I repaired my Sparsebundle on my Time Machine server . I edited the com.apple.TimeMachine.MachineID.plist file and the com.apple.TimeMachine.MachineID.bckup as one of the commenters on that post said that was necessary for his to backup to work again.  However, just moments after starting up the backup, I get the Time Machine error that my last verification failed and I need to create a new backup.  I checked my plist file and Time Machine changed the VerificationState from 0 to 2, obviously without performing another verification.  It seems as if Time Machine is reverting to a previous plist file, or there are other places changes must be made to continue backups. I followed the steps exactly in the post, but still cannot backup to my sparsebundle.  I also tried removing the plist and bckup files, re-running the backup, but the files were simply recreated nearly instantly, and moments later I got the same error that my last verification failed and I need to create a new backup.  I am running macOS Sierra. What could I be missing?  Other users on Ask Different have suggested that my question is a duplicate of , but it is not. I understand why Time Machine initially asked me to create a new backup. I have found that many people have solved the initial problem by , however there appears to be more to it. The top upvoted answer suggests I follow the same instructions I have already followed, and while I was able to repair the sparsebundle, my specific issue is that Time Machine does not recognize the plist setting reset and immediately asks me to create a new backup. The question is why won't my plistsettings take affect and allow me to run a backup?

Every time a backup completes I get this message -  'Time Machine completed a verification of your backups. To improve reliability, Time Machine must create a new backup for you.'  I am backing up to Lacie Network Space 2 drive via wifi.   Does anybody know how to correct this?


In OOP, is it correct to say a method is a function that is located within a class?

Can someone provide a simple explanation of methods vs. functions in OOP context?


The number of subsets {1,2,…,n} with odd cardinality is ?  (Is it asking about number of subsets, we have to take power set then?)

Suppose that a set has an odd number of elements. Explain why half of the subsets will have an odd number of elements .  Now assuming set A is the set with an odd number of integer elements{1,2,3,4,5}  Subset b ={1,2}  subset c={3}  Subset d={4,5}  Now there are two subsets with even number of elements and one subset with an odd number of elements.It seems to contradict the earlier theorem that i have to prove.I think that i am missing something.


Let $a$ and $b$ be two positive integers.      If $ab$ divides $a^2+b^2$ then $a=b$.     I can show that $a$ divides $b^2$ and $b$ divides $a^2$ but then I get stuck. Any ideas?

Some observations I made is for $\frac{a}{b}+\frac{b}{a}$, is either:   the denominator has to be one, the numerator has to be a multiple of the denominator or  the numerator and denominator have to be the same.    Obviously, with the given conditions case 3 is eliminated since  $a \neq b$.  For case 1, if $b=1$, then $a=1$ which is a contradiction to the given condition that says $a \neq b$.  For case 2, I would think of examples. For example if $b=2$ then a multiple is $4$, so $a=4$. Then we have:  $$\frac{a}{b}+\frac{b}{a}=\frac{4}{2}+\frac{2}{4}=\frac{10}{4}$$  which is not an integer, but how would i proceed to show this case for all integers.


(This is a re-upload with a link to the file) I have a scene that is pretty much ready for render, and in the render mode of the viewport it looks good. But whenever I try to render it, materials change and the lighting goes wonky. I can't see any reason why this would happen. I'm using the current version of blender. File:


I have often seen truth tables similar to this one:  The first two rows, where $P$ is true, make sense to me. However, why does $P$ being true and $Q$ being false mean that $P \implies Q$? To make the question clearer to myself, I came up with the following example: let $P$ be whether or not it is raining. Let Q be whether or not I am wearing a coat. Then, there are $4$ possibilities:  It is raining; I am wearing a coat.  It is raining; I am not wearing a coat.  It is not raining; I am wearing a coat.  It is not raining; I am not wearing a coat.   $P \implies Q$ is the same as saying if it is raining, then I will wear a coat. This statement says nothing about what happens when it is not raining. Therefore, why do we say not raining $\implies$ coat?

Provided we have this truth table where "$p\implies q$" means "if $p$ then $q$":  $$\begin{array}{|c|c|c|} \hline p&q&p\implies q\\ \hline T&T&T\\ T&F&F\\ F&T&T\\ F&F&T\\\hline \end{array}$$  My understanding is that "$p\implies q$" means "when there is $p$, there is q". The second row in the truth table where $p$ is true and $q$ is false would then contradict "$p\implies q$" because there is no $q$ when $p$ is present.  Why then, does the third row of the truth table not contradict "$p\implies q$"? If $q$ is true when $p$ is false, then $p$ is not a condition of $q$.  I have not taken any logic class so please explain it in layman's terms.       Administrative note. You may experience being directed here even though your question was actually about line 4 of the truth table instead. In that case, see the companion question  And even if your original worry was about line 3, it might be useful to skim the other question anyway; many of the answers to either question attempt to explain both lines.


