Talk:Steffensen's method

Typo?
The "units" seem to be inconsistent in this formula at the end of the derivation:

$$P = P_n - \frac{(P_{n+2}P_n-P_{n+1})^2}{P_{n+2}-2P_{n+1}+P_n}$$

The numerator is subtracting $$P_{n+1}$$ from $$P_{n+2}P_n.$$ Suppose the values of P are distances measured in meters. Then $$P_{n+1}$$ has units of distance (meters) and $$P_{n+2}P_n$$ has units of area (meters^2). One cannot subtract a distance from an area. Is there a typo in the given formula? - Ac44ck (talk) 04:37, 26 December 2008 (UTC)


 * This was fixed on 11 February 2010. Thank you. Ac44ck (talk) 14:11, 1 August 2010 (UTC)

Quadratic convergence
It's unclear from the article what are the requirements for quadratic convergence. bungalo (talk) 18:24, 20 April 2010 (UTC)