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Date: Fri, 29 May 2009 18:40:46 -0500 From: To: boost-users@lists.boost.org Subject: Re: [Boost-users] POD 3d vectors
On Fri, May 29, 2009 at 5:49 PM, tom fogal wrote:
gtsml owevwr writes:
I need fast low dimensional vector (2, 3 and 4 dimension let say).
Still, you probably want to search around a bit more first. Without checking, I'd bet all of CrystalSpace, Ogre, VTK, Irrlicht, and random google result for "open source 3d engine" here> include their own classes for vectors and matrices.
Fast usually depends on access patterns as lookahead or cache thrashing or VM limits the speed. These off course tend to be app or algorithm specific but if someone wanted to catagorize and parameterize these maybe you could make some general strategy paterns for optimum performance on different platforms but you can appreciate it could be involved. I still often use int[] for arbitrary "vectors" depending on need and often various simple types of encoding ( keeping smaller differences than absolute values ) can make some sense. So, it is easy to find reasons to reinvent your own wheels in this case. I can write a low dimensional add operator easily, I can't go through library code and yank out extra junk. You could probably get at more speed issues from increasing the locality of an algorithm rather than looking for the library with the best vector add code. Mike Marchywka 586 Saint James Walk Marietta GA 30067-7165 415-264-8477 (w)<- use this 404-788-1216 (C)<- leave message 989-348-4796 (P)<- emergency only marchywka@hotmail.com Note: If I am asking for free stuff, I normally use for hobby/non-profit information but may use in investment forums, public and private. Please indicate any concerns if applicable. Note: hotmail is getting cumbersom, try also marchywka@yahoo.com _________________________________________________________________ Hotmail® has a new way to see what's up with your friends. http://windowslive.com/Tutorial/Hotmail/WhatsNew?ocid=TXT_TAGLM_WL_HM_Tutori...