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signal-processingwave

Why sin(0.2*x + pi) is aperiodic function?

I know this might be too easy to be a question... but I can't get why sin(0.2*x + pi) is aperiodic?..

I tried to plot this in matlab and that's what I got:

Matlab sin wave

That should be periodic right? Instead in "Schaum's Outline of Digital Signal Processing" book it says it's aperiodic

Solution of Schaum's Outline book

Solution

  • The function f(x) = sin(pi + 0.2*x) is periodic.

    The sequence sin(pi + 0.2*n) where n=0, 1, ... is not periodic.