I'd like to add a mortgage calculator to a client's site. I've been unable to find the formula.
Well the calculation depends on the companies policy of course. 1. Normal rent calculation would go like this:
where
i = interest or rent over a certain the period of time (
usually between 0 and 1 (1=100%). With 3.5% interest, i is 3.5/100=0.035
n = the amount of timeperiods that passed
$ = pack of money , and $(0) is heap at start, $(n) is at end of n timeperiods
$(n)= $(0) * (1+i)^n
(x raised-to-the-power-of y is sometimes written as x^y, sometimes as x**y (Perl))
in PHP
$startsum=$_POST['startsum'];
$interest=$_POST['interest'];
$timeperiods=$_POST['timeperiods'];
$endsum = $startsum * pow(1+$interest/100,$timeperiods);With a 3% year-rent in 5 years $10 grows to $(n) = 10 * 1.03^5
2. Mortgage calculation
Well how do they pay back?
You can have them pay a fixed part of the loan plus the interest of the month, here called an annuiteiten-hypotheek
Then every month you pay
($in_this_month *interest) + (1/$totalmonths * $startsum )
$in_this_month is probably $n=thismonths number
so the monthly payment would look something like
((1 - $n/$totalmonths) * $startsum ) + (1/$totalmonths * $startsum )
I suppose you can simplify this if you are a mathematician.
If you are a bloody consultant you should have learned these formulas once up on a time.
You can loop through $n of course to make a nice list.
Perl is not that hard to translate to PHP if it is clear what every variable means.In searching php.net, I found a discussion from back in 2000 related to some buggy code. My web search hasn't produced anything other than realtor and mortgage companies and a perl script site. I'm not familiar with perl and would prefer avoiding it until my knowledge improves. There were corrections for a java script somewhere, but I'm beginning to think it is down. Some things seem so obvious that you just don't think you need to bookmark! So why can't I remember...
-- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
