def erfcinv(y): return ndtri((2-y)/2.0)/sqrt(2)
def erfcinv(y): return ndtri((2 - y) / 2.0) / sqrt(2)
def erfinv(y): return ndtri((y+1)/2.0)/sqrt(2)
def erfinv(y): return ndtri((y + 1) / 2.0) / sqrt(2)