Michael Renardy
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Registered User
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2d |
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Is a free alternative to MathSciNet possible? Scraping titles and abstracts is no problem, the web site doing that already exists! It is called Google. The "user-base of open-source reviewers" may be a bit trickier. Why should I spend my time reviewing for some upstart web site which lacks the tradition and reputation of the established review journals? |
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Jun 11 |
answered | Integrating the complete elliptic integral K |
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Jun 7 |
accepted | System of quadratic equations with 18 unknown |
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Jun 7 |
answered | System of quadratic equations with 18 unknown |
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Jun 6 |
accepted | I have this linear PDE… |
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Jun 4 |
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Please recommend some literature on the systematical theory of the elliptic systems! The original papers of Agmon, Douglis and Nirenberg are a good place to start. |
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May 30 |
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Boys and Girls Revisited Well, it does not have to be the blue-eyed islanders. Maybe it will come back as the surprise test. |
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May 30 |
answered | I have this linear PDE… |
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May 27 |
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Estimates for Green’s function On a compact manifold, how is a bound other than near the singularity an issue? Am I missing something here? |
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May 23 |
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Phase transition in dynamical systems This question is much too imprecise for an intelligent answer. For starters, what are P, f and $\phi$? I can sort of guess what $t$ is, but ... Voting to close as "not a real question." |
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May 8 |
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Asymptotics of a function The last term is $n^{-3n}$, which is certainly not dominant! The asymptotics is probably obtainable by comparing with $$\int_0^\infty x^n n^{-4x}\,dx=\frac{n!}{(4\ln n)^n}.$$ |
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May 8 |
answered | Functional equations |
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Apr 26 |
revised |
Is $f$ continuous? removed tag |
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Apr 26 |
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Is $f$ continuous? Why was this tagged special functions? I am going to remove this tag. |
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Apr 25 |
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Volume of a convex set Well, yes, but I thought you were looking for a formula given by an integral in terms of w. |
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Apr 25 |
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Volume of a convex set I see a formula for the perimeter there, not for the area. |
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Apr 24 |
answered | Volume of a convex set |
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Apr 24 |
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Finding Center of Union of Circles From the figure in the link, I am guessing that you want the center of mass of the area common to all the circles. You can always decompose this area into a finite union of polygons and lens-shaped areas which are bounded by a straight line and a circular arc. For each of those parts, you can find the area and center of mass by elementary means. |
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Apr 24 |
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Finding Center of Union of Circles I take back my earlier comment. I think the way the problem is intended, the mass density where the circles overlap is supposed to be 1 rather than adding up the masses of the circles. With that interpretation, the problem does not seem trivial. |
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Apr 24 |
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Finding Center of Union of Circles For one thing, you need to define "center" for something that is not a circle. I presume you mean the center of gravity. Now consider what happens if you concentrate the mass of each circle at its midpoint ... This site is for research level questions. Voting to close. |
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Apr 23 |
answered | Double Integral of plane wave squared over a circular domain |
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Apr 1 |
accepted | Riemann-Lebesgue lemma for measures |
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Mar 26 |
accepted | Choosing boundary conditions for $(\frac{-d^2}{dx^2})^m$ on $H^m((0,1))$? |
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Mar 26 |
answered | Riemann-Lebesgue lemma for measures |
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Mar 21 |
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Finding an optimal $p$ such that $u \in L^p$ The monograph of Lions and Magenes, for instance. |
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Mar 19 |
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Finding an optimal $p$ such that $u \in L^p$ It is supposed to mean $H^{2/3}$ (as a function of x) with values in $L^2$ (as a function of y). |
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Mar 19 |
answered | Finding an optimal $p$ such that $u \in L^p$ |
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Mar 14 |
revised |
Spherical Bessel functions corrected minor error |
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Mar 13 |
accepted | Spherical Bessel functions |
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Mar 12 |
answered | Spherical Bessel functions |
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Feb 25 |
awarded | ● Nice Answer |
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Feb 25 |
answered | weak*-compactness of unit ball in equivalent norm |
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Feb 19 |
accepted | nonnegative Fourier Transform |
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Feb 19 |
revised |
nonnegative Fourier Transform deleted 1 characters in body |
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Feb 19 |
answered | nonnegative Fourier Transform |
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Feb 5 |
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What is the solution of $u_t=u_{xx}+\frac{1}{x}u_x$? The ODE you give can be solved in terms of Bessel functions. But, perhaps more fundamentally, you did not specify boundary conditions for your problem. |
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Feb 5 |
answered | Control of the $C^1$ norm of a diffeomorphism |
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Feb 5 |
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Boundedness of a given boundary value problem. Homework, voting to close. |
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Jan 29 |
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Generator of a generated $C_0$ semigroup. If U is bounded, this is rather obvious. However, if U is unbounded, there is in general an issue of domains. It is easy to come up with example where $U\rho$ is an unbounded operator, but $A(\rho)$ is bounded. Hence the generator of $P_t$ will in general be an extension of $A$. |
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Jan 9 |
awarded | ● Yearling |
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Jan 7 |
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Are All Irrational Elementary Numbers Conjectured to Be Normal? Since it seems to unknown even whether such popular numbers as e or $\sqrt{2}$ are normal, what would be the point of formulating such a conjecture? |
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Jan 7 |
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Looking for higher order Sobolev inequality If you put the $H^2$ norm on the right hand side instead of the $H^1$ norm, this is Ehrling's lemma, which is well known. |
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Jan 6 |
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Who discovered the winding number? No. If you reverse orientation on every successive day, you will have marched around the city seven times. The instructions were to march around the city once on each of days 1-6 and then seven times on the seventh day. |
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Jan 5 |
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Boundary Problem with an Area Constraint In addition to voting to close, I removed the tag "Laplace transforms." |
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Jan 5 |
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Boundary Problem with an Area Constraint removed inappropriate tag |
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Jan 5 |
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Dirac Delta function with a complex argument Functions like $e^{cx}$ are distributions, but not tempered distributions. Hence the theory of the Fourier transform as expounded in most textbooks does not apply to them. The Fourier transforms of distributions are a class of objects known as analytic functionals. An exposition of the theory can be found in Gelfand and Shilov, Generalized Functions. |
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Jan 3 |
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Shortlists and job offers I wonder who publishes short lists of applicants. My department certainly does not, neither before nor after positions are filled. And, of course I cannot speak for our lawyers, but I cannot imagine them embracing the idea. |
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Dec 31 |
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Approximating erf by tanh Not an answer but related: mathapps.net/Holmes/Holmes.pdf |
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Dec 30 |
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The logarithmic fast diffusion equation in one space variable with periodic boundary conditions. Diffusion is fast only for $u\to 0$. In your problem, however, the maximum principle ensures that the solution remains within the range of the initial data. This makes the analysis fairly routine. |
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Dec 23 |
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The origin of sets? This is often referred to as Galileo's paradox. Galilei discusses it in some detail, but it goes back further. The following web site gives references going back as far as Plutarch: earlham.edu/~peters/writing/infinity.htm |
