Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 37 No. 2 2011 12 15 COMPOSITE INTERPOLATION METHOD AND THE CORRESPONDING DIFFERENTIATION MATRIX21 34 en H. MARZBAN H. TABRIZIDOOZ 2008 08 21 Block-pulse functions Lagrange polynomials hybrid functions Gauss pseudospectral method differentiation matrices