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3:23 AM
@R.M You here?
 
R.M
3:58 AM
@belisarius yup
 
4:35 AM
@R.M Do you remember a 3D plot made by Vitalyi something like a cube, in red /yellow tones with solid regions with gaps in between?
 
R.M
Vitaliy or Artes? I think I remember something like that by Artes
 
ahhh ... may be it was Artes
@R.M damn ... searching for an image is not easy here
 
R.M
10
A: 3D Plot: Number of Roots in x of a polynomial in x, a, b and c

ArtesDefining your polynomial as p[x_, a_, b_, c_] := the formula I'd do this : Manipulate[ CountRoots[ p[x, a, b, c], {x, 0, Infinity}], {a, -100, 100}, {b, -100, 100}, {c, -100, 100}] If a plot is needed one can proceed this way : ListContourPlot3D[ Table[ CountRoots[ p[x, a, b...

That?
 
No, the other one was formed by "solid" 3D regions
 
R.M
Hmm...
 
4:45 AM
@R.M it was more like a tetrahedron than a cube
 
R.M
@belisarius The answers here?
If it's tetrahedron-like, then it could be Yaroslav's question nah.
 
@R.M Nope, forget it. Too difficult to search for an image
@R.M No, it was big image with many colored symmetric regions
Thanks a lot anyway :)
 
R.M
ohh.. I think I know what you're referring to. That's Vitaliy's and I even mentioned it should've been a superhero's insignia
hold on
 
OK
@R.M Yep. I think thats the one
 
R.M
10
A: Why don't I get numeric values from this Solve?

Vitaliy KaurovThis works (it's obvious the same will hold for negative integers): Reduce[a^2 + b^2 == c^2 && 0 < a < 100 && 0 < b < 100 && 0 < c < 100, {a, b, c}, Integers] And if you're up for an interesting visualization, here is my take: ListPlot3D[{a, b, c} /...

 
4:54 AM
@R.M Yep +1 :) Thanks a lot. Google haven't find it
hehe it WAS a cube
 
R.M
@belisarius No worries :) If a little bit of context is known, it is possible (although not as easy as it should be) to search. For example: user:13 ListPlot3D OR Plot3D OR ... can be used for all 3D functions used in answers by vitaliy
 
@R.M And that returns all Vitalyi's answers :D
 
R.M
:D
 
@R.M Do you have a fast machine?
 
R.M
yes
 
4:59 AM
and a few minutes of spare CPU?
 
R.M
sure, dump the code
 
@R.M Copy the second code block from here
0
Q: Several functions in one RegionPlot with different grayscale

ApaturaI try to plot the following, but something seems to be wrong in my code and I can't figure out how to fix it: RegionPlot3D[{CountRoots[\[Sigma]q33[\[Omega], V1, V2, V3], {\[Omega], 0, Infinity} == 0], CountRoots[\[Sigma]q33[\[Omega], V1, V2, V3], {\[Omega], 0, Infinity} == 1], ...

from the q
and then
ee[v1_?NumericQ, v2_?NumericQ, v3_?NumericQ] :=
CountRoots[\[Sigma]q33[\[Omega], v1, v2, v3], {\[Omega], 0,
Infinity}];
Show[Table[RegionPlot3D[
ee[v1, v2, v3] == i, {v1, 0, 50}, {v2, 0, 50}, {v3, 0, 100},
Mesh -> None, LabelStyle -> (FontSize -> 14),
PlotStyle -> Directive[GrayLevel[ i/10 + 1/10, 3/10]],
BoundaryStyle -> None], {i, 0, 4}]]
 
R.M
 
Wonderful! do you want to edit the answer and add your plot? Or do you want me to do it?
thanks!
 
R.M
@belisarius Oh, you can just add it
 
5:10 AM
@R.M Ok! I will credit your machine! ;p
 
R.M
Hehe, not necessary :) The answer and code are yours, after all :)
 
done!
 
