Wolfram Mathematica

8:01 PM

Have you visited @Szabolcs?

In my favourite Chinese language book, which is quite outdated (early 80s), it is written that people address each other as 同志 (=comrade). Well, it turns out nowadays that means "gay" (not in the "happy" sense!)

@Rojo China? Yes.

I won't pretend to know much about it though.

Heike

The orchestra I'm playing in is going to China in December. I'm still on the fence about going.

Szabolcs

@Heike What instrument do you play?

Heike

@Szabolcs The cello.

Szabolcs

@Heike That's one of the coolest instruments these days :-)

Sjoerd C. de Vries

8:09 PM

@Szabolcs Used to be different?

Szabolcs

I don't know, but it's definitely very popular now!

Heike

@Szabolcs Is that so? Nearly everyone I meet likes the sound of the cello.

Sjoerd C. de Vries

We have a cross hatching question. I'm sure we have dealt with that before but I cant find it

Heike

@SjoerdCdeVries I remember a discussion about this on mathgroup.

Szabolcs

21

Q: Filling a polygon with a pattern of insets

I am trying to fill a shape with diagonal lines. I am aware of Texture, but it rasterizes the fill pattern, which is not desirable. Here was my crack at it: Graphics[{FaceForm[White], EdgeForm[Black], Polygon[{{0, 0}, {1, 0}, {1, 1}, {0.5, 1.5}, {0, 1}}], Sequence@Table[ Inset[Graphics...

graphics

Sjoerd C. de Vries

8:12 PM

That was a couple of years ago. Iknow I participated in it

Szabolcs

groups.google.com/forum/?fromgroups#!topic/…

Heike

hmm, looks like David Carraher beat me by 12 seconds.

Sjoerd C. de Vries

OK, I see why I couldn't find it. Its not named crosshatching there

Szabolcs

I used Google, it's easier.

Heike

Oh no, David deleted his answer.

Szabolcs

8:15 PM

Does anyone here know what this is?

Heike

a raft?

Sjoerd C. de Vries

@Heike It looks like a full duplicate. Andy Ross' answer is about RegionPlot too. I think I'm going to close this.

Heike

@SjoerdCdeVries That's fine by me,

Sjoerd C. de Vries

Thor heyerdahl

Kon tiki raft

Heike

@SjoerdCdeVries That's it. I couldn't remember his name.

Kon-Tiki

Kon-Tiki was the raft used by Norwegian explorer and writer Thor Heyerdahl in his 1947 expedition across the Pacific Ocean from South America to the Polynesian islands. It was named after the Inca sun god, Viracocha, for whom "Kon-Tiki" was said to be an old name. Kon-Tiki is also the name of Heyerdahl's book and the Academy Award-winning documentary film chronicling his adventures. Heyerdahl believed that people from South America could have settled Polynesia in pre-Columbian times, although most anthropologists now believe they did not. His aim in mounting the Kon-Tiki expedition was ...

newprint

8:20 PM

@Heike you got it first

I read several books about it + seen some documentaries

Szabolcs

They're making a new film about it. I was an extra, a small dot in the crowd ...

Heike

@Szabolcs Sounds like fun.

@newprint Sjoerd got it before me.

Szabolcs

kontikifilmen.no

Heike

Thor Heyerdahl must be one of the most optimistic people around to dare cross the ocean on a raft.

newprint

There was another expedition

Sjoerd C. de Vries

8:26 PM

@Szabolcs They filmed at Malta?

newprint

on the raft that was build based on ancient raft

but I don't remember the name of it

Sjoerd C. de Vries

@newprint Ra, using a papyrus boat

newprint

Ra

you are right

Sjoerd C. de Vries

I remember I read a book about the kon tiki expedition when I was a kid

newprint

Just for fun

Couple day ago

Sjoerd C. de Vries

8:28 PM

This really was scary. No GPS, no followers nothing

Heike

Ra and Ra 2 are the ones I remember.

newprint

I have seen the news that Viking possibly carried Native Americans to Europe !!!!

Sjoerd C. de Vries

what's the evidence like?

newprint

they found some woman skeleton

that is Native American Descent

Sjoerd C. de Vries

Cool.

newprint

8:31 PM

Another fun archeological news was that in one of the Japanese burial sites

they found artifacts from Ancient Rome !!!!

