The h Bar

12:01 AM

I have only tried learning a couple numerical methods, though I'll have a course on it sometime soon

user54412

Numerical Recipes: get it

user54412

it may not have the most cutting-edge version of any one technique, but it is 1000+ pages of saying where people screwed up in the past

ManishEarth

In this month I have been told that around 50 books are must-haves :P

@ChrisWhite wow

Isn't that what physics is all about? Years upon years of screwing up.

user54412

as an added bonus, they implement all the algorithms they discuss - in C++ :P:P

user54412

(actually I rarely read the code itself - the text is better)

user54412

12:05 AM

well, physics tended to actually work to some degree along the way

ManishEarth

@ChrisWhite pointy things?

user54412

yep

ManishEarth

@ChrisWhite Yeah, of course. But my first impression of the history of physics was screwup upon screwup foretelling screwups yet to come :P

Of course, now I understand it all better -- not exactly screwups

user54412

speaking of numerical methods - there exists a Mathoverflow question I know the answer to!

user54412

8

Q: What is a good method to find random points on the n-sphere when n is large?

As part of a more complex algorithm, I need a fast method to find random points of the n-sphere, $S^n$, starting with a RNG (random number generator). A simple way to do this (in low dimensions at least) is to select a random point of the (n+1)-ball and normalize it. And to get a random point of ...

user54412

12:15 AM

their standards must be slipping

ManishEarth

Hm

user1504

@ChrisWhite: Given how many random number generators from the old days were horribly flawed -- e.g., tended to output points on hyperplanes instead of uniformly-- it's a miracle that any of their computations came out rigth.

user54412

@user1504 indeed - the same holds for all the unstable integration schemes they had going

user1504

12:33 AM

BTW, if you ever want to read full-on angry rantings about numerical idiocies, check out Bill Kahan's website, especially cs.berkeley.edu/~wkahan/Curmudge.pdf

user54412

@ManishEarth should see page 6 of that rant ;)

ManishEarth

lol

Crazy Buddy

12:56 AM

@DavidZaslavsky Duh... Leave it... I deleted it. (Have to think of some other thing) ;-)

ManishEarth

@CrazyBuddy why?

Crazy Buddy

1:23 AM

@ManishEarth Regarding the community promotion ads... As they haven't replied us yet, I've deleted it (only from my PC) --> I still have it in the image hosting site :P

I can grab & edit it ~~whenever~~ if I want :D

Crazy Buddy

1:42 AM

Strange comment I've ever seen..! It would've been ridiculous if older reasons were still there :D

This question appears to be off-topic because it is too localized — Dilaton 15 hours ago

Haha... OT & TL at the same time..! And, OT because it's TL ;-)

Crazy Buddy

More strange...

Why's does the trolley car reason not say what Chris said...

Or, Is it the way it is,,, and I'm sleepy :D

Larry Harson

2:45 AM

@ChrisWhite is it true that you're not allowed to use any of the algorithms in the Numerical recipes book? Maybe some of the reviewers at Amazon.com are over reacting.

David Zaslavsky

2:57 AM

@CrazyBuddy actually I did get a reply a little later. They're fine with it and even gave me a link to a hi-res logo.

user54412

@LarryHarson hmm, it is a restricted license - basically, up to 10 routines can be copied for entirely personal use

user54412

but you cannot copyright an algorithm, just source code

David Zaslavsky

@LarryHarson Of course not - if it were, there would be no point in publishing the book at all. You're not allowed to redistribute the implementations they provide, though. So if you use the NR code in a program, you can't share that code with others. You can only share the code you wrote, and then anyone who wants to compile the program has to get their own independent copy of the NR code.

user54412

I don't use any of the source code anyway (the C++-isms are overkill IMO, plus all their code relies on their own defined classes, so the routines are not particularly modular as written)

David Zaslavsky

Yeah, me neither. I usually use GSL

Also the NR code is badly written, with cryptic variable names all over the place

user54412

3:03 AM

yeah - they basically just took their fortran code from the first edition and did the minimum necessary to translate it to C++

