Processing a formula comprised of array keys in PHP
<p>I would like to write a function that will process formulas that are comprised of array keys.  For example, (1+3+5+7-8)*9 or (1-3+5)/6 and etc  Any suggestions?</p>

<p>EDIT:
I think it's better to think of this as an excel grid, with field coordinates being the array keys and one of the fields being the formula field (e.g. A1+A2-B2*B3)</p>
