Wolfram Mathematica

12:56 AM

@JM actually the SSID is considered public information. Even if you disable SSID broadcasting, it's trivial to sniff the packets and obtain it anyway. Similarly for MAC filtering, which is widely recommended: MAC spoofing is so easy it's pointless. In reality it doesn't matter what your SSID is and whether you broadcast it or not; the only important factor is that you use strong encryption (WPA2 and preferably IPSEC as well) with a good password.

J. M.

@OleksandrR Mmm, true. Sadly most people in my neck of the woods are still using WEP.

Oleksandr R.

@JM personally I use IPSEC with a certificate having a 2048 bit RSA key I generated myself.

@acl Interesting. I suppose I have a soft spot for numerical global optimization for whatever reason, but this does look like some horrible MATLAB code that's been translated literally.

Oleksandr R.

1:12 AM

@belisarius Maybe I was born too late, but I always found TAB clear a more interesting type of cola. However, I don't really like cola anyway, so I guess I didn't find it interesting enough to form part of the market it was selling into; maybe a lot of people felt the same way, hence its quick demise...

J. M.

@OleksandrR I think it's more of "cola that isn't colored traditionally is off-putting". Same thing happened with the clear version of Pepsi, for instance.

Oleksandr R.

@JM You might well be right; people do seem quite wedded to the appearance of foods. I saw an amusing experiment whereby people were offered soup, before and after a toilet brush (straight off the shelf and out of the packet; never been near a toilet or any other unsanitary items) was dipped into it. Most people wouldn't eat it afterwards.

J. M.

There was also the nice experiment where soup with blue food coloring was mostly rejected by a tasting panel, even if it smelled and tasted the same as an uncolored soup.

Oleksandr R.

1:28 AM

@acl I think a "normal" normal cup is meant to have about 100mg. My "normal" cups have way more; probably ~250mg or more. I stopped drinking coffee now, except in the mornings: I drink tea instead now. What put me off mostly was the amount of coffee I drank during exams for my first degree; continuous jittering and heart palpitations are enough to put anyone off for life, I think...

J. M.

Reminds me: I got my math.SE swag from the post office yesterday. One of the things there is this huge mug. I figure drinking that much coffee will keep me buzzed for the entire day, since I tend to drink black.

@OleksandrR What kind of tea?

Oleksandr R.

@JM Yep, me too (black, that is). I use a drip coffee maker, essentially with the cone completely full, for one cup. In the way of tea, I prefer green tea and Earl Grey.

J. M.

@OleksandrR "cone completely full" - that indeed's a good way to get jitters. :D

Oleksandr R.

@JM Yep. I'm not sure how many others have their coffee as strong as that; for me it doesn't taste right otherwise but I never met anyone so far who would happily drink coffee I'd made for myself.

J. M.

Coffee doesn't work for keeping me awake anymore. That I once had the bad habit of drinking coffee before going to bed may have something to do with it.

Oleksandr R.

1:38 AM

@JM Yes, I did that too. I'm not generally good at getting to sleep anyway (it's 2:37 here now) but coffee didn't help. Apart from the heart palpitations, though, what really put me off was the agonizing headache when I'd wake up in the morning and not have coffee right away.

J. M.

@OleksandrR Holy crap, you got to the point of having withdrawal symptoms? That's a serious amount of coffee to drink to get to that.

Oleksandr R.

@JM It wasn't that much really; just 5 or 6 cups a day (but full cone each one, so I guess it adds up). But yeah, when I realised I was addicted, that's when I knew it was time to ease up.

J. M.

It does. Good grief. The most I drank in a day was three mugs, counting my "nightcap".

(Admittedly I can't tell if it was causing palpitations; my heart's always ticked fast even before I got into a coffee habit.)

belisarius

1:54 AM

@OleksandrR If you are serious about tea, you may try these guys:

I've two dozens of their cans in my library. (yes, instead of books) :D

Oleksandr R.

@belisarius interesting, although I'm not too keen on cardamom actually. (Also, there is an awful lot of nonsense on Skeptics.SE, isn't there?)

