Function isDefiniteValue

src/compute-engine/symbolic/limit.ts:847–852

* A resolved, usable limit value: free of the limit variable, and neither * (complex) infinity nor NaN. Crucially this accepts finite *symbolic* * constants (`ln 5`, `π/4`, `e`), whose `.isFinite` is `undefined` because the * engine hasn't numericized them.

(e: Expression, x?: string)

    if (!l) return undefined;
    if (l.isInfinity === true) {
      infinities++;
      if (l.isNegative === true) infinitySign = -infinitySign;
    } else if (isDefiniteValue(l)) {
      result = result.mul(l);
    } else return undefined;
  }
  if (infinities > 0) {
    const s = (result.isNegative === true ? -1 : 1) * infinitySign;
    return s < 0 ? ce.NegativeInfinity : ce.PositiveInfinity;