Sjoerd C. de Vries

Uhmm, that doesn't prove anything

You can still find Roman artifacts in Rome

newprint

well, it is in Japan .........

Heike

I saw a documentary once about statues they found in central America that had distinct negroid features but were thousands of years old.

Szabolcs

@SjoerdCdeVries Yes. Quite a few films are shot in Malta.

Sjoerd C. de Vries

@Szabolcs I know the Libanon scenes in "Munic" were shot there

imdb.com/title/tt0408306

Szabolcs

8:43 PM

Troy and Alexander too. Haven't seen them though.

Last year they shot some bug Hollywood zombie film.

Heike

@Szabolcs I think Agora was filmed there as well.

(not a very good film by the way)

Sjoerd C. de Vries

Alexander was pretty bad too

Szabolcs

mfsstudios.com

Sjoerd C. de Vries

@Szabolcs You didn't do your doctoral defence in Malta did you?

Szabolcs

No no.

My gf works in Malta.

Sjoerd C. de Vries

8:45 PM

@Szabolcs so, how do you end up there?

ah, I see

Heike

@SjoerdCdeVries I watched that film with a bunch of historians and classicists which didn't help.

newprint

In NMinimize function, is is possible to specify limits for search ?? Looked over documentation and could not see anything

Sjoerd C. de Vries

@Heike bad script, bad acting

Szabolcs

@newprint next to the expression, e.g. x && x > 0

newprint

I have a function z[x,y] that I want to search from -1 to 1 for both x and y

Sjoerd C. de Vries

8:48 PM

@heike did you see The Prestige? It was on TV last week.

Heike

@newprint you could try something like NMinimize[{z[x, y], -1<x<1, -1<y<1}, {x,y}]

@SjoerdCdeVries I've seen it before.

Sjoerd C. de Vries

What did you think of it?

Heike

It's a bit creepy, but I like it a lot.

Sjoerd C. de Vries

Good acting, interesting script with interesting twists. Some food-for-thought. Reminded me of a few chapters in the Mind's I (hofstadter/Dennett)

newprint

haha
NMinimize[z[x, y], {x, y}]
{-1.27726, {x -> -1.07533, y -> -0.122678}}

while
NMinimize[{z[x, y], -2 < x < 2, -2 < y < 2}, {x, y}]
{-2.47524, {x -> 0.29547, y -> 0.613262}}

NMinimize[{z[x, y], -1 < x < 1, -1 < y < 1}, {x, y}]

Heike

8:56 PM

@SjoerdCdeVries The plot reminded me of a joke about an american and a russian astronaut who are talking about their equipment. The american astronaut is bragging about how they spent years developing special pens that work in zero-gravity whereupon the russian astronaut replies that they just use pencils.

@newprint Under "Possible issues" in the documentation of NMinimize it says that: "For nonlinear functions, NMinimize may sometimes find only a local minimum", so that's probably what happened here.

newprint

my function is somewhat complex z[x_, y_] :=
Exp[Sin[60.0*x]] + Sin[50.0*Exp[y]] + Sin[80.0*Sin[x]] +
Sin[Sin[70.0*y]] - Sin[10.0*(x + y)] + (x*x + y*y)/4.0;

Oleksandr R.

@newprint try setting the NMinimize method. I'm not certain what the default is (I think InteriorPoint for constrained problems), but you can often do better yourself.

newprint

In[25]:= NMinimize[{z[x, y], -1 < x < 1, -1 < y < 1}, {x, y},
Method -> "NelderMead"]

Out[25]= {-0.87776, {x -> -0.73531, y -> -0.301899}}

In[26]:= NMinimize[{z[x, y], -1 < x < 1, -1 < y < 1}, {x, y}]

Out[26]= {-0.87776, {x -> -0.73531, y -> -0.301899}}

R.M

@Szabolcs Is my answer here related to what you were looking for here? (Of course, without the whole redefining Definition bit)

newprint

@OleksandrR it errors out NMinimize::bdmtd: Value of option Method -> InteriorPoint is not Automatic, "DifferentialEvolution", "NelderMead", "RandomSearch", or "SimulatedAnnealing". >>

Oleksandr R.