J. M.

@OleksandrR ...lots of far-fetched ones, sure. (I'm trying to be charitable.)

belisarius

@OleksandrR No, I doesn't mean cardamom, it was just an example

J. M.

@belisarius A library of tea samples isn't a bad thing to have.

belisarius

@OleksandrR Just look

republicoftea.com/oolong-tea/c/36

@JM It's just under my cognac samples :D

Oleksandr R.

1:59 AM

@belisarius Oh right, I see. Yes, there are some good tea shops near-ish to here. But generally I get my tea from the supermarket (not too serious about it, really). I should definitely try some more exotic types though.

belisarius

@OleksandrR Once you start ... it's like like ... uhhh ... I better shut up

J. M.

@belisarius A liquor cabinet is even better. >:)

belisarius

Tea bricks

Oleksandr R.

@belisarius A friend of mine (before he finished his PhD and left our group) was keen on different sorts of tea. Many of them I found too highly spiced... I think I'm quite conservative when it comes to teas (less so with beers!)

belisarius

from uniquelytea.blogspot.com.ar/2009/08/unique-tea-brick-tea.html

J. M.

2:03 AM

@belisarius Prank: "Yes, it's chocolate. Now, try some! Bite!"

@OleksandrR With some of the teas I've tried, my friend put it quite colorfully: "this smells more like something I'd rub on a sore arm than something I'd drink."

belisarius

@OleksandrR Oolong and Green are usually conservative but and superbly flavored

@JM Green and red teas usually are earth-flavored and it takes some training to enjoy them

while black teas are usually much more coffee like

J. M.

@belisarius Oh, yes. I drink green and oolong primarily. Black, only every so often. I have yet to try rooibos red tea, though.

belisarius

I posted a Q on Mma.se 2 days ago, 85 views, 2 upvotes, 0 answers. They are selfish.

2

Q: Finding an invariant under Group operations

Context: I am trying to answer this question about solving the peg solitaire, and I already posted as an answer some code devised for treating the board as a graph. The algorithm in Mathematica for solving the problem I implemented there (please don't care to read the code) is a first try bru...

group-theory

rcollyer

My personal favorite is Constant Comment by Bigelow.

belisarius

@rcollyer Bigelow is tea by other means

rcollyer

2:11 AM

@belisarius ?

Oleksandr R.

According to Wikipedia: "Some tea bricks were also mixed with binding agents such as flour, blood, or manure to better preserve their form so they could withstand physical use as currency." Eurgh!

belisarius

@rcollyer It's no tea at all

@OleksandrR Manure blended are the best!

J. M.

@belisarius Questions tend to get buried there nowadays. :| I'm counting down the days when the first "Unsung Hero" shows up.

rcollyer

@belisarius are you referring to their herbal line?

J. M.

@OleksandrR "This tea tastes like shit" takes on a whole new meaning...

2

belisarius

2:13 AM

@rcollyer When tea is sold in teabags, you can be sure it is crap

Oleksandr R.

Uh, wat?

rcollyer

@belisarius this is some of the smoothest tea I have ever had, including loose.

belisarius

@rcollyer It is a nice beverage, I admit. But does not qualify as tea

J. M.

@belisarius (Corollary: Lipton is no better than sewage water.)

rcollyer

@belisarius there we must disagree. It is an infusion created by steeping dried (and fermented, being black tea and all) tea leaves in hot water. How then does it not qualify as being tea?

@JM Lipton is awful.

J. M.

2:17 AM

@rcollyer It's a neat way to get rid of unwanted guests... >:)

Oleksandr R.

Here's a conundrum: how to destroy a hard disk in an environmentally responsible manner? I took one apart lately, but the number of pieces that came out was more than I expected, and they aren't recyclable.

rcollyer

@JM The problem is that sometimes the people you want to get rid of actually like it.

belisarius

@JM Lipton's and Twinings' are (almost but not quite entirely unlike tea)[en.wikipedia.org/wiki/….

J. M.

@OleksandrR I'm pretty sure that's a question that's frequently been asked on /. ; did you try searching their archives?

rcollyer

@belisarius You can also get that variety loose. :P

J. M.

2:20 AM

Twinings isn't that bad, @bel...

belisarius

@rcollyer I like Bigelow's, but it is not tea. Like instant coffe is not coffee

rcollyer

@OleksandrR you could try thermite, but I doubt you'd consider that environmentally responsible. Fun to watch, though.

