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{\narrower\smallskip\noindent
{\bf Exercise.}

\noindent
Do again the wolves-and-rabbits computation.  This time, the output should
graph~{\tt W} (vertical) against~{\tt R} (horizontal).  Time is not shown.  Use the
revised equations and starting conditions:

{\obeylines\obeyspaces\let =\ \tt
        Initial R=0.5
        Initial W=0.25
        dR/R=0.1(1-0.2R-2W)
        dW/W=0.1(2R-1)
}

Observe relevant rules of good programming practice.  Use an overlaid grid, as in
the previous {\tt W}\&{\tt R} 
problem; the detailed design of the output format is up to you.

Option, no extra credit: graph several solutions, using different initial 
conditions, on the same graph; label them {\tt A}, {\tt B}, {\tt C}, etc.
\smallskip}
}


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\line{\copyright 1984 Robert W. Floyd; \hfil}
%First draft (not published) ??\hfil}
%revised: Date; subsequently revised.\hfill}

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