GJInv:

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   Matrix inverse using Gauss-Jordan elimination with partial pivoting.

   Since version 2.
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   Form:
   b = GJInv( a )
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   Inputs
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   a			  (n,n)  Matrix

   -------
   Outputs
   -------
   b			  (n,n)  Inverse

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	References:	Strang, G.S., "Linear Algebra and its Applications Third Edition"
               Harcourt, Brace and Jovanovich, 1988, pp. 42-58.
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