@acl That's what FourierParameters is for, dude. ;)
It amuses me how a lot of people use Fourier functions in Mathematica and are completely shocked upon learning that the option FourierParameters exists...
I want to generate a graphic using
DiscretePlot[primePercent[x], {x, 10^10}, ImageSize -> Full,
Filling -> None, Joined -> True] where primePercent[x_Integer] := 100 PrimePi[x]/x
When I generate it for 10^6, my computer becomes slow as there are simply too many data points. What I'm ...
@all, here's a weird idea, at least in origin, if not actuality. Jewish Life and Learning does a weekly question challenge wherein the users are challenged to come up with good questions on a given topic. This weeks topic: trees. Any one think we can "contribute" to this challenge?
@JM I still think we are doing ok on the # questions front. One thing I've noticed is that a lot of users are visiting the site frequently but not necessarily taking any actions. I wonder if they are put off by the speed of the high-rep answerers?
When we get a blog, I propose that we have an "Underappreciated Mathematica Function of the Week" post series. Including Inner, Outer and Pick.
@Verbeia I briefly accessed chat on a tablet earlier today and I remembered you saying something about people currently in the room not being visible. It's not shown on the screen, but you can see the list from menu > people. The menu button is at the bottom left
My cache is full of Mathematica stuff (as in: Linux' graph shows a full RAM). Quitting the kernel will solve the problem, but can't I clear the cache from the notebook itself?
Taking a page from this meta.math.SE discussion, and in light of this question, I wonder if it would be worthwhile for us to maintain a community wiki post like this one in meta.math.SE that lists questions that a.) are likely to be asked, in ever so different variations, again and again; and b.)...
@JM I'm not sure I understand completely. Do you suggest asking generic versions of these questions and answering them so we have something to mark these FAQ as duplicates of? (You are right about that question, it is absolutely a FAQ, it comes up all the time)
@David Isn't it the In/Out symbols that are taking up memory? Try Unprotect[In, Out]; Clear[In, Out]; $HistoryLength=1;
@rcollyer How about: How can I efficiently find a small number of edges to remove from a directed graph to make it a DAG? DAGs are pretty close to trees.
@Szabolcs "asking generic versions of these questions" - nothing of that sort; I'm saying we co-opt such questions as they are asked into the FAQ as needed.
@Szabolcs If you'll look at math.SE, most of the questions were not asked as canonicals, but the answers given were so good, that they were selected as canonicals.
@JM There I didn't suggest asking them, but using existing ones.
Is there any chance these timings could have come from an n Log[n] complexity algorithm? --> {1024, 0.047}, {2048, 0.249}, {4096, 1.233}, {8192, 5.428}, {16384, 17.317}, {32768, 49.998}}
@Heike the first number of the pairs if n, the second one is the timing. But I heard these newer Intel processors are quite unpredictable about how fast they run, dynamically adjusting the clock rate depending on how many cores are in use ... I have no experience with them. My own machine is an old Pentium M (I ran these on an i5)
I love this place; I'll have to think about this, but its 2am here and I have to get up for work soon. I'll try to see if something strikes about the n log n data.
I need some quick help: there was an example of using either of Subsets[] or Tuples[] for quickly producing the vertices of a cube, but I can't remember it. Might any of you remember?
I wonder what Salesforce does. Out of the 45 people who have committed to the Salesforce proposal so far there are 4 beginner/learners. The rest is professional/expert.
While playing around with the solutions to this question, I've found some very strange behaviour:
MatchQ[3,_?Composition[Not,OptionQ]]
(*
==> False
*)
MatchQ[3,_?(Not[OptionQ[#]]&)]
(*
==> True
*)
Composition[Not,OptionQ][3]
(*
==> True
*)
So what's wrong with the first pattern? O...
I hadn't noticed that before because my use of PatternTest is invariably either with a single named function: _?testQ or with a pure function and parentheses: _?(test@# &)
Are there any other operators that have greater binding power than function brackets? I know that func@list[[1]] binds to Part first but that's not quite the same.
But J.M., do you bother with subscripting it? yoda, I use Part sometimes. It can help reduce bracket clutter. It also helps with grouping where you would otherwise need (stuff)[[. . .]]
J.M. I think one of the major benefits of infix is that it visually shows that it is a binary operator, therefore you aren't left guessing how many arguments it takes. Anyway, let's not get onto that old topic again.
Plot builds style lists based on the apparent structure of the first argument it is given, before evaluation. List is recognized and elements are styled individually, while generic functions like Table are style as a whole.
