Conversation started Dec 10, 2016 at 6:05.
Martin Sleziak
Martin Sleziak
Dec 10, 2016 06:05
@kayak Since I know nothing about PDEs, I cannot really help you with the question. But perhaps you can try to have a look at the questions found here to see whether they are related to what you are trying to do. And of course you can try searching for other questions or using Google, built-in-search or other search engine.
kayak
kayak
If \phi_1 and \phi_2 are an orthonormal function in a Hilbert space, then for any linear transform L, Is (L\phi_1,\phi_2)=0 generally? I definitely guess it is not true hahaha.
I just make a recall.
@MartinSleziak Yes I should have done that! I didn't haha Ill try!
Kaj Hansen
Kaj Hansen
That's false in $\mathbb{R}^n$
Idk about this setting though
Martin Sleziak
Martin Sleziak
Well, $\mathbb R^n$ is a Hilbert space.
kayak
kayak
of course not... Thanks for refreshing.
Kaj Hansen
Kaj Hansen
Is it "a function"?
kayak
kayak
Dec 10, 2016 06:09
Hilbert space can be thought as a set of functions or set of vectors or so on.
Kaj Hansen
Kaj Hansen
orthogonal vectors I mean
Cool. I've never worked with "Hilbert spaces" before
kayak
kayak
I consider '\phi_1', '\phi_2' as functions
Kaj Hansen
Kaj Hansen
That term at least
Balarka Sen
Balarka Sen
@kayak What do you mean by functions in a Hilbert space? A Hilbert space per se does not consist of functions - it consists of vectors.
Like any vector space does.
Kaj Hansen
Kaj Hansen
@BalarkaSen, the function space could be a vector space
Like continuous functions over R
Balarka Sen
Balarka Sen
Dec 10, 2016 06:12
That's an example of a vector space where vectors are declared to be the functions.
kayak
kayak
@KajHansen Good example.
Balarka Sen
Balarka Sen
But in general that doesn't make any sense.
Sophie
Sophie
if we know the irrationality measure of a transcendental number $x$, is it possible to find the irrationality measure of $\frac{1}{x}$? In particular the irrationality measure of $e^{-1}$
kayak
kayak
@MartinSleziak
I didn't know the search options like here approach0.xyz/search/….
This search engine is cool.
Thanks!!
Martin Sleziak
Martin Sleziak
Yes, it is relatively new.
You can find more about it here: Announcing a third-party search engine for Math StackExchange.. And here various links to posts related to searching this site are collected.
But I slowly get the feeling that I am doing nothing but feeding you lots of links - and such amount of them that nobody would be able to have at least cursory glance to all of them. (Many of them contain a lot of text.)
kayak
kayak
Dec 10, 2016 06:17
Is there kinda 'news' or 'announcement' in MSE?
Sophie
Sophie
on the meta site, yes
kayak
kayak
@MartinSleziak Lolllll I'm a computer lover. I may use all of them.
Kaj Hansen
Kaj Hansen
You can always just Google "[Insert Search Here] inurl:math.stackexchange"
kayak
kayak
@Sophie Oh thanks.
@KajHansen I use to do that. But as you know, having interactions and discussions is really good one.
Martin Sleziak
Martin Sleziak
You might visit meta regularly to be sure to notice all off them. But even if you do not visit meta, the most important ones are displayed in community-bulletin.
@KajHansen I certainly use that often (although I use site: instead of inurl: - I am not sure what a difference is.) But when searching for a formula, this is often much better than Google.
In Google i would have to try "x^2+y^2=z^2" and "a^2+b^2=c^2" and other names of variables. Here I do get all of them at once.
kayak
kayak
Dec 10, 2016 06:22
@MartinSleziak After I found a 'Approach0' search engine.
@MartinSleziak Lolll I used to do that hahahhaa.
@MartinSleziak Wowbow.
Martin Sleziak
Martin Sleziak
Of course, any method has advantages and disadvantages. So does this search engine.
Kaj Hansen
Kaj Hansen
good points
Martin Sleziak
Martin Sleziak
For example, it shows various formulas which are in a sense similar to the search query, so you might actually end up with useless results which are far from your question.
And it is restricted to this site.
kayak
kayak
@MartinSleziak
Could we search some words with tagging?
Martin Sleziak
Martin Sleziak
But still, if I see, for example, some limit which has probably been asked many times, my first attempts to find a duplicate are either using frequent tab for the relevant tag(s) or putting the limit into Approach0.
kayak
kayak
Dec 10, 2016 06:28
Ahha
Martin Sleziak
Martin Sleziak
@kayak AFAIK not in Approach0. But on this site you can restrict search using tags. Like searching for "x^2+y^2=z^2 but only among the questions tagged (diophantine-equations).
kayak
kayak
http://math.stackexchange.com/search?q=%5Bdiophantine-equations%5D%5Bnumber-theory%5D%5Bgeometry%5D+%22x%5E2%2By%5E2%3Dz%5E2%22
Here I tried haha thanks!
 
Conversation ended Dec 10, 2016 at 6:29.