Error in line 32

There is an error on line 32:
PHP Notice: Use of undefined constant l - assumed 'l' in class.bkTree.php on line 32

I assume that:
for($i=$d-$l; $i<=$d+l; $i++)
needs to be changed to:
for($i=$d-$l; $i<=$d+$l; $i++)

Thanks for catching this Jethro, the typo was not in my local copy so I haven't caught this in implementations. Fixing it now.

You're welcome.
And while I'm looking at the code I noticed 2 more small things:

Line 22:
if ($this->members[$d]) $this->members[$d]->addTerm($t);
'PHP Notice: Undefined offset'
I changed it to:
if (isset($this->members[$d])) $this->members[$d]->addTerm($t);

And line 31 I changed to:
if (!$d) $d = $cd;