Find the Argmin of a vector
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Let x be a vector and B_1...B_p p matrices,
I look for the index j* of the matrix such that
||B_j*||=min ||B_i x||, (||.||=norm)
How do I write this with matlab?
5 Comments
Walter Roberson
on 8 Aug 2020
You have variables named B_ followed by a number, and you want to process the whole series of variables. That is bad programming practice. You should have avoided naming the variables that way, and should have used (for example) a cell array.
Are you trying to find which of the B_ arrays leads to the smallest norm given a vector x? If so then if you had the arrays represented as a cell array, that would only be a small number of statements.
Accepted Answer
Matt J
on 8 Aug 2020
Edited: Matt J
on 9 Aug 2020
You should have avoided naming the variables that way, and should have used (for example) a cell array.
Indeed. Here's an example of how to do it when that is the case.
Bcell={rand(5), rand(5), rand(5), rand(5)}; %B1,...,Bp p=4
[~, jstar] = min(cellfun(@(B) norm(B*x),Bcell)) %EDITED
5 Comments
Matt J
on 10 Aug 2020
You're very welcome, but please Accept-click the answer if you got it working.
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