docs: public static double BiCubicKernel(double x) {
          if (x < 0) {
              x = -x;
          }
  
          double biCoef = 0;
  
          if (x <= 1) {
              biCoef = (1.5 * x - 2.5) * x * x + 1;
          } else if (x < 2) {
              biCoef = ((-0.5 * x + 2.5) * x - 4) * x + 2;
          }
  
          return biCoef;
      }