Indices in an array

[ignacio_b]

Hello,

I have a huge list of values in an array M(1432188,3). I need to compare two numbers (in the same column), when these two numbers are equal I need to know their indices.

Does anyone know how to do that?
Is there a built-in function capable of doing that?

If someone can help me, it would help me a lot.

Thanks!!

 

[mikrom]

If the array is not sorted, I would first try to sort it
and then in a loop for every index k compare if array(k) is equal to array(k+1)