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12:44 AM
Too late @belisarius
 
@Rojo Well, the intention was good
 
Integer 0 multiplied by a real/complex should give an integer 0 result, not real/complex, grr
(in a related matter)
 
@Rojo Use Chop
Always use Chop to work with reals disguised as complexes
 
Silver me please:
0
A: How can I display private members of a Mathematica package without the "PackageName`Private`" prefix?

rcollyerTry this: Begin["PackageName`Private`"]; ?`* End[]; which puts you in the private context when you execute ?`*. Also, note the grave mark (`) in ?`*, it ensures that the wildcard (*) is only applied to the current context not your entire $ContextPath. Incidentally, this is the same reason that...

 
@rcollyer How much?
 
12:48 AM
@belisarius 10,000 troy ounces.
 
@rcollyer A flesh lb
@rcollyer Done! Now the payment
 
@belisarius no. you're supposed to give me silver.
 
@rcollyer Silver ??? Ahhh OK. Here it is Agggggggggg
 
Haha
I don't follow stackoverflow. Are there still plenty of MMA questions posted there?
 
Besides, that one vote won't do it alone. I need one more. Where's your sock puppet?
@Rojo not really. But, enough that if you're close to a badge you can get one.
 
12:53 AM
@rcollyer Sleeping now. Do you want it to growl at me?
 
There you are
 
@belisarius point. maybe the sock gnomes will get it.
 
@rcollyer I did my share the other day when Verbeia told me about your badge.
 
:)
I need 1 vote, just one.
 
Damn
 
12:55 AM
never mind. got it.
 
@rcollyer OK. I'll reverse my last one
:D
 
:P
don't downvotes count, too?
 
@rcollyer Wanna try?
 
wait a day, then we can experiment.
brb
 
@rcollyer bye
 
12:58 AM
short trip
 
Strange thing ...
r u there?
@Rojo hhh
 
I'm here @belisarius
a ping away
 
Look at this
from a Q
Load the following in a cell and execute it
K[x_, psi_] :=
Evaluate@FullSimplify@
Sum[Sin[n*Pi*x]*
Sin[n*Pi*
psi]*(2*Exp[-(n*Pi)^2*
Abs[s + r]] - (Exp[-(n*Pi)^2*Abs[s - r]] -
Exp[-(n*Pi)^2*(s + r)])/(n*Pi)^2), {n, 1, j}];

TL[x_, psi_] := Evaluate@Chop@Integrate[K[x - y, psi]*y, {y, -10, 10}];
TU[x_, psi_] :=
Evaluate@Chop@Integrate[K[x - y, psi]*(1 - y), {y, -10, 10}];
 
Running...
 
@Rojo The TU[] and TL[] definitions are symmetrical. You see?
they are almost the same thing
 
1:07 AM
Still running ...
 
Yeah
 
now try this
Timing@TL[.5, .5]
 
Aborting first
 
Nooo
wait
it should run
 
Ok, hehe
Subsession
 
1:09 AM
It's the FullSimplify that's causing the lengthy run time.
 
yep, dont mind. wait for it
oh no
I forgot the followin
j = 10; s = 0; r = 0;
sorry
 
Restarting
 
load that and run again
 
Done
 
had to drop the kernel, K was defined elsewhere and it was interfering. (and i don't mean the system def either.)
 
1:11 AM
Ok.
 
Timing@TL[.5, .5] is {0., -1.27544*10^-31}
 
now try this
Timing@TU[.5, .5]
the same thing ... almost
 
Almost
 
but not quite
 
Right
 
1:13 AM
So? What is happening there?
 
It's chop
It's not symbolic
 
Timing@TL[.5,.5]
{0.00017, -1.27544*10^-31}
Timing@TU[.5, .5]
{0.005044, 1.84852*10^-14 - 1.02796*10^-15 I}
 
and you're evaluating the Chop away in the definition I think
 
Timing@TU[.5, .5]
{9.202999999999994`, 0}
 
@Rojo shouldn't be. f@g@h[q] == f[g[h[q]]]
 
1:15 AM
@rcollyer, what do you mean by that?
 
@ == []
 
Yeahh, soo?
 
