In reference to this question.
Casper and Anna mentioned possible resistance from the SO community. But that was then, this is now. Anna in particular said no "now while the site is still in private beta". Well, that was 8 months ago, and this morning I bumped into this SO question, which is one...
@Verbeia I'm trying to add the new info by the OP to this question. Can you download this and repost to imgur? (Better yet, maybe embed the image yourself.)
I still need another volunteer, as the damn filehost imposes a 12-minute wait in between downloads.
In this question I read the following code:
which I find, er, hard to read; I had to copy and paste it in Mathematica to make anything of it. Can the HTML preprocessor be updated so that "\[Lambda]" shows as "λ", etc.?
In my last blog post, we looked at various examples of electrostatic potentials and magnetostatic fields. We ended with a rectangular current loop. Electrostatic and magnetostatic potentials for squares, cubes, and cuboids typically contain only elementary functions, but the expressions themselves are often quite large compared with simple systems with radial symmetry. In the following, [...]
@IstvánZachar It seems, that if you change the initial value for a manipulator, it is just not wanted, that the value of in this case r does change.
This is consistent to the case where you have min and max-values of sliders which depend dynamically on something else. If eg. the max-slider values changes to something smaller than the current value, then the slider is not updated.
@IstvánZachar Now you may ask why here Manipulate[{x, r}, {{r, x}, 0, 1}, {{x, 0}, 0, 1}] the first slider moves when I first move the second slider
This does only work if you evaluate the Manipulate and move the second slider before you touched the first one. The first slider uses it's initial value as long as it is never touched.
@IstvánZachar Sorry, I thought I understood it but I dont
@halirutan Hmm, yes, I see your point (only first movement of first slider changes other slider), but I still don't get it why the body is not changed when the dependent slider is changed.
He's declinin' yo flags He's snatching your rep points Tryin' to remove 'em, so y'all need to Hide your Q's, hide your A's, Hide your Q's, hide your A's Hide your Q's, hide your A's And hide your comments Cuz he be removin' everythin' out there!
@F'x That one was removed by me (before I was mod), belisarius and Mr.Wizard on Sep, 14. I normally try not to remove dupes, but in this case, I voted to because 1) there was a much better question and 2) the answer (your answer) would not have worked because Check doesn't interrupt evaluations
@halirutan which inturn is not as dangerous as sudo rm -rf / --no-preserve-root :)
@rm-rf remember when I was complaining about my new android phone?
(sorry to jump in but I need to vent here)
well, I had an old iphone 3g that someone handed down to me after they got a new one for free. my 3g barely lasted a few hours as the battery was ran down. so, apple wanted 75 euro to change the battery (actually to give me a new 3g) and I went and bought an android phone instead.
my girlfriend gave the iphone and 75 euro to apple, and they gave her a brand new iphone 4!
so now I've paid 300+ euro for a yellow plastic phone, while she paid 75 for what feels like a piece of industrial art. clever of me
I have the trigonometric equation
\begin{equation*}
\sin^8 x + 2\cos^8 x -\dfrac{1}{2}\cos^2 2x + 4\sin^2 x= 0.
\end{equation*}
By putting $t = \cos 2x$, I have
\begin{equation*}
\dfrac{3}{16} t^4+ \dfrac{1}{4}t^3 + \dfrac{5}{8}t^2 -\dfrac{7}{4}t + \dfrac{35}{16} = 0.
\end{equation*}
How do I ...
However, I wouldn't suggest closing any of them as duplicates of any other, let alone merging. They all have some little bit of info that makes it not technically a dupe and have answers that behave slightly differently for different situations.
The general theme however, is an advice to not use replacements rules relying on structure for mathematical substitutions. I suggest we collect these in a blog post instead of cross closures and merges.
@Mr.Wizard It's not about being qualified — you certainly are, as are many others — but I think Leonid summed it up well in the comments to a recent post:
The possibilities are humungous and each one's needs are so different, that simply maintaining such a package and handling edge cases could easily swamp someone
Educating users to think of the right tools and follow the right steps would be an easier approach.
