Wolfram Mathematica

6:56 AM

hmm, another down vote by the same guy. I don't mind people downvoting for the right reasons but to do it just for strategic purposes is annoying.

Szabolcs

7:33 AM

@Heike Did you notice his downvote count increase? Maybe it's just a coincidence?

Heike

7:56 AM

@Szabolcs Yesterday his rep count for this week was -1 mod 5, today it's -2 mod 5, and there are other clues which make it too much of a coincidence to be a coincidence.

belisarius

12:46 PM

@Heike Yep. Interesting. Many downvotes in answers competing with his. The same amount as his downvotes, to be more precise.

@Heike Yep. Interesting. Many downvotes in answers competing with his. The same amount as his cast downvotes, to be more precise.

Oleksandr R.

@belisarius In one case I note he's praised another answer, but then apparently downvoted it anyway. Rather unsporting, if you ask me.

belisarius

@OleksandrR Statistically it is not significant, but annoying anyway

Oleksandr R.

@belisarius I suppose any time you introduce a metric, there will be people who game it, even though SE is not supposed to be a competition. Oh well.

belisarius

@OleksandrR Darwinian behavior :)

Heike

1:03 PM

@belisarius I tend to upvote many of the answers competing with mine. Guess which ones won't get my upvote this time ;-)

2

belisarius

@Heike There is a badge for that (I think something like sportwomanship). Keep upvoting :D

Heike

@belisarius I already got that one

belisarius

@Heike There should be a gold suicide badge for massively upvoting competing answers :)

Heike

@belisarius Maybe that should be for massively downvoting competing answers.

belisarius

@Heike Probably should work both ways

J. M.

2:07 PM

"...it is the users who request the features; the designers are simply obliging them. But each new set of features adds immeasurably to the size and complexity of the system. More and more things have to be made invisible, in violation of all the principles of design. No constraints, no affordances; invisible, arbitrary mappings. And all because the users have demanded features." - from here

belisarius

2:20 PM

@JM That is one of the better books I've read. Lots of experience condensed in a few pages of very pleasant and easy reading.

The anecdotes in the book are the best.

Somehow it reminds me of "Zen and the art of motorcycle maintenance"

Zen and the Art of Motorcycle Maintenance

Zen and the Art of Motorcycle Maintenance: An Inquiry into Values (ZAMM) is a 1974 philosophical novel, the first of Robert M. Pirsig's texts in which he explores his Metaphysics of Quality. The book sold 5 million copies worldwide. It was originally rejected by 121 publishers, more than any other bestselling book, according to the Guinness Book of Records. The title is an apparent play on the title of the book Zen in the Art of Archery by Eugen Herrigel. In its introduction, Pirsig explains that, despite its title, "it should in no way be associated with that great body of factual info...

The Design of Everyday Things

The Design of Everyday Things is a best-selling book by cognitive scientist and usability engineer Donald Norman about the design of simple objects, and why some objects please their users while others frustrate them. The book was published in 1988 with the title The Psychology of Everyday Things. Norman said his academic peers liked that title, but believed the new title better conveyed the content of the book and better attracted interested readers. It is often referred to by the initialisms POET and DOET. Norman uses case studies to describe the psychology behind what he deems good ...

Heike

@belisarius Looks like an interesting book.

belisarius

@Heike both of them are!

I had them in my nightstand for years

Heike

@belisarius Is Zen and the Art of Motorcycle Maintenance actually about motorcycle maintenance?

belisarius

@Heike No, nor about Zen. It is a very nice effort to conciliate the classic and romantic ways to see the world

It is a novel, BTW

Heike

2:35 PM

I have heard of The Tao of Pooh before, but that's actually about Taoism

belisarius

Regretfully, It is almost impossible to translate into many languages, as a central point in the discussion is based upon the two meanings of the word Quality in English.

Heike

@belisarius I think it would work in Dutch.

belisarius

@Heike Seems it is not easy to translate

tarotforum.net/library/20/2002-07/…

Heike

I rarely read books in Dutch to be honest.

belisarius

@Heike Me too

Heike

2:47 PM

@belisarius Really? How surprising.

belisarius

@Heike I rarely read books ~~in Dutch~~ to be honest.

Heike

With me it comes and goes.

belisarius

3:07 PM

@Heike Just to keep you interested

usabilitypost.com/2010/11/17/the-design-of-everyday-things

Heike

@belisarius Thanks.

Sjoerd C. de Vries

4:23 PM

@mr.wizard what would be the criteria to make a Q a CW Q?

belisarius

4:36 PM

@SjoerdCdeVries That is Q for meta

Szabolcs

@acl @Heike I managed to fix up the time lapse a bit and get rid of the flicker. It introduced some artefacts though. I have lots of ideas to improve the next one :-) vimeo.com/44246390

@SjoerdCdeVries A CW post can be editedd by everyone, even by people with very little rep. For example, community promotion ad posts are CW so everyone can fix mistakes in the ads.

