释义 |
Halley's Irrational FormulaA Root-finding Algorithm which makes use of a third-order Taylor Series
 | (1) |
A Root of satisfies , so
 | (2) |
Using the Quadratic Equation then gives
 | (3) |
Picking the plus sign gives the iteration function
 | (4) |
This equation can be used as a starting point for deriving Halley's Method.
If the alternate form of the Quadratic Equation is used instead in solving (2), the iteration function becomesinstead
 | (5) |
This form can also be derived by setting in Laguerre's Method. Numerically, the Sign in theDenominator is chosen to maximize its Absolute Value. Note that in the above equation, if , thenNewton's Method is recovered. This form of Halley's irrational formula has cubic convergence, and is usually foundto be substantially more stable than Newton's Method. However, it does run into difficulty when both and or and are simultaneously near zero.See also Halley's Method, Laguerre's Method, Newton's Method References
Qiu, H. ``A Robust Examination of the Newton-Raphson Method with Strong Global Convergence Properties.'' Master's Thesis. University of Central Florida, 1993. Scavo, T. R. and Thoo, J. B. ``On the Geometry of Halley's Method.'' Amer. Math. Monthly 102, 417-426, 1995. |