Doug Hull, MathWorks
(Originally posted on Doug's MATLAB Video Tutorials blog.)
If you have a vector of coordinate for a set of points, you might want to differentiate those points. To do that a concept called logical indexing will help you pull out a subset of those points easily.
Here is a quick example.
>> L = logical([0 1 0 1])
L =
0 1 0 1
>> a = [1 2 3 4]
a =
1 2 3 4
>> a(L)
ans =
2 4