*To*: mathgroup@smc.vnet.net*Subject*: [mg12025] RE: [mg11969] Please help: How to assert that an object is a matrix ???*From*: "jmt" <jmthomas@cybercable.tm.fr>*Date*: Fri, 24 Apr 1998 01:52:00 -0400

Maybe you can use MatrixQ Hope this helps, **************************************** Jean-Marie THOMAS Conseil et Audit en Inginierie de Calcul Strasbourg, France **************************************** -----Original Message----- From: Paul Bunyk [mailto:paul@pbunyk.physics.sunysb.edu] To: mathgroup@smc.vnet.net Subject: [mg12025] [mg11969] Please help: How to assert that an object is a matrix ??? Hi, everyone! I'm trying to analyse the block structure of a matrix in Mathematica to figure out the best way to solve a system with this matrix. For example I write A := {{GL,0,0,0,IL[1]}, {GT,0,0,0,0}, {0,GL,0,0, IL[2]}, {0,GT,0,0,0}, {0,0,GL,0,IL[3]}, {0,0, GT,0,0}, {0,0,0,GL,IL[4]}, {0,0,0,GT,0}} X := {XP1,XP2,XP3,XP4,XL} B := {0,PT[1],0,PT[2],0,PT[3],0,PT[4]} where GL, GT, IL, etc., are not elements but (sub-)matrices themself. I want to perform algebraic transformations on A, but I want element multiplication to be non-commutative and inversion to use Inverse rather than 1/element. Can I somehow trick Mathematica to assume that elements are matrices? Any help is appreciated! Paul -- ("`-''-/").___..--''"`-._ UNIX *is* user-friendly, he is just very `6_ 6 ) `-. ( ).`-.__.`) picky about who his friends are... (_Y_.)' ._ ) `._ `. ``-..-' Paul Bunyk, Research Scientist _..`--'_..-_/ /--'_.' ,'art by (and part-time UN*X sysadm) (il),-'' (li),' ((!.-' F. Lee http://pbunyk.physics.sunysb.edu/~paul