def test_add_value(self):
"""Values are added not replaced"""
fp1 = FieldPoint(0, 0, 0)
fp1.add(1 + 2j)
self.assertEqual(fp1.real(), 1)
self.assertEqual(fp1.imag(), 2)
self.assertEqual(fp1.abs(), (1**2 + 2 * 2)**0.5)
self.assertEqual(fp1.phase(), math.atan(2))
fp1.add(2 + 2j)
self.assertEqual(fp1.real(), 3)
self.assertEqual(fp1.imag(), 4)
self.assertEqual(fp1.abs(), (3**2 + 4**2)**0.5)
self.assertEqual(fp1.phase(), math.atan(4. / 3.))
def test_phase(self):
"""check phase is 2pi/wavelength"""
s = SourcePoint(0, 0, 0, 1, 0)
frequency = 1
wavelength = speed_of_light / frequency
k = 2 * pi / wavelength
f = FieldPoint(wavelength / 2, 0, 0)
propagate_single(s, f, k)
self.assertEqual(round(f.phase(), 6), 3.141593)
# positive phase expected in negative directions because
# wave travels outward
fnegx = FieldPoint(-wavelength / 2, 0, 0)
propagate_single(s, fnegx, k)
self.assertEqual(round(fnegx.phase(), 6), 3.141593)
f1 = FieldPoint(wavelength, 0, 0)
propagate_single(s, f1, k)
self.assertEqual(round(f1.phase(), 6), 0)