def test_sqrt_scalar(self):
var = Variable(4, -1)
result = var.sqrt()
self.assertAlmostEqual(np.sqrt(4), result.value)
self.assertAlmostEqual((-1 * 0.5) * np.power(4, -0.5),
result.derivative)
def test_sqrt_vector(self):
var = Variable(4, np.array([-1, 7]))
x = Variable(4, np.array([9, 4]))
y = Variable(0.1, np.array([0.5, 0.7]))
equation = x - abs(y)
result = var.sqrt()
equation_result = equation.sqrt()
self.assertAlmostEqual(np.sqrt(4), result.value)
self.assertAlmostEqual(np.sqrt(equation.value), equation_result.value)
np.testing.assert_array_almost_equal(
(var.derivative * 0.5) * np.power(var.value, -0.5),
result.derivative)
np.testing.assert_array_almost_equal(
(equation.derivative * 0.5) * np.power(equation.value, -0.5),
equation_result.derivative)
