Wolfram Mathematica - 2012-09-05

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12:01 AM

Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers () was a general encyclopedia published in France between 1751 and 1772, with later supplements, revised editions, and translations. It was edited by Denis Diderot and Jean le Rond d'Alembert. As of 1750, the full title was Encyclopédie, ou Dictionnaire raisonné des sciences, des arts et des métiers, par une société de gens de lettres, mis en ordre par M. Diderot de l'Académie des Sciences et Belles-Lettres de Prusse, et quant à la partie mathématique, par M. d'Alembert de l'Académie royale des Sciences de Pari...

Preliminary Discourse to the Encyclopedia of Diderot

The Preliminary Discourse to the Encyclopedia of Diderot (Discours Préliminaire des Éditeurs) is the primer to Denis Diderot's Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers, par une Société de Gens de lettres, a collaborative collection of all the known branches of the arts and sciences of the 18th century French Enlightenment. The Preliminary Discourse was written by Jean Le Rond d'Alembert to describe the structure of the articles included in the Encyclopédie and their philosophy, as well as to give the reader a strong background in the history behind the wor...

That was the true revolution

Down with religion. Down with infix

I,am fond of maxwell, tait, kelvin myself. But that is bias. Anyway, ordering historical figures in order of importance is tricky

The Preliminary Discourse to the Encyclopedia of Diderot is arguably one of the best introductions to the French Enlightenment, giving forth the idea that man possesses the capability, through his own intelligence and analysis, to alter the conditions of human life

And that was said there for the first time ... in history

@Verde but all this on a high level. maybe it plants the seeds for common men (such as you and I) to eventually be able to do that (ie, actually do something with their so-called intelligence) and maybe not.

but I am just disagreeing for the fun of it, I don't really know and have never reached any definite conclusion about these things (nor will I)

I mean, even in physics, people tend to consider feynman as a demi-god while someone like Landau is somewhat human. but in practical terms, Landau changed the face of physics in many way subtle ways, while feynman at most in one (path integral viewpoint)

but anyway, I am babbling

@acl You are misunderstanding them. THEY were the first people ever to say that "you and me" have the rights (and obligation) to do something for ourselves, notwithstanding what the powers that be say.

no god, no king

just you

@Verde maybe I am, but I am not sure that a) they were the first to say it, b) that them saying it is what made it so (to the extend that it is)

(and no I can't come up with someone else saying it!)

but thinking about historical civilizations that I know about, this seems to be the first in which the idea came up

12:12 AM

regarding a) in modern times, yes. perhaps someone else like Spartacus (not Mr Wizard). but I doubt it. It was a real revolution.. Regarding b) Yes, I studied them a lot

@Verde about b, it could be; I just don't know. but thinking about it, that does seem to be the impression I formed in the past. I am just being difficult I guess.

and I doubt anybody in the ancient greek or roman context came up with something like that. this kind of thinking is alien to that genre of civilization

(let's hope I'm not shot on arrival next week when I go back to greece)

@acl No, it's really difficult to get an idea about how they thought. They were not only clever, but very brave. The whole Royal police was following them, and they had to have the intelligence to divert them while they wrote whet was the most important book in history

and it was not the bible :)

to get back to fantasy-land, what you say reminds me of books by Neal Stephenson.

(rather large leap I made there, I guess, but basically, I personally never think of "political" issues when I think of this kind of thing, while Stephenson's books mainly deal with those--sort of)

@acl Oh well, I read mostly older literature

@Verde you might enjoy Stephenson. try "Quicksilver"

12:26 AM

amazon.com/The-Gallic-Oxford-Worlds-Classics/dp/0192835823

Newton is a central character, and done well

read it in Latin, much better

@Verde the problem I have always had with this sort of thing is that it's impossible for me to get into their minds. I just can't get into it, I only read.

and I don't read Latin!

@acl That is not an excuse

@Verde right, I could learn. OK, I'll tack it onto the end of the (constantly re-sorted) todo list.

