Wolfram Mathematica

halirutan

12:45 AM

@Oleksandre Ping..

Oleksandr R.

@halirutan hi!

halirutan

@OleksandrR. Hi.

No luck on Windows?

Oleksandr R.

That is really weird. For me I was seeing undefined references to MLGetRealList etc. using version 3.

halirutan

I got here the following warnigs:

Oleksandr R.

I suppose it could be some oddity in the MinGW libs. qhull itself seemed to work fine.

halirutan

12:53 AM

qh-math.c: In function ‘delaunayQhull’:
qh-math.c:122: warning: passing argument 3 of ‘MLGetByteString’ from incompatible pointer type
/usr/local/Wolfram/Mathematica/8.0/SystemFiles/Links/MathLink/DeveloperKit/Linux-x86-64/CompilerAdditions/mathlink.h:4067: note: expected ‘int *’ but argument is of type ‘long int *’

Did you have a look over the code that all the ML-functions are still called correctly?

Oleksandr R.

Yeah I got that too until I switched to version 2. I got a lot of other warnings as well though. Windows is weird because long and long long are the same according to MSVC and not with GCC. It's a real mess.

Which gcc are you using? 4.7.1 here.

halirutan

patrick@lenerd:/etc/X11$ gcc --version
gcc (Ubuntu 4.4.3-4ubuntu5.1) 4.4.3

Oleksandr R.

OK. Maybe I'm too near the bleeding edge... though I think probably this isn't a compiler bug. I just gave up in the end (rather than try compiling different versions of qhull) but considering the trouble I had, it's surprising it was so effortless for you.

halirutan

What is maybe worth trying is to setup a small extra function calling qh_version and only returning the string to Mma.

So you can be sure it's not the connection to qhull.

I had some hard-time that dependent dll were not found on Windows.

Or are you linking static?

Oleksandr R.

BTW I also had to use g++ to compile qh-math because otherwise #include <string>/<vector> etc don't work and I had to make an extra #define too (per the qhull makefile).

I linked fully static. Saves trouble if I were to send the exe to someone else.

halirutan

1:00 AM

Hmm, I used gcc only.

Oleksandr R.

Well, static as far as qhull goes. Not static MathLink as well (I think that's pointless).

halirutan

@OleksandrR. yes, I meant that.

I really wonder why no one made a working V8 package for this. The build in Delaunay is a mess.

The output is unusable

Oleksandr R.

TBH I never needed anything like that. I just thought I could do a service for paradox2 by compiling it on Windows. But it wasn't so easy as I thought...

halirutan

How do you interpolate on a non-regular grid then?

Oleksandr R.

Well, I don't. :) I never needed interpolation so far.

halirutan

1:03 AM

The easiest thing is to use a triangulation and interpolate the surrounding 3 points to my knowledge.

;-)

Oleksandr R.

Gratz on the 10k btw. I remember at one time we were nearly level, and now you're way ahead!

halirutan

Thanks. That's because you can concentrate on your work, while I enjoy the other funny things far too much.

@OleksandrR. I would trade some rep if you write my paper.. interested? ;-)

Almost everything is finished. Data, analysis, ... just needs to be written down.

Oleksandr R.

Haha. That's exactly the problem for me too. I really hate writing. Currently trying to finish my thesis.

halirutan

Maybe we should ask @Leonid. He seems to be able to concentrate and to reduce other things.

Rojo

2:33 AM

Hello

Mr.Wizard

1:05 PM

@Sjoerd are you around?

Sjoerd C. de Vries

@Mr.Wizard Well yes, but I can't spend much time here now

Mr.Wizard

I would love to see these graphs, among others, for Mathematica.SE:

21

Q: How do I access the StackOverflow API from Mathematica

I was wondering the other day if StackOverflow had an API I could access from Mathematica, and apparently it does: "Saving plot annotations" What's the best way to get data from StackOverflow into Mathematica? Sjoerd used the information to make a plot. I'm interested in adding SO-related noti...

mathematica

Is that possible? If it is, are you willing to do the work?

I don't even know if we have an API on this site. Where would I learn that?

Sjoerd C. de Vries

I could do that. I once made an update to the SE new question alarm, so I know that I can work with the 2.0 API.

Mathematica StackExchange (meta)

1

Q: Include brief explanation of or background for questions?

Someone recently asked how to speed up iterated manipulations of a graph/table and included a (failed) link to an article about why he wanted to do it. It's about something important that has been recently discussed in Seed Magazine, the Publications of the National Academy of Science, and in new...

discussion

Mr.Wizard

Shall I let you ask a question and answer it at your leisure, or would you rather I asked something to kick it off?

