4,310 reputation
1825
bio website google.com
location Italy
age 24
visits member for 1 year, 9 months
seen 6 mins ago

I have approximate knowledge of many things.


29m
comment Prove that a intergral over $\mathbb R$ is finite
+1 nice! Who knows why I didn't think of Lebesgue.
32m
comment Prove that a intergral over $\mathbb R$ is finite
@D.Vente Now I see your point! I'm sorry if I didn't understand it :) Yes you are right, I'll try to fix it. Even though the mrf solution is rather elegant
32m
comment Prove that a intergral over $\mathbb R$ is finite
@mrf Oh right! Thanks.. I'll try to fix it!
44m
comment Prove that a intergral over $\mathbb R$ is finite
@D.Vente You just need to consider $x \to -\infty$, not on the whole real line. And for $x \to -\infty$ one can make the exact same argument, because $\lim_{x \to \pm \infty} f(x) = 0$ (changing some signs of course, but it is pretty much the same thing. You may want to try do write it down yourself! :-) )
47m
comment Is this a metric on matrices?
@Behnoosh You're welcome. Not though that if the norm is not sub-multiplicative this does not answer your question :)
48m
comment Prove that a intergral over $\mathbb R$ is finite
Do not be confused with the letters! $f(x)$ is a function, its variable is $x$. But $f(s)$ is the same function, this time the variable is $s$! If I tell you that $f(x) = e^{-x^2}$ is going to $0$ as $x \to \infty$, do you think that the behaviour of $f(s) = e^{-s^2}$ will be different? Since both $x$ and $s$ are independent variables writing $f(x)$ or $f(s)$ is the exact same thing
56m
answered Is this a metric on matrices?
2h
comment Is this a metric on matrices?
what did you try? Where did you get stuck?
3h
comment Does alternating test show divergence?
@Amad27 $\lim_{n \to \infty} a_n = 0$ is a requirement for every series, not just alternating series. I mean it really is very general; of course it is a requirement for alternating series, because is a requirement for every series
3h
comment Does alternating test show divergence?
@Amad27 you are correct :)
3h
answered Does alternating test show divergence?
3h
answered Is it possible to get a neighborhood with only finitely many points in it, in an infinite set?
3h
accepted Evaluate $\int_1^\infty \frac {dx}{x^3+1}$
3h
accepted Two different results with contour integration
4h
comment Two different results with contour integration
Oh my god. You are correct, obviously. Serves me right for relying too much on formulas, and for remembering them wrong. I forgot to differentiate after multiplying by $(x-x_0)^2$. Thanks!
4h
asked Two different results with contour integration
4h
revised Prove that a intergral over $\mathbb R$ is finite
added 805 characters in body
4h
answered Prove that a intergral over $\mathbb R$ is finite
4h
comment Prove that a intergral over $\mathbb R$ is finite
Note that $F = K * f$, so if you know the properties of convolution it should be easy. You are probably not allowed to use them though
18h
comment Does this algorithm find prime numbers only?
@user3894009 note though that your code will start producing the correct answer, but it will be monumentally slower :)