How can I Improve matlab looping

Hi ,

I would like to know if someone can give me the tips to improve my matlab, mainly in "loop" syntax. How to think in the solution of some problems in short time using matlab programming.

I am realy appreciate you help.

Regards

Answer 1

[Image Analyst]

MATLAB looping was dramatically speeded up several years ago. It's no longer that slow, though the belief persists. If you have less than a few million iterations, it will be pretty fast.

One way to speed it up even more, when you have nested loops, is to have the inner-most loop iterate over the left most index, since MATLAB is in column-major mode, meaning it goes down rows in a single column first before moving over to the next column. So, in summary

% Slower:
for row = 1 : rows
    for col = 1 : columns
        m(row, col) = some formula;
    end
end
% Faster:
for col = 1 : columns
    for row = 1 : rows
        m(row, col) = some formula;
    end
end

And that might only hold for very large matrices (millions of elements). For small matrices (a few tens of thousands of elements) you might not notice a difference.

[paulo sigauque]

Thank you!