std Normal Second Order Loss Function
Computes the 2nd order loss function for the standard normal distribution function for given value of z, G2(z) = (1/2)Emax(Z-z,0)*max(Z-z-1,0)
Return
The loss function value, (1/2)Emax(Z-z,0)*max(Z-z-1,0)
Parameters
z
The value to be evaluated