Skip to content

Instantly share code, notes, and snippets.

@growse
Created January 17, 2019 00:24
Show Gist options
  • Save growse/b075b330b9748f6e9a911d7399bba6a0 to your computer and use it in GitHub Desktop.
Save growse/b075b330b9748f6e9a911d7399bba6a0 to your computer and use it in GitHub Desktop.
#!/usr/bin/env python3
import pytest
def boing(mass_factor):
little_v = 0
big_v = -1
bounces = 0
while not (0 <= little_v < big_v and big_v >= 0):
(little_v, big_v) = bounce(1, little_v, mass_factor, big_v)
bounces += 1
if little_v < 0:
little_v = -1 * little_v
bounces += 1
return bounces
def bounce(m1, v1, m2, v2):
new_v1 = (((m1 - m2) * v1) / (m1 + m2)) + ((2 * m2 * v2) / (m1 + m2))
new_v2 = (((2 * m1) * v1) / (m1 + m2)) + (((m2 - m1) * v2) / (m1 + m2))
return new_v1, new_v2
@pytest.mark.parametrize("m1, v1, m2, v2, expected_v1, expected_v2", [
(1, -1, 1, 0, 0, -1),
(1, 0, 1, -1, -1, 0),
(1, 1, 1, -1, -1, 1)
])
def test_bounce(m1, v1, m2, v2, expected_v1, expected_v2):
assert (expected_v1, expected_v2) == bounce(m1, v1, m2, v2)
@pytest.mark.parametrize("mass_factor,expected", [
(1, 3),
(100, 31),
(10000, 314),
(1000000, 3141),
])
def test_boing(mass_factor, expected):
assert expected == boing(mass_factor)
@pytest.mark.parametrize("num_digits,expected", [
(1, 3),
(2, 31),
(3, 314),
(4, 3141),
])
def test_pi_digits_compute(num_digits, expected):
assert expected == boing(100 ** (num_digits - 1))
if __name__ == "__main__":
import sys
num_digits = int(sys.argv[1])
print(boing(100 ** (num_digits - 1)))
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment