code: function gamma(number) {
      const p = [0.99999999999980993, 676.5203681218851, -1259.1392167224028,
          771.32342877765313, -176.61502916214059, 12.507343278686905,
          -0.13857109526572012, 9.9843695780195716e-6, 1.5056327351493116e-7
      ];
   
      const g = 7;
      if (number < 0.5) {
          return Math.PI / (Math.sin(Math.PI * number) * gamma(1 - number));
      }
   
      number -= 1;
      var a = p[0];
      const t = number + g + 0.5;
      for (var i = 1; i < p.length; i++) {
          a += p[i] / (number + i);
      }
   
      return Math.sqrt(2 * Math.PI) * Math.pow(t, number + 0.5) * Math.exp(-t) * a;
  }
docs: PRIVATE FUNCTIONS TODO: should the math in the gamma function use the precision module?