# diff

diff(A, [dim])

Finite difference operator of matrix or vector.

## Examples

Calculate the difference between consecutive elements in an array:

``````julia> arr = [1, 4, 6, 9, 12];
julia> diff(arr)
4-element Array{Int64,1}:
3
2
3
3``````

This example calculates the difference between consecutive elements in the array `arr`. The resulting array has one element less than the original array.

Calculate column-wise differences in a matrix:

``````julia> mat = [1 2 3; 4 5 6; 7 8 9];
julia> diff(mat, dims=1)
2×3 Array{Int64,2}:
3  3  3
3  3  3``````

Here, `diff` calculates the column-wise differences in the matrix `mat` along dimension 1. The resulting matrix has one row less than the original matrix.

Calculate row-wise differences in a matrix:

``````julia> mat = [1 2 3; 4 5 6; 7 8 9];
julia> diff(mat, dims=2)
3×2 Array{Int64,2}:
1  1
1  1
1  1``````

In this example, `diff` calculates the row-wise differences in the matrix `mat` along dimension 2. The resulting matrix has one column less than the original matrix.

Common mistake example:

``````julia> vec = [1, 2, 3, 4];
julia> diff(vec, dims=2)
ERROR: ArgumentError: dims must be a vector of integers specifying a valid subset of dimensions``````

In this example, `dims` is provided as 2, which is not a valid dimension for a 1-dimensional vector. Make sure to provide a valid dimension when using `diff` with multi-dimensional arrays or matrices.