\documentclass[11pt]{article} \usepackage[paperwidth=8.5in,paperheight=11in,margin=1.25in,noheadfoot]{geometry} \begin{document} \thispagestyle{empty} \begin{center}\textbf{\Large MA497 Numerical Analysis\\Homework 1}\\[2ex]Due: 7 February, 2008\end{center} \noindent The solution to all problems should be typeset using \LaTeX, and the \LaTeX{} source file should be submitted electronically via email. The submitted source file will be compiled using \texttt{pdflatex} and the success of this process will represent the initial assessment step. All source code for numerical algorithms should also be submitted electronically via email.\\[2ex] \begin{enumerate} \item Let $f(x)=2\sqrt{x}-\cos x$. \begin{enumerate} \item What does the intermediate value theorem imply about $f$ on the interval $[0,1]$? \item Show that $f$ on $[0,1]$ satisfies each of the hypotheses of Theorem 2.1 on page 49 of the text. \item Theorem 2.1 recalls that the Bisection method generates a sequence $\{p_n\}_{n=1}^\infty$ that converges to a zero $p$ of $f$, and it implicitly provides an upper bound for the number of iterations needed to guarantee $|p_n-p|$ be within a certain amount. Using this theorem, determine an \textit{a priori} estimate of the number of iterations need to guarantee $|p_n-p|$ be no more than $10^{-4}$ on $[0,1]$. \item Write a bisection method algorithm, called \texttt{bisection.m}, which implements this problem, and use this algorithm to determine the \textbf{ACTUAL} number of iterations $N$ needed to guarantee that \[|f(p_N)|\leq 10^{-4}.\] How does this number compare to the estimate in part (c)? Explain this discrepancy. \end{enumerate} \item \begin{enumerate} \item Determine a contraction mapping $g$ and corresponding Lipschitz constant $k$ on $[1,2]$ with a unique fixed point $x\in[1,2]$ such that $x^3-x-1=0$. \item With an inital starting point $p_0=1$, use Corollary 2.4 on page 59 of the text to estimate the number of iterations required to guarantee the approximate fixed point is accuracate to within $10^{-6}$. \item Write a fixed point algorithm, called \texttt{fixedpoint.m}, which implements this problem, and determine the \textbf{ACTUAL} number of iterations needed to achieve the accuracy in (b). How does this compare to the answer in (b)? \end{enumerate} \end{enumerate} \end{document}