>>> from p2 import g

>>> round(g(0,0,-3.0),2)
-3.3
>>> round(g(0,0,-4.0),2)
-4.0
>>> round(g(1,2,4.0),2)
1.1
>>> round(g(2,1,2.5),2)
2.5
>>> round(g(-2,1,-1.5),2)
0.0
>>> round(g(2,-1,-1.5),2)
0.0
>>> round(g(1.5,2.5,1.3),2)
1.3
>>> round(g(2.5,1.5,10.5),2)
9.5