Re: [eigen] sdgfdf |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] sdgfdf*From*: Gael Guennebaud <gael.guennebaud@xxxxxxxxx>*Date*: Mon, 2 Feb 2009 14:34:40 +0100*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type :content-transfer-encoding; bh=XfZyjy1Kz1O8KaDyYfhrqL3no/p5xIxqIgRu5jed6iA=; b=fdVpAvEm36a8mOCR6wIVacfv+6kd2xqkdEYuyjEPCHQ8SXgQbG7DTFxTQKDZwv+48P GGkEcz7qSDpVQNzFsbAntUBta3XzaJIHtPK+gvV2VTYTx16Dbqizla7OfIdo/Wre/Az/ b5DwI4VLzBr3sn4Mugmq5DbI6xKM43OXOYsxw=*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=OQ4kRNH801Y/6+uwuH6Na099+jm4yr4gpssS7uImxFkMGCBlXnyYCdaJFUA9kpD0fL RyFB7/zqmmO5qyfws4k4uYfn5rEilUOhtSR8oEaWtnlMppju7NULDOrn/qQydXSUuTDt Y2//R52DFKTmLUL70HJkidqCxEsaxADb37BiQ=

On Mon, Feb 2, 2009 at 2:08 PM, Jens Mueller <jens.k.mueller@xxxxxx> wrote: > Hi, > >> yes this is something I've thought about, there is no difficulty. >> Actually my initial concern was rather about "int" which could be too >> small if n > 2^32, so I'll make the types of both "index pointers" and >> "coordinate" template parameters. Note that with "unsigned short" for >> the coordinate type, you are limited to 65k x 65k matrices, that is >> not very large. > > Can't I have different types for each coordinate index, i.e. short for > columns and int for rows? Don't know, if I'm getting your unsigned short > example right. In my case, only one coordinate index fits into unsigned > short. The other one should be int. right, the compressed storage is not symmetric, so if you have a col-major matrix you could use int for the column index and short for the row index but not the other way round. Eventually, I think that's probably a lot of trouble for minor benefits: - this would complexify operators (matrix product, transposition, submatrices, etc.), - the memory gain would be x0.75 for float and x0.83 for double only, - honestly, I don't expect any performance improvement, - I don't think other libs are able to handle short type for indices, so you would not be able to use your matrix with the solvers. gael.

**Follow-Ups**:**Re: [eigen] sdgfdf***From:*Jens Mueller

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**Re: [eigen] sdgfdf***From:*Gael Guennebaud

**Re: [eigen] sdgfdf***From:*Jens Mueller

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