Javascript APR Calculator - Equal instalments

This calculator will work out the APR for loans with regular, equal monthly or weekly instalments and for loans where additional payments are made at the start or end.  To use the calculator, fill in the figures in the boxes marked '*', select the button for the repayment frequency and then click on the 'Calculate' button to display the result in the final box .  Click on the 'Reset' button to clear the calculator for a new calculation.

* Amount of credit (£):
* Amount of initial payment (£):
* Amount of regular repayments (£):
* Number of regular repayments:
* Additional final repayment (£):
Repayment frequency Months Weeks

Coded in JavaScript and HTML by Brian Stewart, v1.1 December 2001