Public Function NCDF(z as double, m as double, k as double)

Dim gamma as double, lambda as double, t as double
Dim u as double, v as double, value as double
Dim i as integer, j as integer

j = 20
gamma = Exp(Application.GammaLn(1+m/2))
lambda = k/2
t = (1/gamma)*(z/2)^(m/2)*Exp(-m/2)
u = Exp(-lambda)
v = u
Value = v*t
For i = 1 to j
	t = t * z/(m+2*i)
	u = u * lambda/i
	v = v + u
	value = value + v*t
Next i
NCDF = 1 - value

End Function