How to Apply Limit in FFT

[shazz]

Dear All ;
Am having a problem in applying limit to a singal how can i do that ,

Es=AsCos(wt+pi) limit [0,T] or [-inf , Inf]
In my following code i have not applied limits cause i don't know how to apply limits using fft.
%code.......................
n=100;
n=0:n;
nodd=2*n+1 % to generate odd numbers
w=2*pi*1.93*10^14;
pi=180; %say [if i vary Pi 0:360 it generates matrix miss match]
t=(n*pi)/(2*w); % [ i have not applied limits in the above equation]
A=-50:50; % size(A)=[ 1 101] " to adjust matrix mismatch
%i have not applied limits in the equation
%is it right to take the fft of amplitude (A)
X=A.*cos((w*t)+pi);% element wise mulitpication [size(X)=[1,101]
Y=real(fft(X))
plot(A,t) %% how i will plot the graph

Regards
%am really thank ful to you.

[aya2002]

Hi friend.

I do not know what you want but as i see here in your program that you defined the word pi and this is wrong in matlab where pi alrady defined in matlab as 3.14159..... and if you need it in degrees you must multiply by 180 and devide by pi.

thanks