Calc Biweeklypayment.php:
<?php
// Mortgage Calculators Plus
// ------------------------------------------------------------------------
// Copyright (c) 2005, MortgageCalculatorsPlus.com
// ------------------------------------------------------------------------
// This file is part of "Mortgage Calculators Plus" software
// ------------------------------------------------------------------------
include('includes/overall.inc.php');
$param = get_request_var('param');
if($param){
$param['loan_amount'] = preg_replace('/[^0-9\.]/', '', $param['loan_amount']);
if($param['loan_amount'] < $config['min_loan_amount'] || $param['loan_amount'] > $config['max_loan_amount']) $err['loan_amount'] = true;
if($param['interest_rate'] < $config['min_interest_rate'] || $param['interest_rate'] > $config['max_interest_rate']) $err['interest_rate'] = true;
if($param['loan_term'] < $config['min_loan_term'] || $param['loan_term'] > $config['max_loan_term']) $err['loan_term'] = true;
if(!isset($err)){
$mo_periods = $param['loan_term'] * 12;
$mo_balance = $bw_balance = $param['loan_amount'];
$mo_interest = $param['interest_rate'] / 12 / 100;
$mo_payment = $mo_balance * $mo_interest / (1 - pow((1 + $mo_interest), -$mo_periods));
$bw_interest = $param['interest_rate'] / 26 / 100;
$bw_payment = $mo_payment / 2;
$bw_periods = round(-log(1 - $bw_interest * $bw_balance / $bw_payment) / log(1 + $bw_interest));
for($period = 1; $period <= $mo_periods; $period++){
$mo_balance = $mo_balance * (1 + $mo_interest) - $mo_payment;
if($mo_balance < 0) $mo_balance = 0;
if(($period % 12 == 0) || ($period == $mo_periods)){
$year = $param['start_year'] + ceil($period / 12);
$balances[$year]['year'] = $config['month_names'][$param['start_month']].', '.$year;
if($param['download_csv']){
$balances[$year]['mo_balance'] = $mo_balance;
} else {
$balances[$year]['mo_balance'] = $config['currency_symb'].number_format($mo_balance, $config['decimals'], $config['dec_point'], $config['thousands_sep']);
}
}
}
for($period = 1; $period <= $bw_periods; $period++){
$bw_balance = $bw_balance * (1 + $bw_interest) - $bw_payment;
if($bw_balance < 0) $bw_balance = 0;
if(($period % 26 == 0) || ($period == $bw_periods)){
$year = $param['start_year'] + ceil($period / 26);
$balances[$year]['year'] = $config['month_names'][$param['start_month']].', '.$year;
if($param['download_csv']){
$balances[$year]['bw_balance'] = $bw_balance;
} else {
$balances[$year]['bw_balance'] = $config['currency_symb'].number_format($bw_balance, $config['decimals'], $config['dec_point'], $config['thousands_sep']);
}
}
}
if(!$param['calculate']) $smarty->assign('balances', $balances);
$summary['mo_periods'] = $param['loan_term'] * 12;
$summary['mo_payment'] = $param['loan_amount'] * $param['interest_rate'] / 12 / 100 / (1 - pow((1 + $param['interest_rate'] / 12 / 100), -$mo_periods));
$summary['mo_interest'] = $summary['mo_payment'] * $summary['mo_periods'] - $param['loan_amount'];
$summary['mo_end_date'] = get_date($param['start_year'], $param['start_month'] + $summary['mo_periods'] - 1, 'M, Y', $config['month_names']);
$summary['bw_payment'] = $summary['mo_payment'] / 2;
$summary['bw_periods'] = round(-log(1 - $param['interest_rate'] / 26 / 100 * $param['loan_amount'] / $summary['bw_payment']) / log(1 + $param['interest_rate'] / 26 / 100));
$summary['bw_moperiods'] = round(($summary['bw_periods'] / 26) * 12);
$summary['bw_interest'] = $summary['bw_payment'] * $summary['bw_periods'] - $param['loan_amount'];
$summary['bw_end_date'] = get_date($param['start_year'], $param['start_month'] + $summary['bw_moperiods'] - 1, 'M, Y', $config['month_names']);
list($summary['time_saved']['years'], $summary['time_saved']['months']) = get_year_month(0, $mo_periods - $summary['bw_moperiods']);
$summary['interest_saved'] = $summary['mo_interest'] - $summary['bw_interest'];
$summary['mo_payment'] = $config['currency_symb'].number_format($summary['mo_payment'], $config['decimals'], $config['dec_point'], $config['thousands_sep']);
$summary['bw_payment'] = $config['currency_symb'].number_format($summary['bw_payment'], $config['decimals'], $config['dec_point'], $config['thousands_sep']);
$summary['mo_interest'] = $config['currency_symb'].number_format($summary['mo_interest'], $config['decimals'], $config['dec_point'], $config['thousands_sep']);
$summary['bw_interest'] = $config['currency_symb'].number_format($summary['bw_interest'], $config['decimals'], $config['dec_point'], $config['thousands_sep']);
$summary['interest_saved'] = $config['currency_symb'].number_format($summary['interest_saved'], $config['decimals'], $config['dec_point'], $config['thousands_sep']);
$smarty->assign('summary', $summary);
if($param['download_csv']){
header('Content-Type: application/octetstream');
header('Content-Disposition: attachment; filename="biweekly-payments.csv"');
header('Cache-Control: no-store, no-cache, must-revalidate, pre-check=0, post-check=0, max-age=0');
header('Pragma: no-cache');
echo '"Year", "Monthly Payment", "Bi-weekly Payment"'."\n";
foreach($balances as $balance){
if(!$balance['bw_balance']) $balance['bw_balance'] = 0;
echo '"'.$balance['year'].'"'.", $balance[mo_balance], $balance[bw_balance]\n";
}
exit;
}
} else {
$smarty->assign('err', $err);
}
} elseif($config['fill_biweeklypayment']) {
$param['loan_amount'] = $config['loan_amount'];
$param['interest_rate'] = $config['interest_rate'];
$param['loan_term'] = $config['loan_term'];
$param['start_year'] = date('Y');
$param['start_month'] = date('n');
$smarty->assign('param', $param);
}
for($i=$config['min_start_year']; $i<=$config['max_start_year']; $i++) $years[$i] = $i;
$smarty->assign('years', $years);
$smarty->assign('contents', $smarty->fetch('calc-biweeklypayment.tpl'));
$smarty->display('main.tpl');
/* ----- FUNCTIONS ----- */
function get_date($year, $month, $group_by = 'M, Y', $month_names = array(1=>'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec')){
$year = $year + intval($month / 12);
$month = $month % 12;
if(!$month){
$month = 12;
$year -= 1;
}
return str_replace(array('M', 'Y'), array($month_names[$month], $year), $group_by);
}
function get_year_month($year, $month){
$year = $year + intval($month / 12);
$month = $month % 12;
if(!$month){
$month = 12;
$year -= 1;
}
return array($year, $month);
}
?>
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