I was reading through the Wikipedia article on  and came across the fact that the most distant Quasar is 29 Billion Light years. This is what the  exactly says      The highest redshift quasar known (as of June 2011[update]) is ULAS-J1120+0641, with a redshift of 7.085, which corresponds to a proper distance of approximately 29 billion light-years from Earth.   Now I come to understand that the  singularity is believed to be around 13.8 Billion years ago.  So how is this possible? Does the presence of such a quasar negate the Big Bang Theory?   I'm not a student of Physics and was reading this out of (whimsical) curiosity. Is there something I'm missing here or the "proper distance" mentioned in the fact is a concept that explains this?  Edit: My Bad! Here's how..  A simple google search led me to  which says the farthest quasar found is 12.9 billion LYs and not 29 billion. So in the end we have just proven that wikipedia needs more moderation.

The observable universe is approximately 13.7 billion years old. But yet it is 80 billion light years across. Isn't this a contradiction?


I have three functions f1(x), f2(x) and f3(x) returning a result (imagine API calls, no control over the functions). Those functions can take an undetermined amount of time to end when called (but usually under 1s). Now I need to call all those functions and select the best result but under the constrain that I need to return some result in max t miliseconds. Pseudocode:  def select_result(x, max_t):     r1 = f1(x) # but stop if it takes longer than max_t miliseconds     r2 = f2(x) # but stop if it takes longer than max_t miliseconds     r3 = f3(x) # but stop if it takes longer than max_t miliseconds     return max(r1, r2, r3) # or None if it took too long   How can I achieve that in Python?

I'm calling a function in Python which I know may stall and force me to restart the script.   How do I call the function or what do I wrap it in so that if it takes longer than 5 seconds the script cancels it and does something else?


(the notation here is compatible with J.E. Humphrey's "Introduction to Lie Algebras and Representation Theory")  Let $\Phi \subset E$ be a root system. Let $\Delta \subset \Phi$ be a base. I already know that $\Phi^\vee \subset E$ is a root system. I'd like to show that $\Delta^\vee \subset \Phi^\vee$ is a base. (the notation $\alpha^\vee$ means $\frac{2\alpha}{(\alpha,\alpha)}$)  I tried 2 approaches and was stuck with about the same problem.  Here's one attempt: I'll denote $\Delta=\Delta(\gamma)$ for some regular $\gamma \in E$. I'd like to show that $\Delta(\gamma)^\vee=\Delta(\gamma^\vee)$. I can easily show that $\Phi^+(\gamma)^\vee=(\Phi^\vee)^+(\gamma^\vee)$. But then, how do I show that the indecomposable elements in $(\Phi^\vee)^+(\gamma^\vee)$ are exactly the duals of the indecomposable elements in $\Phi^+(\gamma)$? (If this is true, than it goes the other way around too, so I'll try to show that the dual of a decomposable element is decomposable). Denote $\alpha=\beta_1+\beta_2$ for some $\alpha,\beta_1,\beta_2 \in \Phi^+(\gamma)$. I'd like to show that $\alpha^\vee$ is decomposable too (in $(\Phi^+(\gamma))^\vee$). It is not true that $\alpha^\vee=\beta_1^\vee+\beta_2^\vee$ as I've seen by checking 2-dimensional examples. That's where I'm stuck.  (the other attempt was to go straight from the definition of a base, and there I had a problem with proving the integrality of the coefficients)  Another idea was to use the correspondence between Weyl chambers and bases. Both $\Phi$ and $\Phi^\vee$ define the same Weyl chambers. This gives a correspondence between the bases of $\Phi$ and the bases of $\Phi^\vee$. The correspondence is probably given by taking the dual of a base, but that's what I'm stuck at showing.

Let $\Phi$ be a root system in a real inner product space $E$. Define $\alpha^\vee = \frac{2\alpha}{(\alpha, \alpha)}$. Then the set $\Phi^\vee = \{\alpha^\vee: \alpha \in \Phi \}$ is also a root system.  Let $B$ be a base for the root system $\Phi$, ie. $B$ is a basis for $E$ and each $\alpha \in \Phi$ can be written as $\alpha = \sum_{\beta \in B} {k_\beta} \beta$ such that $k_\beta$ are integers of same sign.     Question: How to prove that $B^\vee = \{ \alpha^\vee: \alpha \in B\}$ is a base for the root system $\Phi^\vee$?   It is easy to see that $B^\vee$ is a basis for $E$. For the other property, here is what I have so far. Let $\alpha = \sum_{\beta \in B} {k_\beta} \beta$ be a root. Then  $$\alpha^\vee = \sum_{\beta \in B} \frac{k_\beta (\beta, \beta)}{(\alpha, \alpha)} \beta^\vee$$  so to prove the claim, it is necessary to prove that $\frac{k_\beta (\beta, \beta)}{(\alpha, \alpha)}$ is an integer. I don't see how that follows. In the case where $(\alpha, \beta) = 0$ the proportion $\frac{(\beta, \beta)}{(\alpha, \alpha)}$ could be anything, so I am a bit confused.


I am a Vietnamese passport holder. I'm going back to Vietnam from Seattle next week. I will have a half-day layover in Incheon Airport. I want to go into the city - Seoul just for resting, like getting a hotel and stuff. Do I need a Korean visa for this? If I do, where should I go and get it? How long will it take?  My U.S. visa is still valid. Also, I booked tickets from Vietnam to US already.

I'm planning to fly from Ulaanbaatar to Melbourne via Seoul (and Kuala Lumpur).  However, can I actually enter South Korea using this visa waiver? I'm hoping to meet a friend there for a few hours before flying. Also, would traveling via Malaysia affect this policy?  Transit tourists bound for another country Eligible countries  Applicable to all countries (save for Macedonia, Cuba, Syria, Sudan and Iran) that are not granted visa-free entry into Korea.  Applicable to…  Those with a visa (excluding Japanses Group Visa, excluding e-visa) or a re-entry permit for U.S., Japan, Canada, Australia, or New Zealand (5 countries) and traveling to any one of those countries through Korea.  Those traveling from any one of the five countries mentioned above, whose final destination is not Korea.  However, please note that the first bullet points are not applicable to those travelling to/from Guam and Saipan, which are unincorporated territories of the United States.   Requirements  Must have a confirmed onward flight ticket for departure within 30 days after entering Korea, in addition to having no record of criminal offence in the five countries mentioned above.


With Ubuntu 18.04, I need the command line xrandr --output DP-1 --scale 0.5x0.5. How can I automate that command when I power on my computer?  EDIT  I created the /etc/rc.local file, and in that file I have written  #!/bin/bash  xrandr --output DP-1 --scale 0.5x0.5  exit 0   The problem is if I restart the computer, the screen is identical and wrong. It seems to work if I run the command bash /etc/rc.local, but not if I restart the computer. How can I fix that?

How can I run the following xrandrcommand on startup?  xrandr   cvt 1368 768  xrandr --newmode "1368x768_60.00"   85.25  1368 1440 1576 1784  768 771 781 798 -hsync +vsync xrandr --addmode VGA1 1368x768_60.00 xrandr --output VGA1 --mode 1368x768_60.00


How do Stack Overflow and the rest of Stack Exchange sites stay up?   Someone has got to pay for the infrastructure and people's wages. So how do these sites make money?  Is it purely through advertising?  (I'm not looking to copy it! :) I'm just amazed that such a great system works for free!)

I once , but that was . Now, , and they have , but where's the business model? The  its own Q&A about its site (since it wasn't included in the ), and just about the only dig in there that halfway has merit is the business model dig:  We switched to a premium model to keep out of the Venture Capital business (been there, done that, got the t-shirt). Companies like StackExchange couldn't do it without the VC cookie jar. Where's the model? Huh, Spolsky? (I’m sorry. Did that slip out?)  It hurt, but I can't help but wonder if they're on to something.  How would Stack Overflow Internet Services pay back the VCs? Ad revenue alone?  There is only one 'paid' product, Stack Overflow careers, but it doesn't seem like that could sustain a business as large as Stack Overflow (Joel once mentioned on his blog that his jobs board brought in an extra million a year in revenue). So what does Stack Overflow do when the VC cash runs out? Is this a get-big-and-take-the-company-public maneuver? Is that the only viable business model for Stack Exchange? Edit: With the size of Stack Overflow's team, it isn't a stretch to say that payroll is at least $2 million  a year, probably as much as 4 when you think about benefits (average 120K for a developer in New York City; x2 for benefits/taxes/all-that-other-good-stuff). Office space can't be cheap, so how long does $6 million last before you need another VC infusion?


So very shortly, I want a shortcut equivalent to dragging the little handle in the right-bottom in a cell-selection portion in Excel 2013 (for Windows).  There is many similar questions on the site, but either the questions or their answers are non-relevant for me and my needs, so I am going to give you specific details here of what I want to do and my constraints.   I want a keyboard SHORTcut (the answer "ALT+H+F+I+S+ENTER" is superfluous since it is a menu-mnemonic path and not a shortcut) I want to AUTO-fill (the fill-down/right shortcuts "CTRL+D" and "CTRL+R" are not relevant since it just copies values. I am searching something like this, but the action being "autofill", not "fill") I don't want to duplicate formulas, don't propose to make formulas instead of using absolute values, I want to auto fill series (numbers/dates etc...)   Since I didn't find anything during my research I suspect there is no way of doing so, but are there any way to solve this with "custom-shortcuts" or macros (which I have no experience of)?

I have more than 10,000 rows of data I need to do some calculations on one column of the data. I have made the calculation in one cell and now need to fill the formula for the calculation and all the cells.  Usually I just select the cells using the keyboard and then press the Ctrl+D to fill the cells. However, now I have to do this repeatedly, and it is difficult to keep on selecting 5000 rows each file. Is there a simpler way where I can just specify the range using the keyboard? Perhaps even have a macro since all of the files have a fixed length  Also, since I have difficulty in using the mouse because of medical reasons and therefore I have not tested  which involves clicking on a very small fill handle. Maybe there is a parallel solution to this using the keyboard or maybe I can create a macro which will automatically click on a fill handle of a selected cell - please advise if there is a way.


The CLI in  of cmark uses the |= operator for combining on/off options when iterating over arguments. A simplified version looks like:  #define CMARK_OPT_DEFAULT 0 #define CMARK_OPT_SOURCEPOS 1 #define CMARK_OPT_HARDBREAKS 2 #define CMARK_OPT_NORMALIZE 4 #define CMARK_OPT_SMART 8  int options = CMARK_OPT_DEFAULT;  for (i = 1; i < argc; i++) {     if (strcmp(argv[i], "--sourcepos") == 0) {         options |= CMARK_OPT_SOURCEPOS;     } else if (strcmp(argv[i], "--hardbreaks") == 0) {         options |= CMARK_OPT_HARDBREAKS;     } else if (strcmp(argv[i], "--smart") == 0) {         options |= CMARK_OPT_SMART;     } else if (strcmp(argv[i], "--normalize") == 0) {         options |= CMARK_OPT_NORMALIZE;     }      ... }   What is the benefit of using |= and not += to add up the options?