Sjoerd C. de Vries

1:09 PM

@Mr.Wizard I'll look into it tonight or at least this week.

Mr.Wizard

Excellent. Thanks!

Sjoerd C. de Vries

Perhaps best you ask a question when I've finished. I'll ping you by then

Tim Stone

@Mr.Wizard (for future reference: api.stackexchange.com)

Mr.Wizard

Okay. Make sure you include halirutan in the graph as his hitting 10K is what got me thinking about this.

@TimStone Thanks for the link. May I assume the API is available for Mathematica.SE? last I checked the DataExplorer was not, for example.

Tim Stone

Yeah, the API is available for all accessible sites. The API routes take a site parameter, which for Mathematica is either mathematica or mathematica.stackexchange.com.

Mr.Wizard

1:15 PM

Do you know when data.stackexchange.com is likely to include us? I recall reading that there were general delays while it's upgraded.

Tim Stone

They ended up purchasing new hardware to move it to, apparently, so taking the delivery and post-delivery setup time into account, it'll be just a few more weeks (second or third week of November).

Mr.Wizard

Glad to hear it.

Tim Stone

In the meantime, if anyone has any Data Explorer feature requests, be sure to post them on Meta Stack Overflow and hopefully I can squeeze them in in time for the Mathematica.SE data to become available. :)

Mr.Wizard

@TimStone speaking of feature requests I once asked if it would be possible to get a shortcut for inserting links to the Mathematica documentation pages. These have a uniform pattern: http://reference.wolfram.com/mathematica/ref/<FunctionName>.html. I would love to be able to enter something like [help:Sum] and have it rendered as a link to the help page for Sum. Now that the site has graduated I'm hoping this can be considered.

Stack Exchange

2:50 PM

Blog - Stack Exchange: SE Podcast #34 – Kyle Brandt and Nick Craver

Alex Miller on October 23, 2012

On the show this week are Kyle Brand and Nick Craver, two SE employees who are heading up our systems upgrades and relocations – they’ll dish all kinds of details on our infrastructure, plus plenty of chat about other mildly relevant things.

First up on the agenda: Quantcast! Five minutes before we started recording, we noticed that Quantcast is ranking our network at #100! (or at least we were for a bit)

If all that additional traffic should cause our New York data center to go down, what will happen, Kyle? Great segue, Joel! We are working on a system for failing over to our datacenter in Corvallis, OR. …

Wolfram Blog

6:29 PM

Wolfram Blog: Calculating the Energy between Two Cubes

posted on October 23, 2012 by Michael Trott

In my last blog post, we discussed 3D charge configurations that have sharp edges. Reader Rich Heart commented on it and asked whether Mathematica can calculate the force between two charged cubes, as done by Bengt Fornberg and Nick Hale and in the appendix of Lloyd N. Trefethen’s book chapter. The answer to the question [...]

Oleksandr R.

@halirutan success! So it turns out that for qhull 2012.1 many of the files have been renamed, and qhull.h doesn't exist any more for C (only for C++). Last time I had tried to compile as C++ so that I could include the file, but the correct thing to do is apparently to just comment out the #include "qhull.h" line in qh-math.c.

Rojo

6:49 PM

Hey

@OleksandrR. , do you know if there's a function in MMA that gives you the representation of a number as 10^10^10^10^sth, as wolfram alpha does?

e.g, WolframAlpha["13^12^11^10^9^8^7^6^5^4^3^2", {{"Result", 1},
"Content"}]

Oleksandr R.

@Rojo good question. No, I don't know. I suspect not.

Rojo

Oh

@belisarius, whatever the algorithm it uses for that, invesigating it may help in your convergence question

I just tried up to 50^49^48...

and in a few seconds it gave me the answer

and the topmost exponent clearly seems to converge

Rojo

7:10 PM

If that's reliable, then Nest[Log, Nest[Factorial, someNumber, n], n] also converges

belisarius

7:57 PM

@Rojo Hypercalc can do those calculations. See the update in my original question

Rojo

@belisarius Seems like it

How

Don't answer, reading the help

belisarius

@Rojo I used the javascript implementation. Easy, but no programming. One calc at a time.

Rojo

Yeah, I'm wondering how it does the calculations

and reading its help

and now I have to leave. It's an interesting read

Later

halirutan

10:03 PM

@OleksandrR. Very nice. Unfortunately the OP seems to have no experience in C-programming and cannot compile it.

