I have this command "min(A(:,b),[ ],2)", where A is a matrix and b is one of its columns. How does it works?

Hi everyone! I have this piece in a code I am trying to understand but I don't know what does it means when "[]" and "2" are added inside the min function. Thank you for your help. :)

[Stephen23]

Why not simply read the min documentation, which tells us all (including you!) how min can be used? You can easily find the min documentation using your favorite internet search engine, and it would have taken less time than joining some internet forum and waiting for some strangers to tell you how min works. (tip: those strangers know how min works because they read the documentation).

The documentation states clearly:

" M = min(A,[],dim) returns the smallest elements along dimension dim. For example, if A is a matrix, then min(A,[],2) is a column vector containing the minimum value of each row."

You might like to read this:

https://www.mathworks.com/matlabcentral/answers/228557-experts-of-matlab-how-did-you-learn-any-advice-for-beginner-intermediate-users

Answer 1

[MathReallyWorks]

Hello Vio,

 A = [1.7 1.2 1.5; 1.3 1.6 1.99]
M = min(A,[],2) %This gives minimum along rows

and

 A = [1.7 1.2 1.5; 1.3 1.6 1.99]
M = min(A,[],1) %This gives minimum along columns

If you don't use [ ] in your code, it shows a modified matrix with all the elements of A. If any value is greater than n, then it is replaced by n otherwise it is unchanged

 n=6;
A = [1.7 1.2 6.5; 1.3 1.6 6.99]
M = min(A,n);

and

 n=7;
A = [1.7 1.2 6.5; 1.3 1.6 6.99]
M = min(A,n);

This is something I observed while coding. Just wanted to share. I hope it will be helpful.

[VB]

Thank you very much for your answer, it was very helpful. :)