I'm someone who writes code just for fun and haven't really delved into it in either an academic or professional setting, so stuff like these bitwise operators really escapes me.  I was reading an article about JavaScript, which apparently supports bitwise operations. I keep seeing this operation mentioned in places, and I've tried reading about to figure out what exactly it is, but I just don't seem to get it at all. So what are they? Clear examples would be great! :D  Just a few more questions - what are some practical applications of bitwise operations? When might you use them?


I cannot find a way to assign-view the material I chose for a predefined stair.   This is what I have

I am creating a model of a glass and I would like to put a drawing on it (a png picture).  I know how to do it using Blender Render, but not with Cycles Render. Help :)


Mathematical proofs are written as sentences and not as collections of logic symbols. Through logical operations, it is much easier for me to visualize what the symbols are trying to tell us rather than English text filled with grammar. This is my personal opinion, others may have different opinions. I just asked  on another website to find out logical mistakes in  which is entirely done in the language of propositional logic. Some people suggested to write it down in sentences in English. Is there any kind of tragedy in writing proofs as collections of logic symbols?

I haven't read very many proofs. The majority of the ones that I've read, I've read in my first-year proofs textbook. Nevertheless, its first chapter expatiates on the proper use of English in mathematical proofs, so I suspect that most proof authors do use both English (or another natural language) and formal proof systems for writing their proofs. However, I can't imagine many circumstances where mathematical notation and a formal proof system wouldn't suffice to convey the author's pertinent thoughts.   I suspect that proof authors have good reasons for making use of both English and formal expressions in their proofs, but I can't think of what those reasons are. Why do proof authors use English and formal expressions to write proofs? Are there stylistic rules (or guidelines) that state how, and in what parts of the proof, an author should, and shouldn't, use English?


I have downloaded ubuntu onto my computer but the computer wants to use windows media player to read the file which it cannot so what do I need to do ?

I would like to see a full how-to guide on how to install Ubuntu.


This code from a tutorial works fine in PyQt5 if I call it from __main__     window = QWidget()     layout = QVBoxLayout()     layout.addWidget(QPushButton('Top'))     layout.addWidget(QPushButton('Bottom'))     window.setLayout(layout)     window.show()  If I put the code class in the __init__ of a class: class MainWindow (QMainWindow):      def __init__ (self):          print ("HERE 1")         window = QWidget()         layout = QVBoxLayout()         layout.addWidget(QPushButton('Top'))         layout.addWidget(QPushButton('Bottom'))         window.setLayout(layout)         window.show()         print ("HERE 2")         return  then in __main__: app = QApplication (args)  mw = MainWindow.MainWindow ()  return app.exec_ ()  Then the print statemets happen but no widgets display. Why would window not display in the second case? (The corresponding C++ code would display it.)

I'm trying to understand the use of super(). From the looks of it, both child classes can be created, just fine.   I'm curious to know about the actual difference between the following 2 child classes.  class Base(object):     def __init__(self):         print "Base created"  class ChildA(Base):     def __init__(self):         Base.__init__(self)  class ChildB(Base):     def __init__(self):         super(ChildB, self).__init__()  ChildA()  ChildB()


I have a general understanding of how mergers and acquisitions work for symbols being traded in long positions. However, I am confused about how these events are calculated when shorts positions are involved.   Let's say symbol ABC is merging with XYZ. Merger ratio is 1:2 (1 of ABC for 2 of XYZ)   If I am long 10 ABC and long 20 XYZ, after the merger I would be long 20 on ABC.   What happens if I am...  short on ABC and long on XYZ?  long on ABC and short on XYZ?   short on ABC and short on XYZ?   flat on ABC and short on XYZ?

Let's say for the sake of the question you're given the following scenario:   Company BIG is trading at $10/share Company SML is trading at $40/share BIG reaches an agreement with SML for an all stock acquisition/merger whereas SML shareholders will receive 5 shares of BIG for each share they own   How would a call option in SML be affected by this deal?  Specifically, I'm unsure of the following:   How is the strike price for SML options affected by the merger? I've read that the only thing that would change is the deliverable (i.e. instead of receiving 100 shares in SML when exercising, you'd now receive 500), but this result in SML contracts having inflated strike prices due to the difference in the value per share pre-merger... What happens to out of the money SML options? I've read that they'd instantly become worthless... wouldn't this only apply to an all-cash deal? If the deal involved a transfer of shares, wouldn't the contract be adjusted based on the terms of the deal with the deliverable changing from shares of SML to shares of BIG? Assuming the deliverable for the SML options are converted to shares of BIG, how are these converted contracts traded... in other words, are they liquid or only useful if you decide to exercise them?   I just started trading options a few weeks ago and haven't been able to find answers to these questions anywhere... any help from an experienced trader would be much appreciated!


I posted this earlier to no avail. It's an example of a topic i'm struggling with, I'm mostly looking for a sample answer that i can ask about and analyze to try and understand the "characteristic" portion.  $1$) Suppose $Y^3 = Y$ for each element $Y$ of a unital ring $R$. Show that $R$ has a finite characteristic d that is a divisor of $6$.

I'm struggling with some concepts in my algebra class. I've chosen these two completely unrelated examples that demonstrate my struggling topics (characteristics and function rings) the two are the following:  $1$) Let $X$ be a set, and let $S$ be a ring. Give a proof that the left distributive law holds for $(S^X, +, *)$.  $2$) Suppose $Y^3 = Y$ for each element $Y$ of a unital ring $R$. Show that $R$ has a finite characteristic d that is a divisor of $6$.  Any example solutions for these proofs would be helpful. Thank you.


What's the name of a classic sci-fi short story about a planet where their religion makes people willingly merge with a parasite in a cave and die?   Outsiders can't understand why anyone would do such a thing, and when off-world visitors start joining the religion and committing suicide, two humans (a couple) with psychic abilities are sent to get their impressions.  They discover the reason everyone happily merges with the parasite is that, by merging (and slowly dying), in return they join a joyous mental community of every previous person who has joined, with overwhelming feelings of happiness--ecstasy, really.  All the psychic love is nirvana for the very sensitive female partner. She joins the religion and merges. She asks her partner to join the parasite as well but he refuses.  The male leaves the planet with the realization that their love for each other couldn't compete with the parasite-mediated mass love and happiness on the planet.  After finishing the story it brings up thought-provoking ideas on whether you would join such a community, about the ties of your love to your own family,and does organized religion gain our interest by similar promises of eternal happiness?

In the early '80s, I read a story about a Terran man on another planet, where the natives develop skin lesions and eventually die, but are happy, as they become part of the planet they live on. I remember that the protagonist is not developing the lesions, because he hates the planet. Once he starts loving the planet, he starts having the lesions as well. In this story, the planet is "alive".  I have read about "" and "". They do not match my memory. Thank you.


What I'm trying to understand is where does a child process inherit exported variables from it's parent process    What I'm trying to understand is where a child process inherits exported environment variables from? I understand the exec() system call overwrites environment variable created by the fork()... But how does exec() cause exported environment variables to be included with a newly created child process if all the environment variables are overwritten? My best guess is that exported environment variables are somehow excluded from being overwritten... But I can't confirm this  EDIT I edited my question to be clearer with what I am asking

I'm studying 'operation system concepts' on my own and I'm studying the chp3. process part.  There is an example where the 'fork()' function is called and depending of the returned pid value like the following:  pid=fork(); if(pid<0){ //error stuff } else if(pid==0){ // child process stuff } else{ // parent process stuff }   What confused me here is that if this code is executed, among the three scenarios of 'if's, only one would be executed which means that only one out of parent/child procedures would be executed.  But reading a bit more carefully, I found a sentence that kind of helped me solve the confusion but not entirely.     The new process consists of a copy of the address space of the   original process.   From my imagination, I guess this means that whenever the 'fork()' calls is executed, somehow an exact copy of this code will be duplicated and be run as 'child' process when the original c code will be run as 'parent'.  Am I understanding this right?  Also, what does the 'address space' have to do with this? Again, using my imagination I assume that, since the execution of parent code means that the code is loaded to the RAM and executed where it will have a segment of RAM assigned to the code, this segment will be copied to a new segment somewhere else located in the RAM and be assigned for the child process.  Is my understanding correct?


I'm using Ubuntu 14.04.  I've downloaded wine and wine Q4 and I've made sure that i have all the components for wine. I'm trying to play battlefront 2 (it's an exe file which I downloaded online). I have the original cd but I can't play in on my laptop as my disk drive is broken.   When I try to open the file with wine it acts as if it's about to open but then closes down and changes my screen resolution. I know the file works because I've used it before on windows 7.  The file also has .dll and .bink.32 which I think it needs to run.  How can I get it working?

Can .exe and .msi files (Windows software) be installed in Ubuntu?


I am planning to submit for a conference that organized by the (World Congress in Computer Science, Computer Engineering, & Applied Computing ) located and held every year in the US. Looking at their invited speakers over the last 10 years, they managed to attract many top scientists from NASA, SAP, Google...etc  The conference that I am planning to submit my work for named The 20th Int'l Conf on Artificial Intelligence (ICAI'18) and ranked-B according to Qualis. After I checked the dblp database, I noticed that they stoped indexing the Congress proceeding on their website. Do that indicate or reflect any bad signs?

I recently received an invitation to a conference and I'm trying to determine how reputable it is. Is there a good way to go about this?


I'm trying to add two backgrounds in CSS but one image to fill the entire background and the other to be aligned on the centre right of the page. Here is a section of my current StyleSheet:     body {   font-family: 'Nunito', sans-serif;   color: #384047;   background-image: url(http://footyprofit.co/wp-content/uploads/2013/02/golf-background.jpg);   background-color: #cccccc;   background-position: center;   background-repeat: no-repeat;   -webkit-background-size: cover; }   I've tried separating the URLs with a comma and then separating the positioning by comma but this doesn't work. Any ideas?

Is it possible to have two background images?  For instance, I'd like to have one image repeat across the top (repeat-x), and another repeat across the entire page (repeat), where the one across the entire page is behind the one which repeats across the top.  I've found that I can achieve the desired effect for two background images by setting the background of html and body:  html {     background: url(images/bg.png); }  body {     background: url(images/bgtop.png) repeat-x; }   Is this "good" CSS?  Is there a better method?  And what if I wanted three or more background images?


