Mathematics - 2012-09-08 (page 1 of 4)

12:14 AM

@KannappanSampath I lost your skype

12:25 AM

If I NEED to prove something for one case (e.g. $a = 1$), but then I actually go on prove it $\forall a \in \mathbb{R}$, how do I introduce this? Is "For maximum generality, take $a \in \mathbb{R}$ good?

peoplepower

You cannot alter the theorem statement?

Issac M

That's what I thought. I'm a newb at doing this, thanks.

MeAndMath

12:59 AM

Hello!!!Good night!

@PeterTamaroff,@GustavoBandeira!

Gustavo Bandeira

Oi, mary.

MeAndMath

@GustavoBandeira E aí?

e o troço que você ia mostrsr?

Gustavo Bandeira

Tô aqui com ela. :-)

MeAndMath

do it.

Gustavo Bandeira

Vai ficar mais tempo? É que estou na rua.

MeAndMath

1:12 AM

ok.

Gustavo Bandeira

E aí? Tá bem?

MeAndMath

@GustavoBandeira yep.and u?

Gustavo Bandeira

Também. Ce conhece o livro polynomials do Barbeau?

MeAndMath

não...why?

Gustavo Bandeira

Tô lendo ele.

MeAndMath

1:16 AM

is it good?

Gustavo Bandeira

É bacana. :-)

MeAndMath

tô olhando ele aqui...

Kannappan Sampath

@BenjaLim Hey, Ben! Have you changed your Skype user?

I have you on my skype...

Gustavo Bandeira

É leve, mas eu não sei quase , então serve.

MeAndMath

@GustavoBandeira tá em que parte?

Gustavo Bandeira

1:23 AM

Bem no começo. :-(

Kannappan Sampath

Learning the nuts and bolts of programming. Python is awesome.

MeAndMath

@KannappanSampath Python is.

@GustavoBandeira how was your trip yesterday?

Gustavo Bandeira

Cool.

MeAndMath

@GustavoBandeira Good.:)

Gustavo Bandeira

Bbl

Almost at home.

MeAndMath

1:39 AM

ok

Gustavo Bandeira

Its impossible to type latex in the cell phone.

MeAndMath

what do you wanna write?

Peter Tamaroff

@MeAndMath $\sup$?

MeAndMath

@PeterTamaroff what?

Gustavo Bandeira

Sup _ whats up

I guess

MeAndMath

1:44 AM

Is that it,@PeterTamaroff?

Peter Tamaroff

@MeAndMath Is that you?

MeAndMath

@PeterTamaroff Yes.Itsa me!

Peter Tamaroff

@MeAndMath Oh, good. For a moment I doubted.

MeAndMath

@PeterTamaroff Why??

Peter Tamaroff

@MeAndMath I have my reasons.

MeAndMath

1:47 AM

@PeterTamaroff o.O

Gustavo Bandeira

He's trolling...

Peter Tamaroff

@MeAndMath =D

MeAndMath

@PeterTamaroff Pedro,Pedro...

Gustavo Bandeira

Silly marymath......

MeAndMath

@GustavoBandeira I'm not silly...

Gustavo Bandeira

1:51 AM

Yes, you are. :-)

MeAndMath

@GustavoBandeira y?

Kannappan Sampath

Well, I start to feel that Pedro, Gustavo, MeAndMath all know each other IRL.

MeAndMath

@KannappanSampath no.I'd like to,but no.

Gustavo Bandeira

Look, Me and Peter were neighbours once.

We lived in the glorious nation of the Trollland.

But war forced us to flee to other places in the world.

Pronto, Mary.

peoplepower

I took refuge in Trolland.

Gustavo Bandeira

1:54 AM

É assim.

MeAndMath

@GustavoBandeira já chegou em casa?

Gustavo Bandeira

Sim.

MeAndMath

@GustavoBandeira assim o quê?

Peter Tamaroff

First world problems: I finished all the mission on Modern Combat 3. What do I do with my life now? I know: BEER!

MeAndMath

As pessoas têm um negócio com cerveja...

Peter Tamaroff

1:56 AM

@MeAndMath PORTUGULUBRESE!

MeAndMath

MWAHAHAHAH

Gustavo Bandeira

Deixa eu pegar o negócio no meu deskto

user19161

@PeterTamaroff Have tea or coffee instead Pedro!

