Python/maths/polynomials/legendre.py
2024-12-04 14:51:02 +01:00

56 lines
1.6 KiB
Python

# Imports de bibliothèques standard
from math import factorial
# Imports de bibliothèques tierces
import pytest
from numpy.polynomial import Polynomial
def legendre(n: int) -> list[float]:
"""
Compute the coefficients of the nth Legendre polynomial.
The Legendre polynomials are solutions to Legendre's differential equation
and are widely used in physics and engineering.
Parameters:
n (int): The order of the Legendre polynomial.
Returns:
list[float]: Coefficients of the polynomial in ascending order of powers.
"""
legendre_polynomial = (1 / (factorial(n) * (2**n))) * (Polynomial([-1, 0, 1]) ** n)
return legendre_polynomial.deriv(n).coef.tolist()
def test_legendre_0() -> None:
"""Test the 0th Legendre polynomial."""
assert legendre(0) == [1.0], "The 0th Legendre polynomial should be [1.0]"
def test_legendre_1() -> None:
"""Test the 1st Legendre polynomial."""
assert legendre(1) == [0.0, 1.0], "The 1st Legendre polynomial should be [0.0, 1.0]"
def test_legendre_2() -> None:
"""Test the 2nd Legendre polynomial."""
assert legendre(2) == [-0.5, 0.0, 1.5]
"The 2nd Legendre polynomial should be [-0.5, 0.0, 1.5]"
def test_legendre_3() -> None:
"""Test the 3rd Legendre polynomial."""
assert legendre(3) == [0.0, -1.5, 0.0, 2.5]
"The 3rd Legendre polynomial should be [0.0, -1.5, 0.0, 2.5]"
def test_legendre_4() -> None:
"""Test the 4th Legendre polynomial."""
assert legendre(4) == pytest.approx([0.375, 0.0, -3.75, 0.0, 4.375])
"The 4th Legendre polynomial should be [0.375, 0.0, -3.75, 0.0, 4.375]"
if __name__ == "__main__":
pytest.main()