// ---------------------------------------------------------
// Fonction de calcul de polynomes orthogonaux.
// ---------------------------------------------------------
function [PN]=orthopol(N,a,b,c,X)
x=poly(0,X); 
PN(1) = c(1) + 0*x;
PN(2) = a(1)*x + b(1);
for i=3:N+1
 PN(i) = (a(i-1)*x+b(i-1))*PN(i-1) + c(i-1)*PN(i-2);
end
endfunction