Instead of the array elements sort indexes...

my @ix = sort { $myarray[$b] <=> $myarray[$a] } 0..$#myarray;
$div = @myarray;
$myarray[$_] *= $div-- / @myarray for @ix;

print "@myarray\n"
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...or even...

my $div;
$myarray[$_] *= ++$div / @myarray for sort { $myarray[$a] <=> $myarray
+[$b] } 0..$#myarray;
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