Here's code to replicate.  Please see note below as to why these are string values.

<?php
$base="2";
$exp="8";

echo pow($base,$exp);
?>

Gives me the error:

[28-May-2002 12:48:18] PHP Warning:  Invalid argument(s) passed to pow() in (....)/editMatrix.inc on line 74

---

This may seem a low-priority issue, however, in a matrix project I'm working on the base/exponents are usually stored in a database, and the functions to retrieve them are usually typecast as strings when fetch()'ed and stored in an array.  I have to assign temporary variables with the value of the base and exponent re-assigned using settype([$tmp_base|$tmp_exp],"integer") in order to get pow() to work.  This does not seem like a 'clean' solution, could perhaps pow() be a little less strict as far as it's types, or is php heading towards stricter casting for all functions?