Re: Symbolic matrix manipulation

*To*: mathgroup at smc.vnet.net*Subject*: [mg46741] Re: Symbolic matrix manipulation*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Fri, 5 Mar 2004 01:46:36 -0500 (EST)*Organization*: The University of Western Australia*References*: <c238jv$ii5$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

In article <c238jv$ii5$1 at smc.vnet.net>, junk4 at microserf.org.uk (C Rose) wrote: > I'd like to know how one can perform symbolic matrix-vector > manipulations in Mathematica, without having to specify the contents > of the matrices or vectors. > > For example, imagine I have a vector-valued function > > f(x) = x^T A > > where A is a m x n matrix, x is an m-vector, and ^T indicates > transposition > > How can I differentiate f(x)---or perform other symbolic operations > using matrices or vectors---such that I get the result in terms of A > and x (i.e. I don't want to have to specify that > A={{a11, a12, a13}, {a21, a22, a23}, {a31, a32, a33}} or whatever). > > So, in the example above, I want Mathematica to tell me the answer is > > d/dx (f) = A > > I'd appreciate your advice on this matter. See The Mathematica Journal 8(4) (2002): 529-531 Cheers, Paul -- Paul Abbott Phone: +61 8 9380 2734 School of Physics, M013 Fax: +61 8 9380 1014 The University of Western Australia (CRICOS Provider No 00126G) 35 Stirling Highway Crawley WA 6009 mailto:paul at physics.uwa.edu.au AUSTRALIA http://physics.uwa.edu.au/~paul