HP PPL and Statistical distributions

[Albert Chan]

PPL allowed comparing complex numbers with symbolic inf (not DOM_float inf = 1.0/0)

CAS> inf > 3+4i        → 1
CAS> -inf > 3+4i       → 0
CAS> type(approx(inf))       → DOM_SYMBOLIC

This feature extended quad for complex limits, without changes

CAS> f(z) := (2/√π) *e^(-z*z)
CAS> erf(3+4i)                     → -120.186991395-27.7503372936*i
CAS> quad(f, 0, 3+4i)(1)       → -120.186991395-27.750337294*i
CAS> quad(f, 3+4i, inf)(1)      → 121.186991394+27.7503372904*i = 1 - erf(3+4i)
CAS> quad(f, inf, 3+4i)(1)      → -121.186991394-27.7503372904*i = erf(3+4i) - 1