The monk's Martial Arts feature's benefits all require a monk to be "unarmed or only wielding monk weapons". Even if you're a Way of the Kensei monk, that only lets you add a couple of new simple or martial weapons to your monk weapon list. The druid's Wild Shape forms all come wielding natural weapon attacks. Natural weapon attacks are not unarmed attacks, nor are they monk weapons, nor are they simple or martial weapons that can possibly be chosen by a kensei. Therefore, it seems that a beast is never "unarmed", and thus can never use a druid/monk's martial arts benefits even if it wanted to choose to use unarmed strikes instead of its natural attacks. Is this interpretation accurate? Or can a beast choose not to "wield" its teeth and claws? If my reading of the rules is accurate, such a blanket prohibition on Martial Arts when one has natural weapons seems overly-restrictive; it would mean, for example, that a Minotaur can never be a monk, since they are "never unarmed."  I am explicitly not addressing the (already answered and very obvious) question of whether animals can make unarmed attacks. I am asking whether they can ever choose not to "wield" their own natural weapons, so as to be able to use martial arts in the first place.

Can a Druid/Monk who is Wild Shaped perform Unarmed Strikes?


My microphone is not working so I wanted to use my android phone as a microphone via a USB cable.I want to connect my earphones to my phone and then my phone to my PC via USB. I have tried WO mic but as you know its no longer safe. Please suggest me a simple solution. Thanks in advance

I have a USB cable that can connect my Android smartphone to my laptop's USB port.  This scheme is obviously cheaper than buying a separate standalone computer microphone. My computer's microphone is shoddy, and many people can't hear it well.  Does the answer differ if I receive sound thru:   my computer speakers or external speakers connected to my computer?  vs. my phone?


The Cauchy-Riemann condition states that an analytic function satisfies: \begin{split} \frac{\partial u}{\partial x} &= \frac{\partial v}{\partial y}; \frac{\partial u}{\partial y} &= -\frac{\partial v}{\partial x} \end{split} The converse of the statement requires additional conditions: the first partial derivatives of $u, v$ exist and are continuous. I derived the Cauchy-Riemann condition based on the fact that partial derivatives of $f(z)$ with respect to $x, y$ $(z=x+iy)$ must be the same on the point $z$ where $f(z)$ is differentiable. On the other hand, I found something very interesting that I cannot intuitively interpret. I was reading the  Complex Variables and Applications (Brown and Churchill) 9th ed textbook [1]. On p.71-72, the author explains:  If $z=x+iy$, then $x=\frac{z+\overline z}{2}$ and $y=\frac{z-\overline z}{2i}$ By formally applying the chain rule in calculus to a function $F(x,y)$ of two real variables, we can derive the expression $\frac{∂F}{∂\overline z}$ =$\frac{∂F}{∂x}$$\frac{∂x}{∂\overline z}$ + $\frac{∂F}{∂y}$$\frac{∂y}{∂\overline z}$ =$\frac{1}{2}(\frac{∂F}{∂x}+i\frac{∂F}{∂y})$ Now let's define the operator $\frac{∂}{∂\overline z} = \frac{1}{2}(\frac{∂}{∂x}+i\frac{∂}{∂y})$ By applying this operator to a analytic function $f(z) = u(x,y) + iv(x,y)$ which satisfies the Cauchy-Riemann conditions, then  $\frac{∂f}{∂\overline z} = \frac{1}{2}[(u_x-v_y)+i(v_x+u_y)] = 0$ Thus derive the complex form $\frac{∂f}{∂\overline z} = 0$ of the Cauchy-Riemann equations.  I can follow the above proof step by step but I think there's much more to say about the result $\frac{∂f}{∂\overline z} = 0$. Why this result came from the Cauchy-Riemann condition? Is there any geometrical meaning more than just writing a list of formulas? On the Wikipedia page - Cauchy Riemann equations(), some comments are posted like this.  In this form, the Cauchy–Riemann equations can be interpreted as the statement that f is independent of the variable $\overline z$. As such, we can view analytic functions as true functions of one complex variable as opposed to complex functions of two real variables.  But it's quite confusing for me to understand and many questions remained. How can I view analytic functions(that satisfies the Cauchy-Riemann condition) as one complex variable and how such interpretation is directly related to the concept of differentiability? Reference James Brown, Ruel Churchill. Complex Variables and Applications 9thd ed; McGraw-Hill Education, 2013. ISBN 978-0073383170.

Holomorphic functions are one of the most beautiful objects in mathematics. However, Cauchy-Riemann equations are a little bit of a mystery for me. What does that mean intuitively when a function satisfyes those equations?


Good Day I am looking for a Book that contains detailed proofs of theorems in the field of Euclidean Geometry that are used to solve exams and school work of high school students.  theorems like:  inscribed angle theorem:  angle inscribed in a circle is half of the central angle;   Circumscribed circle theorems;   incircle theorems;  stuff like that.  any suggestions?