I have Ubuntu 14.04. I am trying to install the latest version of R (3.3.2) via apt-get, but for some reason, it keeps installing an older version (3.0.2). This is, anytime I type sudo apt-get install r-base, it gets me R 3.0.2. This problem has persisted for a while. I was able to procrastinate finding a real solution by downloading the version of R that I wanted and installing it via   ./configure make make install   However, now that I want to upgrade my R, it is a good time to figure out why apt-get is not working.  I tried updating apt-get typing:  sudo apt-get upgrade sudo apt-get update   But it still insists in installing R 3.0.2.

I am pretty new to Linux. I installed R-base in my Ubuntu 12.04 using the Software Center (which by default is r-2.14). I want to upgrade to/install R 3.02 or newer. How can I do that? Thank you.


The zombies are supposed to drop a piece of paper named "Test" but it just screws up the whole zombie drop and not dropping anything at all.  Here is the part where the zombie is going to drop a named piece of paper:  {   "type": "minecraft:item",   "name": "minecraft:paper",   "functions": [     {     "function": "set_nbt",     "tag": "{display:{Name:"{\"text\":\"Test\"}"}}"     }   ] }   Is there something wrong with the code?

I need help with a specific command that I am using in a new game that I am creating inside of Minecraft. The command is:  /give @p sign 1 0 {BlockEntityTag:{Text1:"{"text":" [MF2]","color":"gold","clickEvent": {"action":"run_command","value":"tellraw @a [""{"text":"[MF2]  ","color":"gold"},{"selector":"@p","color":"dark_aqua"},{"text":" is now an admin of the server!","color":"white"}]"}}",Text3:"{"text":"Click to join Admin","color":"dark_aqua","clickEvent": {"action":"run_command","value":"scoreboard teams join admin @p"}}"},display: {Name:"Custom Sign"}}   If I take out the /tellraw command then the command works fine, but I need the command in there to announce to the game that a new admin has joined.  With the tellraw command, the error message is the following:  Data tag parsing failed: Unexpected token 't' at: text":" [MF2]","color":"gold","clickEvent":{"action":"run_command","value":"tellraw @a [""{"text":"[MF2] ","color":"gold"}, {"selector":"@p","color":"dark_aqua"},{"text":" is now an admin  of the server!","color":"white"}]"}}",Text3:"{"text":"Click to join Admin","color":"dark_aqua","clickEvent": {"action":"run_command","value":"scoreboard teams join admin @p"}}"   If anyone knows how to fix this, please let me know.


I want to create a journey that email one of my dealers when there is a new lead. In the email, the dealer needs to click on 2 buttons: Accept or Decline. If after 48 hours he didn't clicked on anything, the field of the response will automatically changes to Decline and the process start again by sending email to the next dealer in the DE.  Added in edit:I want that if the dealer clicks on Accept, even if it is 1 hour after the email was sent, it will right away continue the journey.  Is it something possible to create from the journey builder? How can I notify the lead after there is a match with dealer from within the journey? If it is possible, can it be done from one journey?  Thank you.

We're injecting records into a journey using a Salesforce data event.  I also want to advance the people in the journey based on updates that happen in Salesforce (e.g., as an Opportunity record advances through the sales process), but I can't figure out how to do that.  I've read all the documentation I can find, but there doesn't seem to be a Journey Builder widget that will wait to be prompted by an event in Salesforce before continuing someone on a journey.  At the moment, I'm completely stuck.    I'd greatly appreciate any advice or information on how I can make journeys event-driven in this way.  Thanks very much!


$$34_\alpha, 63_\alpha, 112_\alpha$$  I did:  $$34_\alpha + r_\alpha = 63\alpha \\ 63_\alpha+r_\alpha=112_\alpha \\ 112_\alpha = 34_\alpha+2r_\alpha \Leftrightarrow 112_\alpha -34_\alpha = 2r_\alpha  $$  Not sure where to go from here. I tried to convert these numbers to decimal but I don't know how many digits r has so that didn't get me anywhere.

Since the formula is $a_n = a_1 + (n-1)d$ I could make $a_1 = 34_a, a_2 = 63_a$ and $a_3 = 112_a$. So what I need is a base a where the difference between $112_a$ and $63_a$ is equal to the difference between 63_a and 34_a. So I did:  $$1*a^2+1*a+2 - 6*a + 3 = 6*a+3 - 3a +4 \iff\\ a^2+a+2-a6+3 = a6+3-a3+4 \iff \\ a^2-5a+5=3a+7\iff \\ a^2-7a-2=0$$  This doesn't give me an integer solution. What went wrong?


I have my own private domain hosting solution with email, for example, test@test.com.  When I am using the iCloud.com website from my browser, let's say for creating a spreadsheet, I will want to shed that with other people, however, I don't want to send it from my iCloud email address, instead I want to be able to send emails from within iCloud.com using my other email address, e.g., test@test.com, how can I do this?  Please note I am NOT asking to be able to send from iCloud from Mail, this is different. I believe my question is not the same as "Can I use a non "me.com" address to send email with iCloud".  If I am logged onto iCloud.com through my browser, I want to be able to use the mail part to send emails from my test@test.com address and not my name@icloud.com address.  I have checked the settings within iCloud and was not able to find anything.

I will  be buying an iPad and will want to use iCloud.  However, I want to use a non "@me.com" address to send email from/reply to.  Is this possible when you sign up for iCloud?  Thanks


A new SP farm has been setup and the content databases are restored from another farm. All the setup have been made in the search service application but it is not crawling all the documents from the sites even after running full crawl. there is no specific pattern of why the document is not crawled. I edited a document and did check in. Ran an incremental crawl on the corresponding content source. The document is showing up in search. Can anyone please explain why this behavior of SSA occurred and if there is any solution ?

We have a SharePoint 2007 site collection that some permissions were accidentally deleted from. It was impossible to determine how it was originally setup, so we decided to do an STSADM restore from the backup.  The restore went fine and the site is back to normal... except that now nothing in the site can be crawled (incremental crawls).  In the crawl log, we see the following error:         The object was not found. (The item was deleted because it was either   not found or the crawler was denied access to it.)   For all the items in the site, the error is:     Deleted by the gatherer (This item was deleted because its parent was   deleted.)   What I know:   The crawler definitely has access (other sites are crawled) It was working before the restore No weird errors in the ULS logs   Has anyone seen this before after a restore? Any idea how to fix it or get more information?


We have  but it doesn't give an approximation of the actual difference. Is there a way without calcualting an approximation of them to prove $e^\pi - \pi^e < 1$  ?


I have one simple question: How do we know that dark matter is not just ordinary matter which is simply not luminous? For example if we would take a black rock and put it somewhere in the universe, then we would not be able to see it, because there is not any radiation in the visible spectrum coming from this object.  My question also relates to the question: How do we know that the relation between baryonic mass and luminosity of one object is correct? (which relation does one use usually in this context?)

There's more gravitational force in our galaxy (and others) than can be explained by counting stars made of ordinary matter. So why not lots of dark planetary systems (i.e., without stars) made of ordinary matter? Why must we assume some undiscovered and unexplained form of matter?


I am reading a lecture note  and it says the following:      If we have a doubly indexed family of nonnegative numbers $a_{ij}, \  i, \ j \in \mathbb{N}$ and if either (i) the numbers are nonnegative,   or (ii) the sum $\sum_{(i,j)} a_{ij}$ is absolutely convergent, then       $$ \sum_{i=1}^\infty \sum_{j=1}^\infty a_{ij} =  \sum_{j=1}^\infty  \sum_{i=1}^\infty a_{ij} = \sum_{(i,j) \in \mathbb{N}^2} a_{ij}$$      More important, we stress that the first equality need not hold in the   absence of conditions (i) and (ii).   I am not sure why the last comment holds regarding the first equality where we change the order of the summation. Is there any well known counter-example?

Let $\{a_{mn}\},~m,n \in \Bbb{N}$, be an arbitrary double sequence of real numbers then does the following equality occur always?   $$\sum_{m=1}^{\infty}\sum_{n=1}^{\infty}a_{mn}^3=\sum_{n=1}^{\infty}\sum_{m=1}^{\infty}a_{mn}^3$$   I think there is no reason for the equality of this iterated series in general but I cannot figure out how to construct a counter example. Can anyone please help me how to create a example of $\{a_{mn}\}$ such that the given equality does not hold...!!


I've learnt a bit of linear algebra and both single variable and multivariable calculus.

I'm really interested in quantum theory and would like to learn all that I can about it. I've followed a few tutorials and read a few books but none satisfied me completely. I'm looking for introductions for beginners which do not depend heavily on linear algebra or calculus, or which provide a soft introduction for the requisite mathematics as they go along.  What are good introductory guides to QM along these lines?


I'm writing a book and I wanted to add sub-chapters like :  Chapter 1  Chapter 2  Chapter 3.1  Chapter 3.2  Chapter 3.3  Chapter 4  I've quite found an answer  but it's not working the way I wanted. Is someone having an idea ?

I'm typesetting a book and one of the chapters separates into two chapters so I need it to count like so:  chapter 1 ---------  chapter 2a ----------  chapter 2b ----------  chapter 3 ---------  chapter 4 ---------   I saw an almost solution . But this solution doesn't allow me to continue with my non-separated chapter counting.  This is chapters only, the sections are not numbered, and I'm using the book class with the hyperref package.


Currently I'm doing a physics related coursework on guitar strings and wave. I would like to ask how I can model the sound wave of a guitar with an equation. I asked some of my teachers and they told me that I should use Fourier analysis, but after reading it from Wolfram Alpha and doing a few example questions, I still don't know how to model the sound wave of a guitar. Can someone give me some advice or tell me if I'm doing anything wrong?

When you energise a taut string, the following resonant modes of vibration occur:    Plotting on the frequency domain, you can see their corresponding frequencies:    But what is the underlying physical principle? Why does this happen?  Is there any way of explaining it that could be understood by a smart 15 year old?  EDIT: I'm going to give my best attempt so far. Here goes:   We can start with sympathetic resonance. Sounding a particular frequency, a pure sinewave.  And noticing the string resonates sympathetically at the frequency of each harmonic. Say this is explained and understood. Now imagine that plucking a string is equivalent to a burst of white noise, which contains frequencies all the way through the spectrum. This could be approached backwards, by starting with random frequencies and noticing that resultant wave produced looks like white noise.   If the above is scientifically correct, then it restricts the domain of the question.  I would really like to be able to understand it scientifically and also be able to explain it intuitively.  PS Images from


I use Bibdesk to manage my bibliographic entries. I would like to put some entries in a paper and typeset them in the AMS format. I use BibLaTex, but this package doesn’t seem to have a preset for AMS style, so I would have to modify the style parameters myself, which seems like a daunting task. Otherwise I can use the amsrefs package. But to use amsrefs, you have to have your bibliography source file in a certain format that does not seem to be supported by Bibdesk. (You have to have entries starting with the \bib command, and for whatever reason Bibdesk does not seem to be able to produce a file in that format.)  So my question is, in short, how do I use AMS formatting while also using Bibdesk?

