CCL: Question Szabo/Ostlund Ex.1.14



Dear Martin,

Please compile the followings with latex,

\documentclass[a4paper,10pt]{article}

\usepackage{ucs}
\usepackage[utf8x]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{fontenc}
\usepackage{graphicx}

\usepackage[dvips]{hyperref}

\author{JCsontos}
\title{1.14 Szabo-Ostlund}
\date{11/04/11}

\begin{document}
Â\begin{align*}
 \int_{-\infty}^{\ \infty}{a(x) \cdot \delta(x)}\ dx & =
 \int_{-\infty}^{-\epsilon}{a(x) \cdot 0}\ dx +
 \int_{-\epsilon}^{\ \epsilon}{a(x) \cdot \delta_{\epsilon}(x)}\ dx +
 \int_{\ \epsilon}^{\ \infty}{a(x)\cdot 0}\ dx \\
 & = \int_{-\epsilon}^{\ \epsilon}{a(x) \cdot \delta_{\epsilon}(x)}\ dx \\
 & = \int_{-\epsilon}^{\ \epsilon}{a(x) \cdot \frac{1}{2\epsilon}}\ dx \\
 & = \lim_{\epsilon \to 0} \frac{1}{2\epsilon} \int_{-\epsilon}^{\ \epsilon}{a(x)}\ dx\\
 & = \lim_{\epsilon \to 0} \frac{1}{2\epsilon}
 {[\epsilon-(-\epsilon)]}{a(\xi)}, \ \xi \in (-\epsilon, \epsilon)
 ;\ \textbf{mean value theorem for integration}
Â\end{align*}


\begin{align*}
\text{if $\epsilon \to 0$ then $\xi \to 0$ and }
 \lim_{\epsilon \to 0} \frac{1}{2\epsilon}
 {[\epsilon-(-\epsilon)]}{a(\xi)} & =
 \frac{2\epsilon}{2\epsilon}{a(0)}
\end{align*}


\end{document}

Best,
Jozsef

On 11/03/2011 04:56 PM, Martin Hediger ma.hed-x-bluewin.ch wrote:
Sent to CCL by: "Martin  Hediger" [ma.hed^^bluewin.ch]
 Dear List
 I also posted this question to the google.gamess user group, but was encouraged
 to do so here. I'm new to the CCL and looking forward to interesting
 discussions.
 I was trying to solve ex. 1.14 from Szabo/Ostlund. If
 d(x) = \lim_{eps->\infinity} d_eps(x),
 where
 d_eps(x) = 1/(2eps) when -eps <= x <= eps and d_eps(x)=0 else,
 we are supposed to show that
 the value of a function a(0) = \int dx a(x) d(x)
 My Ansatz was to insert the definition into the integral, but then I'm
 not exactly seeing how to treat the limit function.
 How does one show this?
 Thank you for any suggestions.
 MartinE-mail to subscribers: CHEMISTRY++ccl.net or use:
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