problems with function pow()

I have a page created to do some calculating with the function pow. When I use it on the site from my employer it works fine. http://www.denb.nl/raster.php3 , when I use it on my local Linux Suse 8.0 or Windows it also works fine. When I use it at my provider http://www.adrieg.nl//files/puntverbreding/raster.php3 I get the following error messages. Warning: Invalid argument(s) passed to pow() in /usr/local/slash/apache/vhosts/adrieg.nl/httpdocs/files/puntverbreding/raster.php3 on line 13 Warning: Division by zero in /usr/local/slash/apache/vhosts/adrieg.nl/httpdocs/files/puntverbreding/raster.php3 on line 13 Warning: Invalid argument(s) passed to pow() in /usr/local/slash/apache/vhosts/adrieg.nl/httpdocs/files/puntverbreding/raster.php3 on line 13 Warning: Division by zero in /usr/local/slash/apache/vhosts/adrieg.nl/httpdocs/files/puntverbreding/raster.php3 on line 13 What can I do or is there a problem at my provider, he is using php 4.2.1 Thanks for advise ...!