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munirah
munirah
06:10
Hai and Good day. May anyone help me how can I evaluate each row and column in matrix in given below,

A={{E^(I*[Beta]1 + I*[Beta]3)Cos[t[Beta]2], E^(I*[Beta]1 - I*[Beta]3)Sin[t[Beta]2]}, {(-E^((-I)[Beta]1 + I[Beta]3))Sin[t[Beta]2], E^((-I)[Beta]1 - I[Beta]3)Cos[t[Beta]2]}}

For[t = 0, t < 10, t++, t = t + TimeUsed[]; Print[newm1]]
[Beta]1 = 0; [Beta]3 = 0; [Beta]2 = Pi/2;

I get the output not for 10 loop.tq
 
2 hours later…
István Zachar
István Zachar
07:41
Another annoying historically frozen factoid:
Why is the operator form of `Unequal` the ill-named `\[NotEqual]`? Aaaargh.
 
2 hours later…
Szabolcs
Szabolcs
09:29
If anyone wants to make more community ads, check this out: meta.mathematica.stackexchange.com/q/1924/12
Meta
Meta
09:48
2
Q: How did you make your community ad?

SzabolcsThis is a thread where you can share your Mathematica code, graphics template, or whatever other source material that you used to create a community ad (if you wish to do so). The purpose is to make it easier for others to create similar ads, or to update your ad in the future if the need arises...

discussion advertising
Szabolcs
Szabolcs
10:33
@Kuba Okay, I didn't read your code, but I read your idea, and it seems to be a very good one. For the permutations question.
Kuba
Kuba
@Szabolcs thanks, undeleted, I thought I made a mistake but that wasn't the case.
Szabolcs
Szabolcs
11:04
@Searke @Vitaliy I posted this ad because I think the link is useful and I hope it will reduce the number of draining novice questions. But I am worried about intellectual property issues ... could you help me find out if there would be any problems? Note that the text is lifted directly form the site that this is linking to.
user image
If this is okay, I would like to post a few more ads, all aimed at beginners: wolfram.com/programming-lab and wolfram.com/language/fast-introduction-for-programmers
Szabolcs
Szabolcs
11:31
If anyone feels like making ads, please make one for this site: reference.wolfram.com/legacy/flash
2
I'm done for today (no time)
 
2 hours later…
kirma
kirma
13:21
user image
Random doodling once again...
Shutao TANG
Shutao TANG
13:42
Hello, everyone! Did somebody know how to look up the source code of C library function, such as sqrt() in head file math.h?
user image
kirma
kirma
@ShutaoTANG That would typically be found on libm supplied by your OS/distribution/operating environment.
Shutao TANG
Shutao TANG
@kirma The main compiler in my laptop is MinGW, howeverm I cannot find the math.cfile via windows search operation.
kirma
kirma
13:59
See this, for instance:
124
A: How does C compute sin() and other math functions?

Jason OrendorffIn GNU libm, the implementation of sin is system-dependent. Therefore you can find the implementation, for each platform, somewhere in the appropriate subdirectory of sysdeps. One directory includes an implementation in C, contributed by IBM. Since October 2011, this is the code that actually ru...

Shutao TANG
Shutao TANG
user image
kirma
kirma
(Square root is a bit special on IEEE circles though, because it's ought to not produce arbitrary results... functions like sin are not really guaranteed to do anything similar.)
Sometimes these things are directly implemented as instructions or helper instructions on machine code, but often nowadays using approximations...
And talking about not finding "math.c" ... usually these functions are compiled into libraries and actual sources are not included in a regular installation.
Shutao TANG
Shutao TANG
@kirma Got it. Thanks a lot for your help.:)
kirma
kirma
Frankly, you don't want to look at implementations of many of these functions. :}
"Rediscovered" A003136 while playing with hexagonal lattices. Well, it was my goal too, I just didn't know the sequence nor its identifier.
Shutao TANG
Shutao TANG
@kirma I think it is very useful for me to learn C, because I have learnt the basic mathematical theoy, such as advanced mathematics, numerical analysis, etc.
kirma
kirma
14:17
@ShutaoTANG Accuracy of IEEE floating point calculations is a field of its own, really. Also, it's related to approximating functions, which is not really a field that so many people have to study, and floating point quirks just complicate the matter.
It's interesting, but I've given up attempts to recreate such functions (at least in C) long ago...
But it's good to know that different implementations of functions beyond addition, subtraction, multiplication, division and square root may be arbitrarily off from true rounded value, and that value may differ from implementation to implementation!
I stick to integer C on my professional work (thankfully it's pretty easy).
 
