Steffensen Method

A variant of the N-R Method. Consider

$$\begin{eqnarray*} p_{n+1}&=& p_n -f(p_n)\bigg/g(p_n)\\ \mbox {where } g(x) &=... ...uire } g &\in& C^3[a,b]\\ &&\mbox {for quadratic convergence } \end{eqnarray*}$$

No $f'(x)$ needed.

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