Can someone recommend a good basic book on Geometry?  Let me be more specific on what I am looking for.  I'd like a book that starts with Euclid's definitions and postulates and goes on from there to prove thereoms about triangles, circles and other plane shapes.  I'm not interested (at this time) in a book that ties geometry in with linear algebra or explains non-euclidean geometry.  All the books I've seen seem to be of two types 1) Let us use linear algebra and other techniques to put geometry on a firm footing. Let us assume you already know Eucliean geometry and move on to more interesting stuff. These are probably too advanced for me. 2) Let us skip all that complicated postulates/proofs and make geometry fun.  Too easy.  When I was in 9th grade Honors Geometry way back in 1981/82 we had a textbook that, as I recall through my foggy memory, was very good and did systematically build up geometry from the propositions (5 of them?).  And it certainly didn't attempt to address Hilbert's contributions to geometry or explain non-Euclidean geometry. Unfortunately, I don't recall the title or author.  I suspect the book was used nationally though and for quite a number of years, so perhaps someone with a better memory than me can provide a title/author.  I do recall it had all the postulates and most major thereoms listed at the end of the book.  My motivation is two fold... 1.  Review the material myself in preparation for my advanced texts. 2.  Help my children in a few years when they take geometry.    Books I could get for the iPad/Kindle or free books (Google?) would be most appreciatied, but I'm not opposed to killing a tree either :) Thanks for all the help. Dave


Some years ago, a friend of mine visited a US city, and went to a supermarket. Upon trying to pay with his credit card, the transaction failed, and the cashier asked if he could write out a check instead. My friend replied "check?" in a bit confused tone. The cashier replied, "well, maybe someday you will get those in your country too".  The thing is though, checks has been practically extinct in Norway, and surrounding countries, for as long as I have activly used my bank account, closing in on 20 years. We manage our accounts online. Absolutely every bank have online options, and the vast majority of all transactions happen through the internet. Lately mobile transactions though smart phones has become popular too.  How come the US still use checks in such a large scale, when there are so many modern solutions that seemingly are so much better?

That might sound a bit silly to people from USA but is it really that common to use checks in America?  I am from Austria and here (Austria, Germany, Switzerland) checks play practically no role in daily life. I haven't actually held a single check in my hands in my entire life.  So is it really common to get a paycheck in the sense that you get a piece of paper?  It would be nice if someone could explain the practice of "money handling" in America a little bit because I think it's really interesting how different cultures can be regarding money.   And I also have had the experience that most people believe that how it's done here, it's done in the whole world. :)  Edit:   I think it would only be fair if I just explain briefly how it is handled here. Maybe it's interesting to other people.  You usually have an account at your bank. Your payment as an employee is deposited there once a month. From there you can transfer money to other accounts. So instead of paying a bill by sending a check to the one getting the money you will send a form to your bank (or more commonly you will just go to the bank) ordering them to transfer money to the account of the other person.  Bills (esp. regular ones) are most often payed by issuing an "Einzugsermächtigung" (collection authorisation) and the companies will more or less just "take" the money from your account.  Today most people with a computer issue the transfer of money through the internet.


This is a follow-up to a question I answered earlier ().    For most questions that have more than one language-related tag and those with fuzzy languages (for instance !), there should be an option to specify which language to use in syntax highlighting because sometimes (and quite often too!) the language inference is wrong.  Take for instance the scenario I describe below.  When an answer is given in a language other than the "primary language" (which happens to be C#), the code is still highlighted as C# even if it isn't in that language!   Scenario     Take any question that has multiple explicit language-related tags. For example:  which is tagged tagged , ,  and .   Try to answer the question with code that is different from the 'major' language. In this case, try answering the question with VB.NET code.   Expected Results: Code should be highlighted in VB.NET. Actual Result: Code was highlighted in C#!  Suggested Solution There should be a way to explicitly set the language for syntax highlighting.  Edit  It also turns out that asking a question with multiple explicit language-related tags can also give you wrong syntax highlighting! You can try creating a new question with the following and observe the preview:       //This is C#     var someValue = GetValue();  some text to separate the two languages      'This is VB.Net     Dim someValue = GetValue()   Tag the question as follows (in the specific order) ,    You'll notice without fail that the C# code gets highlighted properly and the vb.net code doesn't.     Disclaimer   All observations are based on the preview you get while entering the question or answer so my observed result might not be wholly right.

I noticed that sometimes my code gets highlighted in different colors when rendered.   What is syntax highlighting? How does it work? Why isn't my code being highlighted correctly? How do I report a bug or request a new language? How do I use syntax highlighting? What languages are currently available on Stack Exchange?


I seem to be missing something about how the house upgrading system works. I seem to have fulfilled all the obvious requirements: both population classes' needs are fulfilled to 100%, both classes are at their maximum current capacity and happy enough to keep moving in. The warehouses have enough tools, construction blocks, carbon and even wood (not used by the particular faction I'm having this problem with) for them to upgrade. Yet they won't upgrade.    Pictured: the particular situation that keeps me stuck in the campaign, appalling lack of SCIENCE and PROGRESS.  So what are the general requirements for a house to become eligible for an upgrade, regardless of faction? Are there any additional faction-specific requirements?

I can't find a list of needs for lab assistants. I gave them everything (they have carbon to upgrade). What else am I missing? I read researched on the internet and couldn't find a solution.


