Function center

external/.d3.js:64–67

(a, x, lo = 0, hi = a.length)

  }

  function center(a, x, lo = 0, hi = a.length) {
    const i = left(a, x, lo, hi - 1);
    return i > lo && delta(a[i - 1], x) > -delta(a[i], x) ? i - 1 : i;
  }

  return {left, center, right};
}