how to prove that y=x((cos(t))^2 is not Time Invariant?

"Noway2" <no_spam_me2@hotmail.com> wrote in message
news:1129568878.167024.312380@f14g2000cwb.googlegroups.com...
> Non-meaningfull replies.....
>
>  Well guess what, my "non-meaningfull" reply can be found in just about
> any signal processing book as the definition of how to prove wether or
> not a system is time invarient, which, at the risk of offending you, is
> exactly what you asked for!  Perhaps you should get one.
>
if you put cos(t-t0) instead of cos(t) then you should get y(t-t0) instead
of y(t). If not then the system is not TI.

McC

"novellover" <comtech.usa.1@gmail.com> wrote in message 
news:1129533788.609933.131510@o13g2000cwo.googlegroups.com...
> Please help me! Thanks a lot!
>
prove that y=x((cos(t))^2 is not Time Invariant.

Well .... one might try to help with your question except that one does not 
understand the question:

Is it:
Prove that y = x^2, is not Time Invariant; where x is a function of cos(t).

Or is it:

Prove that y = [x*cos(t)]^2 is not Time Invariant.

Or is it:

Prove that y = x*[cos(t)^2] is not Time Invariant.

Geez!

Fred 

On 17 Oct 2005 09:05:47 -0700, "novellover" <comtech.usa.1@gmail.com>
wrote:

>Ooops, it should be y(t)=x((cos(t))^2),
>
>by the way, I created this problem myself...
>
>So please never ask if it is homework problem.
>
>NEVER!!! Otherwise it would be considered as offending.
>
>My questions are all original.
>
>And also please don't give non-meaningful replies -- like the previous
>two guys did. Thank you very much!

Ha ha ha.

That was a truly extrordinary post!
Truly amazing!

To the guys on this newsgroup:  I warned you 
over and over to avoid in-breeding.
A post like this one is what results from 
such activities.
Ha ha ha.

See Ya',
[-Rick-]