  We discuss a pointwise numerical differentiation formula on multivariate
scattered data, based on the coefficients of local polynomial interpolation at
Discrete Leja Points, written in Taylor's formula monomial basis. Error bounds
for the approximation of partial derivatives of any order compatible with the
function regularity are provided, as well as sensitivity estimates to
functional perturbations, in terms of the inverse Vandermonde coefficients that
are active in the differentiation process. Several numerical tests are
presented showing the accuracy of the approximation.
