code: public static function FISHERINV($value)
      {
          $value = Functions::flattenSingleValue($value);
  
          if (is_numeric($value)) {
              return (exp(2 * $value) - 1) / (exp(2 * $value) + 1);
          }
  
          return Functions::VALUE();
      }
docs: FISHERINV.
  
  Returns the inverse of the Fisher transformation. Use this transformation when
  analyzing correlations between ranges or arrays of data. If y = FISHER(x), then
  FISHERINV(y) = x.
  
  @param float $value
  
  @return float