Sjoerd C. de Vries

5:14 PM

@szabolcs Actually, the discussion is whether to turn a certain question into CW or not.

belisarius

@SjoerdCdeVries CW arose in SO trying to stop some users from gaming the system by continually editing their posts and so keeping them in the active page. Much later they found another uses to the concept, but a little bit forced I think. allowing very low rep users to edit something does not sound as a big gain, does it? I think CW should be avoided in a nice community. No need for it.

Heike

@belisarius Then why do you keep turning your own posts into CW ones? ;-)

belisarius

@Heike That was not a courteous question :_(

Heike

5:29 PM

Sorry

belisarius

@Heike :D

Sjoerd C. de Vries

We have a request to turn the mma Programming practices Q into CW. I don't really see the necessity, but if certain traditions require that I'd be happy to oblige.

Heike

How can I search for programming on the main site without the search engine turning programming into the tag [programming]?

belisarius

5:52 PM

@Heike When I have the slightest trouble with the search function I usually switch immediately to Google. The SO staff commented many times in SO meta that, existing Goggle, they are not going to optimize the searching process.

Heike

6:12 PM

@belisarius A programming site with a crappy search function. Who would have thought.

belisarius

@Heike What they told several times is that a good search function consumes too much resources, and it is not their business, but Google's. I thought the same as you ...

Stack Exchange

6:41 PM

0

Q: Code box line width survey

For the purpose of understanding what other users see, and to provide a record of the current SE Beta formatting, I would like to conduct a survey of the line width of the code boxes that users see. Please use a "ruler" like this one to determine how many characters your system displays before t...

discussion

Szabolcs

7:04 PM

@Heike mathematica.stackexchange.com/search?q=%22programming%22

Heike

@Szabolcs Thanks. I solved it by adding another search term

Szabolcs

@SjoerdCdeVries A request from a user or the SE team? The big answer is already CW there, I guess the concern is about the question poster getting "too much" rep.

user465292

Hi !

Szabolcs

Good day citizen 46529.

user465292

I have changed my name, but for some reason

it does not reflect in chat

Szabolcs

7:18 PM

@user465292 change it on StackOverflow then click the button to copy your profile info to all other sites

@user465292 or even on this site, edit your profile and use the button to copy the info to all other accounts

user465292

let see

hmmm........

did a sec ago

Heike

Maybe you need to log out of chat first before the change takes effect.

Then again, maybe not...

user465292

nope, still the same. Database probably has to update

it will take some time

Heike

Ah yes, I forgot the golden rule. If it doesn't work it's probably a caching issue.

Sjoerd C. de Vries

@Szabolcs A user. BTW the main answer is not marked CW on my iPad screen.

Szabolcs

7:38 PM

@SjoerdCdeVries You're right... I was always under the impression that it was CW. I thought post automatically turn to CW after 10 edits (one of my answers certainly did even though no one else has edited it!!) and I thought this answer got the bounty precisely because it was CV after literally a hundred edits. Is there a glitch in the system?

@SjoerdCdeVries I would have sworn I have seen that answers turn into CW before, but you're right: now it is not.

@SjoerdCdeVries was CW maybe removed by a moderator at some point?

belisarius

I have a problem with this question

4

Q: Emulating Sequence with my own function

I just considered if/how one could implement Sequence in Mathematica if it were not predefined. It turned out that the following simple definition has in all my tests exactly the right behaviour: myseq /: f_[x___, myseq[y___], z___] := f[x, y, z] Now my question: Does this already correctly re...

programming

The format: "I did this, what do you think?, can you test it?" does not seem a good fit

user465292

8:14 PM

Got a quick question !

If I am building a loop, within a loop

what would be best option - Do/While, or using Table with Iterators ?

let me give an example

belisarius

The best loop is no loop :)

newprint

Building a table of {x,y} coordinates, such that they are within a unit circle.

So far, I came up with something as following

Heike

Nothing?

newprint

how on

Verbeia

All, I'd like to encourage others to attempt a general answer to the question I have put a bounty on. Heike's is good but I'm not sure it's general, and I'm not sure how accurate Mike's is.

Heike

8:27 PM

@Verbeia I think my answer is a bit fragile. At least the first part of it which contains a magic number that might be system dependent.

newprint

For[x = xLowerBound, x < xUpperBound, x = x + n,
For[y = xLowerBound,(*Check if solution for x^2+y^2==1^2 @{x,
y} is true* & y< yUpperBound *), y = y + n, (*add{x,y} to table*)]

This is what I came up so far,

it looks like a C code !!!!

Heike

do you want x^2+y^2==1 or <=1?

newprint

<= will be the condition

but I am more curious if there is a way not having "C" code

Or there is no other way, since I have conditions in my code

Heike

@newprint One way is to generate all the points with xLowerBound<x<xUpperBound and yLowerBound<y<yUpperBound and just select the points inside the circle:

belisarius

:5007141

n = 100;
pts = Array[Exp[2 Pi I #/n] &, n];
ListPlot[{Re@#, Im@#} & /@ pts, AspectRatio -> 1]

Heike

8:39 PM

With[{xmin = -2, xmax = 4, ymin = -3, ymax = 3, r = 3, dx = .4, dy = .5},
Select[Tuples[{Range[xmin, xmax, dx], Range[ymin, ymax, dy]}], Norm[#] < r &]]

belisarius

Like this?

newprint

not exactly, but close you have them on the circle, I am looking sord of for a grid of points within a circle itself(imagine it drawn on construction paper)

@Heike HM... so generate all the points, and then check if they are within the range

Heike

@newprint That's one way

newprint

Just out of curiosity, you think it will be faster or slower than calculating new points them within loops ?

