Calculate the inverse of a matrix
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amine&&
le 14 Sep 2016
Modifié(e) : Valentin Marinov
le 23 Jan 2021
Hello, i want to calculate the reverse of this matrix :
1 -1 0 0
-1 1 0 0
0 0 1 -1
0 0 -1 1
but I get the following result :
Inf Inf Inf Inf
Inf Inf Inf Inf
Inf Inf Inf Inf
Inf Inf Inf Inf
what are your suggestion? Thanks.
3 commentaires
Brendan Hamm
le 14 Sep 2016
This is a singular matrix, as can be seen by the linear dependence of columns:
X(:,1) == -X(:,2)
and
X(:,3) == -X(:,4)
Réponse acceptée
John D'Errico
le 14 Sep 2016
This is a singular matrix. No matter how badly you want to do so, you cannot invert a singular matrix. Not possible. Never will be. The laws of mathematics are simple in this respect. The inverse does not exist. You cannot form what does not exist.
At best, you can use pinv, to compute a pseudo-inverse. It is NOT an inverse. It does not have the properties of an inverse.
5 commentaires
Valentin Marinov
le 23 Jan 2021
Modifié(e) : Valentin Marinov
le 23 Jan 2021
Sure. Here's a video that explains it good enough: https://www.youtube.com/watch?v=5bxsxM2UTb4. The example is at 3:30. I'm no pro so don't think I know how to use this in real life, but the guy explains the idea pretty good and tells the matlab funtions, you can use to simulate the actions he explains. Hope it helps you out.
EDIT: just saw the post is from 2016, so I assume you don't need that anymore, but I'll leave it just in case.
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