User:Henry kong/Sandbox

From Weierstrass Form:
 * $\displaystyle \frac{1}{\Gamma \left({z}\right)} = z e^{\gamma z} \prod_{n \mathop = 1}^\infty \left[{\left({1 + \frac{z}{n} }\right] e^{-z / n} }\right)$

We can take the reciprocal of the both side and obtain:
 * $\displaystyle \Gamma \left({z}\right) = \frac {e^{-\gamma z}}{z} \prod_{n \mathop = 1}^\infty \frac{e^{\frac{z}{n} }}{1 + \frac{z}{n} }$

Take the derivative of both side:

Divide both side by $\Gamma \left({z} \right)$: