#To determine the pattern of fish reproducing 
    #in a pond
                         #Using the Chaos Theory

&start();


############################################################


sub start{

    print "Welcome to the 'Fish in a Pond' chaos theory solution guide
+.\n" . 
                 "Please enter the number of fish in the pond on the f
+irst year:\n";

    print "\n";

    $nof = <STDIN>;

    print "\n";

        print "Please enter the anual rate of increase: \n";

    print "\n";

    $roi = <STDIN>;

    print "\n";

        print "For what period of time would you like the simulation t
+o run for(in years): \n";

        print "\n";
        
        $yrs = <STDIN>;

        chomp($nof);
        chomp($roi);
        chomp($yrs);
        &confirm();
    }


############################################################


sub middle{

    $ans = $nof;

        $year = 0;

    print "Year $year.    =    $ans fish.";

    print "\n";

        &calc();
}


############################################################

sub calc{

    while($year <= $yrs) 
{
    $year = $year + 1;
    $i = $ans * $roi;
    $x = 1 - $ans;
    $ans = $i * $x;
        print "Year $year.    =    $ans fish. \n ";
}
}

############################################################

sub confirm{
print "The data that you have entered says: \n" . 
      "  *  that there is $nof in the pond on the fisrt year. \n" . 
      "  *  that the annual rate of increase is $roi. \n" . 
      "  *  that the simulation will run for $yrs years. \n";

print " Is this information correct?(Y/N): ";

$answer = <STDIN>;
chomp($answer);

if ($answer = "n")
{
&start();
}
elsif($answer = "y")
{
&middle();
}
else{
    print "Please enter either Y or N. \n";
    &confirm();
}
}

############################################################
[download]