Function acosh

src/compute-engine/interval/trigonometric.ts:398–415

(x: Interval | IntervalResult)

}

/**
 * Inverse hyperbolic cosine.
 *
 * Domain: [1, +Infinity)
 */
export function acosh(x: Interval | IntervalResult): IntervalResult {
  const unwrapped = unwrapOrPropagate(x);
  if (!Array.isArray(unwrapped)) return unwrapped;
  const [xVal] = unwrapped;
  if (xVal.hi < 1) {
    return { kind: 'empty' };
  }

  if (xVal.lo < 1) {
    return {
      kind: 'partial',
      value: { lo: 0, hi: Math.acosh(xVal.hi) },
      domainClipped: 'lo',
    };
  }