pub fn new<T: Into<f64> + Copy>(x: T, dx: T) -> Dual {
        Dual {
            x: x.into(),
            dx: dx.into(),
        }
    }
Syntactic sugar to declare dual

# Type
`(T, T) -> Dual where T: Into<f64> + Copy`

# Examples
```
extern crate peroxide;
use peroxide::fuga::*;

let a = Dual::new(2, 1); // y = x at x = 2
a.print();
```
src/grave/dual.rs