# How can I find the row differences of a matrix?

How can I compute the row differences of an m x n matrix to obtain an m-1 x n matrix; that is, given

how do I obtain

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Maybe this ?

m = {{a, b, c}, {d, e, f}, {g, h, i}};
Differences[m]
(* {{-a + d, -b + e, -c + f}, {-d + g, -e + h, -f + i}} *)

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Thanks @b.gatesucks I didn't know this function existed! –  sebastian c. Jan 11 at 13:06
@sebastian if you are grateful for answers you should be Accepting some of them too. You haven't done this for a very long time. Why not? –  Mr.Wizard Jan 11 at 13:10