R.M
I still have no clue what he wants and why he can't use a simpler example for the problem
Now running with 50 points
 
@R.M Because he doesn't have a clue about where his problem is :(
 
 
1 hour later…
6:30 AM
0
Q: 2012 Moderator Election - Town Hall Chat Digest

Tim StoneThe following is a "digest" version of the 2012 Moderator Election Town Hall Chat. The format, as described on Meta Stack Overflow, is one answer to this question for every question asked in the Town Hall, containing all the candidate's answers to that question. To view the digest chronologicall...

 
Shut up, you robot!
 
@Beli don't you have a GPU?
 
@GustavoBandeira Nahhh ... just an old laptop
 
@belisarius I have a NVIDIA GTX 460
I'll try to render that plot with plot points.
 
@GustavoBandeira ok!
 
6:36 AM
It's not working.
Lemme show ya
 
did you load the function from the question first?
 
hmmm
 
I've insulated it now and evaluated it.
 
which Mma version?
 
6:41 AM
Why do you use ; at the end of the function?
Version:8.0.0.0
 
because it is defined with "=" and not ":="
 
ee[v1_?NumericQ,v2_?NumericQ,v3_?NumericQ] **:= ** CountRoots[σq33[ω,v1,v2,v3],{ω,0,Infinity}];
??
 
Oh that one!
It doesn't matter, really. Just routine
 
Is it possible to make a function without :=?
Didn't know it.
 
a[x_] = 2 x
a[3]
 
6:46 AM
omg
I'm so noob
 
it's just a DownValue
go read about that in some posts. The Mma docs about DownValues stinks
 
If I evaluate the function alone, with = instead of :=, I get:
CountRoots::nupx: [Sigma]q33[[Omega],v1,v2,v3] is not a univariate polynomial in [Omega] with Gaussian rational number coefficients. >>
 
Wait, I will start a fresh session
start a new session and run this
\[Sigma]q33[\[Omega]_, V1_, V2_,
V3_] = (1/48 (Exp[-V1] + Exp[-V2]) (1 + Exp[-V3]) +
1/48 (Exp[-(V2 - V1)/2] - Exp[(V2 - V1)/2])/(Exp[(V2 - V1)/2] +
Exp[-(V2 - V1)/2]) ((Exp[-V1] -
Exp[-V2] Exp[-V3]) - (Exp[-V2] - Exp[-V1] Exp[-V3])) +
1/8 ((Exp[-V1] - Exp[-V2] Exp[-V3]) + (Exp[-V2] -
Exp[-V1] Exp[-V3])) (-2 (Exp[-V1] + Exp[-V2] Exp[-V3] +
Exp[-V2] +
Exp[-V1] Exp[-V3]) (-Exp[-(V1 + V2)/2 - V3] +
Exp[-(V2 + V1)/2])/(Exp[(V2 - V1)/2] +
Exp[-(V2 - V1)/2])/(\[Omega]^2 + (Exp[-V1] +
Exp[-V2] Exp[-V3] + Exp[-V2] + Exp[-V1] Exp[-V3])^2)) +
 
Done.
It works.
 
now you can play with plotpoints
 
6:54 AM
I've switched from 3 to 12.
Let's see...
Is it possible to do OOP on Mathematica?
 
I'll give you a link
wait
here
29
A: Tree data structure in Mathematica

Leonid ShifrinIn Mathematica, most of what you do is based on expressions. Expressions naturally have the tree structure. For depth-first traversals (which are probably most common), you can then use functions like Scan,Map, Cases etc. The difference w.r.t the more traditional languages is that there is no sim...

and the links therein
 
In Mathematica, most of what you do is based on expressions.
Is it differente in other languanges?
 
@GustavoBandeira Well, yes. Other languages may (for example) be data driven
 
What's the difference?
 
@GustavoBandeira You define a data structure (a template for holding data) and then you operate over that.
 
7:07 AM
OOP Languanges are like that, right?
 
@GustavoBandeira err ... no. In OOP you define classes, not data structures
wait, I'll give you a link
this is a nice book on data structures
 
Thanks for it.
 
@GustavoBandeira Did it finish?
 
@belisarius I chose a lower number because it took much time.
 
@GustavoBandeira ok!
 
