51 lines
1.9 KiB
PHP
51 lines
1.9 KiB
PHP
<?php
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/**
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* Copy of Excel's PMT function.
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* Credit: http://thoughts-of-laszlo.blogspot.nl/2012/08/complete-formula-behind-excels-pmt.html
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*
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* @param double $interest The interest rate for the loan.
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* @param int $num_of_payments The total number of payments for the loan in months.
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* @param double $PV The present value, or the total amount that a series of future payments is worth now;
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* Also known as the principal.
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* @param double $FV The future value, or a cash balance you want to attain after the last payment is made.
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* If fv is omitted, it is assumed to be 0 (zero), that is, the future value of a loan is 0.
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* @param int $Type Optional, defaults to 0. The number 0 (zero) or 1 and indicates when payments are due.
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* 0 = At the end of period
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* 1 = At the beginning of the period
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*
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* @return float
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*/
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function wiaas_PMT($interest, $num_of_payments, $PV, $FV = 0.00, $Type = 0){
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/*$interest = $interest / 12;
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$xp=pow((1+$interest),$num_of_payments);
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return
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($PV* $interest*$xp/($xp-1)+$interest/($xp-1)*$FV)*
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($Type==0 ? 1 : 1/($interest+1));*/
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$rates = [
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24 => 4.282,
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30 => 3.451,
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36 => 2.896,
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42 => 2.500,
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48 => 2.223,
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54 => 2.025,
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60 => 1.834
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];
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$interest = isset($rates[$num_of_payments]) ? $rates[$num_of_payments] : 10;
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return round($PV * ($interest / 100));
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}
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function wiaas_get_recurrent_price_mortage($principal_amount, $pay_period, $margin, $interest_rate) {
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$new_principal_amount = $principal_amount - $margin;
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$interest_rate = $interest_rate / 100;
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$fixed_mortage = wiaas_PMT($interest_rate, $pay_period, $new_principal_amount);
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return round($fixed_mortage, 2);
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}
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function wiaas_get_price_margin($fixed_price, $principal_amount, $total_cost) {
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$total_gain = $fixed_price + $principal_amount;
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return $total_gain - $total_cost;
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} |