[PHP] negative infinity is unreachable

[Hugh Danaher]

HELP!

I have been trying variations of the code posted below with little success.  The log() 
function generates a -INF statement when trying to calculate the log of zero or the 
log of an empty value in the associative array.  With the "IF then unset() " 
statements in place, the total contents of log_high[] and log_low[] arrays become 
empty.  Without the "IF then unset()" statements the arrays are full but the program 
times out because it can't use INF in imageline().  I've gone through various rewrites 
on this code block but have come up with nothing that works, and I need professional 
help (but that's a different story).

Thanks,
hugh

Failing code:

for ($year=($current_year-5);$year<=($current_year+1);$year++)
     {
     $x_distance=20+($year-($current_year-9))*20;
     $high_distance=420-round(log($high[$year])*75,0);
     $low_distance=420-round(log($low[$year])*75,0);
     if ($high_distance=="INF")                               / / INF is a double
         {
         unset($high_distance);
         }
      if ($low_distance=="INF") 
         {
         unset($high_distance);
         }    
     if (isset($high_distance) and isset($low_distance))
        {
        imagettftext($image,5,0,($x_distance),($high_distance),$black,$font2,"n");
        imagettftext($image,5,0,($x_distance),($low_distance),$black,$font2,"n");
        imageline($image,$x_distance),$high_distance,($x_distance),$low_distance,$red);
        }
    $log_high[$year]=$high_distance;
    $log_low[$year]=$low_distance;
     }