On Tue, 2003-07-01 at 20:43, Josh Sled wrote: > On Tue, Jul 01, 2003 at 07:59:40PM -0400, Daniel Hannum wrote: > > | I have a number of questions about the mortgage/loan repayment druid. > | BTW, I'm on 1.8.1 (redhat 9). So I this has been fixed, please let me > | know. I'm not prepared to grapple with upgrading (yet)... it was easier > | under Debian...... > > I don't believe the Mortgage/Loan druid has seen any changes since 1.8.0. > > | Now, when I put the principal, rate and term into Gnucash's druid, it > | comes up with 374.13, but that's not good, because that's not what I'm > | actually going to pay. > > 4 whole cents off? Good enough for government work... ;) >
Perhaps, but not for personal finance. I resorted to an Open Office spreadsheet, and enter interest/principal from there. > If it's a constant 0.04, you could modify the formulae to add/subtract that > out, but that's a nasty hack. OTOH, it might solve your immediate problem, > though I imagine that the rest of the calculations would be off, as well. :( > > I had expected that the calculation would vary from most people's actual > payments for various reasons ... this is a good example of this. Sorry. > > | 1. How do I force a particular loan payment? On the page of the Druid > | where you specify the 'Amount' and the accounts where the principal and > | interest will be, I tried replacing the "pmt()" expression with $374.09, > | but it seemed to ignore me; the next page still had 60 payments of $374.13 > > Hmm... that should actually work, IIRC. > > In playing with it, it does look like any changes made to the Payment > field are ignored, which is quite unfortunate. Filing a bug at > bugzilla.gnome.org is appreciated. > > | 2. What does "pmt( 0.07900 / 12 : 60 : 18495.00 : 0 : 0 )" mean? > | Obviously, it's rate, term, principal, but what are the last 2 zeroes? > | Perhaps I shouldn't care. Or perhaps it could help to know. > > This one can be answered by looking in src/scm/fin.scm [I forget where > it's copied on install, but `locate fin.scm` should find it] -- the last > two terms are the "future value" and "type", as defined by the Gnumeric > 1.0.8 functions of the same name. Future value could be non-zero, but > I made the simplifying that it is. > > I was hoping to have a more name=value function syntax in the future, but > time's a bitch. > > | 3. If I were to start paying the loan off faster, with irregular > | amounts, I would have to put these transactions in by hand. Does it seem > | correct to take the balance after the previous payment, multiply it by > | 7.9%/12 and use that as the interest portion? I would think that would > | be right, but when I try that with the current balance, it doesn't come > | up the same as what the scheduled transaction generator is producing... > | so you guys must have a different algorithm. > > Yes ... there's an existing bug [and some design-time requests which were > not incorporated] that any future transactions should be based on the > present value of the account at the time of payment... this would be a > nice expansion of the feature. :( > > | Any help would be appreciated. > > I fear that wasn't a lot of help, unfortunately, but hopefully it's > more clear. My time to enhance this [or any] part of the codebase is > non-existant at present, a situation I don't think will be resolved for > some number of months. Hopefully someone will step up to this. > My auto loan is simple interest. Here's how the payment breakdown works out. Suppose an interest rate of 5%: bal = initial/running principal balance prin = principal portion of payment int = interest portion of payment days = payment date - last payment date amt = amount of payment int = (days * (5%/365)) * bal prin = amt - int bal = bal - prin This formula matches my bank's numbers perfectly, so I'm pretty happy with it. Unfortunately, I couldn't get Gnucash to do the same thing, so I just transfer the numbers from the spreadsheet. Using the spreadsheet also allows me to insert rows for extra payments. I tried all the PMT and INT and FPV and NPV formulas--they all seemed to be a few pennies off at the closest. So I just use my own. *shrug*worksforme. YMMV, etc., etc. -- Matthew Vanecek perl -e 'print $i=pack(c5,(41*2),sqrt(7056),(unpack(c,H)-2),oct(115),10);' ******************************************************************************** For 93 million miles, there is nothing between the sun and my shadow except me. I'm always getting in the way of something... _______________________________________________ gnucash-devel mailing list [EMAIL PROTECTED] http://www.gnucash.org/cgi-bin/mailman/listinfo/gnucash-devel