David Zaslavsky

That explains it

user54412

and since F77 doesn't allow long variable names or more than ~70 characters on a line...

tpg2114

3:29 AM

More tag wiki edits submitted...

user54412

3:51 AM

More tag wiki edits (partially) approved...

user54412

I have to jump in before the mods approve them if I'm to have any chance for a Reviewer badge ;)

ManishEarth

4:06 AM

@crazy ah, I see. If it's a copyright issue for having the post on meta, however, they'll file a dmca takedown request. Not entirely necessary to delete, but ok.

Note that a DMCA takedown is quite different from a @dmckee takedown, the latter involves flying neutrino cupcakes

2

ManishEarth

@crazy trolley car closes show up as an exta temporary option in the close menu, but are in the end just a comment with upvotes. Finally the post is closed as off topic

Re: "OT because it is TL" that's fine, though I would prefer if a closing comment didn't explain one bit of jargon in terms of another :P It should be as clear as possible.

dmckee

4:58 AM

@ManishEarth If you stand back far enough some of them will oscillate into brownies before they reach you. It's a hot field in experimental baking.

David Zaslavsky

5:54 AM

@dmckee I wonder what the prospects would be for a brownie factory....

Crazy Buddy

9:39 AM

@DavidZaslavsky Yeah... Anyway I can get that? :D

@ManishEarth Err... That's why David was appointed to ask them their permission ;-)

7 hours ago, by David Zaslavsky

@CrazyBuddy actually I did get a reply a little later. They're fine with it and even gave me a link to a hi-res logo.

@ManishEarth I know that... What I require an explanation is about the reason that it's closed...

I mean, have a look at the image again/....

> This question does not appear to be on-topic, etc.., etc,.. - QMechanic, Manishearth

What the heck is that? ;-)

ManishEarth

10:32 AM

@crazy I know...

Yeah, that's because QMechanic and I are off topic :p

Crazy Buddy

@ManishEarth BTW, You might be enjoying..! (1 sec)

ManishEarth

More seriously: That lists everyone who vtcd for it

Crazy Buddy

People are believing me (even now) after posting my apologies that it's a FAKE..!

ManishEarth

Thats due to the way the news feed works

Crazy Buddy

@ManishEarth Hey... I didn't post it publicly (because you, twistor, etc.) already knew abt it (and you've already posted it) ;-)

That's why I posted in both of my groups..!

(which had almost many friends from my colg.) - I'm not greedy... It was enough for me :P

David Zaslavsky

12:32 PM

@CrazyBuddy t.co/PNxwW9JpaO

Crazy Buddy

@DavidZaslavsky Cool... It is really a larger version ;-)

ManishEarth

-2

Q: Potential Difference vs. Capacitance

When the potential difference is large the capacitor system is storing more energy than when it is small. Where does the additional energy "come from" as the plate spacing increases?

capacitance

Is this really off topic? It's a comceptual question, though they've missed the "show some effort" . Not really homeworky to me, just simple.

@qmechanic ^

Crazy Buddy

@ManishEarth: Yeah.. Not a homework (actually, I think I saw that question on that day), but it isn't that much clear..!

ManishEarth

Ill edit and reopen

Crazy Buddy

Just two sentences can be confusing...

@ManishEarth Yeah, go on ;-)

ManishEarth

12:42 PM

Clarified

Crazy Buddy

Yeah.. I left a comment just a sec before you edited it ;-)

ManishEarth

Reopened, @qmechanic feel free to close if you disagree , don't wait for my opinion on it :)

Qmechanic

1:04 PM

@ManishEarth : Nah, either way. It is a bit clearer now.

ManishEarth

K

Crazy Buddy

1:18 PM

With me, Mark becomes a 20k user :D

Crazy Buddy

2:33 PM

@ManishEarth: The math paper is really a bless and a curse...

I was happy trolling people for almost 12 hrs..

