QABE_Notes07(1)

# QABE_Notes07(1) - QABE Lecture 7 Matrices III: Matrix...

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QABE Lecture 7 Matrices III: Matrix Algebra & Automatic-Matrices! School of Economics, UNSW 2011 Contents 1 Introduction 1 2 More on Matrix Algebra 2 2 . 1 Con s i s t en cy. .................................. 2 3 Matrices on Computers 4 1 Introduction Having learnt a bit about what is going on with matrices, we just have a few more loose ends to tie up. SpeciFcally, we’ll go over the algebra of matrices. This is just like what we would normally do with ‘scalar’ algebra: rearranging equations, simplifying, making a certain pro-numeral the subject of the equation. However, with matrices, there are some very important di±erences in the rules and how to apply them. Pay attention. ²ollowing this, we’ll cover a couple of important pieces of terminology – singular and non-singular on the one hand and consistent and inconsistent on the other. These are really just labels for concepts that we are already familiar with, but they have especial relevance when we move to using computers. I say this, because although Microsoft Excel (which we’ll be using for the moment) doesn’t have very elaborate error-messages, other programs do. ²or instance, Matlab might report (when trying to obtain A - 1 ), >> inv(A) Warning: Matrix is close to singular or badly scaled.

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## QABE_Notes07(1) - QABE Lecture 7 Matrices III: Matrix...

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