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02:00 - 23:0023:00 - 00:00

2:02 AM
Anyone in here?
Hi Rojo!
Whats up @SjoerdC.deVries
Just arrived on the final leg of my vacation. Finally wifi again.
Nice... How long is the leg?
2:04 AM
6 days Anything of interest happening the last couple of days?
I lost my contiguous presence streak somehow
@SjoerdC.deVries Hi!
Hey @belisarius
Did you got to the center of the earth?
or came short?
@SjoerdC.deVries Well, I haven't been very active this week up to last night
I even asked Mr.Wizard the same yesterday
No, I missed the entrance, but I was close: 13 km of the Hekla vulcano
2:07 AM
Hey @neighbour
@Rojo hi!
How is it in the third world nowadays?
@SjoerdC.deVries I was re/rereading the book with my son a few months ago. The descriptions of Iceland are very impressive
Bus prices just went up 100%
Common stuff
2:09 AM
Just use cars. No problemo
You park it for me? :)
@SjoerdC.deVries USD 5 per gallon :D
That's what drivers are for, aren't they?
In the Netherlands its €1.7 / liter
@SjoerdC.deVries Do you need a maid? I can find one here that can program Mma almost for free
Family of yours?
2:13 AM
@SjoerdC.deVries Well, I cook pretty well
I am nice with kids
I saw your BBQ picture on seasoned advice
Oh no! that was an Internet photograph ... my bbqs are much better
Well, I'm working to lose weight so BBQs on your scale is something to avoid.
In that context, vacationing in the US is dangerous
@SjoerdC.deVries Losing weight. Learning Wavelets. Exercising. They are all in my schedule
@belisarius Where are you learning wavelets from?
I'm interested
2:18 AM
I'm almost at my set goal, I'm now at 83 kg with my 6 ft 4 frame
@Rojo Not yet, but I have a list. I will look for it tomorrow
@SjoerdC.deVries You were on diet on vacations? That is sinful!
@Rojo Did you try my exclusions question?
Well, I started before that. Just tried to not gain to much. Pretty difficult here, given the uhuge portions you get in the restaurants here.
@SjoerdC.deVries What is the typical food there?
I am always interested in learning about the important things in life: food, food, and something else I never remember
Breaded and deep fried stuff. Lots of cheese and fat.
@SjoerdC.deVries Fishy or meaty stuff?
2:26 AM
Everything. I've head tuna, haddock, shrimp, but also chicken and steak.
sounds interesting!
I usually pick just an appetizer and steal a few gfrench fries from my kids
hi rc!
hola! Just checking in.
@SjoerdC.deVries how's the trip going?
Hi rcollyer
Im now very nearby I suppose
Arrived in cape cod this afternoon
2:29 AM
Ah, Massachusetts. Nice.
Got ripped off in NY
Well that sucks.
Remember my $13/night wifi?
It happened to be per device...
We have 4 iPhones and 2 iPads
2:31 AM
@SjoerdC.deVries You can ^&^&$## here all night for $13
Ask Rojo
Talked it down to 3, but it sucks anyway
How do they justify that? Idiots.
Policy, hohum
You can buy a whole access point for that amount
I was thinking something along those lines ... buy an access point (no more than $20-30 required), and set up your devices to use that, while the point is the only thing that accesses their network.
2:34 AM
@SjoerdC.deVries How did they knew all those devices were yours? did you use the same access key for all?
They may get a little pissy with that, but who cares.
You had to go through an access page and press lots of accept buttons. I guess they check MAC addresses
Charged to the room
sounds to me like you'll be using their hotel again.
Not bloody likely
Well, perhaps, but I won't use their wifi
I remember with nostalgia those days when I didn't care about the connectivity at the hotel
2:37 AM
the sarcasm tags seemed to have been stripped, again.
@belisarius Sorry, I'm not getting pinged properly and my firefox is about ot die
I don't blame it with the number of tabs I have
@belisarius I wonder about that ^$^$## thing?
@belisarius Could you link me to the exclusions question?
@Rojo weird. I'm running about 30 right now between 3 or 4 windows. You?
@SjoerdC.deVries Ask Rojo. He is younger
2:39 AM
@rcollyer Only 78
I've been at 250
Q: Managing Exclusions in Plot[]

