Function _mul

src/compute-engine/interval/arithmetic.ts:63–71

(a: Interval, b: Interval)

 * Used by div() and other operations that need plain interval results.
 */
export function _mul(a: Interval, b: Interval): Interval {
  const products = [
    _prod(a.lo, b.lo),
    _prod(a.lo, b.hi),
    _prod(a.hi, b.lo),
    _prod(a.hi, b.hi),
  ];
  return { lo: Math.min(...products), hi: Math.max(...products) };
}

/**
 * Endpoint product using the interval convention `0 · ±∞ = 0`.