“…The recursive approach, proposed in (Ortiz, 1969), permits to obtain an approximate polynomial solution expressed in terms of a special polynomials basis called canonical polynomials. This technique has been thoroughly investigated in a series of papers (see for example (Crisci & Russo, 1983), (Freilich & Ortiz, 1982) and (El-Daou & Ortiz, 1994-1998). In the operational Tau, (see (Ortiz & Samara, 1981)), the ODE is transformed to a system of linear algebraic equations using some simple elementary matrices.…”