[Summary view]

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

   1  <?php
   2  
   3  namespace PhpOffice\PhpSpreadsheet\Calculation\MathTrig;
   4  
   5  use PhpOffice\PhpSpreadsheet\Calculation\Exception;
   6  use PhpOffice\PhpSpreadsheet\Calculation\Functions;
   7  
   8  class SeriesSum
   9  {
  10      /**
  11       * SERIESSUM.
  12       *
  13       * Returns the sum of a power series
  14       *
  15       * @param mixed $x Input value
  16       * @param mixed $n Initial power
  17       * @param mixed $m Step
  18       * @param mixed[] $args An array of coefficients for the Data Series
  19       *
  20       * @return float|string The result, or a string containing an error
  21       */
  22      public static function evaluate($x, $n, $m, ...$args)
  23      {
  24          try {
  25              $x = Helpers::validateNumericNullSubstitution($x, 0);
  26              $n = Helpers::validateNumericNullSubstitution($n, 0);
  27              $m = Helpers::validateNumericNullSubstitution($m, 0);
  28  
  29              // Loop through arguments
  30              $aArgs = Functions::flattenArray($args);
  31              $returnValue = 0;
  32              $i = 0;
  33              foreach ($aArgs as $argx) {
  34                  if ($argx !== null) {
  35                      $arg = Helpers::validateNumericNullSubstitution($argx, 0);
  36                      $returnValue += $arg * $x ** ($n + ($m * $i));
  37                      ++$i;
  38                  }
  39              }
  40          } catch (Exception $e) {
  41              return $e->getMessage();
  42          }
  43  
  44          return $returnValue;
  45      }
  46  }