Power Function In PHP 4.2.2

I have just recently upgraded to PHP 4.2.2 and am trying to get this version to do the following compounding interest problem, which PHP3 had no problem with. $futureValue = $currentAmount * pow( 1 + ($interestRatePercent/100), $timeInYears); In PHP4, it issues a warning saying " Invalid argument(s) passed to pow() in C:\Server\Apache Group\Apache2\htdocs\Compound Interest\cinterest.php3 on line 24". In reading about the pow() function, it appears that in PHP 4 the pow function use to return floats whereas now it returns integers. So my first instinct was to try to cast what power returns into a float. So I tried various tests (since I haven't cast in PHP before). I tried everything from: (float) $futureValue = $currentAmount * pow( 1 + ($interestRatePercent/100), $timeInYears); to: $temp = 1 + ($interestRatePercent/100); echo "<br>$temp to the $timeInYears<br>"; //i.e echos 1.06 to the 2 (float) $temp1 = (float) pow($temp, $timeInYears); $futureValue = $currentAmount * $temp1; I am still getting the warning about invalid arguments passed to pow(). So what is the deal here, how am I suppose to do this type of math problem? Thanks for any help or ideas. -Andrew V. Romero