Method function

tests/root.rs:43–45

(&self, x: [f64; 1])

impl RootFindingProblem<1, 1, (f64, f64)> for Cubic {
    fn function(&self, x: [f64; 1]) -> Result<[f64; 1]> {
        self.eval(x)
    }
    fn initial_guess(&self) -> (f64, f64) {
        (0.0, 2.0)
    }