I'm using TeX live 2010.  I have a .bib file generated from Mendeley, and  I want to use that with amsrefs, but it's confusing and the amsrefs documentation is somewhat hard to follow: how do I massage the .bib file into something that amsrefs can stomach. (I'm using amsart as the document class).


After alot of dependency problems decided to remove all wine related packages from synaptic.  Recently upgraded from 12.04 to 14.04.  Do not understand what is happening. Get depends wine1.6-i386, when I try to install that get cmslib2-2 dependencies   $ sudo apt-get install wine winetricks Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  wine : Depends: wine1.6 but it is not going to be installed or                  wine1.7 but it is not going to be installed E: Unable to correct problems, you have held broken packages. 2014-08-28_15:28 ~ $

I upgraded on a fresh install to Ubuntu 12.10, and I've tried installing wine many times, but I always get this:  This error could be caused by required additional software packages which are missing or not installable.  Furthermore there could be a conflict between software packages which are not allowed to be installed at the same time. The following packages have unmet dependencies:  wine:   It won't let me install the dependencies either it says it needs another set of dependencies to install them. Using Asus KJ50 64bit OS, dual boot with Windows 7  sudo apt-get install wine1.5 Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  wine1.5 : Depends: wine1.5-i386 (= 1.5.15-0ubuntu1) but it is not installable            Recommends: gnome-exe-thumbnailer but it is not going to be installed or                        kde-runtime but it is not going to be installed            Recommends: ttf-droid            Recommends: ttf-mscorefonts-installer but it is not going to be installed            Recommends: ttf-umefont but it is not going to be installed            Recommends: ttf-unfonts-core but it is not going to be installed            Recommends: winbind but it is not going to be installed            Recommends: winetricks but it is not going to be installed E: Unable to correct problems, you have held broken packages.


I need to test my C# code in a SQL Server deadlock scenario.  Is there a way to create a deadlock "on demand"?  I have tried this:  Begin Transaction  Select * from TABLEA with (tablockx, holdlock) Where 0 = 1 WaitFor Delay '00:02:00' --Rollback Transaction   But the second connection just waits and until after the Delay, and then does its job.  In the second session I do   Update TABLEA  Set LastUpdatedBy = 'IT_TESTING' Where OrderRefProviderId = 397685 WaitFor Delay '00:00:30'

I am testing my application I need some code that stable simulates the deadlock on database site (sql script if possible).  Thank you.  ADDED:


I am giving a presentation in the beamer class. I would like the grouped bibliographic references to be displayed as [1]-[3] instead of [1-3]. \documentclass{beamer} \usetheme{AnnArbor} \usecolortheme{beaver}  \usepackage[brazil]{babel}       \usepackage[T1]{fontenc}         \usepackage[utf8]{inputenc}      \usepackage[square, comma, sort&compress]{natbib}  %\usepackage{cite} \begin{document}  \begin{frame}     References \cite{rodrigues2016unbalanced, rodrigues2016considerations, monteiro2018unbalanced}. \end{frame}   \begin{frame}[allowframebreaks]{References}     \tiny          \bibliographystyle{mmc-unsrt}     \bibliography{my_bibliography} \end{frame}  \end{document}  I tried to include the \renewcommand\citepunct{], [} and \renewcommand\citedash{]-[} commands in the preamble but it didn't work. They worked in the article class but in the beamer they don't work.

I have spent a whole day trying to solve the following problem. Please help if you know how to do this.  I am using natbib (\usepackage[sort&compress,square,comma]{natbib}), and my current citation style looks like [1-4], [5, 8-9].  What is the easiest way to change the citation style to [1]-[4] and [5],[8]-[9]?


I just can't understand the concept of $\lim \sup/\inf$ of sets, even after reading a lot about it. In limit infinum why do we have union sign with intersections (infima)? Can someone explain it very easily? Thank you very much.

I've looked at the Wikipedia article, but it seems like gibberish. The only thing I was able to pick out of it was the concept of infimum (greatest lower bound) and supremum (least upper bound), as I had learned them previously in an intro discrete math course.     The limit inferior of a sequence ($x_n$) is defined by      $\displaystyle\liminf_{n\to\infty}x_n := \lim_{n\to\infty}\Big(\inf_{m\geq n}x_m\Big)$      or      $\displaystyle\liminf_{n\to\infty}x_n := \sup_{n\geq 0}\,\inf_{m\geq n}x_m=\sup\{\,\inf\{\,x_m:m\geq n\,\}:n\geq 0\,\}.$      Similarly, the limit superior of ($x_n$) is defined by      $\displaystyle\limsup_{n\to\infty}x_n := \lim_{n\to\infty}\Big(\sup_{m\geq n}x_m\Big)$      or      $\displaystyle\limsup_{n\to\infty}x_n := \inf_{n\geq 0}\,\sup_{m\geq n}x_m=\inf\{\,\sup\{\,x_m:m\geq n\,\}:n\geq 0\,\}.$   Can anybody provide any examples of its use, and why it's used in that context?


I am trying to create a simple edge border to an a4 sheet using the \rule command  \newgeometry{left=0cm,right=0cm, top=0cm, bottom=0cm}  \hbox{ % Horizontal box  %\hspace*{0.1\textwidth} % Whitespace to the left of the title page \textcolor{black}{\rule{20mm}{297mm}} % Vertical line \textcolor{mygray}{\rule{5mm}{297mm}} \hspace*{4mm} \textcolor{black}{\rule{1mm}{297mm}} \hspace*{0.05\textwidth}}   However latex leaves white space before and after each rule as seen in the picture attached . I can use [-1mm] to shift the rule downwards but I can't work out how to shift it to the right hand side so the first two rules lie side by side and the first rule is at the extreme RHS of the page. How do I remove this whitespace?

I see that the code in many packages and examples contains percent signs % at the end of (many) lines. What are they used for? Do they affect the parsing of those lines?


Ubuntu 20.04 fresh upgrade Super key doesn't work as used to. I use it to trigger Arc Menu, however, does nothing even outside of Arc Menu. Until I switched keyboard layout (CZ-EN) I discovered Super key is working. So, Super Key doesn't work in either US or UK layout. Should I report it as a bug or is there some hidden feature?

After upgrading to Ubuntu 20.04 my super-key is no longer opening the activities overview when the keyboard layout is set to the secondary layout.   At first I thought it may have to do with the specific layout, but after switching the order of the layouts I use around the issue kept persisting only on the (new) secondary layout.


My String:  download_recording true Package available http://abc.com/recDownload/635131586215948750.exe  How to get http://abc.com/recDownload/635131586215948750.exe from the above string?  please help

I have an input String say Please go to http://stackoverflow.com. The url part of the String is detected and an anchor  is automatically added by many browser/IDE/applications. So it becomes Please go to http://stackoverflow.com.  I need to do the same using Java.


I have created the required buttons,panels and the frame and now i want to add everything where it needs to,but i have to create the .add method using the       getMethod() but i dont now what arguments to use.Also do i have to create different methods for the buttons and the panels or is there something more general?  Class frame = Class.forName(frame_path); Object obj = frame.newInstance(); Method meth = frame.getMethod("setVisible", Boolean.TYPE); Method meth2 = frame.getMethod("setDefaultCloseOperation", Integer.TYPE); meth.invoke(obj, true); meth2.invoke(obj, EXIT_ON_CLOSE);  Class jb1 = Class.forName(rec_button_path); Object objJb1 = jb1.newInstance(); Class jb2 = Class.forName(round_button_path); Object objJb2 = jb2.newInstance(); Class jb3 = Class.forName(rec_button_path); Object objJb3 = jb3.newInstance();  Class jPanel1 = Class.forName(container_path); Object objJP1 = jPanel1.newInstance();             Class jPanel2 = Class.forName(container_path); Object objJP2 = jPanel2.newInstance();  Method add1 = jPanel1.getMethod(".add", jb1);   // i need helpo here

If I have two variables:  Object obj; String methodName = "getName";   Without knowing the class of obj, how can I call the method identified by methodName on it?  The method being called has no parameters, and a String return value. It's a getter for a Java bean.


Is there any difference between creating a Task constructor with a var vs just a function?  function Task(name, priority, timeout){ this.name = name; this.priority = priority; this.timeout = timeout; this.completed = false; } var task1 = new Task("firsttask",10,70s);   Versus  var Task = function(name, priority, timeout){ this.name = name; this.priority = priority; this.timeout = timeout; this.completed = false; } var task1 = new Task("secondtask",20,30s);

I've recently started maintaining someone else's JavaScript code. I'm fixing bugs, adding features and also trying to tidy up the code and make it more consistent.  The previous developer used two ways of declaring functions and I can't work out if there is a reason behind it or not.  The two ways are:  var functionOne = function() {     // Some code };     function functionTwo() {     // Some code }   What are the reasons for using these two different methods and what are the pros and cons of each? Is there anything that can be done with one method that can't be done with the other?


I've solved quite a bit of these questions with tetrahedrons with a 90 degree angle, but I am not sure how to approach a non-right angle tetrahedron. I am unsure how to find the triple integral's bounds. Calculation itself is no problem.   $ \int_B (x + y + 2z) dV$  where B is the tetrahedron with vertices $(0, 0, 0)$, $(0, 2, 0)$, $(1, 3, 1)$ and $(1, 1, 0)$.  Is the way of finding the bounds same for non-right angle tetrahedrons?

Find the volume of the tetrahedron with the vertices $P(1,1,1)$, $Q(1, 2, 3)$, $R(3, 1, 2)$, and $S(2, 3, 1)$.


Why is the efficiency of Carnot engine regarded as the maximum efficiency possible for a heat engine?

It seems that the only condition used in proving that the Carnot engine is the most efficient is that it is reversible. More specifically, the Carnot engine can be run in reverse as a refrigerator. Furthermore, it is asserted that all reversible engines will have the same efficiency.   However, isn't any closed loop on a PV diagram reversible? The arrows can simply be drawn in the reverse way to create a refrigerator. If any closed loop is reversible then why does the specific Carnot engine (a specific loop) have the highest efficiency?


