Just because the expression is updated whenever i changes. An the code itself changes i. This situation might happen very easily. What we need is to prevent i from being "tracked".
@Rojo To demonstrate that a very minor modification of the code you posted may kill the session or hog the CPU. Introducing any global variable that is being changed my code has a potential to kill the session.
The code I posted above will print/increment every time a notebooks is opened/closed. I haven't found any other situation when it does, but if there is, the If should take care of not evaluating anything unnecessary, as you said. Also, it doesn't hog the CPU.
@Ajasja Just mentioning because you were talking about applying some changes to every opened notebook. For example, my image uploader palette uses invisible notebooks for rasterization/copying.
I think an explanation about it is definitely necessary. Otherwise sooner or later someone who reads the answer will shoot himself in the foot and lose his session (e.g. me, this time ;-) )
Inspired by F'x, here's a 2D analogue of spikey. Done with a bunch of rules because I like them, and they make it clear what is going on.
Start with a pentagon:
p = Polygon[Table[N[{Cos[t], Sin[t]}], {t, \[Pi]/10, 2 \[Pi], (2 \[Pi])/5}]];
Make a rule to split any polygon into triangles (ce...
@RM, @Szabolcs Guys, I think this time you were too fast deleting that question on shadowing. It has a clear title, and it is more than likely that many people would search using something similar.
@LeonidShifrin I've voted to undelete. I initially voted because a recent change to how duplicates w/no answers are handled would've meant that no one would ever see that question (other than users with enough reputation). Low rep/anonymous users are automatically redirected to the other question if they happen to click on it.
But it seems like I misunderstood it (because the behaviour is different based on rep and whether you're logged in or not)
@LeonidShifrin I agree, I thought it's completely hidden unless you're logged in, but the crawler will probably see it either way. (BTW, to see what I mean, open this link when logged in and in an incognito window)
Hello, quick question: is there a way to convert an Overlay figure into a Show figure? More generally where can I read about the virtue of overlay (beyond the obvious) relative to show/graphics ? It seems to me its introducing yet another way of doing things which is a bit confusing
@chris The difference is that Show combines graphics, while Overlay will overlay any two things that can be displayed in the front end without changes---not matter if they're graphics or not.
@chris when you combine two graphics Show, they'll have the same axes, frame, labels, ticks, size, etc.
@Heike Yes, it's useful, but it's messy: the result will not be a resizable graphics object, and great care must be taken to make sure the frames will overlap properly (i.e. fixed ImagePadding without cutting off labels...)
@RM That doesn't sound like vote balancing, rather people who think they should only give a vote to the single best answer. Vote balancing would would be downvotes on (overly) popular answers, right?
(or not voting for popular answers only because they already have lots of votes)
Often being an early but less than thorough answerer, I get that fairly often; I've learned to accept it. Down votes on the other hand still sting a bit when I cannot see the reason.
Another (probably not completely straightforward) question. Is it possible to hack into Integrate so as a to add to the "grammar" of integration a new family of integrals which the user would have qualibrated (in the spirit of what ProbabilityDistribution which allows the user to include his own PDF into the existing tools).
The idea is that mathematica would be able to identify when such integrals pop up and replace it by the given definition. I have specific example in mind involving the integral of MultiNormalDistribution over square subregions of the integration domain.
@chris You could use either of TagSet or TagSetDelayed to define how Integrate[] should behave towards your function. (It's almost never a good idea to tamper with system definitions.)
For example if I was defining the following function
exprod[n_] := Expand[Product[x + i, {i, 1, n}]]
Then why is the underscore after the variable n, necessary in the function definition? Where does this style come from or is it specific only to the Mathematica programming language?
@JM I guess Wolfram cleared that one in the book, so it's not that common (except for the occasional $OtherLanguage user who's pissed that it doesn't use parenthesis)
@JM I always thought the answer to that one was: because we wanted to, alongside making an unambiguous distinction between a function call and a parenthetical expression. But, I could be wrong. :)
@RM what is the explanation in the book? that we "should realise" that "traditional notation" is ambiguous? (I have ver 5 and ver 2 of the book right here in my office but can't find anything in a quick check)
@JM for me it's more along the lines of is it`"f of x"` or "index x in f"... but it has never really been a problem for me though. If people don't use single letter variables and use a sensible naming convention, it's fairly clear to figure out
@Heike I worked on a "simple" parser for patterns at one point (mostly to get MakeCheckedReader to function better, but abandoned for something better), and they start to make a lot more sense.
