Matrix Simple Index Question

Hello Experts,

1) Given matrix A with m rows and n columns, I want to check if there is an entry A(i,j)>alpha and if yes to make it A(i,j) = beta. How to make it without for and if? 2) How to make it in a vector of size (1,m) or (1,n)?

Thanks a lot in advance!

Answer 1

[Oleg Komarov]

Sample inputs:

m = 10;
n =  13;
A = rand(m,n);
alpha = .38;

Use logical indexing

idx = A > alpha;
A(idx) = 10;

Same applies to a vector (just play around with m and n to see that).

[Steve]

Dear Oleg,

Thank you very much for your quick response and smart solution!

Please provide me a link or a book name where can I find all those shortcuts and tricks.

Thanks a lot in advance.

[Oleg Komarov]

Check out the getting started guide and especially this section: http://www.mathworks.co.uk/help/techdoc/learn_matlab/f2-8955.html

[Oleg Komarov]

Demos are also useful: http://www.mathworks.co.uk/products/matlab/demos.html

[Steve]

Dear Oleg, again thank you very very much!!!

It was my great pleasure to get your answer and experts guide!

Steve