Heike

8:57 PM

Not sure to be honest. It depends on the number of points that fall inside and outside the circle.

belisarius

9:14 PM

@newprint You can estimate Pi with that :)

Function[x,
4 N@Length@Select[Tuples[Range[x ], {2}], Norm@# <= x &]/(x x)][100]

newprint

So far I came up with this.
PointsList =
Flatten[Table[{i, j}, {i, -4, 4, 0.5}, {j, -4, 4, 0.5}],
1];(*generate poinst list*)
For[k = 1,
x^2 + y^2 <= 1 /. {x -> PointList[[k, 1]], y -> PointList[[k, 2]]},
k = k + 1]
I still need to go back and check how to take things off the list

*go back to documentation

Heike

@belisarius You can also estimate Pi by dropping a stick on ruled paper a couple of times and counting the number of intersections between the stick and the lines on the paper .

belisarius

@Heike He. And weighting the dust accumulated in a few months in a circle and a square on top of my (dirty) fridge

Heike

@belisarius That's a good excuse for not doing any housework.

belisarius

@Heike I don't need excuses. Just a maid.

@newprint I think you are not looking at the code already posted here

@newprint Your code has already been posted twice

Heike

9:24 PM

The song "Every man needs a maid" is what put me off Neil Young.

newprint

I will take a look in a sec, more into my own coding

Sjoerd C. de Vries

@Szabolcs I can't look back that far. I also seem to recall it being CW.

belisarius

@newprint But you are coding in C. It is useless

@SjoerdCdeVries Yeah, me too

Heike

I wonder why Michael deleted his answer

belisarius

@Heike Perhaps he is improving it

Heike

9:34 PM

@belisarius maybe

Guillochon

9:59 PM

Hi all, I wanted to ask a question here first before I posted to the site, just to make sure it's not buried in the documentation somewhere

Is there a straightforward way to find the maximum value in a SmoothKernelDistribution or EmpircalDistribution?

belisarius

@Guillochon You mean finding the max of the PDF?

data1 = RandomVariate[NormalDistribution[], 10];
d1 = EmpiricalDistribution[data1];
Maximize[PDF[d1, x], x]

Guillochon

10:22 PM

@belisarius That gives me funny results, gigantic numbers for the maximum

belisarius

@Guillochon Errr ... Is that a bug report or a confession?

Guillochon

Well, I'm maximizing a smoothkerneldistribution for one, trying it now with empircal

So, actually...if you take your example, and replace the empirical with smooth, Maximize returns a different result

That's after upping the number of samples from 10 to 1000

They should be slightly different, but I get 0.01 for smoothkernel, and -7 for empirical

belisarius

@Guillochon Someone mentioned in a previous quuestion that EmpiricalDist is still not very well integrated into the kernel. So perhaps it is bug

Guillochon

smoothkerneldistribution seems to work well with Maximize at least for the toy example you proposed

but for some reason doesn't seem to be working with my dataset

i'll probe around some more

seems to work if i include constraints

belisarius

10:39 PM

@Guillochon Probably you should not be evaluating it outside your point's range

Guillochon

yeah, I was hoping that it would be smart enough to automatically detect the boundaries, as the result is just an interpolating function

ok, well anyhow it seems to be working. thanks for the help.

belisarius

@Guillochon You are welcome :D

newprint

@belisarius I looked at your code above, it looks like you are using complex numbers ?

n = 100;
pts = Array[Exp[2 Pi I #/n] &, n];
ListPlot[{Re@#, Im@#} & /@ pts, AspectRatio -> 1]

belisarius

@newprint yep. it is the easier way to describe a circle, but that was not what you were looking for, It is the other snippet

ListPlot@Function[x,
Select[Tuples[Range[-x, x], {2}], Norm@# <= x &]][10]

newprint

this was the 2nd answer:

With[{xmin = -2, xmax = 4, ymin = -3, ymax = 3, r = 3, dx = .4, dy = .5},
Select[Tuples[{Range[xmin, xmax, dx], Range[ymin, ymax, dy]}], Norm[#] < r &]]

I don't understand what is the Norm[#] < r &]] does.
# is operator that selects the first item

belisarius

10:47 PM

@newprint wait

@newprint Here you have it

20

A: What does # mean in Mathematica?

It's a placeholder for a variable. If you want to define a y(x)=x^2 function, you just could do: f = #^2 & The & "pumps in" the variable into the # sign. That is important for pairing & and # when you have nested functions. In: f[2] Out: 4 If you have a function...