bio | website | regularize.wordpress.com |
---|---|---|
location | Braunschweig, Germany | |
age | 36 | |
visits | member for | 4 years, 1 month |
seen | yesterday | |
stats | profile views | 1,745 |
Professor at TU Braunschweig.
Area: Inverse problems, regularization theory, applied functional analysis, mathematical image processing.
Oct 21 |
comment |
Integrals involving trigonometric functions and polynomes
I think that this would get a better response if it would come as a question and not a command and also accompanied by some motivation and more background. |
Oct 21 |
comment |
Quantitative stability: Hausdorff distance between subdifferentials
@RobertIsrael Right, it's indeed simple. Well, this simply reflects that uniform convergence does not imply convergence of the derivative (although, in principle convexity could change things but apparently it doesn't). |
Oct 20 |
comment |
Quantitative stability: Hausdorff distance between subdifferentials
Don't know of anything, but have you checked Rockafellar and Wets' "Variational Analysis"? By the way, I suspect that the situation could be different for smooth $f$ and $g$… |
Oct 20 |
awarded | Custodian |
Oct 20 |
reviewed | Leave Closed A metric on $S^{2}$ |
Oct 20 |
answered | Quantitative stability: Hausdorff distance between subdifferentials |
Oct 15 |
comment |
Inverse Function Theorem on Zygmund Spaces, is the inverse in the same Zygmund Space?
What I mean is that you should post the same question here and at math.stackexchange simultaneously. This produces unrelated threads and wasted time of the community, see here. |
Oct 15 |
comment |
Inverse Function Theorem on Zygmund Spaces, is the inverse in the same Zygmund Space?
Please do not cross-post the same question. |
Oct 14 |
answered | Selecting Rays for Simulated Radon Transform |
Oct 14 |
reviewed | Approve suggested edit on Two Equal Series? |
Oct 13 |
comment |
Is this series well known?
Oops, totally missed that $!$… |
Oct 13 |
comment |
Is this series well known?
Well, its only loosely related. Your f is almost the integral of $\sum t^{n^2}$… |
Oct 13 |
comment |
Is this series well known?
Related to (integral of) the theta function $\theta(0,\tau)$, de.wikipedia.org/wiki/Thetafunktion. |
Oct 9 |
comment |
Proofs without words
I find the underlying argument extremely nice but the picture (especially the animated one) does not really work for me without any words. The animation makes me think that is has some meaning that the yellow dots are visited in a certain order. |
Oct 9 |
comment |
Why are the angular differences of these random complex polynomial coefficients almost constant?
Yeah sorry, I still had the question mathoverflow.net/questions/182412/… in mind. For roots in the unit square the effect I see is much smaller but still can be seen (still working with double precision floating points). I still tend to blame the random number generators; but this is far from my field and so this suspicion is not backed up… |
Oct 9 |
answered | Why are the angular differences of these random complex polynomial coefficients almost constant? |
Oct 8 |
comment |
Can one always find sparse solutions to an $\ell^1$-minimization problem?
Question reformulated in terms of the optimality system: $x^*$ is an $\ell^1$-minimal solution if $Ax^*=b$ and there exists $w$ such that $A^T w \in\partial\|x\|_1$. This says: there is no $m$-sparse solution if the range of $A^T$ (which is $m$-dimensional) does not intersect the $m$-dimensional faces of the unit cube. Answers to this question show that for $m\geq n/2$ this can not happen. (Unfortunately, $m$ and $n$ are swapped in the linked question.) |
Oct 8 |
comment |
Why do roots of polynomials tend to have absolute value close to 1?
This is really strange. My experiments with MATLAB (just with double precision floating points) show strange effects even when I calculate the coefficients of a polynomial which has $N$ roots precisely (up to eps) at the roots of unity when $N$ is as small as 100. I obtain a polynomial with very large coefficients for the middle exponents, and comparably small coefficients close $x^0$ and $x^N$. |
Oct 8 |
comment |
Why do roots of polynomials tend to have absolute value close to 1?
I notice that this answer is close in spirit to the one by @tros443. |
Oct 8 |
answered | Why do roots of polynomials tend to have absolute value close to 1? |