- The  fixed-point method converges at a linear rate;
 
- it is said to be linearly convergent, meaning that the error at each successive iteration is a constant fraction of the previous error.
 
Table 3.4:
The order of convergence for the iteration algorithm with the different forms of  
 .
![\begin{table}
\begin{center}
\includegraphics[scale=0.6]{figures/1-24}
\end{center}\end{table}](img330.png)  | 
 
- If we tabulate the errors after  each step in getting the roots of the polynomial and its ratio to the previous error,
 
- we find that the magnitudes of the ratios to be levelling out at 0.3333. (See Table 3.4)
 
- Example: Comparing Muller's and Fixed-point Iteration methods (http://siber.cankaya.edu.tr/ozdogan/NumericalComputations/mfiles/chapter1/mainmulfix.m m-files: mainmulfix.m,  http://siber.cankaya.edu.tr/ozdogan/NumericalComputations/mfiles/chapter1/muller.m muller.m,  http://siber.cankaya.edu.tr/ozdogan/NumericalComputations/mfiles/chapter1/fixedpoint.m fixedpoint.m)                                                                                                                                                                                                                                                                                                                                                                                                               
 
Cem Ozdogan
2011-12-27