belisariusWhen I do: l = {5, 6, 6, 5, 6, 6, 5}; f = Interpolation@l; g[t_] = D[f[t], t]; p1 = Plot[{f@x, g@x + 4}, {x, 1, Length@l}, Evaluated -> True, Exclusions -> True] I expect: However, since Plot[] doesn't detect the discontinuities, I get: I have two ways to overcome this, ...

@Rojo and I thought I had a lot open. :)
@belisarius I'm a gentleman, we don't discuss things like that.
@rcollyer I don't like boomarks :P
@Rojo apparently not. Oh well. Firefox can handle it, maybe.
2:41 AM
@SjoerdC.deVries I thought int'l goods prices were of your interest.
@belisarius how old are you actually, if I may be so rude to ask?
@SjoerdC.deVries I am 13, since my last divorce
need something to eat
20 sausages?
2:46 AM
@SjoerdC.deVries perhaps a hamburger. Alone tonight
How about a salade nicoise
@belisarius so only 10 then. :)
@SjoerdC.deVries remember YOU are the one on diet!
Hi, @Verbeia!
I'm fascinated by food all the time, just because of my diet
2:47 AM
@rcollyer sounds nice. yesterday I had lamb. superb!
@belisarius yum.
I don't like lamb that much
I am starving. See you l8r!
Hi all, I'm back. I thought this was interesting. I wonder if there is a community with the momentum we had for Maple

Proposed Q&A site for users of all experience ranges with Maplesoft's numerical analysis software.

Currently in definition.

