Undefined Function Help

[Anon]

I downloaded a shopping cart application which I think was created in an earlier version of PHP (I am using 4.2.2). I am in the process of customising it for my website which uses a mysql database.

However, when I execute a particular search script I get the following error:-

Fatal error: Call to undefined function: bcsub() in /mnt/content/php/t/i/www.tiptop-health.co.uk/web/admin/searchReceipts.php on line 89

Line 89 in the script looks like this:-

$d1=bcsub($Yr,5);

Can any tell me what the correct syntax is in PHP4 (if you need to see the entire script let me know).

Thanks

[Anon]

bcsub() is an Arbitrary Precision Mathematics Function. In PHP 4, these functions are only available if PHP was configured with --enable-bcmath.

[Anon]

Can I simply change the php.ini file?