I have this old power adapter with a rating of 6V 2.4 Amp. I used a voltage divider circuit made of two 1000 ohm and one 10000 ohm resistors. when i measured the voltage across the 10k resistance, I got an exact drop of 1 volt, i.e., it was reading 5 V. i connected the ends to the micro USB and connected to my windows phone.  The phone was not charging. When i read the voltage with charger, the voltage was only 2.5 V instead of 5 V. What just happened here? the adapter was a 6 V adapter that was used for a router, why did stepping down voltage result in drop in voltage on connecting load. thanks for helping me out. How would i get a 5V to charge my cell phone from this adapter?

I have a 6V 3AMP power supply and I wanted to reduce the voltage output to 5V 3AMP.  I saw buck converted on ebay of the following spec. Can i use it to step down 6V to 5V without losing Ampere? or any suggestion, how i can step down 6V to 5V while keeping 3AMP.    DC-DC Buck Step Down Converter Regulator Power Supply Module 9V 12V 24V to 5V 3A.  Mini DC-DC Step Down Converter  Input voltage 7V~28V  Output voltage 5V(Precision 1%）  Output current 3A(max),long time work within 1.5A  Conversion efficiency 96%(max)  Output ripple <30mV  Switching frequency 1.5MHz(max), Typical 1MHz


Can you help me proving this equality? $$|x|-|y|\leq |x-y|$$  I think that it's possible to give a too short proof if the things are written correctly.

Is there a clever way to show that  $$|x| - |y| \leq |x-y|$$  I believe I can think of a way to solve this using cases, but the book I'm working out of said that "A very short proof is possible if you write things in the right way" which has motivated me to figure out this quick way, but I've failed thus far and any help would be appreciated


I want to login drupal to magento and magento to drupal . can any body help me how it possible ?  Thanks

We are looking to build a new website which would make use of 2 web applications: Drupal and Magento. Drupal will be used for corporate website while Magento will serve as a web shop. One of the challenges that I'm facing is the single-sign-on (SSO) part. I have done quite a lot of reading about this subject and haven't come across the "best way" to do this.  Do we keep a separate user database on both Magento and Drupal? (Taking into consideration that not every Drupal user will have access to the web shop.)  Should we use a central authentication server (CAS) instead?  Currently I'm testing the following method:   Installed the  Configured that the user is redirected to a file sso.php after he/she logs in on Drupal The sso.php file reads the information of the currently logged in user and optionally creates the Magento session for this user (if an account with a matching username/e-mail) exists   Does anyone have any previous experience in getting the SSO feature between Magento-Drupal? Any input would be appreciated!  Some more info:   The website and web shop will run on the same domain. The web shop is located in a subfolder Preferably the SSO has to be done programatically without using the slow Magento API


In the application section of the launcher, there are folders labeled Utilities and Sundry. When you click on the one labeled Utilities, a container opens up below it with its contents, which are just some system things like help, backups, and archiver. The one labeled Sundry has Adobe Flash Player settings. This is similar to Launchpad on a Mac.  I was wondering if it were possible to create my own folders with apps in them. I can't drag icons on top of others, nor can I find any real folders on my HDD that represent those in the launcher (Nothing in /usr/share/applications)  I am running Ubuntu 18.04.03 with GNOME 3.28.2

Dose anyone know how to make application folders like the 'utilities' folder? It's because I have a lot of apps and want to group them by topic.


I am new to programming.  I am trying to create validation for a UK postcode.  I have found what I believe will do the job (see below), but I do not know what other lines I need to enter to complete the process.  ^(([gG][iI][rR] {0,}0[aA]{2})|((([a-pr-uwyzA-PR-UWYZ][a-hk-yA-HK-Y]?[0-9][0-9]?|(([a-pr-uwyzA-PR-UWYZ][0-9][a-hjkstuwA-HJKSTUW]|([a-pr-uwyzA-PR-UWYZ][a-hk-yA-HK-Y][0-9[abehmnprv-yABEHMNPRV-Y])))&[0-9][abd-hjlnp-uw-zABD-HJLNP-UW-Z]{2}))$   Can anyone please help me with the other lines I would need to type to get this validation to work.  I checked the above code with the source and typed it into my programme (see below) when I tried to run the programme it came up with 54 errors. What am I missing?  namespace Moondog_odering_system {     public partial class CustomerDetails : Form     {         public CustomerDetails()         {             InitializeComponent();         }      private void textBox11_TextChanged(object sender, EventArgs e)     {         ^(([gG][iI][rR] {0,}0[aA]{2})|((([a-pr-uwyzA-PR-UWYZ][a-hk-yA-HK-Y]?[0-9][0-9]?)|(([a-pr-uwyzA-PR-UWYZ][0-9][a-hjkstuwA-HJKSTUW])|([a-pr-uwyzA-PR-UWYZ][a-hk-yA-HK-Y][0-9][abehmnprv-yABEHMNPRV-Y]))) {0,}[0-9][abd-hjlnp-uw-zABD-HJLNP-UW-Z]{2}))$     } }   }

I'm after a regex that will validate a full complex UK postcode only within an input string. All of the uncommon postcode forms must be covered as well as the usual. For instance:  Matches   CW3 9SS SE5 0EG SE50EG se5 0eg WC2H 7LT   No Match   aWC2H 7LT WC2H 7LTa WC2H   How do I solve this problem?


For example, the Belt of Giant Strength is an item with caster level 8.  Can you craft a magic item without meeting its caster level requirement? Is it treated like all other requirements, increasing the DC by 5 if not met? Does the creator have to meet this one particular requirement?

Is an item's Caster Level the Minimum Required Caster Level?  For example a  has a CL of 9th     Aura moderate conjuration; CL 9th   Does that mean a creator has to have a Caster Level of 9?


How do I justify my comments as to inner for loop indentation in the below code:  \documentclass[a4paper]{article} \pagestyle{empty} \usepackage{algorithm} \usepackage{algpseudocode} \usepackage[caption=false,font=footnotesize]{subfig} \begin{document} \begin{algorithm} \label{algoQ} \caption{Algorithm to check quality of methods} \begin{algorithmic} \For{\textbf{each} $methods$ in$methodList$} \For{\textbf{each} $msd$ in$msdList$}  \Comment { \% for each MSD \%} \Statex   \Comment { \% get MSDs referenced method service \%} \EndFor \textbf{endFor} \EndFor \textbf{endFor} \end{algorithmic} \end{algorithm} \end{document}

How do I left justify my comments in the algorithm.  I am using algorithmicx package.  What I want is: to pull the comment to left as shown in the attached snapshot.  The code for my algorithm is       \documentclass[a4paper]{article}     \pagestyle{empty}     \usepackage{algorithm}     \usepackage{algpseudocode}     \usepackage[caption=false,font=footnotesize]{subfig}     \begin{document}     \begin{algorithm} \label{algoQ}     \caption{Algorithm to check quality of methods}     \begin{algorithmic}     \For{\textbf{each} $msd$ in$msdList$}  \Comment { \% for each MSD \%}     \Statex   \Comment { \% get MSDs referenced method service \%}     \EndFor \textbf{endFor}     \end{algorithmic}     \end{algorithm}     \end{document}


Can the rate at which time passes be changed?  For example, can time stop, slow down, or speed up?  If so, how?  Is it really time that is shifting or is it the measuring devices?

This is an attempt to gather together the various questions about time that have been asked on this site and provide a single set of hopefully authoritative answers. Specifically we attempt to address issues such as:   What do physicists mean by time? How does time flow? Why is there an arrow of time?


I've been trying to create a function call in a new Thread because if I use my main thread then my application get's too busy and can't be used anymore while the function is running.  Now I've been trying to create the function call inside a new Thread:  private void bunifuFlatButton2_Click(object sender, EventArgs e) {     Thread thread = new Thread(new ThreadStart(worker));     thread.Start(); }  public void worker() {     using (var streamReader = File.OpenText(filePath))     {         var lines = streamReader.ReadToEnd().Split(new char[] { '\n' });         var count = lines.Count();          bunifuProgressBar1.MaximumValue = count;          for (int i = 0; i < count; i++)         {             string[] words = lines[i].Split(':');             string hash = mega.GenerateHash(words[0].ToLowerInvariant(), mega.PrepareKey(words[1].ToBytes()));              bunifuCustomLabel4.Text = "Working: Total: " + count + ". Currently: " + (i + 1) + ".";             bunifuCustomLabel4.Update();             bunifuProgressBar1.Value = i + 1;         }     } }   But now I receive the following error (Translated using google):     An unhandled exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll      Additional information: Invalid thread-spanning operation: Access to the bunifuCustomLabel4 control was from a thread other than the thread for which it was created.   How could I fix this error? I've been googling solutions but they didn't work also.  My latest attempt:  private void bunifuFlatButton2_Click(object sender, EventArgs e) {     ThreadStart asyncCall = delegate     {         bunifuCustomLabel4.Invoke(new MethodInvoker(worker));     };      Thread thread = new Thread(new ThreadStart(worker));     thread.Start(); }

I have a scenario. (Windows Forms, C#, .NET)   There is a main form which hosts some user control. The user control does some heavy data operation, such that if I directly call the UserControl_Load method the UI become nonresponsive for the duration for load method execution. To overcome this I load data on different thread (trying to change existing code as little as I can)   I used a background worker thread which will be loading the data and when done will notify the application that it has done its work.   Now came a real problem. All the UI (main form and its child usercontrols) was created on the primary main thread. In the LOAD method of the usercontrol I'm fetching data based on the values of some control (like textbox) on userControl.    The pseudocode would look like this:  CODE 1  UserContrl1_LoadDataMethod() {     if (textbox1.text == "MyName") // This gives exception     {         //Load data corresponding to "MyName".         //Populate a globale variable List<string> which will be binded to grid at some later stage.     } }   The Exception it gave was     Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on.   To know more about this I did some googling and a suggestion came up like using the following code  CODE 2  UserContrl1_LoadDataMethod() {     if (InvokeRequired) // Line #1     {         this.Invoke(new MethodInvoker(UserContrl1_LoadDataMethod));         return;     }      if (textbox1.text == "MyName") // Now it wont give an exception     {     //Load data correspondin to "MyName"         //Populate a globale variable List<string> which will be binded to grid at some later stage     } }   BUT BUT BUT... it seems I'm back to square one. The Application again  become nonresponsive. It seems to be due to the execution of line #1 if condition. The loading task is again done by the parent thread and not the third that I spawned.  I don't know whether I perceived this right or wrong. I'm new to threading.  How do I resolve this and also what is the effect of execution of Line#1 if block?  The situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.   So only accessing the value so that the corresponding data can be fetched from the database.