@belisarius bye
Hi @Verbeia
2:49 AM
@Verbeia could be interesting. They need 40, 10+ questions, though.
In the interests of not having proposals languish, of course.
In three days we had that already.
I just received the Founder badge
We only had 21 questions, total
And, 11 at 10+.
How could I automatically translate all my Maple stuff into Mma and be happy?
@Verbeia Hi and bye!
@belisarius go get food, already!
2:53 AM
@rcollyer the rules were different then. I have no doubt we would have worked out the extra questionsin another day or so.
@Verbeia No doubt. Just I think the increase in questions will do more harm than good.
@belisarius You used Maple?
On your question, how about deleting the vertical or "almost vertical" lines in the plot?
Anyway just dashing in and out. Back later, see you.
@Rojo Just enough to be sure that there are better things under the skies
2:54 AM
@Rojo you might like to try Opera. Currently I have 165 windows open, which for me is a fairly small number (300 isn't so unusual). Opera will use a lot of memory, but it's fine in terms of performance, especially with the latest version.
Apparently, Gaming is the one to beat. 18 of their users have founder badges. We need more of our people to log into Area 51 to claim their badges. We can beat 18, I'm sure of it.
@OleksandrR. I might try it
@OleksandrR. Hi. With that many tabs, how do you differentiate between them? Can't be that big.
2:57 AM
@SjoerdC.deVries the tab metaphor completely breaks down. I disabled the tab bar. Opera has other mechanisms for selecting documents.
Brb, I'm gonna restart this
@belisarius You're the first one I know that used it. Nice to know that
Personally I never liked the tab metaphor at all, precisely for the reason you mention.
@rcollyer I thought I would get the founder badge on my mma profile, but it's in the area51 profile ;(
@SjoerdC.deVries Yeah, that sucks. I wonder if we can convince the powers that be that it needs to be on the launched site...
Okay, I should go to bed. Night all!
3:01 AM
My turn. Bye all.
Night. Me too
I feel spammy
3:21 AM
@R.M try {x, x = 7; x} and enjoy the result :P
3:40 AM
@Rojo what?
4:31 AM
@belisarius I'm not sure I understood if your comment was a "that would be nice" or a "I don't like that"
@Rojo Beer has its downsides
What comment?
@belisarius The side that you put on the table is the downside
The one on your Exclusions question
@Rojo I posted two comments in a row
" I'm sure if I understand your proposal, but I don't like my approach because f[x_]:= 10^6 IntegerPart[x] and f[x_]:= 10^6 x should give different results"
That was the one for me
"Interesting point detection routine" sounds out of my reach
@Rojo Look at the image
Plot[] explores discontinuities on its own
4:35 AM
for some reason, it is not finding the discontinuities in f'
I don't know why
@belisarius test this
h[i_?NumericQ] := UnitStep[i]
Plot[{h[t], 2 UnitStep[t - 1]}, {t, -2, 2}, PlotStyle -> Thick]
From that, I don't think Plot finds the discontinuities with that routine
It must be symbolic preprocessing
@Rojo test this
l = {5, 6, 6, 5, 6, 6, 5};
f = Interpolation@l;
g[t_?NumericQ] = D[f[t], t];
data = Reap[
Plot[ g@x, {x, 1, 7}, EvaluationMonitor :> Sow[{x, g[x]}]] ][[-1,
ListPlot[data , Filling -> Axis]
4:43 AM
Well, it samples more points in the discontinuities
but still, it doesn't seem to detect them for the purposes of excluding them
or to detect them at all
nono, it is sampling because it detects a discontinuity
and tracks it down to see if it can plot it or needs to exclude it
... and arrives to the wrong conclusion ... why?
How are you sure of that?
@Rojo At this time I'm pretty unsure of everything
I mean, that it's not simply some recursive division of the domain in parts, giving more points to the parts with bigger jumps between contiguous samples?
@Rojo that is the same dog, just different rope
4:47 AM
Well, no
because it isn't detecting discontinuities first
Just sampling where it needs more points, without ever caring to decide if there's a discontinuity, or anything
In the example I gave you, you see that the very same function (UnitStep) has its jump excluded when its symbolic, but not when it's numeric
At least it can't only be that algorithm what detects exclusions
I see ... your bet is that Mma is unable to exclude on numerically defined functions
let me see if I can find some counter example
@Rojo NumericQ seems to inhibit the exclusions, yes
@belisarius If you had to find the discontinuities of a symbolic expression
how would you do it? Any good MMA function for that that may be what Plot uses?
@Rojo Limit is enough
but you have to guess the disc point
4:57 AM
or you may check the convergence radius of the series expansion
Anyway, too tired now. Need some sleep
@Rojo Good night!
@belisarius Night!
3 hours later…
7:51 AM
@Rojo Currently at 252 myself. Since they added that Panorama thing to Firefox I never seem to close tabs, I just move them around a lot. :o)
2 hours later…
9:57 AM
Does anyone know how I can open a palette from the Palettes menu programmatically so that the "PalettesMenuSettings" will be preserved?
Q: Programmatically opening a palette from the Palettes menu

SzabolcsHow can I programmatically open a palette from the Palettes menu? Is there a Front End token for this? Motivation: Certain settings for the palettes that are installed into standard locations and show up in the Palettes menu are stored in the "PalettesMenuSettings" global option (accessible ...