MeAndMath

OK

Peter Tamaroff

@WillHunting I'll have coffee! With an alfajor!

MeAndMath

1:58 AM

@WillHunting yES!

user19161

@meandmath What does your avatar show?

Peter Tamaroff

@WillHunting Chaplin.

MeAndMath

@WillHunting cHARLIE CHAPLIN

Peter Tamaroff

@WillHunting Ignorance is not bliss in this case.

Charlie Chaplin is bliss.

user19161

@PeterTamaroff Only Pedro is bliss.

user19161

1:59 AM

@MeAndMath Interesting how you spell his name.

MeAndMath

@WillHunting why?

user19161

@MeAndMath aPPLE bANANA cHERRY

Peter Tamaroff

@WillHunting In that order? I think not.

MeAndMath

@WillHunting that was an accident...with caps

user19161

@MeAndMath Yes, I like to make stupid jokes.

Gustavo Bandeira

2:01 AM

1 - I said it was bullshit. =D

Now let me try to remeber what was it.

user19161

@GustavoBandeira That is bullshit.

Peter Tamaroff

@WillHunting No, this is dog.

Gustavo Bandeira

X,Y,Z worked as placeholders, A,B,C is relative to their positions and the s's are their size, I guess.

I wanted to plot various values for it and see what image they would generate. =D

user19161

@EdGorcenski No, when one encounters problems everywhere, look to the consistent factor the world, not themselves.

Peter Tamaroff

@GustavoBandeira Do you realize how sad that is?

user19161

2:04 AM

I just invalidated another chat flag.

user19161

I call these people the flaggers.

user19161

I flag things on main to keep the site distraction free, but I think chat is free for all.

user19161

If there is a problem I think it should be ironed out with the individual personally to better the world.

Gustavo Bandeira

I usually spend sometime ploting functions, it's cool.

wj32

For anyone who feels like wasting 1-2 minutes: i.imgur.com/2sMQL.png

user19161

2:06 AM

Removing specific messages does not better the world, just leads to more hatred and evil.

Gustavo Bandeira

@MeAndMath Tá guardando o insulto, né?

MeAndMath

@GustavoBandeira qual deles?

user19161

I think this world cares too much about superficial things and not things which truly matter, and the above is an example.

Gustavo Bandeira

@WillHunting You should call them: "the battlecruisers"

@MeAndMath Porra, tem vários? =(

anon

@wj32 Hint: The relation is equivalent to saying the image of L(u,v) under the quotient map contains 0; and the quotient space is 1-dimensional.

Gustavo Bandeira

2:08 AM

My mom brought me some coffee.

user19161

@GustavoBandeira By the way, mom is AmE and mum is BrE.

user19161

Sometimes I feel the Americans change the spelling just to be different.

MeAndMath

TAKE A LOOK AT GOOGLE!

Gustavo Bandeira

wow

the beatles

MeAndMath

STAR TREK!

Gustavo Bandeira

2:10 AM

Did you have Set theory at university?

user19161

What is Gus and Me talking about now?

MeAndMath

Not yet

user19161

@GustavoBandeira Set theory can be done at many levels. Elementary set theory is covered in schools for example.

user19161

Just know venn diagrams, union, intersection, complement, notation etc.

Gustavo Bandeira

Will/Jasper, your real name is not Jasper, right?

MeAndMath

2:13 AM

i'm teaching myself

user19161

@GustavoBandeira It is. But I am not sure who the real me is yet.

wj32

@anon thanks

Gustavo Bandeira

As you're from singapore, your name should be something like Yu-Li Kung-Fu Shan.

user19161

@GustavoBandeira No, you don't know about names here!

Gustavo Bandeira

What's the most common name there?

One of the most common names here is Gustavo. =/

user19161

2:14 AM

There are various patterns, I shan't elaborate.

MeAndMath

@GustavoBandeira no,it's not...

user19161

@gustavo If you want to cover formal logic and set theory though, I recommend Goldrei's Propositional and Predicate Calculus followed by his Classic Set Theory.

Gustavo Bandeira

What is then?

peoplepower

At an extreme level of locality, my name is the most common name here.

Gustavo Bandeira

@WillHunting I guess I'm gonna love set theory.

MeAndMath

2:16 AM

josé,joão,lucas,luís...

user19161

@GustavoBandeira I think you worry too much about metamathematics. Just start studying the mathematics itself already! But really, now you are at the precalculus stage. Just get all your elementary algebra, geometry, trigonometry, sets, combinatorics right first.

