### Open the file
if (open (FH, "file.txt"))
{
  ### Run through each line of the file (line will be put in $_)
  while (<FH>)
  {
    ### Set the maximum to -1
    my $max = -1;
    ### Run through all the numbers on this line
    while (m/([0-9\.\-]+)/g)
    {
      ### number is put in $1 by regexp
      if ($1 > $max)
      {
        $max = $1;
      }
    }
    print "$max\n";
  }
  close (FH);
}