12:29 AM

Snorri Sturluson

Snorri Sturluson (1179 – 23 September 1241) was an Icelandic historian, poet, and politician. He was twice elected lawspeaker at the Icelandic parliament, the Althing. He was the author of the Prose Edda or Younger Edda, which consists of Gylfaginning ("the fooling of Gylfi"), a narrative of Norse mythology, the Skáldskaparmál, a book of poetic language, and the Háttatal, a list of verse forms. He was also the author of the Heimskringla, a history of the Norwegian kings that begins with legendary material in Ynglinga saga and moves through to early medieval Scandinavian history. For styli...

don't hold your breath :)

read him too

"As an historian and mythographer, Snorri is remarkable for proposing the theory (in the Prose Edda) that mythological gods begin as human war leaders and kings whose funeral sites develop cults"

@acl snorri was a genius

@Verde but also a "people-person": "Snorri quickly became known as a poet, but was also a successful lawyer"

12:31 AM

@acl nobody remember a lawsuit

his poems and stories are superb

@Verde but everybody remembers those that are succcessful in getting others to listen to them (of course, there should be something to listen to)

come on, surely you've seen this!

what?

@Verde what what?

THIS

that the primary skill is getting yourself in positions of power!

12:33 AM

the problem is how.

just compare R. Reagan with Gandhi

look, I once read a book where the issue of how it is that the fact that Nobel prize winners tend to be students of Nobel prize winners comes about

If you want to learn politics read machiavello and Julius Caesar. They wrote everything everyone repeated after them

conclusion: "N prize winners tend to recognize genius".

nahhh

@Verde no OK, we're talking at cross purposes

12:36 AM

no, I am drinking beer

maybe that's the trick

do you want some?

no I have a number of bottles of wine here

wine is too strong to be able to tall about science

@Verde depends on your baseline

in my case it makes no appreciable difference, which is probably not good

12:40 AM

hmmm ... I had a fellow at university who usually went to finals with a bottle or more. His gaze was the same. They never knew. He became a famous physicist. I can't share his name here ...

:)

the only person I remember being intellectually intimidated by (I know how arrogant that sounds) used to go to his exams stoned. luckily he's a mathematician so we never had to compete for anything

stoned means I saw him sitting on the Queen's Lawn and smoking

@Verde This is the translation I like:

amazon.com/Penguin-Book-Norse-Myths-Vikings/dp/0140258698/…

he didn't look any different

@acl I understand. Regrettably I had quite a few close friends at uni that became very famous. None of them went to an important exam "clean"

@Verde well, that taught me that intelligence is relative, so I count it as a plus

12:46 AM

@rcollyer I used to read Borges'

@Verde Never read him.

borges? you have to read him!

Gustavo Bandeira

1:32 AM

Good evening!

@GustavoBandeira hi!

Gustavo Bandeira

You've read Borges?

amazon.com/Unimaginable-Mathematics-Borges-Library-Babel/dp/…

This book is in my table.

@GustavoBandeira clap beat clap

@GustavoBandeira Borges is one of my favorites

Gustavo Bandeira

@Verde What's it about? I still dunno.

1:38 AM

The Library of Babel

"The Library of Babel" () is a short story by Argentine author and librarian Jorge Luis Borges (1899–1986), conceiving of a universe in the form of a vast library containing all possible 410-page books of a certain format. The story was originally published in Spanish in Borges's 1941 collection of stories El Jardín de senderos que se bifurcan (The Garden of Forking Paths). That entire book was, in turn, included within his much-reprinted Ficciones (1944). Two English-language translations appeared approximately simultaneously in 1962, one by James E. Irby in a diverse collection of Borge...

Gustavo Bandeira

It seems interesting.

The book I suggested seem to be some kind of analysis on it.

@GustavoBandeira Borges is very interesting to read. He is baroque, in a sense. But also very human

A man who loved books

I happen to knew him

Gustavo Bandeira

This is kinda similar to me.

I love books, I have a small amount of books here.

I want a remix on this: Ask Stack Exchange

0

Q: Mathematica is going haywire

Click here Then click on ALG023.MA I then evaluated the notebook. It the asked me to enter the function which is, .5+.25x^2-xSin[x]-.5Cos[2x] The initial approximation is 15.708 The Tolerance is 10^-7 The number or iterations is 50 I then pressed 1 to get it from the screen And then finally pres...

This question.

He asked me about on MSE chat.

