Re: Patterns Problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg28249] Re: Patterns Problem*From*: Ignacio Rodriguez <ignacio at sgirmn.pluri.ucm.es>*Date*: Fri, 6 Apr 2001 01:52:56 -0400 (EDT)*Organization*: UCM*References*: <9a95ji$gs9@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

If you want to multiply matrices, the standard function for multiplication (Times) will not probably be useful for you, because it multiplies the elements of the matrices and not the matrices themselves. You may try with Dot, which contracts the last index in the first tensor with the first index in the second, allowing for multiplication of matrices or matrices with vectors. As for your second question, I am afraid I can't understand what you mean. Janusz Kawczak wrote: > Dear Mathematica Users: > > I am trying to force an output to appeat in a certain way, but without > much > success. Here is my problem. > > First, how to "teach" M. that some symbols are matrices, vectors, etc... > and > that the laws of the real arithmetic do not apply. > > Let's take A to be a matrix, and u and v, vectors. > I would like to have the following: > > u A (u - <u>)=u A u -u A <u> > > the operator is not symmetric. Whenever I do this oparation I get > something like > A u u or A u ^2. I just cannot force the order to be correct! > > Also, I would like to have the oparator to > be iterative, i.e. > > v A {(u A (u - <u>) -<u A (u - <u>)>} > =v A u A u - v A u A <u> - v A <u A u> + v A u A <u>, and so on. > > Any suggestions. > Thank you in advance. > Janusz. > > P.S. Please cc to jkawczak at math.uncc.edu -- Ignacio Rodriguez Ramirez de Arellano Unidad de RMN Universidad Complutense Paseo Juan XXIII, 1 Madrid 28040, Spain Tel. 34-91-394-3288 Fax 34-91-394-3245 e-mail: ignacio at sgirmn.pluri.ucm.es