<?php
namespace PhpOffice\PhpSpreadsheet\Calculation\Financial\CashFlow\Variable;
use PhpOffice\PhpSpreadsheet\Calculation\DateTimeExcel;
use PhpOffice\PhpSpreadsheet\Calculation\Exception;
use PhpOffice\PhpSpreadsheet\Calculation\Functions;
class NonPeriodic
{
const FINANCIAL_MAX_ITERATIONS = 128;
const FINANCIAL_PRECISION = 1.0e-08;
/**
* XIRR.
*
* Returns the internal rate of return for a schedule of cash flows that is not necessarily periodic.
*
* Excel Function:
* =XIRR(values,dates,guess)
*
* @param float[] $values A series of cash flow payments
* The series of values must contain at least one positive value & one negative value
* @param mixed[] $dates A series of payment dates
* The first payment date indicates the beginning of the schedule of payments
* All other dates must be later than this date, but they may occur in any order
* @param float $guess An optional guess at the expected answer
*
* @return float|string
*/
public static function rate($values, $dates, $guess = 0.1)
{
$rslt = self::xirrPart1($values, $dates);
if ($rslt !== '') {
return $rslt;
}
// create an initial range, with a root somewhere between 0 and guess
$guess = Functions::flattenSingleValue($guess);
$x1 = 0.0;
$x2 = $guess ?: 0.1;
$f1 = self::xnpvOrdered($x1, $values, $dates, false);
$f2 = self::xnpvOrdered($x2, $values, $dates, false);
$found = false;
for ($i = 0; $i < self::FINANCIAL_MAX_ITERATIONS; ++$i) {
if (!is_numeric($f1) || !is_numeric($f2)) {
break;
}
$f1 = (float) $f1;
$f2 = (float) $f2;
if (($f1 * $f2) < 0.0) {
$found = true;
break;
} elseif (abs($f1) < abs($f2)) {
$f1 = self::xnpvOrdered($x1 += 1.6 * ($x1 - $x2), $values, $dates, false);
} else {
$f2 = self::xnpvOrdered($x2 += 1.6 * ($x2 - $x1), $values, $dates, false);
}
}
if (!$found) {
return Functions::NAN();
}
return self::xirrPart3($values, $dates, $x1, $x2);
}
/**
* XNPV.
*
* Returns the net present value for a schedule of cash flows that is not necessarily periodic.
* To calculate the net present value for a series of cash flows that is periodic, use the NPV function.
*
* Excel Function:
* =XNPV(rate,values,dates)
*
* @param float $rate the discount rate to apply to the cash flows
* @param float[] $values A series of cash flows that corresponds to a schedule of payments in dates.
* The first payment is optional and corresponds to a cost or payment that occurs
* at the beginning of the investment.
* If the first value is a cost or payment, it must be a negative value.
* All succeeding payments are discounted based on a 365-day year.
* The series of values must contain at least one positive value and one negative value.
* @param mixed[] $dates A schedule of payment dates that corresponds to the cash flow payments.
* The first payment date indicates the beginning of the schedule of payments.
* All other dates must be later than this date, but they may occur in any order.
*
* @return float|string
*/
public static function presentValue($rate, $values, $dates)
{
return self::xnpvOrdered($rate, $values, $dates, true);
}
private static function bothNegAndPos(bool $neg, bool $pos): bool
{
return $neg && $pos;
}
/**
* @param mixed $values
* @param mixed $dates
*/
private static function xirrPart1(&$values, &$dates): string
{
if (!is_array($values) && !is_array($dates)) {
return Functions::NA();
}
$values = Functions::flattenArray($values);
$dates = Functions::flattenArray($dates);
if (count($values) != count($dates)) {
return Functions::NAN();
}
$datesCount = count($dates);
for ($i = 0; $i < $datesCount; ++$i) {
try {
$dates[$i] = DateTimeExcel\Helpers::getDateValue($dates[$i]);
} catch (Exception $e) {
return $e->getMessage();
}
}
return self::xirrPart2($values);
}
private static function xirrPart2(array &$values): string
{
$valCount = count($values);
$foundpos = false;
$foundneg = false;
for ($i = 0; $i < $valCount; ++$i) {
$fld = $values[$i];
if (!is_numeric($fld)) {
return Functions::VALUE();
} elseif ($fld > 0) {
$foundpos = true;
} elseif ($fld < 0) {
$foundneg = true;
}
}
if (!self::bothNegAndPos($foundneg, $foundpos)) {
return Functions::NAN();
}
return '';
}
/**
* @return float|string
*/
private static function xirrPart3(array $values, array $dates, float $x1, float $x2)
{
$f = self::xnpvOrdered($x1, $values, $dates, false);
if ($f < 0.0) {
$rtb = $x1;
$dx = $x2 - $x1;
} else {
$rtb = $x2;
$dx = $x1 - $x2;
}
$rslt = Functions::VALUE();
for ($i = 0; $i < self::FINANCIAL_MAX_ITERATIONS; ++$i) {
$dx *= 0.5;
$x_mid = $rtb + $dx;
$f_mid = (float) self::xnpvOrdered($x_mid, $values, $dates, false);
if ($f_mid <= 0.0) {
$rtb = $x_mid;
}
if ((abs($f_mid) < self::FINANCIAL_PRECISION) || (abs($dx) < self::FINANCIAL_PRECISION)) {
$rslt = $x_mid;
break;
}
}
return $rslt;
}
/**
* @param mixed $rate
* @param mixed $values
* @param mixed $dates
*
* @return float|string
*/
private static function xnpvOrdered($rate, $values, $dates, bool $ordered = true)
{
$rate = Functions::flattenSingleValue($rate);
$values = Functions::flattenArray($values);
$dates = Functions::flattenArray($dates);
$valCount = count($values);
try {
self::validateXnpv($rate, $values, $dates);
$date0 = DateTimeExcel\Helpers::getDateValue($dates[0]);
} catch (Exception $e) {
return $e->getMessage();
}
$xnpv = 0.0;
for ($i = 0; $i < $valCount; ++$i) {
if (!is_numeric($values[$i])) {
return Functions::VALUE();
}
try {
$datei = DateTimeExcel\Helpers::getDateValue($dates[$i]);
} catch (Exception $e) {
return $e->getMessage();
}
if ($date0 > $datei) {
$dif = $ordered ? Functions::NAN() : -((int) DateTimeExcel\Difference::interval($datei, $date0, 'd'));
} else {
$dif = DateTimeExcel\Difference::interval($date0, $datei, 'd');
}
if (!is_numeric($dif)) {
return $dif;
}
$xnpv += $values[$i] / (1 + $rate) ** ($dif / 365);
}
return is_finite($xnpv) ? $xnpv : Functions::VALUE();
}
/**
* @param mixed $rate
*/
private static function validateXnpv($rate, array $values, array $dates): void
{
if (!is_numeric($rate)) {
throw new Exception(Functions::VALUE());
}
$valCount = count($values);
if ($valCount != count($dates)) {
throw new Exception(Functions::NAN());
}
if ($valCount > 1 && ((min($values) > 0) || (max($values) < 0))) {
throw new Exception(Functions::NAN());
}
}
}