I recently replaced the HDD on my 17-inch MacBook Pro (Early 2011) with a SSD. I did a clean install of macOS Sierra on the SSD and had no intention of copying the old HDD to the new SSD. I put the old HDD in a USB enclosure.  The HDD was partitioned and bootable in Windows 7 before it was removed from the machine. Now, however, if I plug the HDD in via USB and boot the machine holding the ALT key, the HDD is shown as a boot option, but the Windows partition is not.  Is it possible to boot in Windows from that partition any longer?  I tried booting using the HDD and then choosing Windows from the Startup Disk preferences menu, but when it attempted to boot that way, I got a black screen with a "No bootable device -- insert boot disk and press any key" message.  Any ideas?

I have a mid-2011 Core i7 Macbook Pro that currently is dual-booting a File-Vault encrypted OS X Lion installation and an OS X Snow Leopard installation. Unfortunately I need to keep both of these on the internal drive which I believe prevents me making yet another partition for Windows 7 via Bootcamp because of some limitation on the number of partitions (though I could be wrong on this).  I only need to run Windows 7 natively (for gaming, etc) every once and a while and what I would ideally like to do is install Windows 7 onto an external USB or Firewire drive and boot/run Windows from the external drive when needed.   I have successfully installed Windows 7 by temporarily swapping my internal drive and for my "external" drive. After installation Windows boots fine while the drive is inside the laptop, but when I move it to an external USB enclosure it is not listed as a boot option either from the startup menu (holding down Option on boot) or from the 'Start-up Disk' System Preferences.  Is it possible to run Windows 7 from an external drive? If so how?


I'm trying to evaluate this limit, but I don't think it's coming out correctly. Could someone please offer me some assistance?     Evaluate limit analytically   $$\lim_{h\to 0}\frac{\sqrt[3]{x + h} - \sqrt[3]{x}}{h}.$$    What I did was multiply $(x+h)^{2/3} + x^{2/3}$ top and bottom to get  $$\lim_{h\to 0}\frac{(x+h)-x}{h((x+h)^{2/3} + x^{2/3})}.$$   I end up getting $\dfrac{1}{2x^{2/3}}$.   The reason why I don't think I did this write is because isn't the limit above the definition of a derivative? And if so, then isn't the derivative of $\sqrt[3]{x}$ equal to $\dfrac{1}{3x^{2/3}}$?  I would really appreciate any kind of help. Thanks.

I need to finding derivative of $\sqrt[3]{x}$ using only limits  So following tip from : I multiplied top and bottom by conjugate of numerator  $$\lim_{h \to 0} \frac{\sqrt[3]{(x+h)} - \sqrt[3]{x}}{h} \cdot \frac{\sqrt[3]{(x+h)^2} + \sqrt[3]{x^2}}{\sqrt[3]{(x+h)^2} + \sqrt[3]{x^2}}$$  $$= \lim_{h \to 0} \frac{x+h-x}{h(\sqrt[3]{(x+h)^2} + \sqrt[3]{x^2})}$$  $$= \lim_{h \to 0} \frac{1}{\sqrt[3]{(x+h)^2} + \sqrt[3]{x^2}}$$  $$= \frac{1}{\sqrt[3]{x^2} + \sqrt[3]{x^2}}$$  $$= \frac{1}{2 \sqrt[3]{x^2}}$$  But I think it should be $\frac{1}{3 \sqrt[3]{x^2}}$ (3 instead of 2 in denominator?)  UPDATE  I found that I am using the wrong conjugate in step 1. But this (wrong) conjugate gives the same result when I multiply the numerator by it. So whats wrong with it? (I know its wrong, but why?)


So.. I'm trying to refactor a piece of code, namely:  v = [0.0, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.0]   By using the .step method. Tried this but it's giving me some odd decimals for some of the numbers. Trying to figure out why this is?  0.0.step(by: 0.1, to: 1.0).to_a   Gives me this result:  => [0.0,  0.1,  0.2,  0.30000000000000004,  0.4,  0.5,  0.6000000000000001,  0.7000000000000001,  0.8,  0.9,  1.0]   Ruby version: 2.3.0p0  How can I go about figuring out why this is happening? Each of those numbers returns a float.

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


I can't achieve updates, I get the following message (see image).    $ df -h Filesystem       Size  Used Avail Use%   Mounted on udev             1,9G     0  1,9G   0%   /dev  tmpfs            384M   11M  373M   3%   /run  /dev/sda5         20G   18G  1,3G  94%   / tmpfs            1,9G  1,1M  1,9G   1%   /dev/shm  tmpfs            5,0M  4,0K  5,0M   1%   /run/lock  tmpfs            1,9G     0  1,9G   0%   /sys/fs/cgroup  /dev/sda6        133G   41G   86G  32%   /home  cgmfs            100K     0  100K   0%   /run/cgmanager/fs  tmpfs            384M   72K  384M   1%   /run/user/1001     i don't want to do a new partition. how can i move unuseful files? how can i add partition via terminal?  sudo dpkg --configure -a dpkg: error: unable to create new file '/var/lib/dpkg/status-new': No space left on device

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


How do you use '' get p.p.''and"be p. p. "differently? For example" get injured "and" be injured". Is there any difference between them?