I recently switched from an HDD to a SSD in a Windows 7 environment. Since then I regularly experience files or folders being locked from renaming or deleting. The lock may take minutes or hours - I'm unsure about it.  It's not a system lock caused by a running application or anything alike. I'm aware that I cannot edit/delete a file/folder while it's in use anywhere else. And I'm experiencing this problem ever since I switched to the SSD, so I'm pretty sure it's related.  Does an SSD cause such lock outs - due to caching or anything? Is there a way to unlock such files manually?  System: Windows 7 Home 64 / Samsung SSD 840 EVO 250G / ASUS Notebook with i7 CPU

I'm trying to delete some folder but this error is preventing from doing it:     Cannot delete [FileName]: It is being used by another person or program.      Close any programs that might be using the file and try again.   How can I identify what application is using the file?   I want to end the application using a Task Manager, but I didn't know what application is using it.  The folder is not shared and my user account is an administrator.


Evaluate: $$S=1+ \frac{1}{2+ \dfrac{1}{4+ \dfrac{1}{8+ \dfrac{1}{16 +\cdots} }} }$$ What have I done, so far? Nothing, couldn't think of a way to solve it. But I know it is around 1.46. I want to solve it myself, so hint on how to solve will be sufficent.

Say you have the infinitely continued fraction: $$x+\cfrac{1}{x^2+\cfrac{1}{x^3+\cfrac{1}{x^4+\ddots}}}$$ When $x=1$, you can see that it's $$1+\cfrac{1}{1+\cfrac{1}{1+\cfrac{1}{1+\ddots}}}$$ which converges upon the golden ratio $\phi = 1.61803398875...$. What if I were to plug in $x=2$? $$2+\cfrac{1}{4+\cfrac{1}{8+\cfrac{1}{16+\ddots}}}$$ Using a caluclator, it seems to converge upon the irrational number: $2.24248109286...$ Is there any way I can represent this irrational number algebraically?


Question: $f\in C^2(-\infty,+\infty)$, $|f(x)|\leq 1$, $[f(0)]^2+[f'(0)]^2=4$. Prove that there exists $\xi$ s.t.  $$ f(\xi)+f''(\xi)=0. $$     I find this question in the chapter about mean value theorem, and I set up function $G=f^2+f'^2$ as usual. WLOG set $f(0)\geq 0$ and $f'(0)\geq 0$. Use Taylor mean value theorem I get  $$ f(1)=f(0)+ f'(0)+\frac{1}{2}f''(\eta). $$ Set $x=f(0)\geq 0$ I get  $$ f''(\eta)\leq 1-x-\sqrt{4-x^2}\leq -1. $$ So I get  $$ f(\eta)+f''(\eta)\leq 0 $$ I want to prove by contradition， then I assume  $\forall x\in(-\infty,+\infty)$, $f(x)+f''(x)<0$. Then I have no idea.  My question is: Is this idea correct? How to use the function $f^2+f'^2$(I haven't use it yet)?

This is from Putnam:     If a function $f: \mathbb{R} \to [-1, 1]$ is such that $f''(x)$ exists for all $x \in \mathbb{R}$ and $\{f(0)\}^{2} + \{f'(0)\}^{2} = 4$ then prove that there is a point $c$ such that $f(c) + f''(c) = 0$.   Now the condition concerning values of $f(0), f'(0)$ (and the fact that range of $f$ is subset of $[-1, 1]$) implies that $f'(0) \neq 0$ so that function is not a constant. If we take $g(x) = \{f(x)\}^{2} + \{f'(x)\}^{2}$ then we can see that $g' = 2f'(f + f'')$. One hope of solving the problem is to show that $g$ attains local extrema at some point different from an extrema of $f$. This would ensure that $g'$ vanishes without making $f'$ vanish and that will lead to $f + f'' = 0$. However the constraint on $f(0), f'(0)$ does not help in analyzing the extrema of $f$ or $g$.  Another line of thought which could be helpful here is to consider $F(x) = f'(x)\sin x - f(x)\cos x$ so that $F'(x) = \sin x\{f(x) + f''(x)\}$ but in this case I am not able to see how to use the condition on values $f(0), f'(0)$ to impose some constraint on $F(x)$.  Perhaps both the approaches which came to my mind are not in right direction (or may be they are, but I am unable to see). Please provide any hints.  Update: Based on the answer by Sandeep Thilakan, I have dropped the requirement for continuity of $f''(x)$.


I've got a machine that is 64-bit, running 32-bit windows 7, which has 8GB ram. I did the official upgrade to windows 10 that Microsoft was offering a few weeks ago, but I'm having a difficult time setting up the /pae boot option, which I have been lead to believe will allow me to use more than 3.5 GB of ram. Is it possible to set up the /pae option to address more than 3.5GB ram on a windows 10 system?

I recently upgraded my computer's RAM to 4 GB. My 32-bit Windows installation shows only 3574 MB of the memory. How can I make Windows use the full amount of RAM?


I could not find any list so I am asking: What type of notifications do we have? From my own notifications, I could find the following:  A badge was awarded. A post I made was edited. A post I made was migrated to a different site. A bounty I started is about to expire.  I believe the notification about edited post is new since  so assume there might be more. Any other types? For example, what about post I made is deleted? I would expect to get notification as well, but can't test this by myself.

The  was once introduced because it became hard "to keep track of all your questions, answers, and comments across every site you participated on".   The small red number tells you how many new replies you have across the entire Stack Exchange network of websites. And by replies, I mean:  New answers to your questions New comments on your posts @replies to you in comments   However, it's been a while since 2010, and there are many more events triggering an inbox notification.


Einstein's theory proved that most properties of a body are relative to something and are not absolute. I am still wondering if physicists still think that there is a way that Newton's absolute space and time still exist? If they do, how are the ways that we prove their existence? and how do they exert their influence (effects)?

As I understand it Newton's Laws imply that space is relative, as the laws of physics are the same in all inertial frames and as such there is no way, even in principle, to distinguish a frame that is truly at rest (absolute space). Hence the concept is physically meaningless, and the positions of (and distances between) physical objects, events, etc. are relative to the frame in which one is observing them from. Advancing on to Special Relativity, by postulating that the speed of light (in vacuum) is constant in all frames of reference, we are forced to conclude that time is relative also (as if it weren't then different observers would observe a different speed of light (in vacuum)). This leads to the result that the concepts of space and time are no longer completely separate and independent of one another and instead intertwined (as an event that occurs at rest over some time period in one frame, will occur over some spatial interval and a different time interval in another frame). Hence they should be considered as should be considered as a single entity, called spacetime.  Sorry for the waffling so far, just want to check that my understanding is correct up to this point?!  My main question is, given that space and time are (individually) relative quantities, is spacetime itself relative, or can it be considered absolute (as after all, it is the mathematical space of all possible events and exists independently of the physical events that occur within it)?


i have a question for you about java program in netbeans. I made this login program in java netbeans project, but i have some problem here. Can any one help me to find any mistakes in my algoritm?  --first, there is my script below :   public static void main(String[] args) {      int i;     int x;     int amountOfData=0;     String user="";     String pass="";     String[] username = new String[100];     String[] password = new String[100];     boolean found=false;      Scanner sc = new Scanner(System.in);      i=0;     while(i<3){         System.out.print("Input username -"+(i+1)+":");         username[i] = sc.nextLine();         System.out.print("Input password -"+(i+1)+":");         password[i] = sc.nextLine();         System.out.println("");         i++;         amountOfData++;     }      System.out.println("============================");     System.out.println("Welcome in Login Form");     System.out.println("============================");     for(x=1;x<=3;x++){         System.out.print("Username :");         user = sc.nextLine();         System.out.print("Password :");         pass = sc.nextLine();         i=0;         while(i<amountOfData && found==false){             **if(user==username[i] && pass==password[i])                 found=true;**             else{                 System.out.print("haha");                 i++;             }         }         if(found==true){             System.out.println("You Succesfully Login");             break;         }         else{             System.out.println("Error ! Please Try again !");         }     }  }    When i running this program, the output is :  Input username-1 :a Input password-1 :1  Input username-2 :a Input password-2 :2  Input username-3 :a Input password-3 :3  ======================  Welcome in Login Form  ======================  Username :a  Password :3  haha  haha  haha  Error ! Try again enter login data !  Username :  as you have seen above, the username and password that i entered for login is true, that's (a,3). But somehow, the function if(user==username[i] && pass==password[i]) can't executed. So, the program is executed the else function 3 times and output "haha". Any answer how this can be happened?? I need the answer immediately... Thank you.

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


Quote from      So in cycles there often is no need for it.   So there must be a need for it in Blender Render  Can you think of a scenario where using ambient occlusion in Blender Render mode is the better choice over the other available option like spot lamps and nodes?

What is Ambient Occlusion and what are some of it's uses? I see it is used in creating what might be called "shadow catchers" in the following node tree setup:


I am trying to convert a NSDate to a String and then Change Format. But when I pass NSDate to String it is producing whitespace.   let formatter = DateFormatter()  let myString = (String(describing: date))  formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"  let yourDate: Date? = formatter.date(from: myString)  formatter.dateFormat = "dd-MMM-yyyy"  print(yourDate)

How do I convert, NSDate to NSString so that only the year in @"yyyy" format is output to the string?


Find the limit of:  $a_1=\sqrt{3}$  $a_2=\sqrt{3\sqrt{3}}$  $a_3=\sqrt{3\sqrt{3\sqrt{3}}}$  ...  By using induction, I found that the limit is 3 but it seems pretty strange to me, I thought it would go to a further number.  I just want to know if I'm right (proof-verification).

I'm trying to find a formula for the following sequence:  $\{\sqrt{3},\sqrt{3\sqrt{3}},\sqrt{3\sqrt{3\sqrt{3}}},...\}$  I thought of solving it recursively and I got this formula:  $a_{n}=\sqrt{3*a_{n-1}}$  $a_{0}=1$  Is there a better and non-recursive formula for the given sequence?


In c is there a way to turn a string into commands? For example:  void x(string n){    //do something } void y(int n){    //do something } void z(int n){    //do something } stringForConvert="z(10);y(2);x(\"Its cool\");"; mysteryCommand(stringForConvert);   Please note that i don't have luxury for writing to another file and compiling it.

I was wondering if there is something like an interpreter for C.  That is, in a Linux terminal I can type in "python" and then code in that interpreter.  (I'm not sure interpreter the right word).  This is really helpful for testing different things out and I'm curious if something similar exists for C.  Though I doubt it.  The only thing I can think of that would do it would be the C shell...


