Why is a periodic function Time Variant?

[Dorshoshani]

Hey,
I hope you can help me.
I can't understand why periodic function is Time Variant.

thanks
Dor.

 

[Orodruin]

Because it does not take the same value for all times.

 

[CWatters]

The definition of periodic means occurring at intervals of time.

 

[Babadag]

In my opinion, a periodic function is a time variant system if the considered time is in the limits of the periodic time constant.
However, since a different input value produces a same output value if the time difference is a multiple of time constant you may consider a periodic function as a "limited time variant”.