@Rojo precedence order of @ dictates that f@g@h == f[g[h]], so the Chop is not evaluated away.
 
@^-1 == ][
 
Hahaha
I still don't get it @rcollyer
What I mean is
if you run ClearAll[x];Chop[x]
not a symbolic Chop[x]
 
1:17 AM
@Rojo You are right
 
so, since these aren't delayed definitions because of Evaluate...
 
Without the Chop they work alike
But both of them are Chopped
TU & TL
 
Are they?
Oh
You can do symbolicChop[x_?NumericQ] := Chop@x
 
I think I'm misinterpreting what you're saying. But, I agree Chop is the culprit.
 
1:18 AM
BOTH are chopped
 
As you copied it to us, none is chopped I think
You need a Chop that only evaluates to numeric arguments, so that they stay there wrapping the symbolic result of your integrals
 
@Rojo Ah, now I see what you're saying.
 
or, you need avoid using Evaluate, and inject the integral results in some other way in the definition
 
TL[x_, psi_] := Evaluate@Chop@Integrate[K[x - y, psi]*y, {y, -10, 10}];
TU[x_, psi_] := Evaluate@Chop@Integrate[K[x - y, psi]*(1 - y), {y, -10, 10}];
 
@belisarius evaluate the integrals symbolically and apply Chop to them.
What do you get?
Actually, only do it to the first integral, it's nicer.
First, look at the output from Integrate then Chop the result.
 
1:23 AM
@rcollyer let e see
@rcollyer I think I don't get you
 
@belisarius, look at the downvalues you loaded in TL or TU
There's no Chop
 
@belisarius what @Rojo has been saying is Chop doesn't do anything as it is applied to the symbolic result because of when it is used, not the numerical result, like you intend.
 
Wait ... my question is why when Evaluate@Chop is used, the second function Timed much worse than the first. I am not trying to evaluate them quickly. I am just puzzled about the behavior
 
Ah, you are puzzled because of the timings
 
yep
 
1:28 AM
Have you actually evaluated the second integral symbolically? The result is huge.
That would account for the timing difference.
 
Quite huge
 
Excessively large, even. :)
 
Terribly ginormous
 
But it is a constant thing (well, almost constant), minus the other integral
Ups
no
I overlooked an y
 
There's an y in K
Yeah
 
1:31 AM
hmmm sorry, my bad
 
Anyway
Timings go down if you Simplify
 
Combined with the fact that Chop isn't having any effect on the result.
 
It goes down from terribly ginormous to just uglily not little
 
@Rojo Hehe .. I lost interest
:D
 
@Rojo right. front loading your evaluation time.
 
1:33 AM
finding strange behaviors is funny. Solving integrals isn't :D
 
That's why I have a set of tables that still beats mma.
 
I use tables to eat on them
at them
whatever
 
@Rojo The preposition usage depends on how hungry you are
 
yeah, but this one was the best bit of money I have ever spent. the book's bindings are broken in several places, pages falling out, and still I find results faster than mma a lot of times.
 
If you're very hungry, just lose the preposition
 
1:35 AM
or eat it.
 
Just lose it
and once you've eaten, go search for it
 
not even as a light snack?
 
if you find belisarius' lost interest instead, have it for desert
 
nah, its probably on vacation with mine. Now if I could just figure out where I lost my mind ...
 
1:38 AM
@rcollyer it's like a semi-blind dude trying to find his lost glasses, you can't figure out where you lost your mind
I've already gave up too
 
@Rojo the problem is, it keeps sending me post cards saying "glad you're not here!"
 
@Rojo You should search nearby the light post. It is darker if you go far from it
 
@belisarius, not if it's "Ambient" or if it doesn't have explicit decay coefficients
 
That's just cheating.
 
@Rojo Have another beer
 
1:40 AM
On it
 
somehow I knew
 
@belisarius no beer in the house. (at least none I'd drink.)
 
Well
There's some truckdriver (not really) thanks to whom I'm not working tomorrow
 
@rcollyer That is a shame. You know no good math results are possible without alcohol
 
@belisarius or bowling, or billiards.
 
1:42 AM
@rcollyer Billiards are too serious things. Addictive
 
@belisarius just like physics. in fact, it is physics.
 
