init commit

README.md

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+# mortgage-calculator
+
+Calculate mortgages in multiple ways
+
+# Overview
+
+The purpose of this program stems from my inability to find loan calculators
+that will let me put in what I want to pay per month to see how much loan
+I can afford.
+
+Thus, this program will be able to calculate mortages in whichever way
+you feel fit.
+
+fixme: Be more specific once program is created
+
+# Useage
+
+fixme: Useage examples
+
+# Documentation
+
+fixme: Write documentation
+
+# License
+
+fixme: Grab ICS

mortgage-calculator-test.asd

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+Unit tests

mortgage-calculator.asd

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+(defsystem mortgage-calculator
+	:author "Joseph J. Green <logen@sudotask.com>"
+	:maintainer "Joseph J. Green <logen@sudotask.com>"
+	:license "ISC"
+	:homepage "https://"
+	:version "0.1"
+	:components ((:module "src"
+				  :serial t
+				  :components
+				  ((:file "mortgage-calculator"))))
+	:description "Mortgage calculators"
+	:long-description
+	#.(uiop:read-file-string
+		(uiop:subpathname *load-pathname* "README.md"))
+	:in-order-to ((test-op (test-op my-project-test))))
+
+#|(defsystem mortgage-calculator-test
+	:author "Joseph J. Green <logen@sudotask.com>"
+	:license "ISC"
+	:depends-on (:mortgage-calculator)
+	:components ((:module "t"
+				  :serial t
+				  :components
+				  ((:file "mortgage-calculator"))))) |#

mortgage-calculator.lisp

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+;;;; Mortgage Calculators
+
+#|
+loan amount (p)
+interest rate (r)
+years (t)
+payments per year (n)
+loan type: fixed-rate
+
+Payment = P x (r/n) * [1+(r/n)^n * t]/(1+r/n)^n *t - 1
+
+or
+
+P = payment
+PV = Present Value
+r = rate per period
+n = number of periods
+
+P = (r(PV)) / (1-(1+r)^-n)
+
+|#
+
+(defun payments (loan-total rate number-of-payments)
+  (/ (* rate loan-total)
+	 (- 1 (expt (+ 1 rate) (* number-of-payments -1)))))
+(defun monthly-payments(loan-total rate number-of-payments)
+  "Number of payments in years"
+  (payments loan-total (/ rate 12) (* number-of-payments 12)))
+(defun payment-total-per-year (loan-total rate number-of-payments)
+  (* (payments loan-total (/ rate 12) (* number-of-payments 12)) 12))
+
+
+
+