In spoken English (at least in America), passives are often formed with "to get" rather than "to be;" I would wager the majority of the time:   he got hit by a car I get driven to work I've gotten called for jury duty eight times   Are there specific verbs that prefer "be" to "get," or vice-versa, or semantic differences between these forms? I cannot think of any.


I've just installed the Ubuntu Raring (with Sandisk Extreme) and I know there're multiple articles over the internet (and here) about TRIM, but I suspect it's a native resource on Ubuntu Raring.  PS: Tried to find something in the Ubuntu's documentation, but did not.  Then I've read lots (and lots) of articles and all of them providing different ways to enable TRIM (fstab, cron job, init scripts, etc ..).  IE:   And I got something interesting -> I've performed those tests (creating testfile / removing / running hdparm) WITHOUT "discard" in the /etc/fstab and I got that same results, I got those expected "zeros" output.  That suggested TRIM test I've uploaded (just in case),   That's why I'm wondering -> Is the TRIM active by default on Ubuntu Raring?  If not .. any recommended way to active it, among so much options? Thx.  PS: This is not the same question as the duplicated one. Here I'm trying to understand the NATIVE trim support (as it looks like)

I know that the Linux kernel supports TRIM as of version 2.6.33, so there should be TRIM support in ubuntu.  Is TRIM enabled by default or do I need to change some settings or install additional software for it to work? If so, how?


I have strange issue, which I don't understand. I would like to make a JSON Object in JavaScript. My example code:  $(document).ready(function(){  var myJson = new Object(); var data = new Object(); myJson.items = [];  data.name  = 'test';  for (i = 0; i < 5; i++){   data.counter = i;   myJson.items.push(data);   } console.log(JSON.stringify(myJson));  });   Output:  {"items":[{"name":"test","counter":4},{"name":"test","counter":4},{"name":"test","counter":4},{"name":"test","counter":4},{"name":"test","counter":4}]}   Why the counter variable in JSON have always value 4 ??????

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


5h ago steam was running well, but now there's an error occuring when i try to launch steam: [0913/173803:WARNING:proxy_service.cc(958)] PAC support disabled because there is no system implementation  I have my system upgraded.  Any ideas?

When I try to start Steam nothing happens. Reinstall doesn't help.  $ steam Running Steam on ubuntu 13.04 64-bit STEAM_RUNTIME is enabled automatically Installing breakpad exception handler for appid(steam)/version(1378500910_client) Installing breakpad exception handler for appid(steam)/version(1378500910_client) Installing breakpad exception handler for appid(steam)/version(1378500910_client) unlinked 0 orphaned pipes removing stale semaphore last operated on by process 7278 with name 0eBlobRegistryMutex_DC7EBB4AEA41D3C6C74E5EFFD6757CEC removing stale semaphore last operated on by process 7278 with name 0eBlobRegistrySignal_DC7EBB4AEA41D3C6C74E5EFFD6757CEC removing stale semaphore last operated on by process 7278 with name 0emSteamEngineInstance removing stale semaphore last operated on by process 7278 with name 0eSteamEngineLock Gtk-Message: Failed to load module "overlay-scrollbar" Installing breakpad exception handler for appid(steam)/version(1378500910_client) [0913/182910:WARNING:proxy_service.cc(958)] PAC support disabled because there is no system implementation   How to fix it?


Let $p(x)$ be a polynomial of degree $n$ satisfying $p(x)\geq 0$ for all $x$. That is, for all $x$, $p(x) = a_n x^n + a_{n-1} x^{n-1} + \cdots + a_1 x + a_0 \geq 0$, $a_n\neq 0$.  Show that $p(x)+p'(x)+p''(x)+\cdots+p^{(n)}(x)\geq 0$ for all $x$ where $p^{(i)}(x)$ is the $i^\text{th}$  derivative.  My interest: I know that, we can rewrite the LDE as follows  $$ p(x)+p'(x)+p''(x)+\cdots+p^{(n)}(x) = Lp(x) $$  where $L := I + D + D^2  + \cdots + D^{(n)}$. Can we say anything about a linear operator of this kind so that it does not change the sign of the input it takes? I can try to solve the question by writing for all the derivatives and factoring them using $p(x)$, but I think there should be a clever way of showing this by the properties of $L$. Can I figure out a solution by just looking at $L$ and the sign of $p(x)$ as in the question? Where should I look for that?


yesterday on SO, as I was not able to get an answer using Google, and some time later a member posted a thread reference which had an answer to my question.  That thread contains question similar to mine with better answers, which brings me to my question that, if I cannot find my answer Googling or using the search facility of SO and post a question to ask it, only to realise later that it has already been asked and had a better-quality answer, what should I do with my question (shall I delete it or add the reference by myself to that question for future visitors)?  A mean sidenote: That question gave me 3 upvotes, so I was little hesitant to delete it too! :)

Let's say I'm a good Stack Overflow citizen: I have a question, I search on SO and on google to see if someone's asked the same thing, and I can't find anything that shows up, so I go ahead and post a well-written question on SO. Then later it gets closed, because it's a duplicate question for something that I wasn't able to find on my initial search. Great, the system worked.  Is there ever a case where I should delete the question I posted? Why or why not? Do duplicate questions cause much resource bloat for the site?


