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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: [mg54456] Re: [mg54383] Re: Why does Inverse[M] hesitate?
  • From: DrBob <drbob at bigfoot.com>
  • Date: Sun, 20 Feb 2005 00:11:17 -0500 (EST)
  • References: <200502190732.CAA06180@smc.vnet.net>
  • Reply-to: drbob at bigfoot.com
  • Sender: owner-wri-mathgroup at wolfram.com

>> If I do justA={{a,b},{c,d}}
>> B={{e},{f}}
>> Inverse[A].BI get the final correct result.

If a d != b c, you mean.

I'm not sure why Inverse is more finicky in the other case, where C == 0 and/or C g + P w - g P w == 0 would make the inversion meaningless.

Bobby

On Sat, 19 Feb 2005 02:32:57 -0500 (EST), Skirmantas <skirmantas.janusonis at yale.edu> 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.
>
>
>
>



-- 
DrBob at bigfoot.com
www.eclecticdreams.net


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