fn main() -> Result<(), Box<dyn std::error::Error>> {
    let x_train: Vec<Vec<f64>> = vec![
        vec![0.00],
        vec![0.22],
        vec![0.44],
        vec![0.67],
        vec![0.90],
        vec![0.16],
        vec![0.34],
        vec![0.50],
        vec![0.73],
        vec![1.00],
    ];
    let y_train: Vec<f64> = vec![
        -0.06, 0.97, 0.25, -0.90, -0.53, 0.94, 0.85, 0.09, -0.93, 0.08,
    ];

    let gp_model = friedrich::gaussian_process::GaussianProcess::default(x_train, y_train);

    let x_test: Vec<Vec<f64>> = (-20..=120).map(|i| vec![i as f64 * 0.01]).collect();

    for x in x_test {
        let y_mu = gp_model.predict(&x);
        let y_sigma = gp_model.predict_variance(&x).sqrt();
        println!("{:.2}, {:>12.6}, {:12.6}", x[0], y_mu, y_sigma);
    }

    println!("{:?}", gp_model.kernel);

    Ok(())
}