Hi! I know the value of a function f and its first and second derivatives at different point r (1D). I know how to fit it using only f(r) and r, but I'm sure its is possible to improve the quality/speed of the fitting by using also f'(r) and f''(r). Is anybody have in mind a fitting algorithm using all (r, f(r), f'(r), f''(r))? Any suggestion (book, web site, paper...) on this topic will be really appreciated. Sincerely, TP EDIT: The fitting probably needs a sum of gaussian type function.