Gustavo Bandeira

@peoplepower Imagine if I were living in the moon: "The most common name here is Gustavo" would be plausible, In this case, I would be alone at the moon. The mode of every set with only 1 element called n is n!!1

@WillHunting I'm doing it, but I'm so fucking curious!

user19161

@GustavoBandeira Yes, the danger is to ponder too much on these matters without really studying them.

user19161

But to ponder a little is good.

Gustavo Bandeira

Will, what is predicate calculus?

It's something that let me curious, but i have no clue of what it is.

MeAndMath

2:20 AM

I really love to stay here and to you, guys , but I gotta sleep! good night!

Gustavo Bandeira

@MeAndMath Banana de pijama!

MeAndMath

boa noite!

user19161

@GustavoBandeira en.wikipedia.org/wiki/Propositional_calculus and en.wikipedia.org/wiki/Predicate_logic

Gustavo Bandeira

Boa noite.

MeAndMath

:D

Gustavo Bandeira

2:23 AM

Boa noite.

@WillHunting I've read this but couldn't understand much.

Peter Tamaroff

@MeAndMath You're weak.

BenjaLim

2:59 AM

@KannappanSampath Yes I have changed it.

Gustavo Bandeira

3:21 AM

0

Q: What mathematical ideas/concepts became obsolete due to technological progress?

As technology evolved, some ideas and methods became obsolete. What mathematical ideas entered this state due to technology progress? We could consider that doing some mathematical operations done by hand are obsolete because we can do them on computer, for example. But these operations still ex...

math-history

Is this question too dumb?

Maybe I'm asking too much. Dunno.

robjohn

3:39 AM

@GustavoBandeira Do questions have IQs?

Gustavo Bandeira

@robjohn Well, I fell ashamed of asking something that is not glorious.

And also "donwvote-o-fobia"

I usualy think I'm elaborating crap questions and all that. Argh.

Gustavo Bandeira

4:09 AM

...

Are there "trolling mathematicians"?

In the history of mathematics, who was the greatest trolling mathematician?

Jayesh Badwaik

@GustavoBandeira You bet!

Gustavo Bandeira

By now, I'm aware that @PeterTamaroff is going to add something on this field...

I almost asked it on MSE, for serious.

Jayesh Badwaik

Its time he changed his name to Trollaroff for better recognition.

Gustavo Bandeira

I'm aware that Archimedes sent fake proofs to his friends, for knowing which of them were stealing his work.

Jayesh Badwaik

@GustavoBandeira If you start asking stuff like that, we might just have a gustrollo Bandeira :P

Gustavo Bandeira

4:16 AM

I guess it was Archimedes.

@JayeshBadwaik lol

Jayesh Badwaik

@GustavoBandeira Well, it was incredibly difficult to convince Fermat to show his proofs. If we did not know any better.....

Gustavo Bandeira

@JayeshBadwaik Why he didn't want to show it?

Every mathematical field started with one simple question, here goes mine:
-Can we make a mathematical body of knowledge about trolling?!

Jayesh Badwaik

@GustavoBandeira Its already a work in progress. But then the definition of troll is much much wider.

Gustavo Bandeira

12/9/2067.

Today, Gustavo Bandeira earned his Fields medal in recognition for his work on Topological Trolling Theory.

Jayesh Badwaik

The current economically relevant are of course the patent trolls. I guess, you would find a lot and lot of studies on it.

Gustavo Bandeira

4:26 AM

@JayeshBadwaik What you mean?

Jayesh Badwaik

@GustavoBandeira Trolls can be of various types. Mostly, resources would be invested to study the behavior of trolls which are currently economically relevant.

Gustavo Bandeira

Yep. But I guess this wouldn't be math specifically, wouldn't it?

Jayesh Badwaik

@GustavoBandeira No, I guess. Mainly statistics (applied)

But thing is definition of troll is dependent on definition of mathematical ideas.

Gustavo Bandeira

I guess it would be more something related to behavior. This would be the end and statistics would be the means.

Jayesh Badwaik

You cannot have a troll independent of the mathematics you do. Hence, all that troll does is emphasize some particular aspect of results while deemphasizing others, and in a way try to present a distorted picture.
How well the picture is distorted is a matter of statistics I would say.

