Relaxed System Assumption (3)
Homogeneity of Set
c1 = scalar
u1 E of Set
N = operation
N(c1, u1) = c1*N(u1)
Additivity
u1, u2 E of Set
N = operation
N(u1 + u2) = N(u1) + N(u2)
Linear Operator
If superposition is satisfied (homogeneity and additivity) then operation is linear
Time Invariance vs Time Varying
u(t) -> N -> y(t)
time invariance: u(t+T) -> N -> y(t+T)
time varying: u(t+T) -> N -> y(t)
Causality vs Non-Causality
Casuality: depends on past/current values of input
Non-Causality: depends on future values of input (physically impossible)
Instantaneous vs Dynamic
Instantaneous: depends on present
Dynamic: depends on past or future values