Re: Can't multiply non-square matrices.

*To*: mathgroup at smc.vnet.net*Subject*: [mg64622] Re: Can't multiply non-square matrices.*From*: bghiggins at ucdavis.edu*Date*: Fri, 24 Feb 2006 00:18:18 -0500 (EST)*References*: <dthgr4$n74$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Chris, A matrice defined in a typical Linear algebra textbook is in terms of rows and columns. Thus a 3-row by 2-column matrix times a 2-row by 1-column matrix yields a 3-row by 1-column matrix. In Mathematica this is done as follows: Here is my 3-row by 2-column matrix: mat32={{a1, b1}, {a2, b2}, {a3, b3}} Here is my 2-row by 1-column matrix: mat21={c1, c2} And the multiplication is then: mat32.mat21 {a1 c1 + b1 c2, a2 c1 + b2 c2, a3 c1 + b3 c2} which is a 3-row by 1-column matrix. Note a row vector and column vector (as defined in Linear algebra texts) are treated the same in Mathematica. Cheers, Brian