This will do an Amortization for a bi-weekly payment schedule, meaning these calculations are for payments made every two weeks.
It will take as an input a payment number, and a requested output value (either interest, Principle, or Combined): The equation will output the Interest or principle paid for that payment number in the Amortization.
An Amortization table will show, for each payment of a loan, the amount applied to Principle and the amount paid as interest.
For a standard fixed rate mortgage, the payment in the beginning is applied more towards the interest than to the principle. As the loan matures, the payment amount each month applied to principle increases, and the amount paid as interest decreases.
This equation will calculate an Amortization table by month and return as a result the requested value for the requested payment period.
The equation will allow you to choose the Interest paid for that payment period, the amount applied as Principle, or the Combined (total) payment for that period.