J. M.

@OleksandrR I wonder what he was smoking while writing that...

rcollyer

@belisarius we'll have to disagree on that point. (at least about Bigelows, not about instant coffee.)

J. M.

@rcollyer That's after DBAN-ing the hard disk, of course...

Verbeia

2:22 AM

I have put a bounty on this question because I was about to post a duplicate of it. I would love to see a general solution to it.

4

Q: How to convert between various ItemSize/ImageSize units?

How can one convert between the implicit units used by Grid (ems and line height for horizontal and vertical dimensions) and printers points (in GraphicsGrid and Graphics)? Grid[{{"sample", "text"}}, Frame -> All, ItemSize -> {{4, 7}, Automatic}] Row@{Framed["sample", ImageSize -> 60...

front-end conversion units

Oleksandr R.

@rcollyer Thermite is not so bad I suppose, except that aluminium costs a lot of energy to refine only to turn it to oxide again. But burning PCBs isn't such a great idea, I think.

J. M.

@rcollyer "I like drinking Swiss coffee. Nescafé counts as Swiss coffee, right?" :D

@OleksandrR The vapors are not a healthful thing to breathe, yes.

rcollyer

@JM Not needed; thermite brings the platter above Curie temp, so no pesky residual data. that, and the whole melting thing ...

@OleksandrR no, no they're not.

@JM I don't think Nescafé counts as anything remotely resembling food, much less Swiss coffee. :)

J. M.

@rcollyer Yes, but you never know if the thermite completely screwed the disk. It's okay to be paranoid for things like these...

@rcollyer I know; I was quoting a friend I was talking to the other day. :)

Oleksandr R.

@belisarius Heike mentioned she liked Twinings green tea a while ago here in the chat. Personally I find it unpleasant, but there is another brand I prefer: Clipper. It's not too bad, though as I say, I'm not exactly a connoisseur of teas.

rcollyer

2:27 AM

@JM true, but if you ensure that the thermite covers the disk casing, then I think it is safe to assume that the disk has been safely demagnetized.

J. M.

Fine aluminum dust is a neat thing, tho. Of course, you'll need tinted goggles if you're going to watch it burn up; some of the radiation gets to UV if memory serves...

@OleksandrR It's not the best, but it's not Lipton-level either.

rcollyer

Thermite does not have to use aluminum, many others are available.

Thermite

Thermite is a pyrotechnic composition of a metal powder and a metal oxide that produces an exothermic oxidation-reduction reaction known as a thermite reaction. If aluminium is the reducing agent it is called an aluminothermic reaction. Most varieties are not explosive, but can create bursts of extremely high temperatures focused on a very small area for a short period of time. The thermite is simply a mixture of metal, often called the "fuel" and an oxidizer. Its form of action is very similar to other fuel-oxidizer mixtures like black powder. Thermites can be a diverse class of compos...

Oleksandr R.

@rcollyer Okay, you can use magnesium too (or beryllium if you're insane).

belisarius

@OleksandrR Me neither. But I've had a Chinese wanna be mother in law that forbade me some pleasant things if I failed to identify tea subtleties

2

Oleksandr R.

@rcollyer Too much Mg in thermit makes the reaction too violent in my experience.

rcollyer

2:30 AM

@OleksandrR or (at least according to wikipedia) titanium, zinc, silicon, or boron. I imagine many others can be added to that list.

belisarius

@rcollyer Phosphor?

J. M.

@rcollyer As long as it's oxygen-hungry.

rcollyer

@OleksandrR my father-in-law burned a 1 lb mound of Mg shavings once. It was visible from a mile away. The parking lot was never the same ...

Oleksandr R.

Si is an interesting suggestion. Ti, Zn, and possibly B aren't environmentally responsible either. Refining Si takes even more energy than Al, though.

J. M.

@OleksandrR Magnesium's nice too. Even hotter than aluminum, last I tried.

rcollyer

2:31 AM

@belisarius I defer to the chemist on the forum.

J. M.

@rcollyer For giggles?

rcollyer

@JM yes.

belisarius

:D

J. M.

@OleksandrR The vapors from combusting B are not so healthful either. It's like inhaling fine sand...