In the new topbar's Achievements dropdown (the graph icon), badges that you earn are listed.  However, when you click the badge notification, it doesn't take you to the badge you earned.  For example:    Here are 2 recent Achievements for me.  The top is a badge, the bottom is earned reputation from an upvote.  Both links go to the post.  The badge earning notification says 'See your profile', but nothing in that notification links to my profile.  In the old topbar, there was a section for recently-earned badges.  When you clicked the badges there, it would take you to a page that showed you the badge, its description, and a link to the post that earned you the badge.  Can we get that behavior back?  It's more useful to understand what the badge is and how you earned it.  The link to the post doesn't tell you anything about what's special about that post that makes it badge-worthy.

When I get such item in the inbox:     You've earned the "X" badge for "Y". See your profile.   The "See your profile" used to be a link to the profile badges tab while only the "Y" was link to the relevant post.  Now the whole item is one big link to "Y":        Can this be changed please?


I have been struggling with the task of creating a least-cost path between two points on a land-use map. So far I have got the raster as follows (category names don't matter right now)    So these 7 categories are the values of my raster cells, right? (0-6). I would like to change these for: 0 to 100 (highest cost) 1 to 0 (lowest cost) 2 to 80 (high cost) 3 to 30  And so on... (the logic behind this would be of an animal crossing it, that's why it looks odd).  The problem is that I can't seem to find a way to reclassify this. I see people talking about this with DEM files, but I haven't found much information about how can I do this with a "simple" land-use raster. Am I trying to work with too little information? I believe once I get this reclassified, it will be easy to calculate the least-cost path between two points in the raster, right?

I'm new in QGIS and I'm trying to reclass a raster with reclassify grid values. I want to reclassify by table, however fixed table has only 3 rows and I need some more, but button to add is not activated.  Do you have any idea about how add more rows?


I have a class DLXMatrix with constructor delegation. it as a simple constructor: DLXMatrix::DLXMatrix(int nb_col);  And another more advanced one which is currently: DLXMatrix::DLXMatrix(int nb_col, const std::vector<std::vector<int>> &rows)     : DLXMatrix(nb_col) {     for (const auto &r : rows)   // TODO : cleanup if an exception is raised         add_row_sparse(r); }  However, depending on the input, the call to add_row_sparse(r) may raise a std::out_of_range exception. I understand that if I simply let the exception pass, I'll be leaking memory in the various attribute (typically one of the attribute is a vector)... Note that, at this stage, this already points to a valid objects since, by delegation, it was constructed by another constructor. Therefore, I'm tempted to call the destructor as in DLXMatrix::DLXMatrix(int nb_col, const std::vector<std::vector<int>> &rows)     : DLXMatrix(nb_col) {     try {         for (const auto &r : rows)             add_row_sparse(r);     } catch (std::out_of_range e) {         this->~DLXMatrix();         throw std::out_of_range(e);     } }   Unfortunately this segfaults. Am I totally out of my mind ? Should I call the destructors only on the  attributes.

Looking for an answer for C# and C++. (in C#, replace 'destructor' with 'finalizer')


I'm pretty new to C++ and I cannot seem to grasp why we would use a referee to a variable instead of just using the variable itself.  #include <iostream> int main() {     using namespace std;     int ival = 1024;     int &refVal = ival;     cout << ival << endl << refVal << ends;     return 0; }   What is the point of the reference if it only ever gives the value of ival? Why not just use ival?

I would like to clarify the differences between by value and by reference.  I drew a picture     So, for passing by value,  a copy of an identical object is created with a different reference, and the local variable is assigned the new reference, so to point to the new copy  How to understand the words: " If the function modifies that value, the modifications appear also within the scope of the calling function for both passing by value and by reference "  Thanks!


I have a simple following code:   \begin{tikzpicture} \draw[thick] (2,0) circle (1.5cm); \end{tikzpicture}`   I would like to create a curved parallel naming arrow around this circle as shown in the image.    Please help

The TiKz command for an arc:  \draw (0,0) arc (-30:30:2) ;   Draws an arc that starts at (0,0), and would be the part of the circle from -30 degrees to +30 degrees of radius 2.    It is very hard to place these arc sometimes.  This is the symbol i want to draw:    (This represents an eye and needs more detail).  I want to draw the arc as _part of a circle with center at where the < meets, but I have to currently fudge the start location of the arc so it properly crosses the < (and it's not even exact).  If I could do a circle from -45 to +45 degrees CENTERED at the <, then that would be much easier.