Gustavo Bandeira

4:32 AM

Yep.

Jay, you know about programming, don't you?

Jayesh Badwaik

Yup. But not user interface kind. Mainly algorithmic.

Gustavo Bandeira

I've learned to program kinda instinctively on Mathematica, BUT I guess I'm still in a very basic level. I learned this way because of two aspects (I guess):
1- Mathematica is REPL, It allow me faster experimentation and results.
2- Mathematica have a nice reference, where you can search for a function that do something and in the help page of this function, you can read suggestions on similar functions.

reference.wolfram.com/mathematica/ref/…

As you can see in this example.

I've searched for a function and in the see also part of the page, there are other similar functions enlisted.

Kannappan Sampath

Missed Ben.

@BenjaLim Hey, OK. I wrote you a mail sometime ago about coffee. So, reply to that with your skype name. K?

Gustavo Bandeira

@JayeshBadwaik Where can I find such comprehensive references on other languanges?

Talking about REPL, there's one cool site: Ideone

Jayesh Badwaik

@GustavoBandeira Hmm, depends on the language (of course). Python is really well documented.

Their documentation is on their website.

For c++ , I guess Stroustrup's books are the primary reference along with a text book like C++ Primer or Modern C++.

Once you are upto that level or even before that, hangout at stackoverflow.

Cppreference.com cplusplus.com are good also.

Gustavo Bandeira

4:44 AM

While I was 16 years old, I tried to program with Delphi, I always had to make an annoying procedure to see it running:
-Write the code.
-Compile.
-Run.
-Get naked.
-Get your body oiled.
-Now the program will run! Voilá!

Jayesh Badwaik

Delphi? never used that.

Gustavo Bandeira

Lemme get a link.

groups.engin.umd.umich.edu/CIS/course.des/cis400/delphi/…

It seems that Delphi is Object Pascal.

At the time I didn't know

Jayesh Badwaik

I learned on BASIC when I was 8 I guess. Then I graduated to C when I was 11. ASM and C++ at 14. Python/Haskell at 17. A little bit of LISP a year later. I had too much free time to worry about programs not running then!

Anyway, there are three aspects of programming I believe.

1. Algorithms
2. Data Structure Representation in Memory
3. The actual Syntax

Gustavo Bandeira

@JayeshBadwaik How did you learned basic while you were 8? Your parents provided you some guidance?

Jayesh Badwaik

@GustavoBandeira I had a toy computer which had basic and there was a manual with it. I would play around with stuff in the manual.

Print "hi there"

10 Print 10

and stuff like that.

I did not know that I knew basic later till when I was 12 when it was taught in our school and I was like, oh I already know all this stuff. :P

Gustavo Bandeira

4:51 AM

While I was 7, I said: "Dad, I want an electronics course". He didn't gave me it. =(

Jayesh Badwaik

I always thought it was some game designed by the toy computer people.

Gustavo Bandeira

My mom gave me it when I was 16...

Do you use LISP now?

Jayesh Badwaik

@GustavoBandeira hmm. I did not particularly like the transistor operations when I was in high school. I thought they were too messy. And then I spent my senior year working on how to improve transistors (and that project was by choice :P )

Gustavo Bandeira

I have interest on it, I'm VERY curious on the metaprogramming stuff.

Jayesh Badwaik

Naah, as I said, I learnt a very little of lisp. I can write small one off programs here and there. Nothing more.

@GustavoBandeira To tell the truth, there is not much magic in it. Even I was initially attracted towards LISP by the same reason, but it is basically higher order functions I would say.

I do not mean to say, it is not interesting, but that since then, other languages have evolved to do what LISP used to do and what made it so popular.

Gustavo Bandeira

4:56 AM

I have a love for AI, then I've read somewhere that some aspects of AI are made with the metaprogramming feature.

@JayeshBadwaik What languanges? I guess I know only Haskell that has some similarity with LISP.

Jayesh Badwaik

@GustavoBandeira LISP is the only language I know which is completely reflecting (that is, it is its own meta language)

But basically ASM is a metalanguage too.

and so if you use pointers in C properly, you can get a meta language with C also.

But basically ASM is a metalanguage too.

it is like, you can write object oriented code in fortran, but is it worth it?

Gustavo Bandeira

Is it?