7:22 AM
I'm doing with 9 now.
 
ok, let's see
 
Where can I upload it?
 
here
like this
upload to imgur and then post the link here
 
ok. downloading
 
7:35 AM
Doing with 11 now - it's taking forever. xD
But it's not freezing the PC
 
nice thanks!
 
I'll make the last: 12 =D
 
OK!
uploaded your n=11 to the answer
 
7:51 AM
12 - last one.
 
awesome. I'll upload it to the answer
@GustavoBandeira Here is it
1
A: Several functions in one RegionPlot with different grayscale

belisariusee[v1_?NumericQ,v2_?NumericQ,v3_?NumericQ]:= CountRoots[σq33[ω,v1,v2,v3],{ω,0,Infinity}]; Show[Table[RegionPlot3D[ ee[v1, v2, v3] == i, {v1, 0, 50}, {v2, 0, 50}, {v3, 0, 100}, Mesh -> None, LabelStyle -> (FontSize -> 14), PlotStyle -> Directive[GrayLevel[ i/10 + 1/10, 3/10...

thanks again. Going for some sleep
 
Ok.
Cya. =)
 
 
6 hours later…
2:08 PM
Anybody around?
@TimStone?
 
What's up?
 
@GraceNote?
 
Joel Spolsky on September 20, 2012

We’ve all heard the stories of seemingly trivial patents being used to mug technology companies. There was the patent on the “Interactive Web” which a troll named Eolas used to extract $521 million from Microsoft–until a jury in East Texas threw out the patents. There are the four patents Lodsys is using to send threatening letters to software developers everywhere–trivial patents that Google says never should have been granted, in fact, Google and Oracle have submitted mountains of prior art to show that the patents should be invalid. …

 
@GraceNote Hi! I have a new user asking in a comment logged in with my google account, does it mean I'm registered or I have sign up differently? (sorry for the silly question)
 
@belisarius Erm, link?
 
2:10 PM
0
A: Solving antisymmetric tensorial equation

belisariusPerhaps f = RandomInteger[{-1, 1}, {4, 4}]; Solve[ And @@ Join[ Thread[Equal[Flatten[Table[ Sum[f[[l, i]] s[j, l, k] - f[[l, j]] s[i, l, k], {l, 4}], {i, 4}, {j, 4}, {k, 4}], 2], 0]], Flatten@Table[s[i, j, k] == s[j, i, k], {i, 4}, {j, 4}, {k, 4}]]]

I can't find a useful link for him
 
He's registered
 
Ok! so I'll ask him to change his name. Thanks!
 
2:21 PM
@belisarius Teeny tip: if a user is unregistered, the word "Unregistered" will appear near the user's name in the corresponding profile.
 
@J.M. I think I saw it. Perhaps he registered later (or I imagined that)
 
 
5 hours later…
6:57 PM
posted on September 20, 2012 by Wolfram Blog Team

Mathematica users around the world answered our call to prove their programming prowess in our recent Mathematica Experts Live: One-Liner Competition. And once again, we were blown away by what our users did with just 140 characters or less of Mathematica code. Videos from the webcast where we revealed the winner and runners-up are now [...]

 
 
3 hours later…
9:58 PM
@WolframBlogFeed Congratulations to faleichik (has to be the same guy, right?)
Oh and congratulations on the honorable mentions to @DavidCarraher and @YvesKlett. I don't recognise any of the other names on the list, but maybe they are members unders a different name. If so, congratulations to them as well.
 
@Verbeia I only feel disappointed about the prizes. WRI could do better than that
 
Oh wow, I'm just playing with faleichik's winning entry. So cool!
Unfortunately the work firewall blocks curated data downloads so I can't try half of them here.
 
10:54 PM
related to the earlier discussion on unupvotes - have a look at this. Is anyone else experiencing what looks like drip-feed serial upvoting?
 
@Verbeia You mean b/c the votes are on old posts?
 
@belisarius Also because it's rarely the same post twice on different days. If it was different users I'd expect more overlap.
anyway, gotta go - lots to do today
 
bye!
 
R.M
11:15 PM
@belisarius doesn't look like it... most of them were bumped to the front page because of an edit, so someone might have come across it then
 
@R.M Yep. I don't feel an "upvoting rage"
 

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