DIFF Difference Function

Section: Elementary Functions



Produce difference of successive vector elements. If x is a vector of length n, diff (x) is the vector of first differences \[ [x_2 - x_1, ..., x_n - x_{n-1}]. \] If x is a matrix, diff (x) is the matrix of column differences along the first non-singleton dimension. The second argument is optional. If supplied, diff (x,k), where k is a nonnegative integer, returns the k-th differences. It is possible that k is larger than then first non-singleton dimension of the matrix. In this case, diff continues to take the differences along the next non-singleton dimension. The dimension along which to take the difference can be explicitly stated with the optional variable dim. In this case the k-th order differences are calculated along this dimension. In the case where k exceeds size (x, dim) then an empty matrix is returned.