Snippet Name: Financial management functions
Description: A suite of financial management functions, including present and future value of an annuity and a loan payment calculation function.
Comment: (none)
Language: PHP
Highlight Mode: PHP
Last Modified: March 01st, 2009

<?PHP
/*
VARIABLES:
$m = number of periods per year. For instance, if you are For
instance, if you are making payments monthly then this number is 12.
$n = total number of periods. For instance, if you are
compounding monthly for 5 years, this number would be 60 (12 months
x 5 years).
$R = annual interest rate (represented as a decimal, 8% = .08)
$pmt = first or reoccuring payment or receipt (this number cannot
vary for differing cash flows)
$principal = present value of an annuity, or current principal of a
loan used in the PaymentCalc function
*/
// present value of an Annuity
// uses include defining Remaining Principal of a loan/mortgage
FUNCTION PVannuity ($m,$n,$R,$pmt) {
$Z = 1 / (1 + ($R/$m));
RETURN ($pmt * $Z * (1  POW($Z,$n)))/(1  $Z);
}
// Given the compounding, principal, interest rate, you can calculate
the monthly payment
FUNCTION PaymentCalc ($m,$n,$R,$principal) {
$Z = 1 / (1 + ($R/$m));
RETURN ((1  $Z) * $principal) / ($Z * (1  POW($Z,$n)));
}
// future value of an Annuity
FUNCTION FVannuity ($m,$n,$R,$pmt) {
RETURN $pmt * ((POW((1 + $R/$n),$m)  1)/($R/$n));
}
// present value of a single payment
FUNCTION PVsingle ($m,$n,$R,$pmt) {
RETURN $pmt * POW((1 + $R/$m),$n);
}
// future value of a single payment
FUNCTION FVsingle ($m,$n,$R,$pmt) {
RETURN $pmt * POW((1 + $R/$m),$n);
}
// future value of a single payment with continuous compounding
FUNCTION FVperp ($m,$n,$R,$pmt) {
RETURN $pmt * EXP($R * ($n/$m));
}
?>
