Function abs

src/compute-engine/interval/elementary.ts:401–413

(x: Interval | IntervalResult)

 * Absolute value of an interval.
 */
export function abs(x: Interval | IntervalResult): IntervalResult {
  const unwrapped = unwrapOrPropagate(x);
  if (!Array.isArray(unwrapped)) return unwrapped;
  const [xVal] = unwrapped;
  if (xVal.lo >= 0) {
    return ok(xVal);
  }
  if (xVal.hi <= 0) {
    return ok({ lo: -xVal.hi, hi: -xVal.lo });
  }
  // Interval straddles zero - minimum is 0
  return ok({ lo: 0, hi: Math.max(-xVal.lo, xVal.hi) });
}

/**
 * Floor function (greatest integer <= x).