Not really
 
@rcollyer That depends on how well you play. If you do it really well, it is money, not physics
 
yes, but it is the physics that is needed to play well, and beer.
 
Well
Physics are needed
Otherwise the ball could start floating around
Dangerous
 
1:45 AM
there's the whole quantum tunneling through the bumpers, anyway. so, we don't need floating balls.
 
@Rojo Or a black hole may come up from the chalk
 
That's why I use blue chalk
 
good choice
 
No black holes?
 
Light blue
The light part is the key
 
1:46 AM
:)
 
That's why billiard chalk is never black
just to prevent black holes
appearing out of thin air
 
:)
nor white, to prevent white holes appearing into fat air
 
Thinking again ... a vacuum fluctuation may bring them out from light blue chalk
 
Brb
 
@Rojo :)
@belisarius the balls aren't really there at all. They're just excitations of the Fermi sea.
 
1:50 AM
@rcollyer Now you know why they are colored. They are not bosons
 
@belisarius nope. and the pockets must be the anti-particles.
 
@rcollyer We are developing a theory about a 2D universe. We should work on conservation laws before it's gone.
 
let's enumerate the symmetries, so we can apply Noether's Theorem.
 
Particle number isn't conserved. That is good
 
true, but anti-particle number is conserved.
 
1:54 AM
We should introduce some kind of obscure thing into which particles transform
 
Back
The number of white particles is conserved however
 
you are late. The theory is ours
 
I know
My theory involved floating balls
That's 3D
Way cooler than yours
 
@Rojo and always reforms whenever it encounters the anti-particles.
 
CHM
@jmlopez yes, I've modified every source file to reflect the fact that I'm compiling under OS X, and it still doesn't work. There's something I'm not getting, but it's the first time I use MLink.
 
1:55 AM
ok. We may graciously allow you to publish some results if you put us as co-authors
 
CHM
@belisarius where do I start reading on that? ;)
 
@CHM third marble from the left.
 
@CHM Are you interested in OUR theory?
 
@belisarius they can turn into money, if used correctly.
 
@rcollyer Almost everything can be turned into money. Look at the NKS book
 
1:59 AM
I refuse to look at that
 
@Rojo Reading it will be an important life lesson for you
 
@belisarius I read it, once. It was 1200 pages of a technique looking for a problem.
 
@rcollyer Nope. It is 1200 pages looking for fame
 
@belisarius
I prefer to
stay away from clever people with an objective higher than truthful analysis
 
@belisarius sorry, trying to respond to a comment ... will be in and out for a few minutes.
 
2:03 AM
@Rojo Hehe so you will never know how many pages can write a capable scientist trying to pave his way into history
 
If he's trying to pave his way more than he's trying not to bend his arguments, then I won't know now at least
 
CHM
@belisarius yes, that's what I was asking for
 
I just don't feel like having my guard up all along, constantly checking fo inconsistencies. It's a sad habit, not for my free time
(I have the habit though)
 
@Rojo You are not made up for social sciences :D
 
:)
 
2:06 AM
@CHM Sorry .. what?
 
CHM
@belisarius woops I meant to reply to @rcollyer !
 
@CHM Ask me. I love answering
 
@belisarius we hadn't noticed.
 
Do you have a question? Throw it up! Anyone!
 
@belisarius, it's about integrals
 
2:08 AM
@belisarius But, please, not while I'm watching.
 
@Rojo The answer is 42. After Chopping.
 
CHM
I was hoping for a TOE.
 
@CHM Don't you have ten?
 
So your granddaughter is 42?
 
@rcollyer Only in the morning
 
2:10 AM
@belisarius that can be interpreted only in a couple of ways. and none of them good. :P
 
42 (forty-two) is the natural number immediately following 41 and directly preceding 43. The number has received considerable attention in popular culture as a result of its central appearance in The Hitchhiker's Guide to the Galaxy as the "Answer to the Ultimate Question of Life, the Universe, and Everything". Mathematics * Given 27 same-size cubes whose nominal values progress from 1 to 27, a 3×3×3 magic cube can be constructed such that every row, column, and corridor, and every diagonal passing through the center, is composed of 3 cubes whose sum of values is 42. * Forty-two is a...
 
