30 ) {
$error_message = 'Years must be less than 31.';
// set error message to empty string if no invalid entries
} else {
$error_message = '';
}
// if an error message exists, go to the index page
if ($error_message != '') {
include('eg003_input.php');
exit();
}
//calculate the future value
$future_value = $investment;
for ($i=1; $i<=$years; $i++)
{
//echo "Year $i: ";
$future_value = $future_value + ($future_value * $interest_rate * 0.01);
//echo $future_value;
//echo "
\n";
}
//formula to calculate mortgage loan payment
// M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
// M = monthly payment; P = principal; i= monthly interest rate; N = total number of payments
$N = $years * 12;
$m_i_rate = $interest_rate*0.01 / 12; //monthly rate
$monthly_payment = $investment * ($m_i_rate * pow((1+$m_i_rate), $N)) / ( pow(1+$m_i_rate,$N) -1);
//echo $monthly_payment;
$mortgage_payment = $monthly_payment * $years * 12;
//formatting
$investment_f = '$'.number_format($investment, 2);
$yearly_rate_f = $interest_rate."%";
$future_value_f = '$'.number_format($future_value, 2);
$monthly_payment_f = '$'.number_format($monthly_payment, 2);
$mortgage_payment_f = '$'.number_format($mortgage_payment, 2);
?>
eg003 input debt calculator
Richard's Debt Calculator