Ask about ploting X(omega)

Dear members:

Im my matlab homework, I am required to plot the spectrum of
x[n]=(0.8)^|n-10|
Using fomular I calculate

X(omega)=exp(-j*omega*10)*(1-0.8^n)/(1-2*0.8cos(omega)+0.8^2)

Because when I plot X(omega) , Matlab warns me that it neglects some
imaginary numbers/, I am wondering if it makes sense to plot X(omega)
in  matlab or noone does that, they plot abs(X(omega)) and phase of
X(omega) instead.

Thanks

"VijaKhara" <VijaKhara@gmail.com> wrote in message
news:1133564147.461543.239110@g49g2000cwa.googlegroups.com...
> Dear members:
>
> Im my matlab homework, I am required to plot the spectrum of
> x[n]=(0.8)^|n-10|
> Using fomular I calculate
>
> X(omega)=exp(-j*omega*10)*(1-0.8^n)/(1-2*0.8cos(omega)+0.8^2)
>
> Because when I plot X(omega) , Matlab warns me that it neglects some
> imaginary numbers/, I am wondering if it makes sense to plot X(omega)
> in  matlab or noone does that, they plot abs(X(omega)) and phase of
> X(omega) instead.
>
> Thanks
>
Depends if it's the Power spectrum or amplitude spectrum. Eitehr way you
don't plot the complex form.
You plot abs(X)^2 for Power and abd(X) for amplitude.

McC