Find elements of type (x,y) and indices for equality of columns x and y

Find number of elements of type (x,y) in two columns, where x is in one column and y in the other. Report the indices for elements of type (x,y) that are equal.

Example a = [1,1,2,1]; b = [1,2,2,1]; should give answer (2,2) for index 3.

[Torbjörn Olsson]

Also the (x,y) elements must occur more than twice across the two columns

Answer 1

[Ameer Hamza]

In case of given 'a' and 'b', same value occur in three rows

a = [1,1,2,1]; b = [1,2,2,1];
idx = find(a==b)

Result

>> idx
idx =
     1     3     4

[Torbjörn Olsson]

Yes but this should work for an arbitrarly sized array. The indices should just be counted if they occur at least two times. Above a=x and b=y.