Homework 3 Part A

Time Invariant
A system is time invariant if the behavior and characteristics of the system are fixed over time.
For example:
y(t)=sin[x(t)] , is time invariant because if the input is shifted to the right by five and then ran through the system,
The output would be the same as if the shift had occurred after the input is ran through the system.
y(t-5)=sin[x(t-5)


Time variant
A system is time variant if the behavior and characteristics of the system are not fixed over time.
For example:
y(t)=x(2t) Let's say this function will compress y(t) by a factor of 2.
Applying a shift of 2 before the function is ran through the system ( y(t)=x(t-2) )
will result in a different graph then if the function is shifted after it is put through the system.

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Prof. Math. Ohio State and Associate Dean
Outstanding Alumnus Purdue Math 2008

Jeff McNeal