Computes a partial moment for the standard normal distribution. This is the
expectation taken not from -Infinity to Infinity but just to z.
Usage
partialMoment_standardNormal(z, n)
Arguments
z
partial moment boundary, the expectation is taken from -Inf to z.
n
which moment to compute, needs to be >= 2.
References
Winkler, R. L., Roodman, G. M., & Britney, R. R. (1972). The
Determination of Partial Moments. Management Science, 19(3), 290–296.
http://www.jstor.org/stable/2629511, equation (2.5)