Selecting a random element from a matrix with a range.

I am trying to select a random element from this matrix with a certain range.

 d = rand(10)
 d(end,randperm(size(d,2), 1))

This creates a 10*10 matrix between 1 and 0. I want to slect a random variable < 0.5 but i am trouble applying this to the code. Any help is much appreciated.

[Cedric Wannaz]

There may not be any element < 0.5. How do you define the number of elements that you will pick? What is the purpose?

[Shane McNamara]

Thanks for your feedback Cedric. There usually is values above and below .5. I only want to pick one element which is what the above does. I wil apply it in the future to a matrix of zeros and 1's and apply a random movement to the element picked.

Answer 1

[Akira Agata]

How about the following script?

d = rand(10);

% Extract elements of d < 0.5
idx = d < 0.5;
d2 = d(idx);

% If d2 is NOT empty, select one element randomly
if ~isempty(d2)
  output = d2(randperm(numel(d2),1));
end

[Shane McNamara]

Hi Akira thanks a million! This works perfectly.