Q&A #5432

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From: Jonathon

To: Teacher2Teacher Public Discussion
Date: 2006030818:59:07
Subject: Difference between a number and matrix

What is the difference between a 1x1 matrix and a number. Why when you multiply a constant by a matirx the dimensions are irrelevant 5*[1,1,1:1,1,1:1,1,1] = [5,5,5;5,5,5;5,5,5] but if you cannot multiply a 1x1 by anything that does not contain either a row or a column of 1. ex [5] * [1,1,1;1,1,1;1,1,1] violates matrix multiplication rules 5*eye*[1,1,1;1,1,1;1,1,1]= [5,5,5;5,5,5;5,5,5] what is the diffence between 5 and [5]?

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