The eq(M1,M2) command tests if the elements of M1 and M2 are equal.  The result is an integer array with 0s where M1[i] <> M2[i], and 1s where the entries are equal.

M1 and M2 must be the same size, or scalars.  If M1 is an array and M2 is a scalar, the result will be an array the same size as M1, with 0 and 1 entries indicating entries that were equal to the scalar value M2.