Function powi

src/compute-engine/library/statistics.ts:692–693

(ce: ComputeEngine, x: Expression, k: number)

        // numericizes what it returns.
        if (nonRealDatum(xs)) {
          if (hasNonFiniteDatum(xs)) return engine.NaN;
          const m = boxedMean(engine, xs);
          return numericApproximation ? m.N() : m;
        }
        if (!numericApproximation) {