Jayesh Badwaik

And in that respect, in recent times, languages like c++ have come up with template meta progrmaming, and the dynamic nature of python also makes it metaprogramming.

@GustavoBandeira Mostly, no.

Gustavo Bandeira

I'll try to replace Mathematica with Python now

johndcook.com/blog/2010/07/09/replacing-mathematica-with-python

Jayesh Badwaik

You may probably know it, but there is SAGEMath.

Gustavo Bandeira

5:03 AM

I can use the math functions on an environment with Python, I guess it will help me on that.

Jayesh Badwaik

It is written in python, FWIW.

Gustavo Bandeira

Yes.

It's syntax is also similar to Python.

What low level languange is worth learning?

Jayesh Badwaik

C, for a forseeable future.

Gustavo Bandeira

Yep. It's the one I'm studying.

Jayesh Badwaik

There is a new one on the market 'D', but I am not sure how really improvement it is over C, except for some cosmetic changes.

If you are interested in Low Level Programming and have some funds, get yourself a microcontroller board so that you can write C/ASM programs and run them on raw hardware. It is a good exercise I believe.

Gustavo Bandeira

5:08 AM

A board like Arduino?

Jayesh Badwaik

Yeah

like Raspberry Pi

but they are too damn hard to obtain.

Gustavo Bandeira

Well, I guess Arduino is easy.

I'm just not sure on Raspberry Pi.

Jayesh Badwaik

There are others by beagle.

beagleboard.org/bone

Gustavo Bandeira

I've made an observation: The market on low level languanges seems to have lower activity than the market on high level languanges.

Is it true?

Jayesh Badwaik

@GustavoBandeira No. ARM is the company which mainly made processors for embedded systems. For a long time, and even now I guess, its sales outstripped any of the other sales (Intel,AMD etc you name it )by a large large margin.

Gustavo Bandeira

5:12 AM

There are more high level programmers than low level programers?

Jayesh Badwaik

@GustavoBandeira Yes.

Gustavo Bandeira

Ops, more low level than high level programmers?

Jayesh Badwaik

No. I do not think so. Basically, even if you write one simple app for your desktop in bash, you are a high level programmer.

For low level programming on the other hand......

also, what happened in earlier days was C was the default language and hence, every thing you do was in C.

Stallman did emacs in lisp, but then he was stallman.

Gustavo Bandeira

In Brazil, I guess that programmers make basically three kinds of software: Cellphone games/Sales controlling software and websites.

Jayesh Badwaik

Since then, attention has shifted and a lot of choice of programming languages is there more suited for specific tasks and people have taken those.

Jeff

5:15 AM

programming languages are too splintered (IMO)

Gustavo Bandeira

Yep.

Jayesh Badwaik

tiobe.com/index.php/content/paperinfo/tpci/index.html

Jeff

hey Jayesh, do you know makefiles?

Jayesh Badwaik

Fortunately, the charging one has been solved now that we've all standardized on mini-USB. Or is it micro-USB? Shit.

@Jeff Yup, I know makefiles.

Jeff

@JayeshBadwaik yup, that's the fact! That was certainly why the programming language APL was created (can anyone guess what "APL" stands for?).

Jayesh Badwaik

5:18 AM

I wonder. Never heard of it I guess.

Jeff

@Jay so there is a command, hostname, which returns a value (the name of the host). but hostname is not an environment variable. how do I get the result of hostname command into a makefile.

Jayesh Badwaik

Are you talking about A?

Jeff

APL=___ Programming Language (guess what the missing word is)

Jayesh Badwaik

@Jeff Okay. Now I get it. You are talking about A. Then there was B and then there was C.

Jeff

yup, you guessed it before I even asked the question. :D APL is "A Programming Language" because it was supposed to be the last, all-encompassing, programming language, which could do what everyone wanted! :D

Jayesh Badwaik

5:20 AM

@Jeff Use the command $(hostname)

Jeff

@JayeshBadwaik that didn't work.

Gustavo Bandeira

Jayesh, C has the feature of being compiled to assembly or binary (I don't remember), D has the same feature, right?

Jeff

${hostname} (I used braces) is for environmnent variables. I'll try parenthises

Gustavo Bandeira

I discovered this some years ago when I tried to make a custom MIDI controller, I discovered I would have to build drivers.

Jayesh Badwaik

@Jeff $(xyz) executes the command xyz and returns the result.