You can see this behavior here, where Sequence acts as a "generic head"...
@MrWizard well, I haven't gotten to the point (or written enough loc/inputcells) where I've started stringing infixes, but I do use it often now for Partition with one argument, N with a specific precision, etc
...for instance: Graphics[Composition[Point, Through, {Re, Im}] /@ Exp[2 I Pi Range[0, 4]/5]].
@MrWizard When quickly reading through code, it sometimes looks as if I'm applying to the functions themselves instead of that thing it's all being applied to down the road. With Composition[], at least I have visual indication that you have a sequence of transformations being applied.
...and I can treat the composition of functions as an atom in itself, so I can work at a higher level of abstraction.
@MrWizard That's admittedly more compact for this case :) but with what I work with, I think it's a great aid to group a sequence of applications as a composition. The Composition[] object reads like Chinese though, so if you're not used to right-to-left languages, I can see why you're not too fond of it.
My idea with starting a line with an operator ( /./@@@@ ) is that it may be more visually apparent what the relationship between lines is; this was inspired by WReach's code, where he starts the line with a comma.
so for instance: Composition[Point, Through, {Re, Im}]: "take real and imaginary parts, use Through[] for simultaneous application, and wrap with Point[]."
@yoda ...and you've just betrayed my traditional nature... :D
@MrWizard I prefer putting the operator on the previous line because sometimes the code breaks if the line before the operator is a complete expression
(FWIW, it's also how I split long expressions in $\LaTeX$. I finish a line with an operator, up until the last operand.)
The other benefit is that visually you see that ({Re, Im}@#) & /@ is incomplete; you're forced to ask "where's the rest?", and then the next line provides your answer.
@JM interesting... I've always been told that operators be placed at the beginning of the new line and not the end of the previous, because it's easy to miss (ok ok, if someone is that careless, they should not be reading it).
Heike I noticed acl's comment in the sidebar and checked the context. You can always copy system files to the $UserBaseDirectory and edit that copy; the change should still take precedence.
One way to deal with problems like this is to use DynamicModule inside the Manipulate:
Manipulate[
DynamicModule[{e1, e2, standardBasis, y, p}
, e1 := {1, 0}
; e2 := {0, 1}
; standardBasis := {e1, e2}
; y := 3
; Dynamic[
p := {x, y}
; arrowsReference =
Table[Arrow[{...
I know I can use shell commands with Import and get the output... but I was thinking of a permanent cell, say at the bottom (toggleable) that gives you shell access (no In & Out cells... just like a terminal)
See, this is why I like chat; I can use it to make sure I'm not asking dumb crap... :) Quality control!
"where a realistic representation of hair and fur has proven a tough challenge." - yes, that's what made Monsters Inc. a rather impressive movie at the time...
Almost all scientists I know write it clockwise, but Greek people always seem to write it counterclockwise, just like the digit 6. @acl what do you think? :-)
Yes, of that is called the Doodle, and I guess I haven't been observant. With music and everything? I know they have had ones with falling snowflakes and the like, but I had not seen a full animation.
Did you see the one on Stanislaw Lem's birthday? I think it was not shown in the US.
The Doodles are different for different language/country editions of Google (and Google.com seems to sometimes give me the US version and sometimes a version based on my IP/location)
If you feel like doing some system spelunking, please see my function contextFreeDefinition. I am hoping someone would come up with some ideas on how to improve it.
@Heike four rushed replies, almost the same, all within 5 minutes.
Please, how would you write this? I use this form often myself and I don't find it surprising. I guess I see your point about the double function in this case.
@MrWizard Why don't you provide an easy to read and understand solution in addition to the clever and short one?
cToMma[s_String] := Module[{result, stream = StringToStream[s]},
result = Read[s, Number];
(* error checking here *)
Close[stream];
result
]
@MrWizard The problem with these is that it's a lot easier to write them than to read them. And to read them one needs to get used to some common constructs. You have your personal standards that you are now familiar with. So for you it's easy to read. But I don't think this pattern you used here is common in the community, so I'd argue most people would need a few seconds to decipher it. And beginners would need a lot of time to decipher it.
@MrWizard It is of course very worth posting. We communicate a lot here and exchange a lot of code which makes it possible to develop some common standards---i.e. some popular patterns will emerge which will still be opaque to newcomers but will probably be very quickly recognizable by more experienced people. I think what is easy to read and what isn't is often a "cultural thing", it's a question of what we're all used to
OK, now you got my +1
Coffee time (no water boiler in the office so I can't make my preferred tea...)
