code: boolean cmppt(float[] a, float[] b) {
          if (a[0] < b[0]) {
              return true;
          }
          if (a[0] > b[0]) {
              return false;
          }
          if (a[2] < b[2]) {
              return true;
          }
          if (a[2] > b[2]) {
              return false;
          }
          return false;
      }
docs: Returns true if 'a' is more lower-left than 'b'.