Re: Dynamic iterators in Do loop

*To*: mathgroup at smc.vnet.net*Subject*: [mg66418] Re: Dynamic iterators in Do loop*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Thu, 11 May 2006 05:36:16 -0400 (EDT)*Organization*: The University of Western Australia*References*: <e3js6u$8jt$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

In article <e3js6u$8jt$1 at smc.vnet.net>, sai <iwillfail at gmail.com> wrote: > I have an (n,n) matrix. I want to define an (m,m) matrix [m<n] whose elements > are defined from the (n,n) matrix. The value of n and m changes from problem > to problem. How can i do this in mathematica? For an arbitrary matrix, say mat[n_] := Table[a[i, j], {i,n},{j,n}] then the easiest way to extract a block of the matrix is to use Part with Range. For example, mat[10][[ Range[2,5],Range[3,6] ]] extracts a 4 x 4 submatrix from the 10 x 10 matrix. Cheers, Paul _______________________________________________________________________ Paul Abbott Phone: 61 8 6488 2734 School of Physics, M013 Fax: +61 8 6488 1014 The University of Western Australia (CRICOS Provider No 00126G) AUSTRALIA http://physics.uwa.edu.au/~paul