@rm-rf I realize that, but nevertheless I think such a collection of methods would be helpful, even though corner cases would fail (which is no different than some built-in functions I should add).
@Mr.Wizard haha, yes :) I only know what it does in vague terms, but have used it successfully as a black box. Daniel uses it quite a good deal and is very comfortable with it
@Mr.Wizard You don't agree that a blog is the right place for it? The blog can also be updated with newer techniques later on. The only problem is of finding a person and the time... I know I too suggested a few topics that I wanted to write and were within my reach, but time quickly flies by and catches up with you.
A blog would certainly be a good start. I guess a comment below each of the questions linked referencing said blog would be acceptable.
Continuing my thought above, consider it an extension of Simplify, which isn't expected (by experienced users) to magically find all simplifications, but nevertheless is very useful.
If we could put together a package that handled a reasonable number of these substitution operations I think it would also be very useful.
Yes, I agree that something that works in a lot of the cases can be put together... if it fails to solve it, well, ask a new question! The answers there could possibly improve the package
@acl oh dear... Apple's warranty and upgrade policy is usually pretty generous (when you're out of warranty) as long as you're being nice and it didn't sustain water damage. But I feel the same way as you — I paid for a plastic phone. The only reason I did was because I couldn't use the cheaper plans otherwise. An iPhone requires a 2yr contract in the US for ~100$/month (or pay $600 upfront for the phone), whereas with mine, I pay about $10/3 months and it's more than sufficient for my needs
Since the launch of this site I've hoped for collaborative projects, but I haven't figured out how to get one started. Do you think this would make a good test case or is it too complex?
@Mr.Wizard Probably too complex to start one. I would suggest starting with, say, Szabolcs' image uploader (improve/extend it) or converting Jens' excellent plot label answer to a package. The latter one has been on my mind for quite some time, because I find myself copying-pasting his answer into a notebook everytime I need it and it would be much simpler to have a handy package
@rm-rf actually, being realistic, it's faster than the iphone 4, it's smaller, lighter and waterproof, and android may be a bit rough but I think it's more functional than ios on a phone (I prefer the notification system, visible indications of background sync or not etc). it's just that when I actually play with the iphone it's really well made. of course apple are good at doing that
well she did offer to exchange phones actually but I turned her down :)
@halirutan I agree... I'm personally motivated because it's a way for me to learn to work collaboratively on software/package development — something I've never done before. Also, my time would probably be better spent learning to do that than race to answer yet another question on manipulating lists
@rm-rf Additionally, I had a look at Leonids code formatter. The next thing which should get more attention. We could use it here!
I spend some interesting time formatting code in posts.
@rm-rf And btw, look with whom you would do a coll. project here ;-) I doubt you have the chance to be around so many excellent programmers in real live.
@rm-rf The bane of equation manipulation (not even to speak about solving) in general is that all the techniques taken together look... ad hoc. A bit like the reason why I hear the under-the-hood C and Mathematica code for Integrate[] and Solve[] are quite long...
Here's one of my favorite uses of GroebnerBasis[]. Guess what this does:
When new visitors arrive to this site and post a question it's very often the case that the question looks like this one
Everyone knows what now usually happens: The question is rarely upvoted and it is heavily commented that question should contain a description what the OP has tried so f...
I have the trigonometric equation
\begin{equation*}
\sin^8 x + 2\cos^8 x -\dfrac{1}{2}\cos^2 2x + 4\sin^2 x= 0.
\end{equation*}
By putting $t = \cos 2x$, I have
\begin{equation*}
\dfrac{3}{16} t^4+ \dfrac{1}{4}t^3 + \dfrac{5}{8}t^2 -\dfrac{7}{4}t + \dfrac{35}{16} = 0.
\end{equation*}
How do I ...
When new visitors arrive to this site and post a question it's very often the case that the question looks like this one
Everyone knows what now usually happens: The question is rarely upvoted and it is heavily commented that question should contain a description what the OP has tried so f...