Jeff

5:22 AM

it didn't work. Did I do something wrong: thishost = $(hostname)

Jayesh Badwaik

@GustavoBandeira Those are the blackhole of a programmer's time. Everytime you say "I work on writing drivers", other programmers would spontaenously get up and give you a consoling hug. "Hang in there bro", they would say.

Jeff

and then: rcom-nodes 'rcp ${thishost}:/hom....

@JayeshBadwaik lol

Jayesh Badwaik

@Jeff You are trying to write a bash script, why are you doing this in a make file?

Gustavo Bandeira

@JayeshBadwaik Why? Is it so nightmarish?

Jayesh Badwaik

@GustavoBandeira Hardware is so so badly documented, you would think it was manufactured by wizards of hogwarts.

Jeff

5:24 AM

because it's part of a compile. after i compile, i have to copy the compiled file to all the nodes because we're having this (stackoverflow.com/questions/12167576/…) problem and the admin won't make the system change to mount "noac".

Jayesh Badwaik

With FOSS, the situation is improving, but there are a lot of blue patches.

@Jeff I have a two-part advice.

First is this quick hack.

24

Q: How can I use bash syntax in Makefile targets?

I often find bash syntax very helpful, e.g. process substitution like in diff <(sort file1) <(sort file2). Is it possible to use such bash commands in a Makefile? I'm thinking of something like this: file-differences: diff <(sort file1) <(sort file2) > $@ In my GNU Make 3.8...

bash shell makefile make

Gustavo Bandeira

@JayeshBadwaik The idea was to use something like arduino to make it. Even with arduino it would be hard? - I built the impressions that arduino is well documented, but I have no basis for that.

Jeff

yeah, it's a quick hack. but it's also the only option i have atm.

Jayesh Badwaik

@Jeff the other option is to write a bash file to do all the stuff you want to do and then use makefile to run that bash file.

that can be done as simple as ./your-file

@GustavoBandeira Arduino is well documented.

Jeff

how do i call the bash file inside make?

Jayesh Badwaik

5:27 AM

Just like you call normal programs like gcc.

but then this time, you have that bash file in your specific folder, which is not a part of the $PATH environment variable

and hence you would need to use the command ./your-file

instead of just your-file

@GustavoBandeira the goal of all the stuff of arduino, raspberry pi is to re-introduce people to low level programming, since actual real-world low level programming is now too complicated (in PC for example)

Gustavo Bandeira

@JayeshBadwaik Didn't know about that.

Jayesh Badwaik

It was reported at one conference that the code size of UEFI (the new generation BIOS) is larger than that of the linux kernel without the drivers.

and UEFI does not include drivers of the system it is installed on! :P

Gustavo Bandeira

Some years ago I bought something similar to arduino, it's a brazilian project. - It's extremelly bad documented. =/

Jeff

@JayeshBadwaik if that worked, then why doesn't the call to gethost work? is that not a bash file?

Jayesh Badwaik

gethost? sorry I must have missed a message in the conversation.

@GustavoBandeira Ohh. Yup, working with badly documented project sucks. I fortunately had a well-documented on. It was a local project, the manufacturers were from my city only.

@Jeff I guessed you did something wrong.

Jeff

5:33 AM

@JayeshBadwaik i meant to type hostname, not gethost.

Gustavo Bandeira

I can't install SymPy on my computer, it says I haven't python installer, But I got python 3.2.2, maybe I need the 2.7

Jayesh Badwaik

@GustavoBandeira Yeah, that can be the stuff. I guess stuff hasn't been ported completely yet.

@Jeff For that, I guess that questions provides a correct answer.

The reason is the support of "$(something)" command

Gustavo Bandeira

Jay, why do you learn math?

Jeff

OK. I have this file which is not working:

thishost = $(hostname)
rcom-nodes 'rcp ${thishost}:/home/schwarz/sundials/instdir/examples/cvode/parallel/${EXAMPLES} /home/schwarz/sundials/instdir/examples/cvode/parallel/'

the first line doesn't work. thishost remains empty

Jayesh Badwaik

@Jeff Try writing it as "export thishost=$(hostname)"

NO SPACES AFTER "thishost"

Jeff

5:38 AM

didn't work

Jayesh Badwaik

@GustavoBandeira I like math and I have fun doing it.

@Jeff you are inside a makefile?

