# Tag Info

Inverse Quadratic Interpolation (IQI) is described on the Wiki and in Section 4.5. Note some of the pitfalls mentioned there. Both of the references give the iteration formula. This method can be used to find all roots of a polynomial, whether they are real or complex. As an example, take $f(x) = 4 x^3-16 x^2+17 x-4$. I usually start by plotting the ...