Re: Matrix multiplication problem fixed via dot operation.
- To: mathgroup at smc.vnet.net
- Subject: [mg64614] Re: Matrix multiplication problem fixed via dot operation.
- From: Chris Young <c1572young at earthlink.net>
- Date: Fri, 24 Feb 2006 00:18:09 -0500 (EST)
- References: <dtjjgo$dfs$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
On 2006-02-23 01:08:24 -0500, Kristjan Kannike <kkannike at physic.ut.ee> said: > Beware: though you got no error messages in case of multiplying square > matrices with a space between them (as opposed to a dot), the result is > NOT a dot product (matrix multiplication), but the matrices are multiplied > element by element, e.g. if > > C = A B > > then > > C[[1,1]] equals A[[1,1]] * B[[1,1]], etc. In short, the ordinary > multiplication has the attribute Listable. (It can be very useful, e.g. > when you have a vector variable x and a vector (list) of coefficients a, > to compose them into a x.) Thanks for the clarification.