@belisarius Wait, so you're a tea snob by force? :P

Oleksandr R.

@JM I have to admit I never tried burning it. I guess B, Si and C (diamond allotrope) are fairly difficult to combust. Maybe by laser plasma though? That can easily be arranged...

rcollyer

2:34 AM

@OleksandrR You could always see how FOOF reacts with it! The sulfur chemistry of FOOF sounds very interesting.

J. M.

@OleksandrR It's not that easy to start, but once started, it keeps going.

Oleksandr R.

@rcollyer I have worked with some nasty stuff (I will not say what in this public forum), but yes, that looks pretty horrific. The explosive ones are the worst I guess.

rcollyer

@OleksandrR the article has me rolling on the floor laughing every time I read it. I read it every once in a while when I need a good laugh.

J. M.

@rcollyer I think I said this before: any molecule with at least three electronegative atoms side-by-side is very likely nasty.

rcollyer

@OleksandrR I guess you could use a mixture of Al and C to get the C burning.

J. M.

2:37 AM

@rcollyer A number of people are surprised that you can actually burn diamonds...

rcollyer

@JM and with those two in particular, upgrade "likely" to "what the hell did you just make?"

@JM It's carbon, why wouldn't it burn?

J. M.

@rcollyer You and I know that; most people don't.

rcollyer

@JM true. But, fire is just essentially a fast way of rearranging electrons, so ...

Oleksandr R.

My ArF laser kicked the bucket today. Turns out, fluorine atoms are quite corrosive.

3

rcollyer

So, what you're saying is it ate itself.

J. M.

2:41 AM

@OleksandrR Who knew, right? ;P

Oleksandr R.

The fan inside the tube siezed up. New tube costs half as much as a whole new laser. Which it's fortunate that we just bought about a month ago.

rcollyer

Have you guys seen the Periodic Table of Videos?

J. M.

(Fluorine is so much fun free; not so much fun (and the list of exceptions is tiny) when it's bound to something else.)

@rcollyer Yep, nice ones!

Oleksandr R.

@rcollyer that is nice!--Although, I suppose Theodore Gray's periodic table table is nice too, while also being Mma-relevant!

rcollyer

@JM I prefer my Fluorine diatomic, and no where near me.

J. M.

2:44 AM

@rcollyer Even ammonium bifluoride is nasty business...

rcollyer

@JM Hmm, F with N. Not FuN.

belisarius

@rcollyer Nice thing that FOOF, I've in mind two or three people who deserve a birthday present

3

rcollyer

I did enjoy intercalating graphite with FeCl; a really interesting green color.

Oleksandr R.

@rcollyer I heard a story about a professor who used to do fluorine chemistry years ago. His gas line leaked... and the leak was right in front of his forehead when it occurred, with fluorine at 200 bar. His body was donated to the medicine department and the skeleton is still somewhere around, complete with hole burned straight through the cranium, so I hear.

belisarius

@rcollyer The only interesting similar ting I did is manufacturing "black gold"

rcollyer

2:46 AM

@belisarius if you can get it to them ... it is still reactive at liquid nitrogen temp, when it is a solid!

@belisarius black gold?

J. M.

@OleksandrR I don't think there'll ever be a shortage of F horror stories...

@belisarius colloidal?

rcollyer

@JM but it is such a pretty yellow color.

J. M.

@rcollyer More yellow-green than yellow I think.

belisarius

@JM By evaporation at very low pressures. It forms an amorphous perfect black body

rcollyer

@JM the closest I've come is the video.

Anyway, I should run.

Enjoy your tea, @belisarius.

Oleksandr R.

2:48 AM

@JM Only reason I ever had to use ammonium bifluoride is trying to recover sapphire substrates that had been etched using photolithography... it doesn't work, it turns out.

rcollyer

Night all.

J. M.

@rcollyer Oh. Seen it through a tube. Now that I think about it, I should have asked what the tube was made from...

@rcollyer see u!

See ya rcollyer!

Bye @rcollyer!

2:50 AM

@OleksandrR Sapphires and rubies are remarkably unreactive. Took me a while to appreciate that, too.

rcollyer

@JM a good God, I would have. Chlorine was nice. The Fe reacting with it was beautiful to watch. My lab partner imprinting the hot glass with his finger prints, priceless.

