Reputation
3,788
Next privilege 5,000 Rep.
Approve tag wiki edits
Badges
2 24 52
Newest
 Good Answer
Impact
~395k people reached

Oct
13
comment Questions concerning convergence rate of Iterated Projections
Added the oc tag as per @StefanKohl's request.
Oct
13
revised Questions concerning convergence rate of Iterated Projections
edited tags
Oct
7
revised A question on unconditionally $p$-summable sequences
Improved formatting
Oct
1
comment Proposals for polymath projects
Sounds interesting. The Wikipedia article for the Worm problem lists known upper and lower bounds for the area as 0.260437 and 0.232239, respectively. Do you hope for tighter bounds, an explicit solution for the area or even the shape?
Sep
29
awarded  Yearling
Sep
25
reviewed Leave Open Mochizuki's “phenomena in number theory” outside the scope of Langlands
Sep
24
comment SVD vs Fourier analysis for data.
@PaulSiegel I guess the OP has in mind that the discrete Fourier transform transforms discrete "spatial" data to discrete "frequency" data. I would say that the SVD decomposes every matrix $A$ as $U^TDV$ with a diagonal $D$ and orthonormal $U$ and $V$ while the diagonal Fourier transform $F$ is also orthonormal and gives $C = F^HDF$ with diagonal $D$ for circulant matrices $C$.
Sep
23
comment In which sense Daubechies wavelets converge to the Shannon wavelet?
Well, after your edit, 2 can well be. It would be good to make edits in a way that comments and answers (if there are any) still make sense…
Sep
22
comment In which sense Daubechies wavelets converge to the Shannon wavelet?
Interesting - do you have a reference for the claim? Well 2. can not hold, since the Fourier transform of the Shannon wavelet is discontinuous while the transforms of the Daubechies wavelet are continuous (if I remember correctly).
Sep
22
comment Fréchet differentiability of functional defined by a integral
I'm doing my thesis on optimal control so I'm trying to avoid advanced math. Sounds like a not-so-good plan...
Sep
21
reviewed Leave Open Spaces $C^\infty(\mathbb T^n\times \mathbb R^n)$, $C^\infty_0(\mathbb T^n\times \mathbb R^n)$ and $\mathscr{S}(\mathbb T^n\times \mathbb R^n)$?
Sep
21
reviewed Close Unbounded operator
Sep
14
awarded  Electorate
Sep
3
comment What are your favorite instructional counterexamples?
@columbus8myhw The support is the closure of the set where the function is not zero.
Sep
1
reviewed Leave Open Non-standard numbers and exponential form of Zeta function
Sep
1
reviewed Leave Open Solutions of an nonlinear evolution problem
Aug
29
comment Convergence of Fixed-Point Iteration of a dependent map
Have you looked at the properties of the corresponding iteration the product space?
Aug
24
comment Hyperfunctions supported at a point
Ha! Page 5 is not available in google books for me, this explains my ignorance…
Aug
24
comment Hyperfunctions supported at a point
I don't know much about hyperfunctions but I am not sure what "coincide" should mean here. A distribution is an element in the dual of smooth functions with compact support while a hyperfunction is an equivalence class of holomorphic functionals. I do not see a canonical way to map one set into the other… E.g. how should a hyperfunction act on a smooth function and how to make such an identification that respects all wanted rules (such as the rules for the derivative…)?
Aug
22
comment Construct a PDE solution from a net of approximations
@AlexM. I guess that your limit is something like "largest set in the partition goes to zero". Why not pick sequences of such converging partitions and show that limits are independent of the subsequences?