I am working on a test scenario.The interest formula is ipmt( 0.03500 / 12.00 : i : 180.00 : 172,000.00 : 0 : 0 ), the others have the same numbers and the 71st payment contains the error. I am using these numbers because they are exactly the same as the numbers that have already generated an error. i started the test loan in Jan 2000 with the first repayment in February and I am creating one month at a time in case that makes a difference. If the test can repeat it I will submit the bug report.
David C On Tue, Jan 8, 2019 at 10:52 PM John Ralls <jra...@ceridwen.us> wrote: > The answer is probably in app-utils/calculation. All of that was probably > written before Guile grew a rational number class and I think that > GncNumerics get converted to doubles before being passed to the interest > functions. That would pretty much guarantee rounding issues. > > Regards, > John Ralls > > > On Jan 8, 2019, at 5:46 PM, Christopher Lam <christopher....@gmail.com> > wrote: > > > > Well the SCM has numerous references to "round" and "rounding errors" so > it's to be expected. > > > > Please file a bug with example numbers, and hopefully these errors may > be fixed. > > > > On 9/1/19 7:35 am, David Carlson wrote: > >> John, > >> > >> Thanks for the reference. Alas, I will need to do some homework to > >> properly read SCM. There must still be some sort of rounding issue > >> creeping in if the Scheduled Transaction SLR sometimes generates an > >> imbalance from ppmt = pmt - ipmt. > >> > >> David C > >> > >> On Tue, Jan 8, 2019 at 3:44 PM John Ralls <jra...@ceridwen.us> wrote: > >> > >>> The thee functions are defined in > >>> > https://github.com/Gnucash/gnucash/blob/maint/libgnucash/app-utils/fin.scm > , > >>> prefixed with gnc: (so gnc:ipmt etc.). > >>> > >>> At line 41ff you'll see that ppmt = pmt - ipmt. > >>> > >>> Regards, > >>> John Ralls > >>> > >>> > >>>> On Jan 8, 2019, at 12:48 PM, David Carlson < > david.carlson....@gmail.com> > >>> wrote: > >>>> My point is that the equations are defined by the assistant, and I > think > >>> that they can be expressed in a form that concentrates all the errors > into > >>> one line where a simple rounding would not generate a problem where the > >>> parts do not add up to 100%. Granted, the errors may sometimes cause > >>> inaccurate results, but they would not add the imbalance line to the > >>> transaction. > >>>> The current equations are three evaluations called pmt(numbers), > >>> ppmt(numbers) and ipmt(numbers) with no clue how they are actually > >>> evaluated. > >>>> Apparently pmt is not always the sum of ppmt and ipmt. when rounding > >>> happens. If ipmt were expressed as pmt-ppmt, there would be no > imbalance, > >>> but one of the other two ways to express all three may be less likely > to > >>> generate inaccurate results. > >>>> David C > >>>> > >>>> On Mon, Jan 7, 2019 at 10:19 PM John Ralls <jra...@ceridwen.us> > wrote: > >>>> > >>>> > >>>>> On Jan 7, 2019, at 3:14 PM, David Carlson < > david.carlson....@gmail.com> > >>> wrote: > >>>>> I just had a scheduled transaction that was set up by the > loan/mortgage > >>>>> repayment assistant appear with 0.01 Imbalance-USD. > >>>>> > >>>>> I would think that GnuCash should have an accuracy method that would > >>>>> prevent this from happening. Is this a bug? > >>>>> > >>>>> I am using GnuCash 2.6.17 in Ubuntu 16.04 today. > >>>> The accuracy method is what created the imbalance entry. ;-) > >>>> > >>>> There’s nothing in the SX system to pre-instantiate future scheduled > >>> transactions and ensure that they’re balanced. What would you have the > >>> check function do if it found an imbalanced case? How would you handle > >>> variables whose values are set by the user in the SLR dialog? > >>>> Regards, > >>>> John Ralls > >>>> > >>> > >> _______________________________________________ > >> gnucash-user mailing list > >> gnucash-user@gnucash.org > >> To update your subscription preferences or to unsubscribe: > >> https://lists.gnucash.org/mailman/listinfo/gnucash-user > >> If you are using Nabble or Gmane, please see > https://wiki.gnucash.org/wiki/Mailing_Lists for more information. > >> ----- > >> Please remember to CC this list on all your replies. > >> You can do this by using Reply-To-List or Reply-All. > > _______________________________________________ > > gnucash-user mailing list > > gnucash-user@gnucash.org > > To update your subscription preferences or to unsubscribe: > > https://lists.gnucash.org/mailman/listinfo/gnucash-user > > If you are using Nabble or Gmane, please see > https://wiki.gnucash.org/wiki/Mailing_Lists for more information. > > ----- > > Please remember to CC this list on all your replies. > > You can do this by using Reply-To-List or Reply-All. > > _______________________________________________ > gnucash-user mailing list > gnucash-user@gnucash.org > To update your subscription preferences or to unsubscribe: > https://lists.gnucash.org/mailman/listinfo/gnucash-user > If you are using Nabble or Gmane, please see > https://wiki.gnucash.org/wiki/Mailing_Lists for more information. > ----- > Please remember to CC this list on all your replies. > You can do this by using Reply-To-List or Reply-All. _______________________________________________ gnucash-user mailing list gnucash-user@gnucash.org To update your subscription preferences or to unsubscribe: https://lists.gnucash.org/mailman/listinfo/gnucash-user If you are using Nabble or Gmane, please see https://wiki.gnucash.org/wiki/Mailing_Lists for more information. ----- Please remember to CC this list on all your replies. 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