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Differences Between: [Versions 400 and 401] [Versions 400 and 402] [Versions 400 and 403]

   1  <?php
   2  
   3  namespace PhpOffice\PhpSpreadsheet\Calculation\Financial\CashFlow\Variable;
   4  
   5  use PhpOffice\PhpSpreadsheet\Calculation\Functions;
   6  
   7  class Periodic
   8  {
   9      const FINANCIAL_MAX_ITERATIONS = 128;
  10  
  11      const FINANCIAL_PRECISION = 1.0e-08;
  12  
  13      /**
  14       * IRR.
  15       *
  16       * Returns the internal rate of return for a series of cash flows represented by the numbers in values.
  17       * These cash flows do not have to be even, as they would be for an annuity. However, the cash flows must occur
  18       * at regular intervals, such as monthly or annually. The internal rate of return is the interest rate received
  19       * for an investment consisting of payments (negative values) and income (positive values) that occur at regular
  20       * periods.
  21       *
  22       * Excel Function:
  23       *        IRR(values[,guess])
  24       *
  25       * @param mixed $values An array or a reference to cells that contain numbers for which you want
  26       *                                    to calculate the internal rate of return.
  27       *                                Values must contain at least one positive value and one negative value to
  28       *                                    calculate the internal rate of return.
  29       * @param mixed $guess A number that you guess is close to the result of IRR
  30       *
  31       * @return float|string
  32       */
  33      public static function rate($values, $guess = 0.1)
  34      {
  35          if (!is_array($values)) {
  36              return Functions::VALUE();
  37          }
  38          $values = Functions::flattenArray($values);
  39          $guess = Functions::flattenSingleValue($guess);
  40  
  41          // create an initial range, with a root somewhere between 0 and guess
  42          $x1 = 0.0;
  43          $x2 = $guess;
  44          $f1 = self::presentValue($x1, $values);
  45          $f2 = self::presentValue($x2, $values);
  46          for ($i = 0; $i < self::FINANCIAL_MAX_ITERATIONS; ++$i) {
  47              if (($f1 * $f2) < 0.0) {
  48                  break;
  49              }
  50              if (abs($f1) < abs($f2)) {
  51                  $f1 = self::presentValue($x1 += 1.6 * ($x1 - $x2), $values);
  52              } else {
  53                  $f2 = self::presentValue($x2 += 1.6 * ($x2 - $x1), $values);
  54              }
  55          }
  56          if (($f1 * $f2) > 0.0) {
  57              return Functions::VALUE();
  58          }
  59  
  60          $f = self::presentValue($x1, $values);
  61          if ($f < 0.0) {
  62              $rtb = $x1;
  63              $dx = $x2 - $x1;
  64          } else {
  65              $rtb = $x2;
  66              $dx = $x1 - $x2;
  67          }
  68  
  69          for ($i = 0; $i < self::FINANCIAL_MAX_ITERATIONS; ++$i) {
  70              $dx *= 0.5;
  71              $x_mid = $rtb + $dx;
  72              $f_mid = self::presentValue($x_mid, $values);
  73              if ($f_mid <= 0.0) {
  74                  $rtb = $x_mid;
  75              }
  76              if ((abs($f_mid) < self::FINANCIAL_PRECISION) || (abs($dx) < self::FINANCIAL_PRECISION)) {
  77                  return $x_mid;
  78              }
  79          }
  80  
  81          return Functions::VALUE();
  82      }
  83  
  84      /**
  85       * MIRR.
  86       *
  87       * Returns the modified internal rate of return for a series of periodic cash flows. MIRR considers both
  88       *        the cost of the investment and the interest received on reinvestment of cash.
  89       *
  90       * Excel Function:
  91       *        MIRR(values,finance_rate, reinvestment_rate)
  92       *
  93       * @param mixed $values An array or a reference to cells that contain a series of payments and
  94       *                         income occurring at regular intervals.
  95       *                      Payments are negative value, income is positive values.
  96       * @param mixed $financeRate The interest rate you pay on the money used in the cash flows
  97       * @param mixed $reinvestmentRate The interest rate you receive on the cash flows as you reinvest them
  98       *
  99       * @return float|string Result, or a string containing an error
 100       */
 101      public static function modifiedRate($values, $financeRate, $reinvestmentRate)
 102      {
 103          if (!is_array($values)) {
 104              return Functions::VALUE();
 105          }
 106          $values = Functions::flattenArray($values);
 107          $financeRate = Functions::flattenSingleValue($financeRate);
 108          $reinvestmentRate = Functions::flattenSingleValue($reinvestmentRate);
 109          $n = count($values);
 110  
 111          $rr = 1.0 + $reinvestmentRate;
 112          $fr = 1.0 + $financeRate;
 113  
 114          $npvPos = $npvNeg = 0.0;
 115          foreach ($values as $i => $v) {
 116              if ($v >= 0) {
 117                  $npvPos += $v / $rr ** $i;
 118              } else {
 119                  $npvNeg += $v / $fr ** $i;
 120              }
 121          }
 122  
 123          if (($npvNeg === 0.0) || ($npvPos === 0.0) || ($reinvestmentRate <= -1.0)) {
 124              return Functions::VALUE();
 125          }
 126  
 127          $mirr = ((-$npvPos * $rr ** $n)
 128                  / ($npvNeg * ($rr))) ** (1.0 / ($n - 1)) - 1.0;
 129  
 130          return is_finite($mirr) ? $mirr : Functions::VALUE();
 131      }
 132  
 133      /**
 134       * NPV.
 135       *
 136       * Returns the Net Present Value of a cash flow series given a discount rate.
 137       *
 138       * @param mixed $rate
 139       *
 140       * @return float
 141       */
 142      public static function presentValue($rate, ...$args)
 143      {
 144          $returnValue = 0;
 145  
 146          $rate = Functions::flattenSingleValue($rate);
 147          $aArgs = Functions::flattenArray($args);
 148  
 149          // Calculate
 150          $countArgs = count($aArgs);
 151          for ($i = 1; $i <= $countArgs; ++$i) {
 152              // Is it a numeric value?
 153              if (is_numeric($aArgs[$i - 1])) {
 154                  $returnValue += $aArgs[$i - 1] / (1 + $rate) ** $i;
 155              }
 156          }
 157  
 158          return $returnValue;
 159      }
 160  }