Function mul

src/compute-engine/interval/arithmetic.ts:93–101

(
  a: Interval | IntervalResult,
  b: Interval | IntervalResult
)

 * If inputs are IntervalResults, propagates errors (empty, entire, singular).
 */
export function mul(
  a: Interval | IntervalResult,
  b: Interval | IntervalResult
): IntervalResult {
  const unwrapped = unwrapOrPropagate(a, b);
  if (!Array.isArray(unwrapped)) return unwrapped;
  const [aVal, bVal] = unwrapped;
  return ok(_mul(aVal, bVal));
}

/**
 * Divide two intervals (or IntervalResults).