Talk:Steffensen's method

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

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

The numerator is subtracting ${\displaystyle P_{n+1}}$ from ${\displaystyle P_{n+2}P_{n}.}$ Suppose the values of P are distances measured in meters. Then ${\displaystyle P_{n+1}}$ has units of distance (meters) and ${\displaystyle P_{n+2}P_{n}}$ 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)Reply

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

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