how to find the location of a number in a matrix matlab code example

Example: matlab find position of value in array

Indicating indexes between ([]) retrieves corresponding values in Matlab. 
array_borders=array([1 end])
As end defines size of the array, retrieve first and last border values of array
even_values=array(2:2:end)
Retrieve only second elements of array, from secon with 2 step iteration 
increase until end of array.
first_3_values=array(1:3)
Retrieve only first 3 elements of array.