Let's say you have this list of branches in a git repository:  * master | | * b2 |/ * b1 | * b // etc   I know that technically branches are only symbolic references in the DAG that is the commit graph.  If I am on the master branch here, is there a command to obtain a list of branches which are only direct ancestors of master? In the above, that would mean b1 and b, but not b2.

I have a git repository with multiple branches.   How can I know which branches are already merged into the master branch?


I have one table in Postgres which has following columns:  processtransactionid bigserial, TenantID uuid, ProcessInstanceId bigint attributename varchar(250), attributevalue varchar(250),   createddate timestamp, queueid int   The attributename contains values like 'filename', 'documentstatus', 'batchImportdate', etc. and attributevalue columns contains corresponding values of the attribute, like filename = abc.jpg, documentstatus ='Present' & batchImportdate='2019/08/26 12:57:51'  I want output in the following way:   ProcessInstanceId filename  documentstatus batchImportdate        queueid     6008            abc.jpg   Present        '2019/08/26 12:57:51'  2    6008            abc.jpg   Absent         '2019/08/26 12:57:51'  3   grouping of the records to be done by ProcessInstanceId, queueid  I am able to create query in SQL Server using the PIVOT keyword but facing a problem in creating the same query in Postgres.  Could you please help me write the Postgres query?

Having the following data in a table:  ID     Category   Value 1234   Cat01      V001 1234   Cat02      V002 1234   Cat03      V003 1234   Cat03      V004 1234   Cat03      V005   I want to have the following output:  ID     Cat01  Cat02   Cat03 1234   V001   V002    V003 1234   V001   V002    V004 1234   V001   V002    V005   The output I want to achieve is a kind of pivot table where I have all the values vertically in a table and I want to have those values, horizontally, having the category as a column. But there are some categories that have multiples values, in that case, I need to repeat the values of all other categories and create a row per each repeated value  How can it be done in PostgreSQL?


Int a[] = {1,2};  String s = a.toString(); //what's going on here.  My output is   I@something for integer array. C@something for char array.  How to I correctly convert any array into string.

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


We have a standard SAP BI App and we don't have the code for that and our company purchased it for our internal use and now my PM has asked me to open SAP BI App from our custom App programmatically and I have done it using url scheme's and then I am facing the problem he wants me to open  our custom App automatically when ever the user clicks on a specific button in standard SAP BI App for which I don't have any code.  Is it possible to open my custom App from SAP BI App.

Is it possible to launch any arbitrary iPhone application from within another app?, For example in my application if I want the user to push a button and launch right into the Phone app (close the current app, open the Phone app).  would this be possible? I know this can be done for making phone calls with the tel URL link, but I want to instead just have the Phone app launch without dialing any specific number.


This is my code, here when i input the  Product name i.e. Laptop/Mobile and then input the price. after that the program does not input eask and simply goes to the eask if-else case and prints the Invalid option as:  import java.util.*;     class Main {           public static void main(String[] args) {             int discount=0,ediscount=1;             Scanner sc = new Scanner(System.in);             String Product = sc.nextLine();             int Price = sc.nextInt();             String eask = sc.nextLine();                      if(Price>100){               if(eask == "Yes" || eask == "No"){                 if(Product == "Mobile"){                 discount = 10;                 if(eask == "Yes")                   ediscount=12;               }               else if(Product == "Laptop"){                 discount = 20;                 if(eask == "Yes")                   ediscount=10;               }               else if(Product == "gadgets"){                 discount = 0;                 if(eask == "Yes")                   ediscount=0;               }               else System.out.println("Invalid product");               }               else                 System.out.println("Invalid option");             }             else System.out.println("Invalid price");                      float TBA = discount * Price;             System.out.println(TBA);           }        }

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


Hello blender community. using Blender2.79b I am working on creating leaf with PNG transparent image file. but alpha part is not working as transparent part. My node setup is wrong ? or any other cause?

After converting to nodes in order to render using Cycles I've no idea where to enable the z-transparency. I guess the image textures alpha channel needs to be pluged somewhere but I've no idea which node would be suitable.   The question is how could I correctly setup the nodes to have the same effect as when using z-transparency in BI?      The materials original settings for BI are:    Which renders like:    I had no luck with DarenWs suggestion:


I am studying preposition related to mode of transportation (English is not my first language). Despite knowing the rule for by, on, in prepositions, I still find them confusing. Can you tell how below sentences differ?   I am in a bus. I am on a bus.  I travelled by bus. I travelled on a bus. I travelled in a bus.  Thank you.

Examples:   In a car, van, etc. On a bus, boat, motorcycle, etc.   How can one decide which preposition to use? Is memorization the only way or is there a better way?  Note: People generally explain this by either distinguishing between open and closed vehicles or between large and small vehicles. However, the examples I've given defeat both explanations.


How to find the coefficient of $x^2$ in the polynomial $$(1-x)(1+2x)(1-3x)....(1+14x)(1-15x)$$  Is there any particular way to look at such problems?

Let $C$ be the coefficient of $x^2$ in the expansion of the product $(1 - x)(1 + 2x)(1 - 3x)\cdots(1 + 14x)(1 - 15x).$ Find $|C|.$   Just to begin,  $(1-x)(1+2x) = -2x^2 + x + 1$  $(1-x)(1+2x)(1-3x) = 6x^3 - 5x^2 - 2x + 1$   But expanding on like this take too long.  In the end the terms will be like:  $(1 - 15x)(a_0 + a_1x^1 + a_2x^2 + ....)$  Then just looking at the $x^2$, it will be:  $(a_2x^2 - 15a_1x^2) = x^2(a_2 - 15a_1)$  But it it still a very hard problem, any hints?


I am trying to grasp the difference between Raman scattering and fluorescence. To me it appears that the former is described in a somewhat more classical context as ordinary inelastic scattering, while the latter actually has a meaningful quantum mechanical description. So what is the quantum explanation for Raman scattering? I have read it involves a "virtual state" as an intermediate state. What is that supposed to mean? If it just means (extremely) short lifetime, then there should be a mixed regime between Raman scattering and fluorescence, but I have never heard about that. How does one calculate the virtual state if it "exists"?    This question is focused on the mathematics behind Raman scattering. How does one formulate Raman scattering of a photon and an atom, we may for simplicity assume that we have a hydrogen atom. e.g given some electronic state, how do I calculate the virtual states involved with Raman scattering?

What is the difference between  and ?  Both phenomena involve the emission of photons shifted in frequency relative to the incident light, because of some energetic transition between states that the system undergoes. As far as I can tell, fluorescence is caused by ionization of the atomic electrons while Raman scatterings agitate phonon modes - but technically speaking, aren't they effectively the same?


I was reading about SR Latches and this very weird (and silly) question popped up in my head.  Here, when A and B is 0, then Q is 1. Suppose that this NOR gate is lying in air, not connected to any power supply. Then as there is no potential or current passing through A or B, we can say that the inputs are 0 and 0. Then according to the truth table, Q must be 1! How is that even possible? What does it even mean?

I know that a NOT gate always inverts its input.  When the input is "ON" I can imagine the gate stopping the flow of current.  But how does the gate generates flow of current when the input is OFF?  Please could you explain how this happens as simply as possible, I'm new to electronics ;)


Is s/he eating enough through the day?  I see this all the time these days. Why do they do this? This means:  Is s or he eating enough through the day?  which makes no sense. Clearly, they meant to type:  Is (s)he eating enough through the day?  Or:  Is he/she eating enough through the day?  Or:  Is [s]he eating enough through the day?  Why do they not realize that "/" means "or"? They must have read this somewhere prominent as it has spread a lot. Even though I can "interpret" it, it's very annoying to see this and know that other eyeballs are registering it and their brains make "mental notes" for future times when they are themselves in need to express the same thing, and then they use the same practice.

As far as I know, a period is commonly used for an abbreviation (e.g., Feb., Mon., Inc.). But I can also see a slash in these cases: w/, w/o.  Is there any grammar rule for an abbreviation? or is latter case an exception?


My class  class student    {  public string studentid { get; set; }  public string groupid { get; set; }//Group id }   My List  List<student> pupils = new List<student>();   here I select students with no group ID. I have assigned students with no group ID as ="00"        var studentWithNogroupID = from student in pupils where student.groupid == "00" select student;   I have an integer which I'm gonna increase each time and convert to char and assign each student.   int groupid=001; string grid = myInt.ToString(groupid);   Here I'm assigning each member with group id like this..  foreach(var student in studentsWithNoGroupId) {   student.groupid = "grid"; }   My problem is I have to assign three members to a group.  In other words 3 members should have same group id. And after each 3 members it should increase the group id which is like this to create a new group id.   groupid+=1;   How to go three by three in for loop or can anyone provide me a solution to assign three students to a group.

Is there any way I can separate a List<SomeObject> into several separate lists of SomeObject, using the item index as the delimiter of each split?  Let me exemplify:  I have a List<SomeObject> and I need a List<List<SomeObject>> or List<SomeObject>[], so that each of these resulting lists will contain a group of 3 items of the original list (sequentially).  eg.:   Original List: [a, g, e, w, p, s, q, f, x, y, i, m, c] Resulting lists: [a, g, e], [w, p, s], [q, f, x], [y, i, m], [c]   I'd also need the resulting lists size to be a parameter of this function.


I have a grid that I am searching for a specfic row. If the row is not there I want to run a conditional statement. I pull the row like this:  var $row = $table.find("tr[data-id=" + item + "]");   When I use an alert on it, it comes out as what I would expect and 'undefined' when the value is not there. However, when I do a condtional on it I can never get the proper part of the conditional. I have tried:  if(row === 'undefined'){}  if(row == 'undefined'){}  if(row === null){}  if(row == null){}

I'm using jQuery and I want to check the existence of an element in my page. I have written following code, but it's not working:  if($("#btext" + i) != null) {     //alert($("#btext" + i).text());     $("#btext" + i).text("Branch " + i); }   How do I check the existence of the element?


I desperately want to avoid asking "do we need tag tags".  Many of the SE sites have tag pages inundated with titles; most notably  and to a lesser extent ,  and .  I am of the opinion that having titles for tags on these sites is 100% necessary and relevant and allows proper categorization of related questions.  Unfortunately, as evidenced by the tag pages of these sites, having titles obfuscates more general tags of other relevance, such as utility tags (using Movies & TV as an example: , , , , etc.), title tags (again, M&TV: , , etc.), and possibly site-specific categorized tags (M&TV; category would be "genre": , , etc.).  Even tag aliases could be categorized as such, if they aren't already.  Every SE Meta already does this to some extent with the "required" tags.    While the expected practice is for the tag pages of these sites to sort themselves based on usage (in Movies & TV, a lot of the common utilities have bubbled to the top as expected over the lesser titles, but then-again, it's still in Beta), there are other sites (notably, Arqade) where applicable tags are drowned in titles and therefore will never be found in order to be used enough to sort in the expected fashion.  Yes, I do understand it is up to each community's participants to manage their tags, but even general clean-up is somewhat daunting and might not prove to be effective.  Why do I think we need this?  Without foreknowledge or expertise, or knowing what to type out during a question, it is very tough to locate a tag you might want to use in these sites.  Tag categorization could help a user properly tag a question by suggesting categories of tags to choose from, then relevant tags.  Is tag categorization needed, and if so, how should categorization be applied; via a new built-in SE utility, an adopted practice, or other enhancement?