What's the 42nd happy magic cube?
 
@rcollyer After you have your socks on, you don't know how many toes you have. Like The Schroedinger's cat.
 
If they were my socks, I would know that I had at least one
 
@belisarius there are times, though, it is to cold at night not to where them all night. So, you only know you have ten for the brief period between taking off the old ones and putting on the new.
 
2:16 AM
Reminds me of that guy that turned invisible whenever noone was watching him nor himself
 
@rcollyer Exactly. Human anatomy is a mysterious science
 
The Weeping Angels (also known as the Lonely Assassins) are an ancient race of aliens from the Doctor Who television series. Steven Moffat, their creator, attributes their appeal to childhood games such as Grandmother's Footsteps and the notion that every statue out there is secretly a Weeping Angel. Their usual mode of feeding is to send their victims back in time, feeding on the resulting energy difference. When they are not being observed by another sentient being, they can move very quickly and silently, but when they are being observed they become "quantum-locked", occupying a singl...
 
@rcollyer
 
CHM
@Rojo I always thought it was a cat.
 
so Canadians or Russians in winter are just a face, like the face of bow (or however it's spelled)
 
2:19 AM
@Rojo no, they're related to the Sasquatch, though.
 
CHM
Time for some Diablo III
See you guys in Tristram.
 
Night!
I should go myself.
 
@CHM, ia.media-imdb.com/images/M/…, that's what I was referring to
 
Night all!
 
Night all who leave
 
2:20 AM
brb
 
@Rojo I had forgotten about that. Awesomely bad movie. I wish I owned it.
Night.
 
@rcollyer night
 
2:49 AM
@RM please pardon my confusion, but I wasn't able to discern how your k-means code implements expectation maximization. Isn't it just Lloyd's algorithm? (Still +1 for a fine implementation, of course.) Or am I missing something?
 
R.M
3:07 AM
@OleksandrR yeah, it is Lloyd's algorithm. You can interpret it as EM in the following way: the centroids are your unknown parameters $\theta$. The partition step computes the best estimate of the hidden vector $Z$ (clusters) using the given distance function for the current estimate of $\theta$ (initialized to a random choice), which is the expectation step and the update step maximizes the underlying likelihood function. Implicit is the fact that the sample mean is the MLE
 
@RM I see, okay. It's just that the method usually referred to as expectation maximization in the context of clustering maximizes the log-likelihood of a Gaussian cluster model, with both the means and variances being estimated, and the results of Lloyd's algorithm and "the EM algorithm" typically are different. However I haven't really looked at clustering before so this confusion may just be due to my naïveté here.
 
R.M
Heh, might not necessarily be your naïveté... it is common in engineering fields to be more handwaving and generalize similar approaches and call one as the other and vice versa. So it could just as well be my conditioning ;)
 
 
11 hours later…
1:53 PM
Are there some tools to help with indentation when editing .m files in the Front End (not Workbench)?
 
R.M
2:07 PM
@Szabolcs if you use the package editor to edit your .m files, then you can use this answer by @acl which will help preserve indentation, which in itself is good step forward
I'm not aware of anything to block indent/remove indent from code
 
 
1 hour later…
3:25 PM
Can anyone give an example where ButtonNotebook and EvaluationNotebook are different?
The docs say, "If a button in a palette initiates evaluation in another notebook, then ButtonNotebook[] will be the palette, but EvaluationNotebook[] will be the other notebook. " How can a palette button initiate an evaluation in another notebook?
 
@Szabolcs That seems to contradict the example in the documentation of EvaluationNotebook where they use EvaluationNotebook[] to close a palette.
The example was:
pal = CreatePalette[{Button["Test",
NotebookWrite[InputNotebook[], "Done"];
NotebookClose[ EvaluationNotebook[]]]}];
 
4:04 PM
@Heike I thought that when running code through a palette button, EvaluationNotebook always points to the palette. I think I'll ask on main.
 
@Szabolcs Someone like Leonid will probably know.
 
