SummationByParts/sbp/src/operators/traditional8.rs

use super::SbpOperator;
use crate::Float;
use ndarray::{ArrayView1, ArrayViewMut1};

#[derive(Debug)]
pub struct SBP8 {}

impl SBP8 {
    #[rustfmt::skip]
    const HBLOCK: &'static [Float] = &[
        2.94890676177879e-01, 1.52572062389771e+00, 2.57452876984127e-01, 1.79811370149912e+00, 4.12708057760141e-01, 1.27848462301587e+00, 9.23295579805997e-01, 1.00933386085916e+00
    ];
    #[rustfmt::skip]
    const DIAG: &'static [Float] = &[
        3.57142857142857e-03, -3.80952380952381e-02, 2.00000000000000e-01, -8.00000000000000e-01, -0.00000000000000e+00, 8.00000000000000e-01, -2.00000000000000e-01, 3.80952380952381e-02, -3.57142857142857e-03
    ];
    #[rustfmt::skip]
    const BLOCK: &'static [[Float; 12]] = &[
        [-1.69554360443190e+00, 2.24741246341404e+00, -3.38931922601500e-02, -7.81028168126749e-01, 2.54881486107905e-02, 3.43865227388873e-01, -8.62858162633335e-02, -2.00150583315761e-02, 0.00000000000000e+00, 0.00000000000000e+00, 0.00000000000000e+00, 0.00000000000000e+00],
        [-4.34378988266985e-01, 0.00000000000000e+00, 9.18511925072956e-02, 4.94008626807984e-01, -2.46151762937235e-02, -1.86759403432935e-01, 5.27267838475813e-02, 7.16696483080115e-03, 0.00000000000000e+00, 0.00000000000000e+00, 0.00000000000000e+00, 0.00000000000000e+00],
        [3.88218088704253e-02, -5.44329744454984e-01, 0.00000000000000e+00, 3.89516189693211e-01, 1.36433486528546e-01, 1.03290582800845e-01, -1.79720579323281e-01, 5.59882558852296e-02, 0.00000000000000e+00, 0.00000000000000e+00, 0.00000000000000e+00, 0.00000000000000e+00],
        [1.28088632226564e-01, -4.19172130036008e-01, -5.57707021445779e-02, 0.00000000000000e+00, 1.24714160903055e-01, 2.81285212519100e-01, -3.94470423942641e-02, -1.96981310738430e-02, 0.00000000000000e+00, 0.00000000000000e+00, 0.00000000000000e+00, 0.00000000000000e+00],
        [-1.82119472519009e-02, 9.09986646154550e-02, -8.51090570277506e-02, -5.43362886365301e-01, 0.00000000000000e+00, 6.37392455438558e-01, -1.02950081118829e-01, 2.98964956216039e-02, -8.65364391190110e-03, 0.00000000000000e+00, 0.00000000000000e+00, 0.00000000000000e+00],
        [-7.93147196245203e-02, 2.22875323171502e-01, -2.07999824391436e-02, -3.95611167748401e-01, -2.05756876210586e-01, 0.00000000000000e+00, 5.45876519966127e-01, -9.42727926638298e-02, 2.97971812952850e-02, -2.79348574643297e-03, 0.00000000000000e+00, 0.00000000000000e+00],
        [2.75587615266177e-02, -8.71295642560637e-02, 5.01135077563584e-02, 7.68229253600969e-02, 4.60181213406519e-02, -7.55873581663580e-01, 0.00000000000000e+00, 8.21713248844682e-01, -2.16615355227872e-01, 4.12600676624518e-02, -3.86813134335486e-03, 0.00000000000000e+00],
        [5.84767272160451e-03, -1.08336661209337e-02, -1.42810403117803e-02, 3.50919361287023e-02, -1.22244235731112e-02, 1.19411743193552e-01, -7.51668243727123e-01, 0.00000000000000e+00, 7.92601963555477e-01, -1.98150490888869e-01, 3.77429506454989e-02, -3.53840162301552e-03],
    ];
}

impl SbpOperator for SBP8 {
    fn diff1d(prev: ArrayView1<Float>, fut: ArrayViewMut1<Float>) {
        super::diff_op_1d(
            ndarray::arr2(Self::BLOCK).view(),
            ndarray::arr1(Self::DIAG).view(),
            false,
            prev,
            fut,
        )
    }

    fn h() -> &'static [Float] {
        Self::HBLOCK
    }
}

#[test]
fn test_trad8() {
    use super::testing::*;
    let nx = 32;
    let ny = 16;

    // Order one polynomial
    check_operator_on::<SBP8, _, _, _>(
        (ny, nx),
        |x, y| x + 2.0 * y,
        |_x, _y| 1.0,
        |_x, _y| 2.0,
        1e-4,
    );

    // Order two polynomial
    check_operator_on::<SBP8, _, _, _>(
        (ny, nx),
        |x, y| x * x + 0.5 * y * y,
        |x, _y| 2.0 * x,
        |_x, y| y,
        1e-4,
    );
    check_operator_on::<SBP8, _, _, _>((ny, nx), |x, y| x * y, |_x, y| y, |x, _y| x, 1e-4);

    // Order three polynomials
    check_operator_on::<SBP8, _, _, _>(
        (ny, nx),
        |x, y| x * x * x + y * y * y / 6.0,
        |x, _y| 3.0 * x * x,
        |_x, y| y * y / 2.0,
        1e-4,
    );
    check_operator_on::<SBP8, _, _, _>(
        (ny, nx),
        |x, y| x * x * y + x * y * y / 2.0,
        |x, y| 2.0 * x * y + y * y / 2.0,
        |x, y| x * x + x * y,
        1e-4,
    );
    check_operator_on::<SBP8, _, _, _>(
        (ny, nx),
        |x, y| x.powi(3) + 2.0 * x.powi(2) * y + 3.0 * x * y.powi(2) + 4.0 * y.powi(3),
        |x, y| 3.0 * x.powi(2) + 4.0 * x * y + 3.0 * y.powi(2),
        |x, y| 2.0 * x.powi(2) + 6.0 * x * y + 12.0 * y.powi(2),
        1e-4,
    );

    // Order four polynomials
    check_operator_on::<SBP8, _, _, _>(
        (ny, nx),
        |x, y| x.powi(4) + x.powi(3) * y + x.powi(2) * y.powi(2) + x * y.powi(3) + y.powi(4),
        |x, y| 4.0 * x.powi(3) + 3.0 * x.powi(2) * y + 2.0 * x * y.powi(2) + y.powi(3),
        |x, y| x.powi(3) + 2.0 * x.powi(2) * y + 3.0 * x * y.powi(2) + 4.0 * y.powi(3),
        1e-4,
    );
}