Everytime I try to launch the game (v1.7.4), it starts out normal, then starts getting timeouts half way in while trying to connect to the server, then just says it's assuming that the local file is good, after that I get this:  [17:13:35 ERROR]: Couldn't unpack natives! java.util.zip.ZipException: error in opening zip file at java.util.zip.ZipFile.open(Native Method) ~[?:1.7.0_45] at java.util.zip.ZipFile.<init>(Unknown Source) ~[?:1.7.0_45] at java.util.zip.ZipFile.<init>(Unknown Source) ~[?:1.7.0_45] at java.util.zip.ZipFile.<init>(Unknown Source) ~[?:1.7.0_45] at net.minecraft.launcher.GameLauncher.unpackNatives(GameLauncher.java:469) ~[launcher.jar:?] at net.minecraft.launcher.GameLauncher.launchGame(GameLauncher.java:213) [launcher.jar:?] at net.minecraft.launcher.GameLauncher.onDownloadJobFinished(GameLauncher.java:619) [launcher.jar:?] at net.minecraft.launcher.updater.download.DownloadJob.popAndDownload(DownloadJob.java:120) [launcher.jar:?] at net.minecraft.launcher.updater.download.DownloadJob.access$000(DownloadJob.java:12) [launcher.jar:?] at net.minecraft.launcher.updater.download.DownloadJob$1.run(DownloadJob.java:89) [launcher.jar:?] at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.7.0_45] at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.7.0_45] at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.7.0_45] at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.7.0_45] at java.lang.Thread.run(Unknown Source) [?:1.7.0_45]

Similar to  on the bugs in Minecraft, I would like a complete list of what error codes exist in Minecraft and how they occur, as well as how they can be resolved.


$$\lim _{n\to\infty}\sum_{k=0}^n\frac{k+1}{10^k}$$ What I've tried is to create a function out of it in order to derivate it, but I am getting nowhere. I would like to know if there is an easier way to it (I would like a high school level method for this, if there is one).

How can I evaluate $$\sum_{n=1}^\infty\frac{2n}{3^{n+1}}$$? I know the answer thanks to , but I'm more concerned with how I can derive that answer. It cites tests to prove that it is convergent, but my class has never learned these before. So I feel that there must be a simpler method.  In general, how can I evaluate $$\sum_{n=0}^\infty (n+1)x^n?$$


I'm studying about the central force and Kepler's law, and I was wondering: by the first law, the trajectories of planets suppose to be elliptical. but from what I understood, most physical trajectories are almost circular in practice. so why does this happen?

Except for Mercury, the planets in the Solar System .  Is this property special to the Solar System?  :     Most exoplanets with orbital periods of 20 days or less have near-circular orbits of very low eccentricity. That is believed to be due to tidal circularization, an effect in which the gravitational interaction between two bodies gradually reduces their orbital eccentricity. By contrast, most known exoplanets with longer orbital periods have quite eccentric orbits. (As of July 2010, 55% of such exoplanets have eccentricities greater than 0.2 while 17% have eccentricities greater than 0.5.) This is not an observational selection effect, since a planet can be detected about equally well regardless of the eccentricity of its orbit. The prevalence of elliptical orbits is a major puzzle, since current theories of planetary formation strongly suggest planets should form with circular (that is, non-eccentric) orbits.   What is special about the Solar System that orbits of planets here are nearly circular, but elsewhere they are moderately or highly eccentric?


I have a dual boot Lenovo W520 system, with Windows 7 and Ubuntu 14.04. In Ubuntu, when I set the brightness to the lowest value, the backlight actually turns off, which is a brilliant battery saver.  On Windows, I could install the bulky Lenovo Power Manager which turns off the screen with Fn+F3, but I'm trying to keep my laptop completely bloatware free. Can I somehow adjust the minimum brightness in Windows (e.g., in the registry?) Or is this a driver thing, and did I just luck out with Ubuntu not using Lenovo's PM drivers?  I have seen  but that question is about eye strain: they all just make the pixels 'dark' rather than the backlight. I want to set the screen backlight to zero, to save battery life.  Added note from barlop  The OP reasons, not unreasonably, that it seems the software that appears to reduce brightness, e.g. flux/dimmer, doesn't reduce the backlight, hence the taskbar doesn't get darkened, so he reasons that it is darkening the pixels.  So if anybody does want to recommend software, then it should reduce the brightness of the taskbar too. And ultimately his concern/interest is battery life rather than eye strain. So a neutral density filter / vinyl sheet, or sunglasses, don't apply to his case.

I usually just use Fn + Left or Fn + Right to adjust my screen's brightness but the minimum settings are still too bright for me (especially when I'm working at night). I tried going through the Power Options in the Control Panel (plan brightness already at the lowest settings). Is there a way to dim my laptop's screen beyond the minimum?  I'm already using . I was wondering if there was a utility similar to it that adjusts my screen's brightness/contrast instead of its color temperature.


I'm trying to write my own bash script that detects if Debian's release version is less than 9.0  code:  VERSION=$(cat /etc/debian_version) echo $VERSION  if [ "$VERSION" -lt "9.0" ]; then     echo "Debian version is less than 9" else     echo "Debian version is greater than 9" fi   but the error i'm receiving is:     ./test.sh: line 4: [: 8.2: integer expression expected   basically, $VERSION is a string type, but it's 8.2. I'm trying to make it become 8.2, but as a float. so I can use <= on it.

