[GNC] Loan/Mortgage payments with "adjusted" principle (eg after an extra principle payment), SOLVED

[azalea4va]

Sorry, I missed this reply.  So a little late, but ...


Mike or Penny Novack-3 wrote
> a) method? << by "present value" of series of "rents" or by "trial and
> error" >> 

I am not sure what ""present value" of series of "rents"" means, but the
answer is by math.  This is just a mathematical calculation.  As was
indicated in the code provided.  I did not specify, but the math was based
on 30/360 calculations, the one most often used in determining mortgage
payments.


Mike or Penny Novack-3 wrote
> b) where will rounding take place? 

I addressed this in the file I provided.  There is one and only one correct
answer mathematically.  But both gnucash rounds to the nearest penny, and a
bank does as well.  They may not round in the same manner.
I have given two solutions. First, there is a recursive function where the
payments are rounded at each payment. Second there is the exact math
solution that is then rounded at the monthly payment to be made.  I expected
the former to be what I would need to be consistent with my bank but it has
turned out the latter has been what has worked.  So yes I agree there could
be some minor variations that result in fractions of a penny differences,
all of which are "correct" answers.  If your lender uses something
different, it could require making a penny adjustment every few payments, or
make a minor change in the code, for example change the code so instead of
rounding, it truncates or ceilings. I cannot think of two many different
ways this can be done, assuming 30/360 calculations. /(Note there is a bug
in gnucash 2.6 that causes a problem with using the recursive solution, see
the comment in the code to see how to work around that bug.)/  



Mike or Penny Novack-3 wrote
> c) how will the final payment be figured? 

To be honest, I forget (because I do not care).  Did I add the code to to
make the final payment the amount due at that time?  Or does the code just
generate the same old payment amount?  I do not care because this is
something for the schedule system so it handles the hundreads of payments
that will be coming out. It is designed to eliminate all the work of dealing
with those hundreds of payments.  If it handles the one final payment
correctly or not, I do not care.  If you do, plug it in, run a trail case to
see how it handles the entire series of payments, and see what happens. 
I'll leave that to you, since you can do it as easily as I can and by doing
it yourself get an answer you have more confidence in.



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