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; bh=Qk5XJ3d8xlMBZG9mhq9Wf/HoE7OSUmV/fqJ3nfS0P0c=; b=Fq8hVQvrX40AjY131QLqEbSMtwwkWm4IA1rZsIW0Z1VOIFIUPAFan+1lUR5VpDU6u2 7ShVEZWK9irPQ2OZBriOx2+zD+fHQHaSD5L5erq+zowL6xDBHKeNfYma2w1sfdXJ4BBZ OAZ0gRWenAh/rlf2OCEm6uDbv07Prkwkcw5Rs=*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; b=GpxVm2a0l752xuRkQ3imzyHL3h6wqaBTNiJs+rztJ/y37k/l0iSPwKwsAoPsaVfe1m qRiswbdXjR2iE8KUHnic8dXqoMDUTmm/3jjFxByzlYEDe+8RRKOnMEKXGKOX6sJeDRCB nUCNIn03YTMoWN85Xh2TI22HHrlLY/F72FPwA=

Could a unit test be added? Maybe just take his matrix, decompose, reconstruct original matrix, compare. My understanding is that before your fix, eigen would have given a completely wrong reconstructed matrix, so just a fuzzy compare at default test precision would be good enough. Benoit 2011/2/3 Gael Guennebaud <gael.guennebaud@xxxxxxxxx>: > yes but was is strange in Radu's example is that the direct method > find a negative eigenvalue while they should all be positive (or equal > to zero). I guess that's because of the multiple trigonometric > functions. Anyway, now I start to compute the eigenvectors from the > biggest eigenvalue and compute the last eigenvectors from the first > two while taking care of some degenerated cases. > > gael > > On Thu, Feb 3, 2011 at 1:52 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote: >> Yeah, it's hard to be accurate when there are degenerate eigenvalues. >> Radu's example had well separated eigenvalues. > > >

**Follow-Ups**:**Re: [eigen] inconsistency in fast eigen decomposition***From:*Gael Guennebaud

**References**:**[eigen] inconsistency in fast eigen decomposition***From:*Radu Bogdan Rusu

**Re: [eigen] inconsistency in fast eigen decomposition***From:*Gael Guennebaud

**Re: [eigen] inconsistency in fast eigen decomposition***From:*Benoit Jacob

**Re: [eigen] inconsistency in fast eigen decomposition***From:*Gael Guennebaud

**Messages sorted by:**[ date | thread ]- Prev by Date:
**Re: [eigen] inconsistency in fast eigen decomposition** - Next by Date:
**Re: [eigen] inconsistency in fast eigen decomposition** - Previous by thread:
**Re: [eigen] inconsistency in fast eigen decomposition** - Next by thread:
**Re: [eigen] inconsistency in fast eigen decomposition**

Mail converted by MHonArc 2.6.19+ | http://listengine.tuxfamily.org/ |