Function u_tp 

pub fn u_tp(t: f64, p: f64) -> Result<f64, IAPWSError>

Calculates the water internal energy in kJ/kg at a given temperature and pressure.

Temperature is assumed to be in K Pressure is assumed to be in Pa

Example

use rust_steam::{u_tp};
let u = u_tp(300.0, 101325.0).unwrap();