I guess the procedure he's trying to achieve is incredible heavy.

I ran it here.
Mathematica - 4GB ram.
Math Kernel - 2GB ram.

Computer almost froze.

3 hours later…

Gustavo Bandeira

4:42 AM

library.wolfram.com/howtos/faster/#procedural

"But procedural programming compared to functional programming gives, with very few exceptions, extremely poor performance." It wasn't so clear to me: It gives poor performance on Mathematica or procedural programming gives poor performance in general?

@GustavoBandeira in Mathematica. It makes no sense to insist on functional programming in a language that doesn't support the paradigm.

Gustavo Bandeira

@J.M. Oh. Sad...

I've learned to program instinctively.

On Mathematica.

And I see all my code is functional.

@J.M. I'm curious with something: Every programming languange - depending on it's level - should have core basic functions - for manipulating data. Isn't it?

@GustavoBandeira Sure, you have objects, and functions that act on them...

Gustavo Bandeira

Where can I find reference on what are these core functions? - I'm searching specificaly for some generalist book - considering it exists.

I want something like this:
There's a list. And there are n basic functions to deal with them.

I hope I'm being clear.

I don't know what's being read now, but you seem to be looking for a language-agnostic book on programming, yes?

Gustavo Bandeira

4:53 AM

Exactly.

The nearest books I have on this are:
Concepts in Programming languanges - Robert W. Sebesta
Concepts in Programming languanges - John C. Mitchel, krzysztof Apt

To be honest, if I were you, I'd focus more on learning algorithms themselves than focusing on being language agnostic.

If you understand the algorithms intimately, you shouldn't have trouble adapting what you know to a language you're confronted with.

In other words: look for algorithm-oriented books. Like Sedgewick's.

Gustavo Bandeira

5:09 AM

@J.M. Ok. Thanks for your suggestion.

The language agnosticism will naturally drop out of you comfortably knowing the algorithms, in that you can write the algorithm whether you use a for() loop, a while() loop, or (heaven forbid) a label and goto.

Gustavo Bandeira

@J.M. It seems he's giving a free course on Coursera: coursera.org/course/algs4partI

2 hours later…

6:56 AM

hello: quick stupid question: do you have to sign up to gravatar to change your avatar on SE?

@chris yes

@R.M ok then.

Gustavo Bandeira

@chris It depends, whenever I have to change my avatar, I must change it on google's account.

I guess it takes the avatar of the account you're using to log in.

@GustavoBandeira the avatar is tied to your email, not the openid

Gustavo Bandeira

Oh, ok.

@Verde I am a one element on the set of nice people.

7:03 AM

@GustavoBandeira nice people don't claim to be nice, ergo... :)

Gustavo Bandeira

@R.M But I am different.

I can be nice and claim it.

youtube.com/…

lol

4 hours later…

11:00 AM

Hmm, no one around again...

user image

I decided to update old Mathematica code I had for an old toy. It turned out okay, I suppose.

3 hours later…

Sjoerd C. de Vries

2:14 PM

@J.M. Nice! I had that toy once, and my son got it for solving a math quiz or so.

Not sure whether the snake had a continuous rubber band built in. You could wind it up as much as you liked.

@verde I asked for migration.

@SjoerdC.deVries OK!

2:48 PM

@SjoerdC.deVries Glad you liked it! :) Actually, I combined two versions of the snake in that diagram; the version that had prismatic segments, and the version with quarter-torus segments. It looked cool to have both at the same time... (seeing that Opacity[] wasn't in the old Mathematica).

This one's my favorite:

user image

A Transformer?

Well, something like that... :)

I've managed to do most of those shapes; still, it doesn't beat having the actual toy...

@J.M. That page has a troyan

delete your link

It does? Damn...

yep

user image

3:02 PM

Ah, Firefox. Didn't get a warning in Opera... oh well.

As with all alerts ... It could be fake, but ...

...better safe than sorry.

2 hours later…

Gustavo Bandeira

5:13 PM

Good afternoon.

Can you guys help me with something?

This:
Clear@a
Table[Table[a \[And] b, {a, 0, 1}], {b, 0, 1}] // TableForm

Evaluates to:
0&&0 1&&0
0&&1 1&&1

I want it to evaluate to the truth table of and.

