Inverting a matrix

Asked Jan 31 '13 at 19:02

Active Jan 31 '13 at 19:06

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Why does MatrixForm affect calculations?

I am facing a strange behaviour from Mathematica when asking it to invert the following matrix:

m = {{a, b, b, 0, 0, 0}, {b, a, b, 0, 0, 0}, {b, b, a, 0, 0, 0}, 
     {0, 0, 0, c, 0, 0}, {0, 0, 0, 0, c, 0}, {0, 0, 0, 0, 0, c}} // MatrixForm

Inverse[m] // MatrixForm

It doesn't output the inverse of the matrix but just the command I entered. But, knowing that my matrix is bloc diagonal, when I enter each one of the blocs separately it does compute their inverses. Where is the trick?

edited Apr 13 '17 at 12:55

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asked Jan 31 '13 at 19:02

Learning is a mess

try removing the //MatrixForm in the definition of m – Pinguin Dirk Jan 31 '13 at 19:04
1

Duplicate of http://mathematica.stackexchange.com/q/3098/61 perhaps... – cormullion Jan 31 '13 at 19:05
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or add braces (m={{a..},..})//MatrixForm – Jan 31 '13 at 19:06
@cormullion, Thanks, I figured there must be one, thanks for pointing that out – Pinguin Dirk Jan 31 '13 at 19:07
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Probably shouldn't invert matrices anyway, it makes them dizzy. – Daniel Lichtblau Jan 31 '13 at 19:13
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@DanielLichtblau try sleeping on them instead – cormullion Jan 31 '13 at 19:20
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@cormullion No thanks, I'm more the Cauchy type. – Daniel Lichtblau Jan 31 '13 at 19:31

Inverting a matrix

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