function pData::getStandardDeviation

5.x pData.class.php pData::getStandardDeviation($Serie)
1 call to pData::getStandardDeviation()
pData::getCoefficientOfVariation in inc/pchart/pchart/class/pData.class.php

File

inc/pchart/pchart/class/pData.class.php, line 309

Class

pData

Code

function getStandardDeviation($Serie) 
 {
  if (isset($this->Data ["Series"][$Serie])) 
   {
    $Average = $this->getSerieAverage($Serie);
    $SerieData = $this->stripVOID($this->Data ["Series"][$Serie]["Data"]);

    $DeviationSum = 0;
    foreach ($SerieData as $Key => $Value) {
      $DeviationSum = $DeviationSum + ($Value -$Average) * ($Value -$Average);
    };

    $Deviation = sqrt($DeviationSum / count($SerieData));

    return ($Deviation);
  }
  else {
    return (NULL);
  }
}