function invert({a, b, c, d, e, f}) {
  const n = a * d - b * c;
  return {
    a: d / n,
    b: -b / n,
    c: -c / n,
    d: a / n,
    e: (c * f - d * e) / n,
    f: -(a * f - b * e) / n,
  };
}