logenkain/mortgage-calculator
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Logen Kain 2020-10-28 17:04:37 -04:00
parent 967d7d594d
commit 50bc939cf3
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mortgage-calculator.lisp
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@ -1,25 +1,27 @@
;;;; Mortgage Calculators ;;;; Mortgage Calculators
#| #|
Formulas:
P = payment P = payment
PV = Present Value PV = Present Value
r = rate per period r = rate per period
n = number of periods n = number of periods
Find payments
P = (r(PV)) / (1-(1+r)^-n) P = (r(PV)) / (1-(1+r)^-n)
Okay, but I want to find PV instead Find total
Guess I need to remember algebra
P = (r(PV)) / (1-(1+r)^-n) P = (r(PV)) / (1-(1+r)^-n)
P * (1-(1+r)^-n) = r * PV P * (1-(1+r)^-n) = r * PV
(P * (1-(1+r)^-n) / r = PV (P * (1-(1+r)^-n) / r = PV
monthly-payments conversion Find rate
TODO
Find payments
TODO
(find-payments loan-total (/ rate 12) (* number-of-payments 12)))
find-payments = loan-total
|# |#
(defun find-payments (loan-total rate number-of-payments) (defun find-payments (loan-total rate number-of-payments)