Moments of a function

Generates the nth order moment of a function.

Computes the nth moment mean of a function (needs more implentation).

m = moment(x, y, n)

m = nth moment of y
x = domain
y = data
n = nth moment == 1 by default

m = int(x^n * y) / int(y)

where int is integral over all x integral is calculated using trapezium rule