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MathGroup Archive 2005

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Re: Re: Why does Inverse[M] hesitate?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54387] Re: [mg54383] Re: Why does Inverse[M] hesitate?
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Sun, 20 Feb 2005 00:07:47 -0500 (EST)
  • References: <200502190732.CAA06180@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

On 19 Feb 2005, at 08:32, Skirmantas wrote:

> The Inverse function sometimes calculates the inverse of a matrix
> immediately, sometimes it does not. Try this example in Mathematica
> 5.1:
>
> A={{(1-g)-1,1},{-w P(1-g)/C,-1}}//MatrixForm
> B={{0},{-P(w+1)}}//MatrixForm
>
> I get
> Out: Inverse[(expanded A)].(expanded B)
>
> If I do just
> A={{a,b},{c,d}}
> B={{e},{f}}
> Inverse[A].B
>
> I get the final correct result.
>

The correct input is:

(A = {{(1 - g) - 1, 1}, {-w P(1 - g)/C, -1}}) // MatrixForm
(B = {{0}, {-P(w + 1)}}) // MatrixForm

An expression with head MatrixForm is not a matrix.



Andrzej Kozlowski
Chiba, Japan
http://www.akikoz.net/andrzej/index.html
http://www.mimuw.edu.pl/~akoz/


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