Do you mean this?

#!/usr/bin/perl

use warnings;
use strict;

my $string = 'p(0)=0,35 p(1)=0,54 p(2)=0,12 p(3)=0,96 p(4)=0,43';
print join ' ',
    map { s/\./,/; $_ } sort {
        my ($x, $y) = map { s/,/./; /=(.*)/; $1 } $b, $a;
        $x <=> $y }
    split / /, $string;
print "\n";
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You might also consider using Schwartzian Transform or Orcish Manœuvre.