Is there a more clear yet fairly concise way do this?:# &[code for return, code for cleanup] I specifically want to avoid: x = code for return; cleanup; x
Szabolcs if someone as knowledgeable as you found it confusing then I'm sure others will too. I would like to find something both clear, and more concise than the Module approach.
@MrWizard Perhaps it'd be useful to include a link to that "cautionary tale". It's not at all obvious that it's so important to close streams. He was using StringToStream exactly for the same purpose, and that's how he ended up with a gazillion open streams.
Heike I didn't mean to imply that your version wasn't clearer; I just don't feel competent to judge at this point. I personally thought that pure functions were at a more basic level than Sow/Reap and would be introduced earlier in one's exposure to Mathematica.
@Szabolcs I write the o anticlockwise starting from the top, then when I reach the top again I draw the horizontal bar. not sure how general this is though
(I am the person who has been writing y mirror imaged my whole life, and only realized it last year when I was told)
@Heike I don't, but I have trouble with zeta (as in, I don't know how it is supposed to be written by hand; I just put something vaguely like the typeset version and hope that people pattern match it)
I am cypriot actually, but greek is my mother tongue yes. still, the last time I wrote anything longer than a few sentences in greek was more than a decade ago
The link button in the post editor incorrectly escapes square brackets in inline code.
To reproduce:
Write the following MarkDown in the editor
text text `function[]` text text
Select `function[]`, press the link button (), and enter some link
the result will be [`function\[\]`][1] which ren...
@MrWizard yes sometimes background beats upbringing. I find that simply randomly inserting a 42 somewhere in my slides in any talk I give anywhere cracks the audience up, independently of country
@Heike Only in Modern Greek. "υ" is the Greek letter whose pronunciation has changed most recently. Just 1000 years ago it was still different from i (I imagine it to be similar to the Norwegian y, somewhere halfway between i and ü, some time before that it was ü, and in Homeric times it is said to have been u)
@Heike an acquaintance is doing a phd in ancient greek music. they are basically trying to work out how everything was supposed to be played, how it sounded etc to start with. seems not much is known. same problem as for pronunciation
@Heike There are some ancient works on pronunciation. I read a lot about these when I was learning Modern Greek. There are also some comparisons between languages (a Greek textbook for Romans maybe? :-)
But there's always a lot of debate because Greeks like to use the modern pronunciation even for ancient texts while scholars from other countries like to use the Erasmian pronunciation (which is said to be different from the actual Ancient Greek pronunciation again), and they all have a very emotional attitude to it
also, Greek has a very long written history and its pronunciation has been changing continuously throughout all those centuries
@Szabolcs maybe long and tedious lessons of classical greek, with modern pronunciation and medieval accent system, has something to do with emotional attachment to what they know
it was different 2800 years ago from 2000 years ago, so Homeric Greek almost certainly sounded quite different from the Koine Greek of the time when the New Testament was written
@acl I also use the Modern pronunciation even when talking about ancient things
@Heike there's an ancient Greek play where the author said something like "sheep say βηηη βηηη. That's how they know that β was pronounced like b and not like v (as it is in Modern Greek) :D
I want to generate a graphic using
DiscretePlot[primePercent[x], {x, 10^10}, ImageSize -> Full,
Filling -> None, Joined -> True] where primePercent[x_Integer] := 100 PrimePi[x]/x
When I generate it for 10^6, my computer becomes slow as there are simply too many data points. What I'm ...
While playing around with the solutions to this question, I've found some very strange behaviour:
MatchQ[3,_?Composition[Not,OptionQ]]
(*
==> False
*)
MatchQ[3,_?(Not[OptionQ[#]]&)]
(*
==> True
*)
Composition[Not,OptionQ][3]
(*
==> True
*)
So what's wrong with the first pattern? O...
Plot builds style lists based on the apparent structure of the first argument it is given, before evaluation. List is recognized and elements are styled individually, while generic functions like Table are style as a whole.
You can see this behavior here, where Sequence acts as a "generic head"...
One way to deal with problems like this is to use DynamicModule inside the Manipulate:
Manipulate[
DynamicModule[{e1, e2, standardBasis, y, p}
, e1 := {1, 0}
; e2 := {0, 1}
; standardBasis := {e1, e2}
; y := 3
; Dynamic[
p := {x, y}
; arrowsReference =
Table[Arrow[{...
The link button in the post editor incorrectly escapes square brackets in inline code.
To reproduce:
Write the following MarkDown in the editor
text text `function[]` text text
Select `function[]`, press the link button (), and enter some link
the result will be [`function\[\]`][1] which ren...
