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Re: Inverse Matrix Function appears a bit wonky
From: |
Dmitri A. Sergatskov |
Subject: |
Re: Inverse Matrix Function appears a bit wonky |
Date: |
Wed, 03 Nov 2004 14:17:05 -0700 |
User-agent: |
Mozilla Thunderbird 0.8 (X11/20040913) |
Geraint Paul Bevan wrote:
octave> inv (m)
warning: inverse: matrix singular to machine precision, rcond = 0
ans =
~ 3.00000 2.00000 2.00000 1.00000
~ 0.33333 1.33333 0.33333 1.66667
~ 0.33333 1.00000 2.00000 2.00000
~ 0.66667 0.50000 0.75000 0.00000
How come I do not get a warning?
(Octave 2.1.60 / ATLAS 2.7.8)
octave:35> m = [1 2 3 4; 2 2 3 3; 1 2 1 2; 3 2 2 1];
octave:36> det (m)
ans = -1.3323e-15
octave:37> inv (m)
ans =
-4.5036e+15 6.0048e+15 1.5012e+15 -3.0024e+15
4.5036e+15 -6.0048e+15 -1.5012e+15 3.0024e+15
4.5036e+15 -6.0048e+15 -1.5012e+15 3.0024e+15
-4.5036e+15 6.0048e+15 1.5012e+15 -3.0024e+15
octave:38> which inv
inv is a built-in function
octave:39> which inverse
inverse is a built-in function
octave:40> [x,r] = inv (m)
x =
-4.5036e+15 6.0048e+15 1.5012e+15 -3.0024e+15
4.5036e+15 -6.0048e+15 -1.5012e+15 3.0024e+15
4.5036e+15 -6.0048e+15 -1.5012e+15 3.0024e+15
-4.5036e+15 6.0048e+15 1.5012e+15 -3.0024e+15
r = 4.1633e-18
- --
Geraint Bevan
http://homepage.ntlworld.com/geraint.bevan
--
Dmitri.
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- Re: Inverse Matrix Function appears a bit wonky, (continued)
Re: Inverse Matrix Function appears a bit wonky, Dmitri A. Sergatskov, 2004/11/03
- Re: Inverse Matrix Function appears a bit wonky, Robert A. Macy, 2004/11/04
- Re: Inverse Matrix Function appears a bit wonky, David Bateman, 2004/11/04
- Re: Inverse Matrix Function appears a bit wonky, John W. Eaton, 2004/11/04
- Re: Inverse Matrix Function appears a bit wonky, David Bateman, 2004/11/05
- Re: Inverse Matrix Function appears a bit wonky, John W. Eaton, 2004/11/05
- Re: Inverse Matrix Function appears a bit wonky, David Bateman, 2004/11/05
Re: Inverse Matrix Function appears a bit wonky, Geraint Paul Bevan, 2004/11/03
- Re: Inverse Matrix Function appears a bit wonky,
Dmitri A. Sergatskov <=
- Re: Inverse Matrix Function appears a bit wonky, Geraint Paul Bevan, 2004/11/03
- Lapack issues? (Was Re: Inverse Matrix Function appears a bit wonky), Dmitri A. Sergatskov, 2004/11/03
- Re: Lapack issues? (Was Re: Inverse Matrix Function appears a bit wonky), Geraint Paul Bevan, 2004/11/03
- Re: Lapack issues? (Was Re: Inverse Matrix Function appears a bit wonky), Dmitri A. Sergatskov, 2004/11/03
- Re: Lapack issues? (Was Re: Inverse Matrix Function appears a bit wonky), Dmitri A. Sergatskov, 2004/11/04
Re: Inverse Matrix Function appears a bit wonky, Przemek Klosowski, 2004/11/05