Fourier transform - what integral limits

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
4 replies · 4K views
zezima1
Messages
119
Reaction score
0
Find the Fourier transform of the unit rectangular distribution f(t) = 1 for ltl<1 else 0
Since e-iωt is zero except for t in ]-1;1[ it must be an integral over this interval. But should I take the boundaries as -1 and 1? Because they are not included in the interval where e-iωt is not zero but rather supremum and infimum for it. Would it better to put the limits lim t->1 and lim t->-1?
 
Physics news on Phys.org
umm the Fourier transform is:

-∞f(t)e-iωtdt

But since f(t)=0 for t≥1, t≤-1 you integrate from -1 to 1?
 
zezima1 said:
Find the Fourier transform of the unit rectangular distribution f(t) = 1 for ltl<1 else 0
Since e-iωt is zero except for t in ]-1;1[ it must be an integral over this interval. But should I take the boundaries as -1 and 1? Because they are not included in the interval where e-iωt is not zero but rather supremum and infimum for it. Would it better to put the limits lim t->1 and lim t->-1?
I think you meant f(t) where you wrote e-iωt.

Regarding your question about the limits, it turns out it doesn't matter. You can look up some statement about the uniqueness of Fourier transforms. I think it's something like two functions have the same Fourier transform if they differ over a set of points of measure 0.