sys_mimo = ct.rss(4, 2, 2)

timepts = np.linspace(0, 10, 100)

# Combine two response with ntrace = 0

# Combine two responses with ntrace = 0

U = np.vstack([np.sin(timepts), np.cos(2*timepts)])

resp1 = ct.input_output_response(sys_mimo, timepts, U)

combresp4 = ct.combine_time_responses(

[resp1, resp2, resp3], trace_labels=labels)

assert combresp4.trace_labels == labels

assert combresp4.trace_types == [None, None, 'step', 'step']

# Automatically generated trace label names and types

resp5 = ct.step_response(sys_mimo, timepts)

combresp5 = ct.combine_time_responses([resp1, resp5])

assert combresp5.trace_labels == [resp1.title] + \

["test, trace 0", "test, trace 1"]

assert combresp4.trace_types == [None, None, 'step', 'step']

assert combresp5.trace_types == [None, None, None]

# ntraces = 0 with trace_types != None

# https://github.com/python-control/python-control/issues/1025

resp6 = ct.forced_response(sys_mimo, timepts, U)

combresp6 = ct.combine_time_responses([resp1, resp6])

assert combresp6.trace_types == [None, 'forced']

with pytest.raises(ValueError, match="must have the same number"):

resp = ct.step_response(ct.rss(4, 2, 3), timepts)