Oleksandr R.

@halirutan I posted a comment with the binaries I created. I thought that since the procedure is not exactly simple (at least not the way I did it) and most Windows users don't have any compiler installed or know how to use one, just providing the binaries would be the most straightforward approach.

halirutan

Let me look..

@OleksandrR. Ok, I see. I upload your files onto our git-repo.

Oleksandr R.

Ok, great!

halirutan

10:58 PM

Hi @user141603.

@user141603 Can you talk in here?

@belisarius Does one need a certain amount of rep to talk in the chat?

belisarius

@halirutan yep

halirutan

How much?

@belisarius and if I create and invite someone in a room?

Mr.Wizard

@halirutan mathematica.stackexchange.com/privileges/chat

belisarius

@halirutan I think yes

Mr.Wizard

@halirutan So, yes, that user can talk in here.

halirutan

11:03 PM

@Mr.Wizard Ok.

because I asked him to join and he joined but is silent ;-)

@Mr.Wizard Thx. I always wonder how you find those things so fast.

@Mr.Wizard The bug from his question here is really strange

4

Q: Adding ContourLabels changes contour colors?

I have a set of data s5 such that ListContourPlot[s5, InterpolationOrder -> 6, ColorFunction -> "TemperatureMap", ContourLabels -> True, ColorFunctionScaling -> True] but ListContourPlot[s5, InterpolationOrder -> 6, ColorFunction -> "TemperatureMap", ContourLabels ...

output-formatting

Mr.Wizard

I'm not fast at all. In fact there is one page of the Moderator tools that I can never find. Literally, I've never found it. I have to keep a bookmark to get back to it.

halirutan

Ahh..

This data here spans the interval [1,2] completely:

data = Table[.5 Sin[x y] + 1.5, {x, 0, Pi, .05}, {y, 0, Pi, .05}];

Look at this

ListContourPlot[data, ColorFunction -> "TemperatureMap",
 ContourLabels -> False, ColorFunctionScaling -> True]

and then at that

ListContourPlot[data, ColorFunction -> "TemperatureMap",
 ContourLabels -> True, ColorFunctionScaling -> True]

First one is

second one is

Jin

I saw the Wolfram conf photo, looks great!

Hope whomever went had a good time there

Mr.Wizard

@halirutan In version 7 I get this:

halirutan

@Mr.Wizard You're on Win?

Oleksandr R.

11:13 PM

@halirutan Windows, ver. 8: same result as yours

Mr.Wizard

@halirutan Yes, Windows 7 64-bit.

halirutan

Really weird.

Mr.Wizard

@Jin Which photo is that?

halirutan

@Mr.Wizard The one in Meta..

Jin

yes that one

halirutan

11:15 PM

From this post

Mr.Wizard

Thanks, I hadn't seen that.

Jin

@Mr.Wizard bubububut you're a wizard, you should know everything...

Oleksandr R.

@Mr.Wizard since you're using 7 on Windows, would you mind giving this a try using the binaries I compiled and linked in a comment? (No keyloggers, I promise!) Although I have version 7 installed, the MathLink libs are updated with each version and I want to be certain that something compiled against the version 8 MathLink works in previous versions too.

halirutan

11:30 PM

@OleksandrR. hehe... says the hacker and places his trojan inside qh-math.exe ;-)

Mr.Wizard

@Jin I'm afraid I'm a very bad wizard.

@OleksandrR. Hm... do I take the risk or not. :o)

@OleksandrR. It works fine here.

Oleksandr R.

@Mr.Wizard excellent, thanks.

Disappointingly, the MathLink overhead seems to have grown from version to version. In version 8, with a mesh of spacing 0.005, the triangularization takes 5.3 seconds. In version 5.2, only 3.9 seconds.

Mr.Wizard

Which part takes that long?

Oleksandr R.

Just the triangularization itself. Of course I'm not trying to plot the result.

Mr.Wizard

Sorry, I didn't ask that well. What portion of the time is in the calculation and what is in overhead?

Welcome @David

Oleksandr R.

11:44 PM

Oh, sorry. Okay, well AbsoluteTiming is 5.34 and Timing is 0.34, so that's not enough to account for it; on second though I think the most probable reason is marshalling data between MLINTERFACE version 2 (used by qh-math and Mathematica 5.2) and MLINTERFACE version 3 (Mathematica 7/8).

Mr.Wizard

@J.M. you know you can still use regular stars for things that amuse you...

@DavidSlater are you with us?