How can i locate where two column values are the same in a row?

I have a column of 400 numbers that vary depending on input and i want to detect when the become constant (towards the end).

[Adam Danz]

The quesiton is unclear. An example would probably clear things up.

Answer 1

[JESUS DAVID ARIZA ROYETH]

a=[1 2 3 4 4 4 4];
s=find([diff(a) 1]==0,1,'first')