Night.

belisarius

@JM You need a naughty girl. They are quite reactive with rubies.

Oleksandr R.

@JM Sapphire is a great material. We are diamond lovers in my lab, but I think sapphire is highly unappreciated even if it isn't as extreme in its properties as diamond is.

J. M.

@belisarius You have it backwards; it's the gal who reacts, not the ruby. :P

belisarius

@JM Pls understand me. It's late here :D

@JM So the ruby is a catalyst?

Never heard that :D

@JM Also, catalysis (AFAI studied at uni) is more effective with small particles (as it is proportional to the exposed surface). Rubies seems to act inversely. Is that a studied phenomena?

J. M.

3:06 AM

@belisarius Eh, the chemistry of women is complicated. Sadly, irreproducible as well.

@belisarius See, it's counterintuitive!

belisarius

@JM General Relativity and Quantum Mechanics are counter intuitive too. One is probabilistic and the other is causal, nonetheless both are right as far as experiments went up to this day. But using rubies as catalysts, being them a few billion years old seems too counter intuitive. Do you have a theory to explain that?

J. M.

@belisarius I don't. But it works with women nevertheless (I've seen a few exceptions tho.)

belisarius

@JM Yeah. My fourth spouse preferred diamods

Mr.Wizard

I don't really know anyone in the StackOverflow Moderator Election. Do any of you have reason for me to vote for one or more of the candidates?

belisarius

@MrWizard I discussed a few things with Brad Larson and George Stocker. The seemed nice and knowledgeable guys

Mr.Wizard

3:16 AM

Thanks, I'll give their profiles a look.

belisarius

@MrWizard Of COURSE that doesn't mean they will be good moderators. But I prefer high rep people almost always, since they saw many war flames and know they must be stopped before insults arise.

Mr.Wizard

Speaking of rep, I'm only 24 points away from 20K! Unless everyone stops voting for me my answers I should hit it in the next 24 hours. Not bad for less than five months. It's nice that lots of people vote on this site (compared to SO).

belisarius

@MrWizard What do you think about using rubies as catalysts? (read above)

Mr.Wizard

Mental block -- I cannot remember how to do strikethrough text here. Help?

Re rubies I defer to those will more experience. :^)

belisarius

@MrWizard 'a

--- a ---

J. M.

3:23 AM

~~Like this, you mean? Interesting.~~

belisarius

yep

you have the help far down right

Mr.Wizard

Really strange; I don't remember using that before. Thanks.

belisarius

neither do I :D

Mr.Wizard

I wonder why <s></s> isn't enabled here (chat).

brb

belisarius

I wish some standards on typography arise on this dawn of civilization

J. M.

3:28 AM

@belisarius "Standards"? Plural? :P

belisarius

test follows

damn

@JM I've been using MS-Word since version 2., and each version update is a nightmare. And I use (probably) 10 more text editor environments. I just want to free some neurons for fishing more often.

J. M.

@belisarius That's sorta kinda my point. Wouldn't it be great if all these text editors had just one standard to adhere to?

(...and with some programs, you're better off deleting the hell out of them, and then go fishing.)

Mr.Wizard

lol one of you just put to over 20K didn't you? That wasn't the aim of my comment, but thanks.

belisarius

@MrWizard hehe

Mr.Wizard

Also, I notice that belisarius is over 50K network wide now. Nice!

Oleksandr R.

3:34 AM

@MrWizard Yes, it was me, catching up on my voting since I haven't logged in for a while. Gratz on your 20k!

Mr.Wizard

Thanks Oleksandr. :-)

@MrWizard Happy 20K!

@MrWizard Nice. :)

Thanks guys.

speaking of votes, this damn answer took me a lot of time. I still don't understand why I did it :D

2

A: How can I pack circles of different sizes into a spiral?

(* Position of a circle tangential to other two circles *) pos[{{x1_, y1_}, r1_}, {{x2_, y2_}, r2_}, r3_] := (k = N@( ((x1 - x3)^2 + (y1 - y3)^2 == (r1 + r3)^2) && (x2 - x3)^2 + (y2 - y3)^2 == (r2 + r3)^2); ({x3, y3} /. FindInstance[k, {x3, y3}, Reals, 2]) ) (*Select the ...

