Mortgage Calculation Model
This simple model can be used to calculate the monthly payment of a fixed-rate mortgage. You can also define a stepped-up payment schedule and see how it affects the payoff time and total payment amount. The mortgage calculator computes the remaining balance and cumulative payments using user-defined input parameters. A user-defined termination condition is also used to halt payment when the remaining balance reaches zero.
This Monthly Payment Calculator handles the real number-crunching. The monthly interest factor (A/P) is computed based on the interest rate and number of payments. A timed event is used to simulate the monthly payments. Discrete Change elements are used to update the stock elements tracking the mortgage balance and cumulative payments. The Extra Payment Calculator handles the extra payments, which are assumed to occur annually. A timed event is used to simulate the annual payments. Consequence elements are used to update the integrators used to store the remaining balances.