Gustavo Bandeira

You study some math topics beyond what you really need on your profession, right?

Jeff

no. it's just a file called "copyfiles". those two lines are the only content. i changed copyfile to be executable.

Gustavo Bandeira

Once you mentioned something about analysis, I guess you don't need analysis for electrical engineering, right?

Jayesh Badwaik

@Jeff Strange. Just a sec. I will try that myself and get back.

Jeff

5:40 AM

k

Jayesh Badwaik

@GustavoBandeira Analysis is required in electrical a lot. Algebra and topology are not required much.

Jeff

@gustavo you probably need some analysis for EE.

Jayesh Badwaik

@Jeff Heavy analysis :P Not formal, not epsilon delta proofs, but the techniques.

Gustavo Bandeira

I thought engineering wouldn't require analysis.

Jayesh Badwaik

@Jeff It works for me

@GustavoBandeira Naah, stuff is too complicated now a days. Everywhere, you require all kinds of techniques.

Control systems is a direct outgrowth of complex analysis and calculus of variations for example.

Jeff

5:44 AM

@jay something is wrong with the second line. i tried this: at the commandline i typed export thishost=$(hostname)

then I typed echo thishost and it replied "node8".

Jayesh Badwaik

@Jeff Yup. hence, first line is working correct.

Gustavo Bandeira

12

A: Are calculus and real analysis the same thing?

A first approximation is that real analysis is the rigorous version of calculus. You might think about the distinction as follows: engineers use calculus, but pure mathematicians use real analysis. The term "real analysis" also includes topics not of interest to engineers but of interest to pure...

I thought it because Quiachu's answer.

Jeff

Then in the file, I deleted the second line, so all i had was rcom-nodes 'rcp ${thishost}:.... and it still did not work, as if thishost was empty.

why won't it expand ${thishost}? is it because it's in quotes?

Jayesh Badwaik

@Jeff for env variables you just need to type $thishost

@GustavoBandeira One stuff is calculating all right. But then, even (or is it especially?) engineers need to provide guarantees that their formulas will work!
See the thing is too much stuff is too complex too be modeled analytical. So, to be able to choose good analytical models requires a lot of analysis background. A lot of info about how tight are the error bounds, how strong is the convergence and stuff. Much of the required experience is gained from a mathematician like study of analysis course.

Jeff

@JayeshBadwaik that still didn't work

Jayesh Badwaik

5:48 AM

does it give a no such file or directory error?

what is rcm-nodes?

Jeff

it says "Unknown host" over and over again.

Jayesh Badwaik

what does it do?

Jeff

rcm-nodes is a command which runs whatever is in quote on all the other nodes

Jayesh Badwaik

okay

then you can see why that is a problem

Jeff

I use rcm 'md5sum FPU' to check if all the files on all the nodes are the same.

Jayesh Badwaik

5:50 AM

the environment variables are not transferred

Jeff

ok, but isn't ${thishost} expanded before transfer to the other nodes?

if not, how do i get it to expand first?

Jayesh Badwaik

I did not know the answer to that question. But now I guess not. and it is pretty normal I guess.

Jeff

so i need to find out how to make the variable expand before sending to other nodes. maybe i'll post it on stackoverflow

(i mean if i can't find an answer by searching first - but i'm not sure exactly what to search on)

Jayesh Badwaik

@Jeff Yup. Or may be you can just hardcode your node hostname for now?

Jeff

yeah. that's kind of a lame solution. but i may have to do it.

Jayesh Badwaik

5:53 AM

@Jeff Sometimes good enough but lame is good enough!

Jeff

@jay that is so true

:D

Jayesh Badwaik

Or may be you can try removing quotes and then see.

I am not sure though.

Jeff

if i remove the quotes, then rcom doesn't work

Jayesh Badwaik

@Jeff ohh, thought so.

hmm, may be you can expand the command before like this?
export command=rcp ${thishost}:/home/schwarz/sundials/instdir/examples/cvode/parallel/${EXAMPLES} /home/schwarz/sundials/instdir/examples/cvode/parallel/

And then run rcom-nodes $command ?

Gustavo Bandeira

@JayeshBadwaik Yes, Installing Python 2.7.3 allowed me to install SymPy, yay!

Jeff

5:59 AM

@jay that might work.

Jayesh Badwaik

@GustavoBandeira good.

Transcript for

$Mathematics$ Mathematics