0
Q: When are EvaluationNotebook[] and ButtonNotebook[] different?

SzabolcsI am looking for a concrete code example where EvaluationNotebook[] and ButtonNotebook[] will return different results. The docs for ButtonNotebook say: If a button in a palette initiates evaluation in another notebook, then ButtonNotebook[] will be the palette, but EvaluationNotebook[] ...

 
4:41 PM
Sorry about the other question, deleted it because I made a mistake.
 
4:59 PM
@RM For searching purposes, it might be a good idea to mention "Lloyd's algorithm" in your answer. :)
 
R.M
5:19 PM
@JM Done :)
 
5:35 PM
Hi
Can anybody test a small snippet?
SetOptions[EvaluationNotebook[],
TaggingRules -> "InputFieldState" -> "initial string"];
InputField[
Dynamic@CurrentValue[
EvaluationNotebook[], {TaggingRules, "InputFieldState"}]]
 
@beliasarius Is that what you expected to see?
 
I see Inherited
It's a bug in this version, I guess
 
Since you guys are here... I can't find it in the docs, so: how do you set a notebook to save after each evaluation?
 
@belisarius That's what I see if I use Szabolcs' first copy to SE option
 
me too, I am trying to see why
 
5:41 PM
@JM I have done that befor. BRB
@JM It's NotebookAutoSave
 
@SjoerdCdeVries Ok. I executed it first in the help window, and then in my notebook. Started a clean session. Executed only in my nb, and works
 
In the option Inspecor
 
@SjoerdCdeVries Thanks! It sucks that entering plain "autosave" in the help file doesn't give that as a suggestion...
 
@JM No, but "auto save" does ;-)
 
Should we migrate this one?
2
Q: Mathematica: ListDensityPlot behavior different for arrays and points

Roberto MiguezI am using ListDensityPlot to output the results of a physical simulation. I've passed both an array of values and coordinates coupled with magnitudes to ListDensityPlot. Although I expect identical functionality it seems the points are interpolated differently. I've recreated the problem in a ...

 
5:45 PM
@belisarius Yes.
 
@JM ?*AutoSave* also works
 
@JM What is the right way? flagging for mod attention?
 
@SjoerdCdeVries My search skills are clearly at a decline... :)
@belisarius Yep, flag it; it seems there are SO mods actively buzzing about, so turnaround shouldn't be too long...
 
CHM
6:16 PM
Dear god...
0
Q: The way to release carbon by either

VictorIs there a way to turn organic compound into inorganic compound even it is very difficult? So, if it is possible, can people release carbon from their DNA to suicide. Also, what is the different between physics way and chemistry way?

 
R.M
I had a lot of fun trying to learn and write some java code for my answer yesterday... I can now see why Leonid is trying to popularize his java reloader
 
CHM
@RM the only Java I ever wrote was when I played with Processing. Fun.
 
@CHM Wouldn't setting it on fire turn most organic compounds to inorganic ones?
 
CHM
@Heike You'd have to define organic and inorganic first, words between which a boundary is hard to draw.
But yes, in the usually understood sense of "inorganic", it would.
 
@CHM it was "voluntarily" removed by the user.
 
CHM
6:28 PM
@Heike there's also this advice, if you're interested.
@rcollyer Yes, I've just seen that.
He removed both his questions.
I have no problem with neophytes asking questions, as long as the questions are clear xD
 
Sometimes the questions you get are just surprising, and not in a good way. It is also a question of where do you begin to explain things to them.
 
CHM
Exactly. When the question is too vague, you could basically refer the OP to a textbook.
 
and hope it works ...
 
CHM
Heh.
 
or at least they come away with some questions that are answerable.
 
CHM
6:33 PM
Well the kid is in highschool, and seemingly not fluent in English. So the threshold is lower than if he were a graduate student, as is the guy offering advice on how to extinguish a sodium fire.
 
@CHM Oh, dear me...
 
CHM
Haha.
 
@CHM oh, absolutely. I give non-native speakers a lot of leeway, and tend to go out of my way to edit there questions to be readable to a native speaker.
 
Alkali metal fires are fun when you're just watching them from afar. When you're directly in front of them... hoo boy.
 
High school students may as well be non-native speakers of any language ...
@JM isn't there something about UV radiation coming off of them?
 