2 hours later…
J. M.
J. M.
15:58
@kirma I am a bit interested in how you're generating the black honeycomb. The code I have for those is rather messy.
kirma
kirma
16:16
@J.M. I abuse VoronoiMesh in this case... NeighborhoodGraph would be another option.
Shivanand
Shivanand
Hi People. This is my first time on chat
:)
;3
kirma
kirma
16:31
@J.M. Heh. I'm trying to reduce my code to a simple example, and seem to fail on it. :)
J. M.
J. M.
@kirma I see; mine is messy because of the multiple rules on how to translate hexagons. :D
kirma
kirma 
With[{vecs = {{Sqrt[3], 0}, {0, 1}, {Sqrt[3]/2, 1/2}}},
  {FaceForm[],
   With[{r = 10},
    {EdgeForm@Black,
     Select[Norm@RegionCentroid@# <= r - 3 &]@MeshPrimitives[#, 2] &@
      VoronoiMesh@
       Select[Norm[#] <= r - 2 &]@
        N@Flatten[
          Table[{i, j, k}.vecs, {i, -Ceiling[r/Sqrt[3] + 1],
            Ceiling[r/Sqrt[3] + 1]}, {j, -Ceiling[r], Ceiling[r]}, {k,
             0, 1}], 2]}]}] // Graphics
Not pride of my life!
J. M.
J. M.
It's not that long and incomprehensible... ;)
kirma
kirma
16:46
Hmm...
Michael Hale
Michael Hale
@kirma @J.M. Wolfram uses the following hexagon tiling code in NKS 
With[{m = 10, n = 10},
 Graphics@Table[
   RegularPolygon[{i Sqrt[3], j}, 1, 6], {i, 1, m}, {j, Mod[i, 2], n,
    2}]]
J. M.
J. M.
@MichaelHale I already have something like that (and it generates a GraphicsComplex[] to boot!); what I was interested in was the hexagonal arrangement of those hexagons.
Generating that particular arrangement required messy code on my part, involving a long Which[].
4
A: Create a torus with a hexagonal mesh for 3D-printing

J. M.As The Toad remarked in a (now deleted) comment, I have had some experience with building hexagonal meshes (after seeing previous work by Mark McClure). In fact, this was one of the reasons why I asked this question on generalizing Partition[]; I wanted to be able to construct a GraphicsComplex[]...

kirma
kirma
@MichaelHale Hmm.
J. M.
J. M.
user image
That previous Gravatar of mine relied on generating the hexagons in an arrangement similar to kirma's.
As I said, messy code.
 
1 hour later…
kirma
kirma
18:01
@J.M. Most code tends to be messy when it's functional. I think Mma has a tendency to make that happen, but at the same time that ease to bring those interesting results out.
Shivanand
Shivanand
Nobody is answering my question: mathematica.stackexchange.com/questions/120723/… :(
JasonB
JasonB
@Shivanand Or the other one that seems like a duplicate.....
It's a tricky situation, you are trying to get the volume of a region that is/might be vanishingly small
Shivanand
Shivanand
18:21
@JasonB @JasonB What do you suggest?
JasonB
JasonB
@Shivanand If I had a suggestion I would post it there. I've played around with the code from the first post a bit (Are the posts asking different question? If not, delete the second one), and I didn't come up with anything
I do wish there was a nice way to find the volume of the region you are seeking, but I can't figure it out. The posted answer leaves out the first region - which won't discretize so you can't go that route.

You mention other values that lead to non-zero volume. Maybe post those as well, so that you aren't first seeking a vanishingly small volume
Shivanand
Shivanand
@JasonB The second question uses a theta of 85 degrees and that has a non-zero volume of intersection. I will delete the first one.
mathematica.stackexchange.com/questions/120723/… is the question which needs attention.
Wolfram Blog
Wolfram Blog
18:38
Wolfram Blog: Behind Wolfram|Alpha’s Mathematical Induction-Based Proof Generator
posted on July 14, 2016 by Connor Flood

An idea, some initiative, and great resources allowed me to design and create the world’s first proof generator using induction, which recently went live on Wolfram|Alpha. Motivation It is no secret that Wolfram|Alpha is a well-used tool for math students, especially those taking first-year college and university math courses. In fact, one of the most [...]

Searke
Searke
@Szabolcs I'll send an email to the right people. I'm not sure I've ever been asked something like this :)
Szabolcs
Szabolcs
19:13
@Searke Thank you!
Searke
Searke
@Szabolcs They said it was fine.
Szabolcs
Szabolcs
@Searke Wow, that was quick!
Thanks again
Searke
Searke
Yes, well I happen to know how to contact lawyers very quickly
it's a skill you develop when you talk to customers a lot
Szabolcs
Szabolcs
19:38
@Everyone: I posted a few more ads. meta.mathematica.stackexchange.com/a/1917/12 Please vote on them, or if you don't like them let me know what to change.
2
Karsten 7.
Karsten 7.
20:24
search.wolfram.com/?q=new+in+11.0
The Summary of Features in 11.0 New Since 10.4 link is already there.
search.wolfram.com/?q=new+in+11
The New in 11: Alphabetical Listing link too.
Szabolcs
Szabolcs
21:01
@Karsten7. No page there ...
Ah, I see what you mean. It comes up in the search.
kirma
kirma
21:15
Plenty of features one can work out just by reading search results.
Simon Woods
Simon Woods
user image
Work finally bought me a new computer :-)
kirma
kirma
Most functions found by that search in v11 are related to machine learning, some to audio and "channels" (?), and even smaller portion to good old math...
m_goldberg
m_goldberg
@Mr.Wizard. I am waiting for an answer to the email I sent you before proceeding on the edit you proposed. Did you receive the email? I don't want to put pressure on you, but you should know that I will not begin the task until I get your response to the issues I raised.
 
1 hour later…
Simon Woods
Simon Woods
22:27
@blochwave , have you seen this? mathematica.stackexchange.com/q/102538

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