9:09 PM

@belisarius I was confused by that as well until Mr.Wizard pointed out to me that it is more a matter of racial stereotyping than actual profiling. For instance, in the US there is a stereotype that "Asians" (by which I think it means [Han] Chinese, Koreans, and Japanese) are more intelligent and harder-working than other ethnic groups (if you can group those three together as a single ethnicity in the first place).

As this is a technical site with a global membership of people who mostly have rather international tastes, Quantserve probably gets confused when mapping visitors here to a narrow US-focused ethnic stereotype.

R.M

Hmm... looks like Leonid's answer does the same.

@OleksandrR It's IP and census based, and generally they use only US data

Oleksandr R.

@newprint sorry, "InteriorPoint" is either a postprocessor or a FindMinimummethod. The docs suggest Method -> {"RandomSearch", "PostProcess" -> "InteriorPoint"}, which sounds sensible to me.

@RM Oh, I didn't realise that it was only based on US data. Okay then.

R.M

@OleksandrR quantcast.com/mathematica.stackexchange.com

Oleksandr R.

@RM I have Quantcast/Quantserve blocked. Have to unblock them to see that...

R.M

The "discrepancy" is probably due to the higher concentration of visits from US universities (given the scope of our site) and the census records for the neighbouring areas are bound to have a higher concentration of Asians than in the rest of the state.

Oleksandr R.

9:17 PM

@RM makes sense, although stackexchange.com as a whole seems to have more Asian visitors than average.

R.M

@OleksandrR Again, the same argument... Gaming, Math, SU are among the biggest sites :)

Oleksandr R.

@RM our site also has a younger but more affluent than average audience. I wonder if that reflects a similar kind of confusion, or do grad students get paid more in the US? :)

R.M

@OleksandrR No, but college areas are generally high PCI regions — Cambridge, MA, Berkeley, CA, etc.

Oleksandr R.

@RM indeed.

Szabolcs

10:06 PM

@RM Can you ping me again? I'm too tired to look now and I hate it that I can't mark messages as unread!

R.M

10:16 PM

Ok, I'll ping you tomorrow

acl

10:30 PM

@SjoerdCdeVries it is, but for me it is worth the money, mainly because it has a non-zero repertoire of classical; I guess that surprised me enough to make me pay for it in the beginning, and now I use it as a radio replacement.

@SjoerdCdeVries I don't think you can. I use an app (Goodreader) to store pdfs on my ipad. But I understand @Heike's problem, if you view it as a computer it's limited

@Szabolcs Kon-Tiki!

(ok should read the whole discussion before answering.... I read about it as a child and got excited when I saw it!)

Sjoerd C. de Vries

@acl I have tried it a few days. It has all kinds of fringe composer's like Steve Reich, so it's pretty good. But then the idea taht you buy for like 6 CD's per year, but at the end you don't have nothing, is less appealing.

acl

@SjoerdCdeVries there also exists a full seaworthy replica of this

Kyrenia ship

The Kyrenia ship is the wreck of a 4th century BC Greek merchant ship. It was discovered by Greek-Cypriot diving instructor Andreas Cariolou in November 1965 during a storm. Having lost the exact position Cariolou carried out more than 200 dives until he re-discovered the wreck in 1967 close to Kyrenia in Cyprus. Michael Katzev, a graduate student at the University of Pennsylvania Museum of Archaeology and Anthropology, directed a salvage expedition from 1967-69. Preservation of the ship's timbers continued during the winter of 1970. Katzev later was a co-founder of the Institute of Naut...

@SjoerdCdeVries I agree, but that is a general problem with this model.

Sjoerd C. de Vries

@acl But that's not one of Thor H's ships isn't it?

acl

@SjoerdCdeVries no, I hadn't realized you were talking about rafts. I had more in mind ancient ships that have been re-built and are seaworthy

Sjoerd C. de Vries

@rojo you were passed by @JM

@acl szabolcs played as an extra in a movie about Thor Heyerdahl

acl

10:43 PM

@SjoerdCdeVries yes I am slowly reading the rest of the discussion...

the closest I've been to movie stardom was being accidentally featured smoking in the background while the Rector of Imperial College was being interviewed by the BBC

Sjoerd C. de Vries

@acl That's nice too ;-) Count your blessings

Or was smoking prohibited, and you were fined afterwards?

acl

@SjoerdCdeVries luckily not :)

Sjoerd C. de Vries

@acl I'm going to bed. I wanted to stay up to see me pass the 10k line, and that happened a couple of minutes ago. Happy camper.

