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Differences Between: [Versions 400 and 401]

   1  <?php
   2  
   3  namespace PhpOffice\PhpSpreadsheet\Calculation\Statistical\Distributions;
   4  
   5  use PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
   6  use PhpOffice\PhpSpreadsheet\Calculation\Exception;
   7  use PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
   8  
   9  class Weibull
  10  {
  11      use ArrayEnabled;
  12  
  13      /**
  14       * WEIBULL.
  15       *
  16       * Returns the Weibull distribution. Use this distribution in reliability
  17       * analysis, such as calculating a device's mean time to failure.
  18       *
  19       * @param mixed $value Float value for the distribution
  20       *                      Or can be an array of values
  21       * @param mixed $alpha Float alpha Parameter
  22       *                      Or can be an array of values
  23       * @param mixed $beta Float beta Parameter
  24       *                      Or can be an array of values
  25       * @param mixed $cumulative Boolean value indicating if we want the cdf (true) or the pdf (false)
  26       *                      Or can be an array of values
  27       *
  28       * @return array|float|string (string if result is an error)
  29       *         If an array of numbers is passed as an argument, then the returned result will also be an array
  30       *            with the same dimensions
  31       */
  32      public static function distribution($value, $alpha, $beta, $cumulative)
  33      {
  34          if (is_array($value) || is_array($alpha) || is_array($beta) || is_array($cumulative)) {
  35              return self::evaluateArrayArguments([self::class, __FUNCTION__], $value, $alpha, $beta, $cumulative);
  36          }
  37  
  38          try {
  39              $value = DistributionValidations::validateFloat($value);
  40              $alpha = DistributionValidations::validateFloat($alpha);
  41              $beta = DistributionValidations::validateFloat($beta);
  42              $cumulative = DistributionValidations::validateBool($cumulative);
  43          } catch (Exception $e) {
  44              return $e->getMessage();
  45          }
  46  
  47          if (($value < 0) || ($alpha <= 0) || ($beta <= 0)) {
  48              return ExcelError::NAN();
  49          }
  50  
  51          if ($cumulative) {
  52              return 1 - exp(0 - ($value / $beta) ** $alpha);
  53          }
  54  
  55          return ($alpha / $beta ** $alpha) * $value ** ($alpha - 1) * exp(0 - ($value / $beta) ** $alpha);
  56      }
  57  }