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% exercise3.tex
%    Exercise 3.
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% Irit Dinur
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% Title
\title{Introduction to Computer Science - Fall Semester 1998/9\\
   { {{Exercise}} 3}}

\author{{\bf Due:} 7/1/1999}

\date{}

\begin{document}
\maketitle


\section*{Some Matrices}
Write a program that asks the user for a positive integer $n$, and prints the following $n\times n$ matrices on the screen:
\begin{enumerate}
\item The zero matrix.
\item The unit matrix.
\item The matrix with ones on both diagonals and zeros everywhere else.
\end{enumerate}
For example: 
\begin{verbatim}
Please enter the dimension of the matrices: 5
The 5x5 matrices are:
The zero matrix = 
00000
00000
00000
00000
00000
The unit matrix = 
10000
01000
00100
00010
00001
The X matrix =
10001
01010
00100
01010
10001
\end{verbatim}
The program should check if the user entered a negative (or zero) number and output an error message.
\end{document}