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MathGroup Archive 1998

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RE: Please help: How to assert that an object is a matrix ???



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

--
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