How do I find the (right) null space of a matrix?
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Hi everyone.
I am trying to find the (Right) null space of a matrix - Aptech-Gauss' style - but the command "null" does not result in the same answer. How do I yield the same null space? I do not have Gauss, I am working only in Matlab. Thank you
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John D'Errico
le 3 Mai 2023
Modifié(e) : John D'Errico
le 3 Mai 2023
Easy.
A = rand(5,2)*rand(2,3)
A has rank 2.
Arnull = null(A)
A*Arnull
It kills A, which is what the right nullspace would do. The left nullspace is also easy.
Alnull = null(A')'
Alnull*A
Again, only floating point crap remains.
Maybe your real question is the answer is not the same. But, do you understand that the nullspace need not be unique? You can always scale the nullspace vectors by any constant, and they are still valid nullspace vectors. And if there is more than 1 nullspace dimension, then linear combinations of the nullspace vectors are equally valid.
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