Re: Don't want to calculate scalar product

*To*: mathgroup at smc.vnet.net*Subject*: [mg19739] Re: Don't want to calculate scalar product*From*: phbrf at t-online.de (Peter Breitfeld)*Date*: Mon, 13 Sep 1999 02:41:04 -0400*Organization*: das ist ein breites Feld ...*References*: <7ree45$489@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Toshiyuki (Toshi) Meshii <meshii at mech.fukui-u.ac.jp> schrieb: > Hi, > > I understand that one of the unique point of Mathematica is that you don't > have to be conscious about whether a vector is a "row" or a "column" vector. > > However, I think there is a case in which you have to specify whether you > want Mathematica to recognize a vector as a row vector or a column vector. > Let me explain my case. > > a={1,2,3}; b={4,5,6} > > I want to define "a" as a column vector (3x1 matrix) and "b" as a row vector > (1x3 matrix). > > I expect the product > a.b > as a 3x3 matrix, but the answer Mathematica gives is a scalar product "32". > Mathematica doesn't distiguish between row and column vectors. You have to use Outer: In[1]:=Outer[Times, a, b] Out[1]={{4, 5, 6}, {8, 10, 12}, {12, 15, 18}} Peter -- =--=--=--=--=--=--=--=--=--=--=--=--= http://home.t-online.de/home/phbrf =--= =--= Peter Breitfeld, Saulgau, Germany PGP public key: 08548045 =--=--=