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Jan 10, 2018 at 11:48 vote accept Dominic Wynter
Jan 10, 2018 at 3:54 history edited Pedro Lauridsen Ribeiro CC BY-SA 3.0
Added explanation
Jan 10, 2018 at 3:43 history edited Pedro Lauridsen Ribeiro CC BY-SA 3.0
obsolete passage removed
Jan 10, 2018 at 3:34 history edited Pedro Lauridsen Ribeiro CC BY-SA 3.0
small rephrasing
Jan 10, 2018 at 3:24 history edited Pedro Lauridsen Ribeiro CC BY-SA 3.0
small rephrasing, added remark
Jan 10, 2018 at 3:18 history edited Pedro Lauridsen Ribeiro CC BY-SA 3.0
small rephrasing
Jan 10, 2018 at 3:12 comment added Pedro Lauridsen Ribeiro I've added the missing discussion on the title's question. Moreover, any $m\in\mathscr{S}′$ yields $T_m$ as a map from $\mathscr{S}$ into $\mathscr{S}′$, since it's just convolution with $\check{m}$ which also belongs to $\mathscr{S}′$. Since $L^\infty\subset\mathscr{S}'$, any Fourier multiplier fits into this picture. In other words, it makes sense to ask whether $T_m$ maps $\mathscr{S}$ into $L^p$ for a given $m\in L^\infty$ and, if that's the case, whether it's bounded in the $L^p$ norm.
Jan 10, 2018 at 2:57 history edited Pedro Lauridsen Ribeiro CC BY-SA 3.0
Grammar fix, incomplete sentence amended
Jan 10, 2018 at 2:39 history edited Pedro Lauridsen Ribeiro CC BY-SA 3.0
Added previously missing discussion on title's question
Jan 10, 2018 at 2:34 comment added Dominic Wynter Actually, I’ve found a potential issue in your answer — $m$ need not be smooth, according to the Mikhlin Multiplier Theorem. Therefore an upper bound on the order is in fact required to do what you’re suggesting.
Jan 10, 2018 at 2:26 comment added Willie Wong @MonstrousMoonshine: I agree, but you did (unfortunately) use the Mikhlin-Hormander theorem as a motivating example. It may pay to edit the question so that the motivation is somewhat de-emphasized.
Jan 10, 2018 at 0:27 comment added Dominic Wynter That’s a bit besides the point of my question though. I was wondering specifically about just how “rough” the Fourier transform of a bounded function can get.
Jan 9, 2018 at 20:36 history edited Pedro Lauridsen Ribeiro CC BY-SA 3.0
Added explanation
Jan 9, 2018 at 20:25 history answered Pedro Lauridsen Ribeiro CC BY-SA 3.0