avoid division by zero warning for z0=0
@@ -251,7 +251,7 @@ class NetworkTestCase(unittest.TestCase):
nport = rf.Network()
nport.frequency = freq
nport.s = npy.zeros((10, nport_portnum, nport_portnum))
- nport.z0 = npy.arange(nport_portnum)
+ nport.z0 = npy.arange(start=1, stop=nport_portnum + 1)
# Connect the line to each port and check for port impedance
for port in range(nport_portnum):
