Hello, The following code, which finds the optimal price a company should charge to maximize profit, works fine:

#!/usr/bin/perl
#finalproject_1.pl
use strict;

our $p1 = 0;
our $p2 = 0;
our $pT = 10;
our $a = 0.1;
our $b = 0.1;
our $k = 0.005;
our $d2 = 0.5;
our $d1i = 1000;
our $ci = 200;

our @profit; our @price; 
my $profit = &profit();
our $A;
our $B;
our $C;
our $s;

while ($p1 < 10){
    $p1 += .01; $p2 = $p1;
    $A = ($a*($p1-$p2) + $b*($pT-$p1)/(-2));
    $B = ($p1*($a*($p2-$p1) + $b*($pT-$p1)-$k*$d2-$d1i*$k));
    $C = ($d1i - $ci);
    $s = (((-1)*$B + sqrt($B**2 - 4*$A*$C))/(2*$A));
    $profit = &profit();
    push @price, $p1;
    push @profit, $profit;
}

our @alias = @profit;
my $maxprofit = pop @alias;
foreach (@alias){
    $maxprofit = $_ if $maxprofit < $_;
}
our $index = 0;
++$index until $profit[$index] == $maxprofit or $index > $#profit;

print "The largest profit is $maxprofit and is obtained when price is 
+$price[$index] \n";

#Here thar be subroutines

sub profit {
    (($A*$s**3)/3 + ($B*$s**2)/2 + $C);
}
[download]

But when I try to get the optimal prices as demand changes, perl prints the same price over and over again:

#!/usr/bin/perl
#finalproject_2.pl
use strict;
use Math::Complex;

our $p1 = 0;
our $p2 = 0;
our $pT = 10;
our $a = 0.1;
our $b = 0.1;
our $k = 0.005;
our $d2 = 0.5;
our $d1i = 0;
our $ci = 200;

our @profit; our @price; 
my $profit = &profit();
our $A;
our $B;
our $C;
our $s;
while ($d1i <= 9000){
    while ($p1 < 10){
        $p1 += .01; $p2 = $p1;
        $A = ($a*($p1-$p2) + $b*($pT-$p1)/(-2));
        $B = ($p1*($a*($p2-$p1) + $b*($pT-$p1)-$k*$d2-$d1i*$k));
        $C = ($d1i - $ci);
        $s = (((-1)*$B + sqrt($B**2 - 4*$A*$C))/(2*$A));
        $profit = &profit();
        push @price, $p1;
        push @profit, $profit;
    }

    our @alias = @profit;
    my $maxprofit = pop @alias;
    foreach (@alias){
        $maxprofit = $_ if $maxprofit < $_;
    }
    my $index = 0;
    ++$index until $profit[$index] == $maxprofit or $index > $#profit;

    print "$d1i\t\t\t$price[$index]\t\t$index\n";
    $d1i+=100;
}

#Here thar be subroutines

sub profit {
    (($A*$s**3)/3 + ($B*$s**2)/2 + $C);
}

Please help!
[download]

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