def test_fun():
assert (FiniteSet(
*ImageSet(Lambda(x, sin(pi * x / 4)), Range(-10, 11))) == FiniteSet(
-1, -sqrt(2) / 2, 0,
sqrt(2) / 2, 1))
def test_infinitely_indexed_diophantine():
assert (imageset(Lambda(m, 2 * pi * m), S.Integers).intersection(
imageset(Lambda(n, 3 * pi * n),
S.Integers)) == ImageSet(Lambda(t, 6 * pi * t), S.Integers))
def test_ImageSet_iterator_not_injetive():
L = Lambda(x, x - x % 2) # produces 0, 2, 2, 4, 4, 6, 6, ...
evens = ImageSet(L, S.Naturals)
i = iter(evens)
# No repeats here
assert (next(i), next(i), next(i), next(i)) == (0, 2, 4, 6)