differential-equations 0.5.3

//! IRK with Newton solves and adaptive step size.

mod ordinary;

use crate::{
    methods::{Adaptive, ImplicitRungeKutta},
    tableau::ButcherTableau,
    traits::{Real, State},
};

// Adaptive step constructors
macro_rules! impl_irk_adaptive_step_constructor {
    ($method_name:ident, $order_val:expr, $s_val:expr, $m_val:expr, $doc:expr) => {
        impl<E, T: Real, Y: State<T>>
            ImplicitRungeKutta<E, Adaptive, T, Y, $order_val, $s_val, $m_val>
        {
            #[doc = $doc]
            pub fn $method_name() -> Self {
                let tableau = ButcherTableau::<T, $s_val>::$method_name();
                let c = tableau.c;
                let a = tableau.a;
                let b = tableau.b;
                let bh = tableau.bh;

                ImplicitRungeKutta {
                    c,
                    a,
                    b,
                    bh,
                    order: $order_val,
                    stages: $s_val,
                    dense_stages: $m_val,
                    ..Default::default()
                }
            }
        }
    };
}

// Gauss–Legendre (A-stable, symplectic)
impl_irk_adaptive_step_constructor!(
    gauss_legendre_4,
    4,
    2,
    2,
    "Creates a new Gauss-Legendre 2-stage implicit Runge-Kutta method of order 4."
);
impl_irk_adaptive_step_constructor!(
    gauss_legendre_6,
    6,
    3,
    3,
    "Creates a new Gauss-Legendre 3-stage implicit Runge-Kutta method of order 6."
);

// Lobatto IIIC (L-stable)
impl_irk_adaptive_step_constructor!(
    lobatto_iiic_2,
    2,
    2,
    2,
    "Creates a new Lobatto IIIC 2-stage implicit Runge-Kutta method of order 2."
);
impl_irk_adaptive_step_constructor!(
    lobatto_iiic_4,
    4,
    3,
    3,
    "Creates a new Lobatto IIIC 3-stage implicit Runge-Kutta method of order 4."
);