@Heike I guess my objection to the question is that it seems like another RTFM question, and no effort went into reading the docs to see if they said anything, like what a_ means.
I think TagSet does not quite "extend the grammar"; for instance 'Unprotect[Integrate]; Integrate /: Integrate[f[x], {x, a_, b_}] = F[a, b] Protect[Integrate];'
I understand why its less dangerous to associate new rules to user symbols rather than built it symbol; but my purpose is really to extend mathematica's integration ability in a direction I am interested in rather than (in my context) extend properties of MultinormalDistribution as a far Expectation is concerned.
@Heike I think standard is to have the function keys to not be f1, f2 etc but to be brightness, "dashboard and all the rest. but there is an option in the prefs to change the behaviour so that pressing f1 actually send f1, and so on.
Here I am interested in 2 built in objects though Integrate and MultinormalDistribution (well technically 3 since I want Expectation to work with Boole in a regime it does not by default.
@acl most of the systems I deal with use vim by default. and once I got used to the syntax, I haven't gone back. using a single command, I refactored flawlessly 24 similar lines of code to their new equivalents without a hassle.
@Heike Pixar is smart— they do stuff like "Cars", "Up", "Finding Nemo", "Toy Story", etc which don't have as much hair as Dreamworks' stuff. No wonder their films are hits... better use of CPU time to, you know, create a good story
I was reading this paper on how to use PDEs to generate synthetic textures like the giraffe pattern, but I haven't fully thought about how to translate their ideas into a Mathematica implementation...
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does anybody know how I can export a notebook object as pdf? (short of scripting mathematica externally)?
Export["~/Desktop/nb.pdf", nb] and the like don't seem to work. I'm not knowledgeable about fronted programming so am probably missing something obvious
So, trying out those solution it appears that my problem is something else entirely, since when I load the Time Series package it is the package LogLikelihoodfunction that I can't access, even when using the full context in referring to it. — Mr Alpha5 hours ago
If this is true, the question which has been closed as a duplicate, might need to be reopened
i am tring to solve differential equations with variable parameter (p) :
x''[t] == (1/(p*p))*y[t], y'[t] == -x'[t] - y[t] + u, the sign of u change depending on the position of x[t]
if x[t+1]> x[t] and x start from (0) so u = 10 until x[t]=4
if x[t+1]< x[t] (and normally x start...
I had such expression in "applicative form", like : Y [X][X][Z][X][Y [X][M][Z][X]][Y [X][F][Z][X]]. In these structure we have different types: Y,X, Z, F .
And I want to index such structure, in a way to rewrite this expresion like ..we have :
Y [X][X][Z][X][Y [X][M][Z][X]][Y [X][F][Z][X]], this ...
@acl My first reaction was to start editing, but as I read a little further, I realized it can't be salvaged... at least, not in its current form and not without going through his code in depth
@Heike yes but I think we shouldn't encourage too many questions where it comes down to one of us guessing what's being asked and answering (like I did yesterday)
Inspired by F'x, here's a 2D analogue of spikey. Done with a bunch of rules because I like them, and they make it clear what is going on.
Start with a pentagon:
p = Polygon[Table[N[{Cos[t], Sin[t]}], {t, \[Pi]/10, 2 \[Pi], (2 \[Pi])/5}]];
Make a rule to split any polygon into triangles (ce...
For example if I was defining the following function
exprod[n_] := Expand[Product[x + i, {i, 1, n}]]
Then why is the underscore after the variable n, necessary in the function definition? Where does this style come from or is it specific only to the Mathematica programming language?
i am tring to solve differential equations with variable parameter (p) :
x''[t] == (1/(p*p))*y[t], y'[t] == -x'[t] - y[t] + u, the sign of u change depending on the position of x[t]
if x[t+1]> x[t] and x start from (0) so u = 10 until x[t]=4
if x[t+1]< x[t] (and normally x start...