Actually belisarius's comment answers it. I missed the correct token yesterday.
10:15 AM
Any Mac users around? @R.M?
What does a MessageDialog look like on Mac? Is it that "rolling down" sheet or an independent window?
11:04 AM
Can anyone try evaluating the following? Import["https://github.com/downloads/szhorvat/SEUploader/SE%20Uploader.nb", "String"]
It gives an error for me, but my web browser does manage to download it.
"For HTTPS connections, you might need to inspect the authenticity of the server's SSL certificate and choose to accept it." - if only I knew how to do it within Mathematica...
:( why oh why oh why does github have to force https for downloads???
really have to find alternative file hosting
@Szabolcs Paranoia?
@J.M. What happens if you remove the s?
just use http, for downloads it should work (just tried)
I'm still getting a FetchURL::conopen error within Mathematica. Odd, since I can download images from within Mathematica...
11:14 AM
@J.M. I think the problem is the space in the name, but I am not sure how to work around it.
Other than upload a file with no spaces in the name.
@Szabolcs Well, how about a different separator, like a dash?
Yes, I'll need to do that.
@J.M. Are you still going to be around for 15 minutes more? I'd really like you to test something :-)
I won't be leaving until 40 minutes, so sure. :)
@J.M. Do you have the image uploader palette installed?
Apparently, not on this computer. Wait...
11:25 AM
@J.M. Can you install it using the instructions here? --> meta.mathematica.stackexchange.com/a/32/12
Let me know if there was something in the installation instructions that was not clear.
I'm on Ubuntu, so I had to un-hide the directory where the palette has to be, but otherwise, it seems clear. (I don't know what's the directory structure in Windows nowadays, so I can't say anything about it...)
@J.M. Okay, so you got the palette in the palettes menu now?
@J.M. Does the Update button work?
It should tell you that there are no updates right now.
@Szabolcs I get the Version Information dialog box.
11:34 AM
@J.M. Does it say that both the online and local versions are 102?
@J.M. Could you try again please?
I really hope the updating will go smoothly.
@J.M. Did it work ... ?
Wait, I'm about to click on the "Update to new version" button...
Well, the update worked nicely. It's now the 103 version.
Phew ...
I'm really happy. :-)
@J.M. One final question: does this work, or does it also complain about HTTPS problems? --> Import["https://raw.github.com/szhorvat/SEUploader/master/ImageUploader.m", "String"]
On the other hand, it might be a good idea to give feedback that the Markdown has been successfully copied to the Clipboard...
@Szabolcs That worked, I see the content of the package file.
11:46 AM
@J.M. If it's not copied successfully, it does give feedback
Hmm, okay.
@J.M. The upload dialog should disappear only when the upload has finished, that should give an indication of how long it takes.
Yes, I tried it just now on a more complicated image.
@J.M. One more update pushed, can you test once more please? Then I'm leaving.
12:02 PM
@Szabolcs It works but complains about SSL Certificate
@RHall Are you on Linux?
@Szabolcs Mac OSX 10.8
@RHall Can you please try Import["https://raw.github.com/szhorvat/SEUploader/master/SEUploaderLatest.nb", "String"]? Does it also complain? What about Import["https://raw.github.com/szhorvat/SEUploader/master/version"]?
@Szabolcs It works.
@Szabolcs it works with the same SSL warnings.
12:05 PM
@RHall Hmmm ... I'll look into that when I come back. Need to go now. I guess in the worst case I can Quiet the specific warning. Can you post what it is exactly, including the message name? (I don't get it on Windows.)
@Szabolcs Yea it's a system message and since I'm on the developers version of 10.8 I can not legally post it yet. Easy to note that you need to answer it though and everything after that runs clean.
@RHall version 10, huh?
@J.M. of OS X, not Mathematica
If it's a system message I can't Quiet it anyway
@Szabolcs Mountain Lion 10.8 current is 10.7
@J.M. Still waiting for MMA 9 like the rest of us though ;)
@Szabolcs Ah. I was about to ask how one gets two versions ahead... :D
5 hours later…
5:37 PM
@J.M. Shhhh
2 hours later…
7:31 PM
I had written an answer for this question, but changed my mind and erased all the text, links, etc. Now, if I try to close the window, I'm asked "Are you sure you want to leave this page? You have started writing or editing a post.", even though I've erased all the text
If I close the tab and then reopen the page, the erased text is still there.
This isn't a problem but I am curious: suppose I want to get rid of the text completely and never see it again. How could I do that?
@OleksandrR. but why not store them as bookmarks? I have my bookmarks indexable and accessible by typing a few characters and pressing return, systemwide. Or is there some reason you need them actually open?
@acl Hey ! I want to see your answer!
@acl you should see a "discard" link somewhere close to the submit button
@R.M ah, I missed that. stupid! thanks
@belisarius if I get some time to finish it I'll post it, but don't imagine any revelations...
7:48 PM
@acl It is tightly related to a very good answer of yours. So, yes, I've high expectations
A: A curious Plot with IntegerPart[x]