6:35 PM
@rcollyer "Yo, wazzup pops?" ;)
 
@JM exactly.
 
CHM
@rcollyer Ha!
 
@rcollyer I was thinking more of the caustic smoke, actually...
 
@JM that doesn't help matters either. I suppose you could deal with the "sunburn" once you can breathe.
 
CHM
@rcollyer Hmm.. UV, not sure, but IR and Vis, definitely.
| Section2 = | Section3 = | Section4 = | Section5 = | Section6 = }} Chlorine trifluoride is an interhalogen compound with the formula ClF3. This colourless, poisonous, corrosive and extremely reactive gas condenses to a pale-greenish yellow liquid, the form in which it is most often sold (pressurized at room temperature). The compound is primarily of interest as a component in rocket fuels, in industrial cleaning and etching operations in the semiconductor industry, in nuclear reactor fuel processing, and other industrial operations. Preparation, structure, and properties It was f...
 
6:37 PM
@CHM Not an alkali metal, but I thought Mg fires gave off UV.
 
@CHM visible light in spades, natch. Why else are flame tests so popular for these ones?
 
@JM Nice yellow color for Na.
 
@rcollyer I don't remember Mg fires going up to UV emission myself. If I wanted UV, I'd melt silica in a kiln...
 
@CHM sounds almost as appealing as FOOF!
@JM I thought I had read that somewhere ... Oh, well, I'll defer to the experts.
 
@rcollyer I still think that stuff should have been called OOFF. FOOF just sounds too innocent.
 
6:39 PM
@Heike But the (implied) bonding ain't right...
 
@Heike FOOF is the sound something makes when it comes in contact with dioxygen diflouride.
 
Also, the treachery is part of the nastiness.
 
@CHM Oh joy, fun. :) :P
 
@rcollyer "as if millions of voices suddenly cried out FOOF in terror and were suddenly silenced"
 
6:41 PM
@CHM I remember reading that. Somehow I blocked it.
 
CHM
TL;DR "a one-ton spill of the stuff. It burned its way through a foot of concrete floor and chewed up another meter of sand and gravel beneath"
@rcollyer I follow him. I'm not an org_chem, but I like the perspective on the industry.
 
@CHM I liked the bit about "self-igniting flamethrowers!" But, I'm a closet pyro ... Then again, I wouldn't touch (or go near) the stuff.
 
@rcollyer Pyrophores are nice. I once had "fun" with Raney nickel myself...
 
@CHM another fine quote 'That means that it can potentially go on to “burn” things that you would normally consider already burnt to hell and gone, and a practical consequence of that is that it’ll start roaring reactions with things like bricks and asbestos tile.'
@JM Raney nickel?
 
CHM
@rcollyer Catalyst.
 
6:45 PM
@CHM Ah. So, its fun to work with, for some absurd definition of fun?
 
Chock-full of nice inflammable hydrogen in a powdery metal, so...
 
CHM
@rcollyer Haha. It's a catalyst for when you want to hydrogenate alkenes. Maybe it's used for more than that... but that's all I know.
 
I made the mistake of letting it out of the oil it was immersed in (being a dumb student at the time), and thus...
 
Big flames?
 
CHM
@JM Does it make a sound when burning?
 
6:46 PM
I scorched the hood, yes.
 
CHM
Fuck, k.
 
@CHM I don't remember, but maybe that was because the instructor's screams of panic were louder...
 
The most exciting thing I ever did under a hood involved making iron chloride (not sure of the exact electrical state of iron). It made pretty crystals. Of course, my lab partner (the actual chem major in the equation) decided to leave his fingerprints in the reaction vessel glass by touching it shortly after it was sealed.
 
CHM
Either +2 or +3
 
@rcollyer If it's the one used for printed circuit boards (the orangey kind), it's ferric (+3)...
 
6:50 PM
@CHM I think it was +3, but I'm not sure it was that well controlled.
 
Ferrous would be somewhat greenish, OTOH.
 
had to be ferrous, but it was well over a decade ago, so I honestly don't recall the color.
 
CHM
Gotta go.
See you.
 
@CHM See you.
 
@CHM bye.
That makes two of us. Talk to you later, @JM
 
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