True != 1

Change your iterators to be {a, {False, True}}

Hi @Verde

Gustavo Bandeira

@Verde Won't it consider this operation as valid?

s = {True, False}; Table[a && b, {a, s}, {b, s}] // TableForm

@Rojo Hi!

Gustavo Bandeira

Oh thanks.

Is there a way to "translate" the Falses and Trues to 0 and 1?

5:19 PM

{True, False}/. {True->1, False->0}

Gustavo Bandeira

@Verde Thanks.

:)

Gustavo Bandeira

I didn't know I could do this: {a, {False, True}}

it's most useful

In[1]:= Boole /@ {True, False}
Out[1]= {1, 0}

5:22 PM

yep

Gustavo Bandeira

Supose I'm trying to program something like this:
http://turner.faculty.swau.edu/mathematics/materialslibrary/truth/

I imagine that I should have a function to count the number of variables inside my boolean expression.

And generate a table for everyone, like the previous example:
Table[Table[a \[And] b, {a, {False, True}}], {b, {False, True}}]

Gustavo, did you check out the related built-ins?

Gustavo Bandeira

What can I use to do this? It's some kind of nesting function, right?

For example

BooleanTable

and all his friends

Gustavo Bandeira

BooleanTable

Yep.

I didn't know about that.

Thank you.

But the knowledge on the suposed nesting function is also going to be useful.

I usually like to program things for no specific reason, more like a challenge.

5:30 PM

So what's the issue now?

Detecting the variables?

Gustavo Bandeira

The nesting function.

I'm trying something around:
t[y_] := Table[y]
Nest[Table, x, 4]

Well

You'll have to look for another challenge again

Gustavo Bandeira

What one?

You can do Table[blah, {a, iter}, {b, iterb}, ...]

No need to nest

Gustavo Bandeira

I could have n variables in my boolean function, then I could have n {a,iter}, right?

How could I make a "builder" that would build n of those structeres inside the table?

I would try something with tuples.

5:36 PM

Well

Depends on where you start from

Gustavo Bandeira

Tuples[{{a, 0, 1}}, 2]

Like this.

With[{list = {True, False}, op = {And, Or, Xor, Xnor, Nor}},
 	TabView[# -> Framed@TableForm[Outer[#, list, list], TableHeadings -> {list, list}] & /@ op]]

@GustavoBandeira ^^

Gustavo Bandeira

@R.M Yep. But it lacks generality: I could have a boolean expression like: a&&b&&¬c||d&&f||g||¬h

uhh... well, you're on your own then :)

On your own, with BooleanTable offended for life

2

5:46 PM

but in all seriousness, that's not hard to implement either, although I don't see the point of having such an n-dimensional "table".

Gustavo Bandeira

2 days ago, by Verde

How he dares to insult FindMinimum so easly

@Rojo Now I'm insulting BooleanTable

@Verde Verde = Green. Why is your avatar blue, then?

@GustavoBandeira @Rojo pushed me away from the RGB triplet

2

Gustavo Bandeira

I'll get some color for my nickname.

Yellow.

Mathematica community will be similar to GB Pokemón versions.

If I go yellow, it means Pikachu will chase me forever. =/

6:03 PM

Hahaha

Gustavo Bandeira

Anyone played metal slug?

I love this theme.

@GustavoBandeira don't take green… I claim green-on-white

user image

and I get my awesome new power, which is… “approve tag wiki edits”?! wtf

you also get the suggested edit queue :)

@R.M I already did: mathematica.stackexchange.com/review-beta/suggested-edits

not that there's much to do on this site

@F'x Isn't that now, after you have 5k? I don't see any reviews by anyone with <5k

6:13 PM

@R.M I have one, from before I had 5k

@F'x that must've been in beta, no?

but probably, I will now get the main-menu notification if there is any review to be done

@R.M no, no, the link was there already, I think

those beta tools lowered the bar for the review queue (which is good)

oh well... it's a big gap from 3k to 10k anyway (privileges wise)

well, it's not bad, really…

it's just that, you know, I got used to the super tools, so now I feel frustrated not having them on some sites

:)

@Verde you around?

