Function numericDerivative

test/compute-engine/derivatives.test.ts:718–719

(f: (x: number) => number, x: number)

      expect(result.toString()).toMatchInlineSnapshot(
        `1/2 * BesselI(n - 1, x) + 1/2 * BesselI(n + 1, x)`
      );
    });
  });

  describe('BesselK (modified second kind)', () => {