(till they actually believed me)

Now, this spreads throughout the college faster than an epidemic...

ManishEarth

3:21 PM

nice

ShuklaSannidhya

6:06 PM

The last message was posted ~~3 hours ago.~~ now

tpg2114

8:39 PM

@ChrisWhite Do you have an opinion on the tag moon? Should it refer to questions about all bodies in orbit around another except a star or should it only refer to Earth's Moon and a new tag, natural-satellite should be used for non-Earth moons?

user54412

@tpg2114 it is certainly being used for both

user54412

i feel like there's no harm in leaving it as-is - after all, it's not like there are many questions about our particular moon that can't at some level apply to other planet-moon systems as well

tpg2114

Right, it would be a retagging effort

Okay, no problem. Just wanted to check how particular your community is about terminology :)

user54412

along the same lines, last I checked we have jupiter, but not saturn or any other planet

user54412

seems a bit inconsistent...

tpg2114

8:50 PM

Yeah

user54412

Maybe we should just synonymize jupiter -> planets

user54412

maybe manually add in solar-system to those questions before that though

tpg2114

Or jupiter -> gas-giants which would be a new tag but would cover extra-solar planets as well as the outer planets

user54412

true - gas-giants would overlap with exoplanet a bit, but I don't think that's an issue; the former would probably be more about general physical characteristics, the latter about search methods and planet-formation as a whole

user54412

hmmm, on that note, why is exoplanet not plural?

tpg2114

8:54 PM

Aren't rocky planets also exoplanet?

user54412

yes - so that's why I think it's okay to have both that tag and gas-giants

tpg2114

Or do we just use planets for talking about planets in general and exoplanet is about the search?

user54412

that would be acceptable

user54412

@tpg2114 btw, I was approving your tag wiki edits, but then I was told I had approved too many today and that I had to stop :P

tpg2114

Heh, I think I'm close to the badge

There's a bunch more pending

user54412

8:57 PM

maybe the Stackexchange AI is trying to prevent them from being approved

tpg2114

Do they just go into a review queue too? So you can only do 20 a day?

user54412

yeah - same queue for questions, answers, and tag wikis

tpg2114

Poor people, I've been flooding suggested edits

I knocked out a lot of the low-hanging fruit excerpts though

user54412

at some point I got that number, which is just the pending edit review queue

user54412

9:00 PM

yet I can't do anything about it, despite its urgent appearance

tpg2114

I think I had 20 more before I could get the badge... I wasn't counting so I don't know what I'm at

Turns out 50 is a lot

user54412

i'd be interested in seeing how many various people have, but I can't figure out what all the data.SE fields are called

user54412

in particular, I don't know how to look up tag wiki statistics

tpg2114

What kind of statistics?

59

Q: Database schema documentation for the public data dump and Data Explorer

The data dumps are currently released once a month. Over time as new features are introduced to Stack Exchange sites and other bits of data added, the 'anatomy' of the data dump is likely to change. What is the current structure of the public data dump? A copy of the data dump can be obtained fr...

support data-dump data-explorer faq-proposed

It looks like you would pull all the ExcerptID's from the Tag table

Then pull all the authors and sites from the Posts table where the ID was the ExcerptID (or the WikiID if you so chose, or both)

I guess you don't need to pull the site, the query is site specific

So just the authorID

user54412

ahh, that would help - maybe i'll get around to it later

tpg2114

9:07 PM

Then count the number of times the authorID appears

Actually, it's even easier. Just pull straight from posts where PostTypeID is 4 or 5

Wait wait! Pull from the badges table the number of people who have the badge :)

user54412

ummm, no one has the badge on this site... physics.stackexchange.com/help/badges/87/research-assistant

tpg2114

I know...

Gotta get it

Seems more likely to be the first to get than

physics.stackexchange.com/help/badges/27/legendary

I think I've done 46...

Gugg

9:49 PM

Does the rear wheel of a motorcycle function as a lift-vortex during a wheelie? What kind of nonsense is that?

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