/**
* Evaluate a math expression
*
* @since 1.0.0
*
* @param string $expression without leading = sign
* @return string Result of the evaluation
*/
protected function _evaluate_math_expression($expression)
{
// straight up evaluation, without parsing of variable or function assignments (which is why we only need one instance of the object)
$result = $this->evalmath->pfx($this->evalmath->nfx($expression));
if (false === $result) {
return '!ERROR! ' . $this->evalmath->last_error;
} else {
return $result;
}
}