// [[file:../fire.note::*code][code:1]]
#[test]
fn test_fire_opt() {
    use fire::lj::LennardJones;
    use fire::*;
    use vecfx::*;

    // LJ38
    let mut positions = [
    50.27754123,     50.04898929,     50.13164926,
    49.54021264,     50.20208324,     49.33142540,
    50.36795885,     50.91366213,     49.53932153,
    49.71004612,     49.12254218,     50.30950773,
    51.59992702,     50.93225616,     49.75465016,
    49.54096326,     50.01499737,     50.89785480,
    49.27589571,     49.40276757,     51.78288271,
    50.84293978,     51.39416756,     50.37578558,
    50.85011555,     49.18468518,     49.88733738,
    50.48954837,     48.31866393,     50.39752223,
    49.54570033,     50.99619360,     50.39370291,
    50.83198382,     49.97838559,     49.15111253,
    48.68259959,     51.76333286,     50.71665986,
    48.78703201,     50.74137148,     48.70964574,
    50.46846546,     50.64822201,     51.05913458,
    50.32617974,     51.72202742,     51.25600177,
    48.98719425,     48.57072315,     50.86630469,
    49.41532317,     48.01960200,     49.86479222,
    50.33160898,     51.97929717,     49.55667898,
    50.05747126,     48.65423592,     51.34871762,
    49.47506697,     52.40222682,     50.09998700,
    50.08941533,     50.76191893,     48.51033008,
    49.66096522,     52.51096459,     51.72590563,
    49.26806275,     51.61276429,     49.24438196,
    51.33222714,     48.66903395,     51.03264292,
    48.82443599,     48.10619401,     51.83279474,
    49.32661434,     51.45251656,     51.52447147,
    48.60626152,     50.67040668,     51.00622736,
    48.66876297,     50.02851267,     49.95976353,
    48.45421774,     49.58111803,     50.93806524,
    49.23169585,     49.11782673,     49.33972073,
    50.51551634,     47.49882067,     49.67074204,
    50.53443706,     49.65001264,     51.43455000,
    51.64327906,     48.46431354,     49.94896031,
    51.54629763,     49.42747135,     51.83066872,
    49.51504504,     50.47172337,     51.84485663,
    49.10265035,     52.00399992,     52.61150826,
    49.66462610,     47.60012985,     50.93620680];

    let lj = LennardJones::default();

    let fire = fire()
        .with_max_step(0.2)
        .with_max_cycles(4000)
        .with_max_gradient_norm(0.1)
        .with_line_search();

    // alternative interface with user defined monitor
    fire.clone().minimize_alt(
        &mut positions,
        |x, gx| {
            let energy = lj.evaluate(x.as_3d(), gx.as_mut_3d());
            gx.vecscale(-1.0);
            energy
        },
        monitor(|prgr| {
            prgr.report();
            false
        }),
    );

    // iterator interface for fine grained control on the stopping criteria
    let mut ncalls = 0;

    // The return value in closure is a workaround to FnMut's limitation:
    // exclusive mut access
    let steps = fire.minimize_iter(positions.to_vec(), |x: &[f64], out: &mut Output| {
        out.fx = lj.evaluate(x.as_3d(), out.gx.as_mut_3d());
        // convert force to gradient
        out.gx.vecscale(-1.0);
        ncalls += 1;
        let gnorm3 = out.gx.as_3d().iter().map(|x| x.vec2norm()).float_max();
        // these values will be avaialbe in iterator interface
        Ok((ncalls, gnorm3))
    });

    for (x, i) in steps.take(500).zip(1..) {
        // unpack temp data, so we call access `ncall` now
        let (ncalls, gnorm3) = x.extra;
        println!(
            "niter = {:5}, fx = {:-10.4}, gnorm = {:-10.4}, ncalls = {}",
            i, x.fx, x.gnorm, ncalls
        );
        dbg!(gnorm3);

        if x.gnorm <= 0.1 {
            break;
        }
    }
}
// code:1 ends here