I improved a test for an error condition yesterday. If one tries to find out how long it will take to pay off a loan (i.e., the Number of Payments field is blank), but the Regular Payment amount specified is below the minimum amortizable payment, the loan can never be paid off, since the payment isn’t even covering the interest that’s due. In such a case, the calculator raises an error condition.
This test existed before, but it wasn’t always reliable right at the cusp of amortizability, so I made a tweak which should have handled it. It did the job as I intended, but there was a consequence: it also disabled negative amortization scenarios if one is seeking a payoff time when a Balloon Payment has been also specified. So I have fixed yesterday’s fix, and finding the loan payoff time for a negative amortization scenario should work again.
I also added a link to this blog from the calculator page itself, for the curious.