A study is presented on the computation of pseudospectral differentiation m
atrices for higher derivatives using the general Lagrangian polynomial inte
rpolation formulation. The diagonal elements of the differentiation matrice
s are computed as the negative row sum of the off-diagonal elements and we
show why this technique should be used instead of the explicit formula that
is usually given in the literature. An efficient recursive algorithm for c
omputing the higher order differentiation matrices are derived. For the Eve
n-Odd Decomposition algorithm a similar efficient recursive algorithm is al
so provided. The Chebyshev and Legendre collocation methods commonly used i
n applications are one of the special case, (C) 2000 IMACS. Published by El
sevier Science B.V. All rights reserved.