Re: Dot Product of Vectors

*To*: mathgroup at smc.vnet.net*Subject*: [mg15] Re: [mg89044] Dot Product of Vectors*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Sun, 25 May 2008 02:02:07 -0400 (EDT)*References*: <200805240755.DAA20910@smc.vnet.net>

On 24 May 2008, at 16:55, Gregory Lypny wrote: > Hello everyone, > > I've got two n x k matrices called X and Y. I'd like to compute an n > x 1 vector whose elements are the dot products of corresponding rows > of X and Y, that is, > > {{X[[1]].Y[[1]]}, {X[[2]].Y[[2]]}, {X[[3]].Y[[3]]}, ... > {X[[n]].Y[[n]]}. > > I found that this can be done using MapThread as > > MapThread[Dot, { X, Y}], > > which is straightforward. I'm curious, given that there a zillion > ways to do any given calculation in Mathematica, if anyone knows of > another way that is as compact. > > Regards, > > Gregory > > > Total[X*Y, {2}] Andrzej Kozlowski

**References**:**Dot Product of Vectors***From:*Gregory Lypny <gregory.lypny@videotron.ca>