This is more of a "research problem" wrt UI's, but I think the tagging system needs a better UI overall.  Assuming that tags are supposed to categorize content (akin to sticking labels on things), a good tag system should make things easy to find.  But what you have is a kind of soup of things with labels on them.  You can search through the soup pretty easily.  Tags as they are, are kind of browsable through the search box UI. You've made it work, kinda.  But I don't think browsing on SE sites, especially those that house multiple topics, is as pleasant or clear as it could be.  What would be clearer?  I'm not exactly sure, but that's why I said this was a bit of a "research" problem.  The  regarding music.se is to combine all music interest into a single site, instead tons of smaller, less significant mini-sites.  To have violins, guitars, piano, music-theory and song-writing all on one site, you have to be able to organize things quite well.  I think the tagging system is sufficient.  Even with the 5 tag limit on each post, tagging is enough to cleanly divide the site, but its the front end UI to the tagging system that needs work.  Tags replace folders, and tags are arguably better because they don't force you to repeat structure.  For example, if using "folders" on SO:  Folders are bad example 1:  C++     operators     variables   You'd also have  C#     operators     variables   Or you could do  Folders are bad example 2:  operators     C++     C# variables     C++     C#   with repeated structure. With tags you essentially get "virtual folders"  Tags are good example 1:  C++  & operators C++  & variables C#   & operators C#   & variables   Can't do that with folders, and the beauty is, you can VIEW tags as folders.  So perhaps a user-configurable navigation structure that presents a tree view.  Root Tags  You select your "root" tags, for example, piano and guitar (or these can be hard-set by the site manually OR tags can become root tags when there is excess of 10,000 or so posts in them)  piano     technique     fingering  guitar     phrasing     strings     effects   So, with piano as one of your/the site's "root tags", the site takes on an artificial folder structure on top of the tag system.  Each post must contain a "root" tag, which roughly defines the site's scope (kind of like how MSO has "discussion" "support" etc).  This helps you define the scope of the site, and in addition it gives you the opportunity to create a hierachical browse mode, instead of tag-soup mode.  So one possible UI for a front page that has root tags might be  (Where piano, guitar and song are defined as root tags, and the topics shown below are popular tags that also have that root tag.)


I have a custom module already installed, and I am trying to add a new table to the database with hook_update_N(). So, I edited hook_schema() and hook_update_N() in the my_module.install file as below.  function my_module_schema() {   $schema['my_table'] = array(     'fields' => array(       'application_setup_id' => array(         'type' => 'serial',         'not null' => TRUE,         'description' => 'Primary Key: ID',       ),     ),     'primary key' => array('application_setup_id'),   );   return $schema; }  function my_module_update_8601(&$sandbox) {   $spec = array(     'fields' => array(       'application_setup_id' => array(         'type' => 'serial',         'not null' => TRUE,         'description' => 'Primary Key: ID',       ),     ),     'primary key' => array('application_setup_id'),   );   $schema = Database::getConnection()->schema();   $schema->createTable('my_table', $spec); }   I am running drush updatedb to update the database after the changes. No database changes are done.  What am I missing?

I know there is a question  but I checked its answers and it didn't help. I'm just learning developing modules for Drupal so maybe it's something really stupid but I have no idea...  My hook (in testModule4.install):  function testModule4_update_7001() {  $schema['testModule4_table'] = array(     'description' => 'TODO: Description',     'fields' => array(         'main_id' => array(             'description' => 'TODO: Description.',             'type' => 'serial',             'not null' => TRUE,         ),         'settings' => array(             'description' => 'TODO: Description',             'type' => 'text',             'not null' => FALSE,         ),         'uid' => array(             'description' => 'TODO: Description',             'type' => 'int',             'not null' => FALSE,         ),         'created' => array(             'description' => 'TODO: Description',             'type' => 'int',             'not null' => FALSE,         ),         'changed' => array(             'description' => 'TODO: Description',             'type' => 'int',             'not null' => FALSE,         ),     ),     'primary key' => array('main_id'), );  db_create_table('testModule4_table', $schema['testModule4_table']);  }   My module is working just fine. The schema_version of module in database is 0 but update.php just cannot see it. What can be the cause of that? :/ I was trying clearing cache and reenabling a module but without success. I just don't know where to search for source of the problem. If you need more data, just comment :/ .  Edit:  I created simple module:  testModule.module:  <?php   function testModule_myform($delta = "") {      $form['something'] = array(         '#type' => 'markup',         '#markup' => 'Something',     );     return $form; }    /**  * Implements hook_menu();  */  function testModule_menu() {     $items["test/test"] = array(         'title' => 'testModule',         'description' => 'TODO: Description',         'page callback' => 'drupal_get_form',         'page arguments' => array('testModule_myform'),         'access callback' => TRUE,      );     return $items; }   testModule.info:  name = testModule description = Test module for Drupal experiments. package = CustomTest core = 7.x   testModule.install:  function testModule_update_7001() {     drupal_set_message('It works!');     print 'Show something!'; }   And it still ignores this hook... Is it officially a Drupal bug and I need to reinstall the whole Drupal? >_<


How to prove that the Einstein velocity addition is a one-parameter composition formula of a one parameter group?

Lorentz contraction and time dilatation can be deduced without Lorentz transformation. Can you deduce also the theorem of    $$w~=~\dfrac{u+v}{1+uv/c^2}$$   without Lorentz transformation? Using just the constancy of light speed.


In a lot of books that I've read about calculus the authors will sometimes use the operator $d$ to mean a differential (an "infinitesimal" change), and sometimes they'll use it to mean an actual derivative. For example they'll write: $d(x_1x_2)=dx_1x_2+ x_1dx_2$ or they'll write $d x^2 = 2x$ when if they at least write it as $d x^2 = 2xdx$ it would make more sense as a derivative notation. When should one interpret this $d$ operator as a "small change" or conversely as a derivative? This mix-up gets even more confusing when manipulating differential equations. Thanks.

In elementary calculus (and often in courses beyond) we are taught that a differential of a function, $df$ quantifies an infinitesimal change in that function. However, the notion of an infinitesimal is not well-defined and is nonsensical (I mean, one cannot define it in terms of a limit, and it seems nonsensical to have a number that is smaller than any other real number - this simply doesn't exist in standard analysis). Clearly the definition $$df=\lim_{\Delta x\rightarrow 0}\Delta f =f'(x)dx$$ makes no sense, since, in the case where $f(x)=x$ we have that $$ dx=\lim_{\Delta x\rightarrow 0}\Delta x =0.$$  All of this leaves me confused on how to interpret expressions such as $$df=f'(x)dx$$ Should it be seen simply as a definition, quantifying the first-order (linear) change in a function about a point $x$? i.e. a new function that is dependent both on $x$ and a finite change in $x$, $\Delta x$, $$df(x,\Delta x):=f'(x)\Delta x$$ then one can interpret $dx$ as $$dx:=dx(x,\Delta x)= \Delta x$$ such that $$\Delta f=f'(x)dx+\varepsilon =df +\varepsilon$$ (in which $\varepsilon$ quantifies the error between this linear change in $f$ and the actual change in $f$, with $\lim_{\Delta x\rightarrow 0}\varepsilon =0$).  I feel that there must be some sort of rigorous treatment of the notion of differentials since these kind of manipulations are used all the time, at least in physics?!  I've had some exposure to differential geometry in which one has differential forms, in particular $1-$forms which suggestively notationally "look like" differentials, for example $$\omega =df$$ but as I understand it these are defined as linear maps, members of a dual space to some vector space, $V$, which act on elements of $V$, mapping them to real numbers. Furthermore, the basis $1-$forms are suggestively written as what in elementary calculus one would interpret as an infinitesimal change in x, $dx$. But again, this is simply symbolic notation, since the basis $1-$forms simply span the dual space and are themselves linear maps which act on elements of $V$.  I've heard people say that differential forms make the notion of a differential of a function mathematically rigorous, however, in my mind I can't seem to reconcile how this is the case, since at best they specify the direction in which the differential change in a function occurs, via $$df(v)=v(f)$$ (since $v(f)$ is the directional derivative of a function $f$ along the vector $v$).  If someone could enlighten me on this subject I'd really appreciate it.


My question is, which of the below sentences is more correct?        1) Precise Mapping Using Unmanned Aerial Vehicle (UAV) data.   2) Precise Mapping Utilizing Unmanned Aerial Vehicle (UAV) data.      And,        1) Modern mapping utilizing laser scanners.   2) Modern mapping using laser scanners.      I know both are correct, but as it would be a Thesis title, so in my opinion here as I am using a Sensor or Machine, therefore utilizing looks more correct, but I need to be sure about it.

The situation is I'm writing a paper, and I want to use different words to express the meaning of "adopt" a method or approach.  All the three words "use", "utilize" and "employ" have the meaning of   to make use of something  So, is there any difference of the three words in aspect of expressing this meaning. And is there a best word to use in some specific conditions?


In the end of Avengers: Age of Ultron movie,      Avengers were talking about Infinity Stones and they seemed to know about all 4 Infinity Stones discovered so far.   Knowing about      Tesseract, Aether and Mind Stone was Okay.   But,      How did they come to know about the Infinity Stone introduced in Guardians of the Galaxy?

Sorry for the cryptic title, but I realise the film has only just been released in the UK and Europe and is yet to be released in the US.  I'll hide all substantial parts of my question, just in case. I don't want to spoil anything.     At the end of Age of Ultron, Thor states that 4 infinity stones have now shown up in the last few years.   So,     By my count we have the Tesseract, from several of the first few films. The Aether, from Thor 2. The Chitauri Scepter, again from several films. And finally, we have The Orb, from Guardians.    Now, to my knowledge     Thor, and indeed none of the Avengers, should know about The Orb. I don't remember Thor visiting the Collector between GoTG and the AoU. So, how did Thor know that The Orb had appeared? Or is he referencing a different infinity stone?   I'm looking for an in universe answer, ideally.