function [p]=polyfit(x, y, n, s) // return coefficient vector or poly if fourth string argument given [lhs, rhs] = argn(0) x = x(:); y = y(:) m = length(x) if length(y) <> m, error('x and y must have same length'), end v = ones(m,n+1) for i=2:n+1, v(:,i) = x.*v(:,i-1), end p = (v\y)' if rhs > 3, p = poly(p, s, 'coeff'), end endfunction