R.M

@SjoerdCdeVries congrats! :)

acl

@SjoerdCdeVries congratulations!

Sjoerd C. de Vries

10:49 PM

@r.m @acl Thanks

Beers are on the house!

R.M

Cheers!

@acl You could try this: itunes.apple.com/us/app/air-sharing-for-iphone-ipod/…

Although it says ipod/iphone, I think it works on the ipad too

yeah, just found it in the store under ipad apps

acl

@RM Thanks. Goodreader is fine for what I need (I also have a program for my papers). Most of my documents are pdfs, with a small number of powerpoint presentations that I've downloaded, so I'm not that worried about other formats

Sjoerd C. de Vries

well, good night guys.

acl

@SjoerdCdeVries night

R.M

@acl oh, certainly. Goodreader is great! I used to use Papers for mac on my laptop, but I read that it isn't all that great for the ipad

good night @SjoerdCdeVries

acl

10:54 PM

@RM I use Sente on both

expensive, but it works well

papers on the mac I thought was all flash not much power (I got it on a grant, paid for sente myself; that tells you something)

R.M

Papers (v1) was the only cataloging system I've used, so can't say much other than it was better than my folderwise organization.

acl

@RM what do you do now? put papers in manually organized folders?

R.M

@acl No, I still use papers on mac, but on my ipad I just have goodreader. The thing is only 3 days old, so trying to come up with a sane organization (topic wise in folders)

On my laptop, I also maintain (by hand) a large .bib file of every paper that might potentially be useful, rather than exporting from papers

acl

@RM yes, exporting from anything can get ugly. I end up constructing bibliographies by hand

every single time! guess I am doing something wrong...

R.M

yeah, each journal has its own wonky way of entering the metadata (and some don't at all) and papers adds its own flavour to it and shakes things up sometimes... I'm perfectly comfortable with doing it manually (doesn't take that long) to keep things organized and the way I can remember/recall in future

acl

11:01 PM

@RM doesn't take long, but it's tedious

R.M

Well, when I wrote my first paper, that was when I was just starting to build my bibliography file after getting frustrated with export formats. That was tedious. Now if I spend more than 15-20 minutes reading a paper and think it might be something worthwhile, it goes in the bib file. That way, the work is spread out over days and I have most things in there before the next paper is written

I bought wacom's bamboo stylus to write on the ipad... it's not bad, although I feel it could've been a lot better

Rojo

@SjoerdCdeVries, not much I can do, I've been at 200 rep today for about 8hs :P

R.M

@Rojo have you tried not overachieving? ;)

acl

@RM I also have a stylus but don't really use it. I like a mechanical pencil on thick paper for calculating and writing notes, then I type them and store them on the computer (or scan them if they are heacy calculations)

@RM yes and emacs/auctex can find the reference for you (ctrl-[ then a few letters and it finds it), right?

R.M

@acl yeah, that's pretty much exactly how I use it (vim, but the idea is the same)

Rojo

11:06 PM

@RM, that's I try, but it's hard :P

acl

@RM vim, right :)

R.M

@Rojo I get more annoyed on the days I stop at 180-190 and can't get two more to hit the cap than on days when I get upvotes after hitting the cap

I think I have about 20 or so days at 180, with 10 or more at 190+... one day it was at 199!

@acl It's now more a smudge-free replacement for my finger :)

Rojo

haha

acl

@RM yes the smudges... terrible. when I think of how much it cost me...

R.M

I didn't care so much for the ipod touch, because I didn't buy it.. but this — my precioussssss

acl

11:15 PM

@RM soon the smudges will become invisible

Oleksandr R.

@RM thorlabs.com/thorproduct.cfm?partnumber=MC6

R.M

ha, I'd look funny with that

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