traversing a long matrix

i've a matrix named A of size 2 x 16421

i want to compare one row with the other rows and whenever there is a match it spaecifies their index i mean which row number matches

A=[ 12 45
    32 56
    19 89
    12 45
     1  0
     0  0
    44 21
    32 56
    32 56
    12 45
    33 78
    90 32
    19 89 and so on....]

it starts with 12 45 and compare it with all other rows and shows there index value next it starts with 32 56 and compare it with other rows and when there is a match shows their index.

when i traverse it one by one it takes very long time can anybody tell me how can i do so?

Answer 1

[John Doe]

I think this should work

ind = find(A(:,1) == A(:,2));

- Rob