Re: Don't want to calculate scalar product

*To*: mathgroup at smc.vnet.net*Subject*: [mg19734] Re: [mg19708] Don't want to calculate scalar product*From*: BobHanlon at aol.com*Date*: Mon, 13 Sep 1999 02:41:02 -0400*Sender*: owner-wri-mathgroup at wolfram.com

Toshi, a = {a1, a2, a3}; b = {b1, b2, b3}; a.b a1 b1 + a2 b2 + a3 b3 Transpose[{a}].{b} {{a1 b1, a1 b2, a1 b3}, {a2 b1, a2 b2, a2 b3}, {a3 b1, a3 b2, a3 b3}} a = {1, 2, 3}; b = {4, 5, 6}; a.b 32 Transpose[{a}].{b} {{4, 5, 6}, {8, 10, 12}, {12, 15, 18}} Bob Hanlon In a message dated 9/11/1999 8:36:59 PM, meshii at mech.fukui-u.ac.jp writes: >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". > >Please give me an advice to get the 3x3 matrix as a product. >