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/*
    Nyx, blazing fast astrodynamics
    Copyright (C) 2021 Christopher Rabotin <christopher.rabotin@gmail.com>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published
    by the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

use super::RK;

/// `Verner56` is an RK Verner integrator of order 5-6.
///
/// Coefficients taken from [here (PDF)](http://people.math.sfu.ca/~jverner/classify.1992.ps).
pub struct Verner56 {}

impl RK for Verner56 {
    fn order() -> u8 {
        6
    }
    fn stages() -> usize {
        8
    }

    fn a_coeffs() -> &'static [f64] {
        &[
            1.0 / 6.0,
            4.0 / 75.0,
            16.0 / 75.0,
            5.0 / 6.0,
            -8.0 / 3.0,
            5.0 / 2.0,
            -165.0 / 64.0,
            55.0 / 6.0,
            -425.0 / 64.0,
            85.0 / 96.0,
            -8_263.0 / 15_000.0,
            124.0 / 75.0,
            -643.0 / 680.0,
            -81.0 / 250.0,
            2_484.0 / 10_625.0,
            3_501.0 / 1_720.0,
            -300.0 / 43.0,
            297_275.0 / 52_632.0,
            -319.0 / 2_322.0,
            24_068.0 / 84_065.0,
            3_850.0 / 26_703.0,
            12.0 / 5.0,
            -8.0,
            4_015.0 / 612.0,
            -11.0 / 36.0,
            88.0 / 255.0,
            0.0,
            0.0,
        ]
    }
    fn b_coeffs() -> &'static [f64] {
        &[
            3.0 / 40.0,
            0.0,
            875.0 / 2_244.0,
            23.0 / 72.0,
            264.0 / 1_955.0,
            125.0 / 11_592.0,
            43.0 / 616.0,
            0.0,
            13.0 / 160.0,
            0.0,
            2_375.0 / 5_984.0,
            5.0 / 16.0,
            12.0 / 85.0,
            0.0,
            0.0,
            3.0 / 44.0,
        ]
    }
}