How to find the common values in two arrays

Suppose I have two vectors

 a= 1 2 3 4
 b= 4 5 6 7 9

How do I find which value is common to both

in above case it is 4

Answer 1

[Thomas]

You need the intersect command

 doc intersect

in your case

 [val,pos]=intersect(a,b)  % gives common val and its position in 'a'

[bhawya b]

Thanks!!