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.
>