Re: Matrix with number of rows / columns not fixed

*To*: mathgroup at smc.vnet.net*Subject*: [mg112325] Re: Matrix with number of rows / columns not fixed*From*: apjs64 <apjs64 at gmail.com>*Date*: Thu, 9 Sep 2010 04:23:52 -0400 (EDT)*References*: <i627tm$bm$1@smc.vnet.net>

On Sep 6, 6:14 pm, Hayley <hayley0... at gmail.com> wrote: > I'm new to Mathematica and would like to know if I can specify a > matrix where the number of rows / columns is not fixed. > > As a simple example, how can I input a diagonal matrix with elements > (s1, s2, ..., sL) where I don't specify what L is? > > I'd like to multiply together a few such matrixes and find the inverse > of the product, and would ideally like Mathematica to give me the > answer in terms of summations from 1 to L. > > Hope this sounds possible...! I am fairly new as well and this may not be optimal. I guess you may mean import data in which case I am sure the mathematica routines will do the right thing for you. You need to be clear on the difference between a list and a matrix in mathematica. Try for a start the help : guide/ConstructingMatrices. Clear[list, matrix, max] max = 3 list = Table[0, {i, max}, {j, max}] list[[1, 1]] = 1 (* etc etc *) matrix = MatrixForm[list] Partition, Flatten, PadRight will be of great assistance to you. good luck and don't be discouraged, Jeremy