Yoni Rozenshein
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 Jan 19 awarded Nice Answer Oct 10 awarded Inquisitive Jul 27 awarded Yearling May 18 awarded Good Question May 9 comment Why are nodes and nodal sets called this way? My native language is Hebrew. What do you mean by that they "look like nodes"? What does a node look like? May 6 comment Why are nodes and nodal sets called this way? Why the downvote? May 2 revised Why are nodes and nodal sets called this way? added 47 characters in body; edited tags Apr 30 asked Why are nodes and nodal sets called this way? Apr 28 comment Prove that $371\cdots 1$ is not prime @HyoyoungJung, if $37\underbrace{1\cdots1}_{n}$ is divisible by one of the primes then so is $37\underbrace{1\cdots1}_{n}000000$, thus so is $37\underbrace{1\cdots1}_{n}111111=37\underbrace{1\cdots1}_{n+6}$, because the difference $111111$ is divisible by all of them. Apr 24 awarded Nice Answer Apr 23 answered A problem that I'm not sure whether to use Weierstrass Approximation Theorem Apr 22 accepted Haar's theorem for the rotation-invariant distribution on the sphere Apr 22 answered Haar's theorem for the rotation-invariant distribution on the sphere Apr 13 comment Haar's theorem for the rotation-invariant distribution on the sphere Thanks for your comment @user24142, you are right. In fact, the Lebesgue measure on $\mathbb R^n$ splits to $\mu \times$ (a measure on $\mathbb R$ with density $r^{n-2}$) or something like that. Apr 13 comment Haar's theorem for the rotation-invariant distribution on the sphere Oh, I like this approach, but I don't understand something. Clearly $\mu \times m$ is invariant under orthogonal transformations. Why is it invariant under translations? Apr 7 comment Haar's theorem for the rotation-invariant distribution on the sphere Thanks for the answer, but I am looking for something more elementary, i.e. without Lie theory or the general theory of compact groups, just this case of the sphere and orthogonal-matrix-invariance. Preferably in a book that I can just quote as in "it is a well-known fact that the Lebesgue measure is the unique rotation-invariant measure on the sphere [1]" :) Apr 6 awarded Good Answer Apr 6 answered Stuck on crucial step while computing $\int_{- \infty}^{\infty} e^{-t^2}dt$ Apr 6 comment Stuck on crucial step while computing $\int_{- \infty}^{\infty} e^{-t^2}dt$ It's not a dirty trick, it's one of the most beautiful computations in mathematics :) Mar 14 comment A functional equation: $4f(x)^3 +f(3x)=3f(x)$ Certainly there are more functions. For instance, $0$ on the rationals and $1/\sqrt 2$ on the irrationals.