Obvioulsy. there are a lot of people that also don't understand ;p

J. M.

3:40 AM

I'm too lazy to go through the geometric proof at the moment, so I haven't seriously looked into that question. OP could have used a simpler example, though...

belisarius

@JM Hehe. I escaped from the trigonometry issues with a FindInstance. Let Mma do the hard work

J. M.

Yes, that was a buzzsaw for a toothpick. :P The problem is constructing a less drastic method takes some mathematical effort.

belisarius

@JM If you want the full trigonometry script look at my first version. It's lame but very quick

brb

Mr.Wizard

@belisarius I haven't looked at that yet. Thanks for pointing it out. By the way, I think it is helpful to point out answers, your own and otherwise, that aren't getting the attention.

Oleksandr R.

@MrWizard agreed with that. If you're like me and don't log in for a few days at a time, it's easy to miss good answers. If they're mentioned here in the chat, it's a lot easier to keep track of activity in chronological order.

Oleksandr R.

4:08 AM

@belisarius Word 2000 to XP to 2003 went fairly smoothly for me. So far I've resisted Office 2007 or 2010. (Stupid menu bars require far more clicks to get to any given function.)

J. M.

@OleksandrR The situation's even worse with high-traffic sites like SO and now math.SE as well.

@OleksandrR I still don't get the point of that damn ribbon...

Oleksandr R.

@JM I rarely visit SO. The volume of stuff there is just overwhelming, and most of it is crap. I don't have time to browse and pick out the gems (and don't have an SO account anyway).

J. M.

@OleksandrR "overwhelming" - precisely why I don't like being there much.

Oleksandr R.

@JM the ribbon seems to be there for the same reasons as almost all new features since Word XP: to make it easier for people who don't know how to use Word, to blunder through and make a horrible hash of their documents, but sort-of "use" it regardless.

@JM the "auto"-X, Y, and Z functions seem to be particularly targeted to annoy the experienced user. I actually like Word; I consider it the best of the Office applications by far. But I would go mad if I had to use it with default settings.

J. M.

"I would go mad if I had to use it with default settings." - seconded.

Oleksandr R.

4:19 AM

@JM Which is why I find it particularly irksome that they removed the Save Your Settings tool from Office 2007 when actually (if you install Office 2003 alongside) it works fine! I refuse to use the newer versions out of spite now. :)

Anyway, once again it's getting light, so I probably ought to get to bed if I want to get any work done later today. Bye!

belisarius

4:34 AM

@OleksandrR bye!

Sjoerd C. de Vries

7:41 AM

@JM Did you do anything with mike's recent post?

J. M.

9:26 AM

@SjoerdCdeVries It's relevant; I don't really see what's wrong.

Szabolcs

9:44 AM

3

Q: Clearly distinguishable colours for scientific figures

I am looking for pointers on how to pick a set of colours (or a colour gradient) that are clearly distinguishable, for use in scientific figures. Was there any systematic research on this? If yes, I'd appreciate some links. When creating scientific figures, colour is often used to distinguish ...

color information-graphics contrast

J. M.

10:12 AM

@Szabolcs Three relevant links: one; two, three.

Sjoerd C. de Vries

@JM I mean this one: mathematica.stackexchange.com/a/6878/57. It was a larger post which has been edited away before being deleted. I got a flag but was still thinking about it when it was gone. Thought you might have been in contact about this or so.

J. M.

@SjoerdCdeVries I saw the original version; I'm not entirely sure there's something wrong. IIRC it's kosher to show off your own product as long as it's relevant and not done excessively.

(I don't like self-promotion myself, but that's just my opinion.)

Sjoerd C. de Vries

@JM I was searching SO meta for general policies. Seemed ok

Why did it disappear then?

J. M.

@SjoerdCdeVries Dunno why he deleted it either.

@Szabolcs Also, one of the most-recommended "diverging" color schemes is implemented in Mathematica as ColorData["GreenPinkTones"].

Sjoerd C. de Vries

Perhaps got whipped by verbeia?

J. M.

10:33 AM

Oh well.

Sjoerd C. de Vries

@Szabolcs I believe there are various color blindness simulators for iPhone, working on its camera image. You might try that. It's good to know there are three types of color blindness so it might not be the case that one set fits all.

