Calculate mixed-trigonometric-polynomial moment of random variables

reference method: Moment-Based Exact Uncertainty Propagation Through Nonlinear Stochastic Autonomous Systems

The distributions of the random variables are normal, uniform, and exponential.

[dependencies]
tri_poly_moment = "0.1.0"

Example

if calculate moment of Gaussian distribusions

use tri_poly_moment::Gaussian;
let arg = Gaussian::new(-2.1, 0.4 * 0.4);
arg.x(); //if calc E[x], arg.x() = -2.1