Function asec

src/compute-engine/interval/trigonometric.ts:483–491

(x: Interval | IntervalResult)

}

/**
 * Inverse secant: asec(x) = acos(1/x).
 *
 * Domain: |x| >= 1. Has a singularity at x = 0.
 */
export function asec(x: Interval | IntervalResult): IntervalResult {
  const unwrapped = unwrapOrPropagate(x);
  if (!Array.isArray(unwrapped)) return unwrapped;
  const [xVal] = unwrapped;
  if (containsZero(xVal)) {
    return { kind: 'singular', at: 0 };
  }