Pi Function
see math notation, integral, euler's constant
notation PP z
definition given a CC z with z^re > 0,
PP z = $ t[z] -- ee[t] | dd t {@@ . 0}
note the pi function is defined for all
CC zsuch that+NN (.z . 1)(it is not defined for negative integers but is defined for0).the gamma function then is defined as the analytic continuation of this integral function to a meromorphic function that is holomorphic in the whole complex plane except zero and the negative integers, where the function has simple poles --- https://en.wikipedia.org/wiki/Gamma_function
theorem given a NN z,
PP z = 1 | ... z