6:18 PM

@R.M yep

Gustavo Bandeira

@R.M He went for his GB after I mentioned pokemon.

@GustavoBandeira I gave one to my son last month

Gustavo Bandeira

@Verde You have a son? I thought you were 19 years old.

@GustavoBandeira mentally, yes

Gustavo Bandeira

...

6:20 PM

perhaps 12

Gustavo Bandeira

Oh, 19 years old mentally? Or you mentally have a son?

whatever you prefer

Gustavo Bandeira

Haha

countryPolyArea[country_String, poly_String: "Polygon"] :=
 Graphics`Mesh`PolygonArea /@ (CountryData[country, poly] /.
    Polygon[x__List] :> Polygon /@ x)
Total@Abs[countryPolyArea["World", #]] & /@ {"FullPolygon", "Polygon",
   "SchematicPolygon"}
Function[{poly},
  Total@Flatten@
    Abs[countryPolyArea[#, poly] & /@
      CountryData[]]] /@ {"FullPolygon", "Polygon",
  "SchematicPolygon"}

@Verde see the results for "Polygon". Of course, this is based on Mercator projection, so not indicative of actual area, but probably gives a hint

Gustavo Bandeira

@Verde To you.

Shit. I wanted my dad to be a pro Mathematica user. =/

6:24 PM

@R.M Are you sure "polygon" and "area" are connected? ... I think the area should be curated data

no, not sure. But their numbers didn't seem to coincide with Wikipedia, so I'm wondering if each of those are from different sources which account for disputed territories differently...

If GB declares the English Channel as hers, WRI should add up that "surface"

but not the polygon

hmmm are the lakes and rivers considered "land"?

@Verde "LandArea" doesn't count water bodies

"Area" does

7:01 PM

Why is this question so popular? It has nothing to do with Mathematica really, and everyone seems to be jumping in for the fun... not that there's anything wrong with it (I did too), but is this a common question to ask on a programming site?

@R.M It's just fun. I am writing another answer OCRing Fred's table

haha!

Reminds me of WReach's classic answer on SO... the question was something like "How can I <some trivial operation> using For loops" and he had several answers, all of them a variation of For[i=1, i<10, i++,];<obvious answer>

@R.M Brilliant! I don't remember those

it's gone now...

3 hours later…

9:51 PM

@R.M. Probably because it is so simple and it does not take much time to do something funny. I guess a lot of people do not really have that much time to post lengthy answers. At least I don't (or maybe I type too slow).

10:03 PM

@RolfMertig well, at least people are enjoying themselves :)

I was more curious about the problem... sounded like an intro to computation class assignment (or an intro to an intro). I find it weird that someone would be asked to implement this without multiplication and I don't know if it is standard for programming courses (I've never had a formal introduction to programming, so I can't tell)

@R.M introception!

10:52 PM

This gives errors in version 7. Anyone know why?

NonlinearModelFit[{
 {1,0,0},{1,1,0},{1,2,0},{1,3,0},{1,4,0},{1,5,0},
 {1,6,0},{1,7,0},{1,8,0},{1,9,0},{1,10,0},
 {2,0,-1},{2,1,-(1/4)},{2,2,-(1/13)},{2,3,-(1/28)},
 {2,4,-(1/49)},{2,5,-(1/76)},{2,6,-(1/109)},
 {2,7,-(1/148)},{2,8,-(1/193)},{2,9,-(1/244)},
 {2,10,-(1/301)}
 },
 KroneckerDelta[i,1]*Re[1/(p1+I*p2+I*(p3+I*p4)*x^2)]+
 KroneckerDelta[i,2]*Im[1/(p1+I*p2+I*(p3+I*p4)*x^2)],
 {p1,p2,p3,p4}, {i,x}
]["ParameterErrors"]

I mean, it produces messages. It also yields the sought-after errors in the parameters, apparently correctly. It's the messages I'm concerned about.

11:16 PM

@OleksandrR. Internal`LocalizedBlock::novar: -- Message text not found

@OleksandrR. Table[3*n^2+1, {n, 10}]

user image

Plot3D[-y/(3 x x + 1), {x, 0, 10}, {y, 0, 1}, PlotRange -> All]

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