aclI've completely overhauled my answer. I believe this now answers the questions posed (why mma thinks the violet line is the derivative of IntegerPart'[x]). Let's first look at ND, simply because its internals are easier to access and we may obtain some insight. Try: Needs["NumericalCalculus`"] ...

@belisarius yes well at that time I was less busy. this period things are too hectic... (and any downtime is invested into beer-drinking)
@acl As in "I spent a lot of money in beer and women, and wasted the rest"
@belisarius right...
@R.M Thanks for the edit. I liked the " " in the title though ...
8:04 PM
@belisarius, the FindCounterExample will be a 3x1
@Rojo ?
FindProof and Prove probably have the same syntax,
ahh .. ok
and I think that Prove calls first FindCounterexample
and if it fails, tries with Find Prove
TraceInternal shows a lot. Let's see if something is understandable
@Rojo Feel free to edit the question if you want
damn repcap
8:07 PM
@belisarius Capped already?
@Rojo yep
I'll go upvote some of your stuff
@Rojo Sadistic impulses on Sunday?
@belisarius oh. I thought you were trying to indicate that it's a function using that instead of backticks...
@belisarius Hehe
I haven't capped since 1st july it seems
I'm on a low rep streak
July 7 my last >100
8:09 PM
@R.M Nope, but the name of the function is so large that I thought the title was clearer with apostrophes
I'm 100 away from 20k... then I can rest
@R.M yeah you may let the hypnotoad to hibernate
8:49 PM
@belisarius Does it tell you anything that the first argument are the "goals" and the second the "axioms"?
and the third argument probably is some kind of integer specifying "how much it searchs for a counterexample", that defaults to Infinity in which case I got no clue what it means
It uses FindInstance
@Rojo Let me think about it
@Rojo EquationalLogic`FindCounterexample[Tan[y/x] == 1, 1 == x^2 + y^2]
returns 100
EquationalLogic`FindCounterexample[x == y, 1 == x^2 + y^2]
returns 31
does not make much sense
9:11 PM
@belisarius Do EquationLogic`FindProof[x == 0, x == 0]
We are getting somewhere
EquationalLogic`FindProof[x x + y y == 2 x x , x == y]
It's probably a work in progress
Well, they can prove that x==0 if x==0. That is something :)
9:17 PM
Still need to work on FindProof[2 x == 2 y, x == y]
EquationalLogic`FindProof[x + x == 2 , x == 1]
@Rojo Hey!
EquationalLogic`FindProof[ x == y , x == 1 && y == 1]
That's smart!
9:33 PM
@Rojo EquationalLogic`FindProof[x == 1, x == 1 && x == 2]
Your axioms are insane already
Your fault
as always
1 hour later…
10:50 PM
@Rojo Found a thing in the trace named skolemconst$
Reduction to Skolem normal form is a method for removing existential quantifiers from formal logic statements, often performed as the first step in an automated theorem prover. A formula of first-order logic is in Skolem normal form (named after Thoralf Skolem) if it is in conjunctive prenex normal form with only universal first-order quantifiers. Every first-order formula can be converted into Skolem normal form while not changing its satisfiability via a process called Skolemization (sometimes spelled "Skolemnization"). The resulting formula is not necessarily equivalent to the original...
02:00 - 23:0023:00 - 00:00

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