bquadpy/src/quadpy/c2/_albrecht_collatz.py at ncube-adaptive · Brishen/bquadpy · GitHub

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from sympy import Rational as frac
from sympy import sqrt

from ..helpers import article
from ._helpers import C2Scheme, register

source = article(
    authors=["J. Albrecht", "L. Collatz"],
    title="Zur numerischen Auswertung mehrdimensionaler Integrale",
    journal="ZAMM",
    volume="38",
    number="1-2",
    year="1958",
    pages="1–15",
    url="https://doi.org/10.1002/zamm.19580380102",
)


def albrecht_collatz_1():
    d = {
        "zero2": [[frac(5, 12)]],
        "d4_a0": [[frac(1, 8)], [1]],
        "d4_aa": [[frac(1, 48)], [1]],
    }
    return C2Scheme("Albrecht-Collatz 1", d, 3, source, 4.442e-16)


def albrecht_collatz_2():
    r = sqrt(frac(3, 5))
    s = sqrt(frac(1, 3))
    t = sqrt(frac(14, 15))
    d = {
        "zero2": [[frac(2, 7)]],
        "c2": [[frac(5, 63)], [0], [t]],
        "sxy": [[frac(5, 36)], [r], [s]],
    }
    return C2Scheme("Albrecht-Collatz 2", d, 5, source, 4.627e-16)


def albrecht_collatz_3():
    r = sqrt(frac(7, 15))
    s, t = (sqrt((7 + i * sqrt(24)) / 15) for i in [+1, -1])
    d = {
        "zero2": [[frac(2, 7)]],
        "c2": [[frac(25, 168), frac(5, 48), frac(5, 48)], [r, s, t], [r, -t, -s]],
    }
    return C2Scheme("Albrecht-Collatz 3", d, 5, source, 4.442e-16)


def albrecht_collatz_4():
    d = {
        "zero2": [[frac(2, 45)]],
        "d4_a0": [[frac(2, 45)], [1]],
        "d4_aa": [[frac(1, 60), frac(8, 45)], [1, frac(1, 2)]],
    }
    return C2Scheme("Albrecht-Collatz 4", d, 5, source, 8.883e-16)


register(
    [albrecht_collatz_1, albrecht_collatz_2, albrecht_collatz_3, albrecht_collatz_4]
)