J. M.

ColorData["TemperatureMap"] is also good. But the consistent recommendation is not to use rainbow-type coloring (jet() for MATLAB users) for serious work.

@Szabolcs: another one, and another one.

Re: color blindness, see this.

J. M.

11:20 AM

At the risk of looking like an unrepentant link spammer, here's two more.

Verbeia

11:34 AM

@SjoerdCdeVries no, he deleted it himself. It was more of a message for me than an actual answer.

Sjoerd C. de Vries

11:47 AM

@verbeia Ok. Was the removed message intended for me? I was to late to read it.

J. M.

@SjoerdCdeVries You can use your mod powers to see it. :)

Sjoerd C. de Vries

How?

Verbeia

@SjoerdCdeVries Sort of - I'm trying to find a way to express it that doesn't reveal work stuff I shouldn't mention publicly.

J. M.

@SjoerdCdeVries Click on the downward triangle that appears when you hover on a line; click the "history" link.

Sjoerd C. de Vries

Found it. Had to switch modes first, cause Im using my iPad right now.

Verbeia

11:50 AM

Does that make sense?

Hi @MichaelWijaya

Michael Wijaya

Hi Verbeia

J. M.

Hi Michael.

Michael Wijaya

Sorry to intrude on your conversation. I just discovered a subtle error in my circle spiral program. What is the recommended way to do this? I don't mind deleting the post until I figure a fix, but it seems to suggest I have to go through a voting process.

Hi J.M.

J. M.

@Verbeia Yeah, nondisclosure and all that. Oh well.

@MichaelWijaya Nah, you can unilaterally delete if need be; I don't understand the point of the dialog box either, but just click on OK.

Michael Wijaya

Hi Heike. I just went through your code for the circle spiral. It is a really elegant solution.

@J.M. It works! Thanks.

Verbeia

11:56 AM

@JM It's not a big drama, but writing the proof-of-concept code has elucidated a lot of business rules that until now have only been implicit.

Heike

@MichaelWijaya Thanks. I haven't had time to go through your code in detail yet I'm afraid.

Michael Wijaya

@Heike I found ways to make it more concise, and then found out there is a subtle error. That is what I get for only checking on RandomInteger. I missed the rare cases where the circle jumps over two underlying circles.

@Heike Out of curiosity, how long did it take you to write your code? It is so elegant, I am jealous :)

Heike

@MichaelWijaya That's just the result after a lot of cleaning up. You should see the working notebook :-)

J. M.

12:23 PM

"No self-respecting architect leaves the scaffolding in place after completing the building" - C.F. Gauss

Sjoerd C. de Vries

@MrWizard didn't you think mathematica.stackexchange.com/questions/6862/… was a dupe of mathematica.stackexchange.com/questions/3458/…?

J. M.

12:55 PM

Full disclosure: I didn't want to do anything mod-ish because 1) I answered that question, and 2) I haven't seen that dupe thread before. The two aren't exact dupes, but are pretty close. I'd rather we have a canonical question that can have those two questions as dupes.

Mr.Wizard

2:07 PM

@SjoerdCdeVries Artes asked to reopen it on the ground that it was specifically about Sine on a unit circle rather than merely a generic complex-value Plot question. Seeing the answers that were already posted I tended to agree. Pardon me if I stepped on your toes in the process; you weren't around at that time or I'd have asked.

Sjoerd C. de Vries

@MrWizard This has nothing to do with sensitivities. I.m.o. this question differed from the original one only wrt to the application area, but they are the same in principle. You and I have been closing questions as dupes that differed more than these two, and I just wanted to discuss policy here.

Mr.Wizard

Okay. In light of the answers posted do you think they are different enough? Could we edit the question to better differentiate it from the first while preserving that validity of the answers? Should we?

@Sjoerd are you there?

Sjoerd C. de Vries

2:27 PM

@MrWizard Sorry, was talking on the phone

Mr.Wizard

no problem

Sjoerd C. de Vries

@MrWizard I don't mind leaving this alone. Perhaps we might do something along the lines of J.M's suggestion above.

We have covered the 2D and 3D situations now. I don't expect more variants.

