Re: [eigen] State of the problem with std::vector |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] State of the problem with std::vector*From*: "Benoit Jacob" <jacob.benoit.1@xxxxxxxxx>*Date*: Thu, 8 Jan 2009 21:40:44 +0100*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=KuWorTIxVi5qVhJGk8PBbeaZliyyd/cTO3w5MsEpADw=; b=x1NbQGVUoEFe3NEuNcAh2tXOUefauV2KdwnT0FzRTaSMzm1VenKRSZZWU7OcOZ9z+q 1MYPkREhZAGULOhWUJxBfg8OOp3icAiCAzH/f9k0vE98XsFG9M/bddIi6fAgGgc+5+nu MSR6nTC1dCkhUGY/zm6dp3E8bGzBkqdAgxi8s=*Domainkey-signature*: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=tjDye57Hy99RDRHbMbCMLgL1SwF4tXL5ZQMHIOA4qSoQLAAvlMHb3tW+jkWy3RuVjR Hmt2rOTyhaEwo1oxl0E4O3tXy+pfbn/Sq5Ow2QMyCHBrFt9uMS92VdYitnjDlm+qm8T+ SO/wav+0Y4sF4iaMWaUHU+vWcwv+8rLyvAiwg=

2009/1/8 Keir Mierle <mierle@xxxxxxxxx>: > A "non-solution" is to not use Vector4f. Instead use Matrix4Xf, which is > fixed at 4 rows and X columns; each column is a different vector. I use this > all the time in libmv to represent a collection of 4D vectors (homogeneous > in my case). This is also handy for bulk transforms that take advantage of > vectorization (i.e. by multiplying by a matrix). This is perfect for users for whom this is an option, of course. But it doesn't do all what std::vector does (insert...) and many users simply have to use std::vector. > On another note: Does eigen have shorthands for small numbers of rows / > colums, but variable numbers for the other? i.e. 4 x n, or n x 4, etc? Not for now. > I > have defines for Mat2X...Mat5X, MatX2...MatX5 in libmv for exactly this > reason. Lots of convenience typedefs are great! Promotes mutual > understanding for users of the library if they don't have to make their own > different typedefs. One has to find the right compromise between this, and the fact that we already have a large number of typedefs and this proposal would make it even much larger. Here before taking any decision what's needed is a measurement of the impact on compilation time. If it's costly one can still consider a separate header Eigen/MoreTypedefs. Cheers, Benoit ---

**References**:**[eigen] State of the problem with std::vector***From:*Benoit Jacob

**Re: [eigen] State of the problem with std::vector***From:*Keir Mierle

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