question about formulas in mortgage/loan druid

[Alan Munter]

I was trying to set up a loan in the druid and I am a bit confused
about what all of the arguments to the ipmt, ppmt, and pmt functions
are.

I went through the druid and set up a loan for 10000, 24 months, 3.9%
interest, and at the end Review screen I can see what the amortization
would be which looks correct.  The payment, pmt, is approximately $400
total per month.

However, those are the bank terms of the loan.  I would like to repay
the loan faster, so I would like the pmt amount to be, for example,
$450 per month instead of $400.  Can I just go back and edit the
scheduled transaction and in the "Credit Formula" replace
pmt(0.039/12:24:10000:0:0) with the number 450 and leave the two Debit
formulas alone to let them calculate it correctly?

Thanks a lot and thanks to the developers for not just making a great
program but also in the process teaching me about double-entry
bookkeeping.