TVM Amortization Rounds to Cents (or other)

[Albert Chan]

(04-03-2021 08:44 PM)Rick314 Wrote:  But with cents display, you end up with a BALance of $3.00, which is correct if you made actual monthly payments to cents resolution for 30 years. I made an Excel spreadsheet with 360 rows to prove to myself this is what is going on.

Yes. I tried calculated it (in cents, so to avoid binary/decimal conversion errors)
I used rint(), i.e. bankers rounding.

lua> n=360; r=7.75/1200; pv=18e6; pmt=-128954 -- whole cents
lua> k = (1+r)^n -- compounding factor
lua> rint(pv*k + pmt*(k-1)/r) -- calculated balance, in cents
289

Now, actually round the balance, for each period

lua> for i=1,n do pv = pv + rint(pv*r) + pmt end
lua> pv -- actual balance, in cents
300