Well, perhaps complex function maps

Anyway, have to go now. See ya

Mr.Wizard

By Sjoerd!

J. M.

2:45 PM

@SjoerdCdeVries Also I note than nobody's tried the Riemann sphere visualization in the other thread...

belisarius

Hi

Can somebody check my answer here

1

Q: Having difficulty with the Minimize command

I am having trouble getting an answer to this question...Am I missing something that anybody can see. Simplify[Minimize[{( x (-a + x))/(-a + H) + (1 - (-a + x)/(-a + H)) ((y (-b + y))/(-b + H) + H (1 - (-b + y)/(-b + H))), 0 <= a < 100, 0 <= b < 100, a < x &...

mathematical-optimization

I am not sure if it is not bullshit

Heike

@belisarius I think the OP wants to minimize the equation with respect to x and y for fixed values of H, a, and b

In your solution you are varying H.

belisarius

@Heike Mmm .. you are right. deleting.

Mr.Wizard

3:30 PM

whuber just posted a great answer:

2

A: Tiling a square

With some diffidence (because there appears to be a Mathematica bug: see below), I would like to offer an answer in the spirit of the OP's original attempt to solve the problem algebraically. Solution This problem can be formulated as a binary integer linear program. The reformulation represe...

Rojo

Great answer

belisarius

yep

@Rojo And it is related to your senku problem

@Rojo See my comment under the answer

Rojo

Very interesting

Mr.Wizard

It looks like Leonid just posted a fine answer too, but it will take some reading before I understand it:

0

A: Performance tuning for game solving (peg solitaire)

Preamble This is a great problem. And here is my first stab at it. This will not be the fastest possible solution (I hope to add some faster ones later), but even it will eat your boards for breakfast, including the full one you started with. Before we dive into code, I will list the prerequisi...

Rojo

Niiice

I knew that guy would succeed by sheer brute performance tuning

belisarius

7:24 PM

@SjoerdCdeVries Take a look at this answer!

1

A: Finding an invariant under Group operations

A symmetry group acts on a set of data structures (the occupancy vectors). The question asks for a procedure to create group-invariant hashes of those data structures. Here is a very general way, requiring only a presentation of the group and explicit definitions of the actions of its generator...

Mr.Wizard

8:10 PM

Does anyone know why Evaluated -> True does not appear to work with ContourPlot? For example:

i = 0;
ContourPlot[i++; Cos[x] + Cos[y], {x, 0, 4 Pi}, {y, 0, 4 Pi},
  PlotPoints -> 2, Evaluated -> True];
i

(* Out= 275 *)

belisarius

8:30 PM

@MrWizard Seems a bug. Works of course with Evaluate[...] inside the function

Sjoerd C. de Vries

8:56 PM

@belisarius Nice. With this and Leonid's answer it should be now easy to check the correctness of my intuition that the number of symmetric situations is relatively low. Have you already tried this?

belisarius

@SjoerdCdeVries Not yet, working now, perhaps later

Szabolcs

10:49 PM

Went to the beach today and brought back a mauve stinger in a bottle. It glows in the dark if I poke it a bit. I'll let it go tomorrow, hope ti survives til then.

@JM Thanks, a lot of good into in your links!

@JM This is exactly what I was looking for!!

belisarius

@Szabolcs what is a stinger?

Ohh I see The mauve stinger produces bioluminescent light shows, which are often admired from passing boats, but it also has a reputation as a ferocious stinger.

I guess they come in different sizes

Heike

11:07 PM

@belisarius I doubt the passengers on the boat were looking at the jellyfish when that picture was taken.

2

belisarius

@Heike What jellyfish?

Heike

the mauve one

belisarius

@Heike Oh, yes, now that you mention it, there is something under the beast

Heike

11:27 PM

Thanks to the mention of jellyfish, I now know that the portugese man o'war isn't a jellyfish but a colony of highly specialised organisms, and that blanket octopuses use the tentacles of portugese man o'wars as weapons.

Mr.Wizard

11:54 PM

I've got a chance to get a rare Populist badge on English.SE. Will a few of you with accounts there help me get it? I don't even need you to vote for my answer, it's got enough (and that might be vote fraud or something), I just need three votes for the accepted answer. Link

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