Hi,

I was asking myself about some necessary and/or sufficient conditions for a function to be bandlimited (i.e. its Fourier transform is zero t residing out of [-B,B] for some B>0).
Of course, if a function is bounded (timelimited), it cannot be bandlimited.
But for a non-bounded function, how can we tell if it's bandlimited or not?
Or, how can we know if a function is both time- and band- unlimited? Any sufficient/necessary conditions.
I'll be glad if you can share with me some known results.

Thanks!