Inversion on a non square matrix using PDL (or similar?)


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Inversion on a non square matrix using PDL (or similar?)

by Angharad (Pilgrim)

on Jul 28, 2005 at 16:34 UTC ( #479031=perlquestion: print w/ replies, xml )

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Angharad has asked for the wisdom of the Perl Monks concerning the following question:

I'm having a little play with PDL at the moment. Neat but I was wondering if anyone knew of a way in which you can invert a matrix that isnt square.
There is a function in MatLab called pinv which will invert a rectangular matrix. Perhaps there is something similar offered in PDL?
Or, if not, does anyone know of another way to implement this using Perl?

Comment on Inversion on a non square matrix using PDL (or similar?)
Re: Inversion on a non square matrix using PDL (or similar?) by gjb (Vicar) on Jul 28, 2005 at 16:56 UTC
You're looking for the Moore-Penrose pseudoinverse. It is defined on MathWorld and is easy to implement for a matrix `A` as `(A^t A)^{-1} A^t` where `A^t` is `A` transposed, `A^t A` is a square matrix, `(A^t A)^{-1}` being its inverse (if it exists). Hope this helps, -gjb-	[reply] [d/l] [select]

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