fn f(xs: &Vec<AD>) -> Vec<AD> {
    let x = xs[0];
    let y = xs[1];
    vec![x.powi(2) * y, 5f64 * x + y.sin()]
}
Test function

# Function
$$\begin{pmatrix} x^2 y \\\ 5x+ \sin y \end{pmatrix}$$

# Jacobian
$$\begin{pmatrix} 2xy & x^2 \\\ 5 & \cos y \end{pmatrix}$$
tests/jacobian.rs