def test_var():
f = Forward("x", 0)
assert f.value == approx(0)
assert f.get_gradient("x") == approx(1)
f = Forward("x", -10)
assert f.get_gradient("x") == approx(1)
assert f.get_gradient("y") == approx(0)
def test_multi_dim_var():
f = Forward("x", 0) * Forward("y", 0)
assert f.value == approx(0)
assert f.get_gradient("x") == approx(0)
assert f.get_gradient("y") == approx(0)
f = Forward("x", 2) * Forward("y", -2)
assert f.value == approx(-4)
assert f.get_gradient("x") == approx(-2)
assert f.get_gradient("y") == approx(2)
def test_multiplication():
f = 4 * Forward("x", 1)
assert f.value == approx(4)
assert f.get_gradient("x") == approx(4)
f = Forward("x", 2) * 4
assert f.value == approx(8)
assert f.get_gradient("x") == approx(4)
def test_power():
x = Forward("x", 5)
f = x**5
assert f.value == approx(5**5)
assert f.get_gradient("x") == approx(5 * 5**4)
x = Forward("x", 0)
f = x**5
assert f.value == approx(0)
assert f.get_gradient("x") == approx(0)
f = Forward("x", -5)**2
assert f.value == approx((-5)**2)
assert f.get_gradient("x") == approx(2 * -5)
def test_constant():
f = Forward(1)
assert f.value == approx(1)
assert f.get_gradient("x") == approx(0)
assert f.get_gradient("y") == approx(0)