code: public function variance()
      {
          $float_variance = pow($this->float_sigma, 2);
  
          if ($this->int_precision) {
              return round($float_variance, $this->int_precision);
          }
  
          return $float_variance;
      }
docs: Compute the variance and return the result.
  
  @see NormalDistribution::precision()
  @access public
  @return float