Suppose I want to compare gcc version to see whether the system has the minimum version installed or not.  To check the gcc version, I executed the following  gcc --version | head -n1 | cut -d" " -f4   The output was  4.8.5   So, I wrote a simple if statement to check this version against some other value  if [ "$(gcc --version | head -n1 | cut -d" " -f4)" -lt 5.0.0 ]; then     echo "Less than 5.0.0" else     echo "Greater than 5.0.0" fi   But it throws an error:  [: integer expression expected: 4.8.5   I understood my mistake that I was using strings to compare and the -lt requires integer. So, is there any other way to compare the versions?


My laptop is: "Lenovo G580" and it comes with a very sensitive touchpad. Specially, when I place my hands comfortably to type, it "thinks" I'm touching the top-left corner. This becomes really annoying when I have to use both (the keyboard and touchpad), as it thinks I'm performing a 2 finger click (the mouse stop moving). I have disabled the 2 finger click, which defaults to right click, in order to prevent the right-click-menu randomly (imagine that!).   Using Xubuntu 12.10. These are my settings:  LeftEdge                = 2300 RightEdge               = 5000 TopEdge                 = 1652 BottomEdge              = 4658 FingerLow               = 25 FingerHigh              = 30 FingerPress             = 256 MaxTapTime              = 180 MaxTapMove              = 242 MaxDoubleTapTime        = 180 SingleTapTimeout        = 180 ClickTime               = 100 FastTaps                = 0 EmulateMidButtonTime    = 75 EmulateTwoFingerMinZ    = 282 EmulateTwoFingerMinW    = 7 VertScrollDelta         = 110 HorizScrollDelta        = 110 VertEdgeScroll          = 0 HorizEdgeScroll         = 0 CornerCoasting          = 0 VertTwoFingerScroll     = 1 HorizTwoFingerScroll    = 0 MinSpeed                = 1 MaxSpeed                = 1.75 AccelFactor             = 0.036324 TrackstickSpeed         = 40 EdgeMotionMinZ          = 30 EdgeMotionMaxZ          = 160 EdgeMotionMinSpeed      = 1 EdgeMotionMaxSpeed      = 440 EdgeMotionUseAlways     = 0 TouchpadOff             = 0 LockedDrags             = 0 LockedDragTimeout       = 5000 RTCornerButton          = 0 RBCornerButton          = 0 LTCornerButton          = 0 LBCornerButton          = 0 TapButton1              = 1 TapButton2              = 0 TapButton3              = 2 ClickFinger1            = 1 ClickFinger2            = 1 ClickFinger3            = 0 CircularScrolling       = 0 CircScrollDelta         = 0.1 CircScrollTrigger       = 0 CircularPad             = 1 PalmDetect              = 0 PalmMinWidth            = 10 PalmMinZ                = 200 CoastingSpeed           = 20 CoastingFriction        = 50 PressureMotionMinZ      = 30 PressureMotionMaxZ      = 160 PressureMotionMinFactor = 1 PressureMotionMaxFactor = 1 ResolutionDetect        = 1 GrabEventDevice         = 1 TapAndDragGesture       = 1 AreaLeftEdge            = 0 AreaRightEdge           = 0 AreaTopEdge             = 0 AreaBottomEdge          = 0 HorizHysteresis         = 8 VertHysteresis          = 8 ClickPad                = 0   What I have tried:  1) The "CircularPad" option could solve my problem, but for some reason it doesn't work :(  2) Palm detection seems to fail as well... (currently disabled)  3) The "Block touchpad while typing" option resulted annoying as well, as I often use both input methods at the same time (like when you are searching for a file in a directory and type part of its name, and then clicking on the correct file). With that option, I have to wait about 3 secs in order to be able to use the touchpad, which I think is too much.  4) I could disable 2-finger scroll, but I use it a lot.   5) I thought that changing the Edges could be the easy way to go. I checked X and Y values in: "synclient -m 100" , and change the LeftEdge and RightEdge values as shown above. But even after setting them (using synclient LeftEdge=...) the cursor still moves below the LeftEdge and after the RightEdge, what am I doing wrong?  It seems that many options have no effect (like TapAndDragGesture), while changing others do (like setting 3 finger middle-click, etc.). Is that possible?  What other alternatives could I try to solve it? Thanks in advance!

I'm using (K)ubuntu 12.04 LTS with a Synaptics touchpad. The palm sensitivity it terrible, whenever I'm typing the mouse suddenly jerks off to a different place. Is there a way to enable/increase palm sensitivity?


I understand that some very distant objects (galaxies) are moving away from us at speeds exceeding the speed of light and that such expansion induced speed is not limited by the theory of relativity. However these objects may also be moving within space at speeds limited by relativity. How do we distinguish between these 2 components of speed, following different laws?

just after the Big Bang and before inflation the currently observable universe was the size of a coin. One millionth of a second later the universe was the size of the Solar System, which is an expansion much much faster than speed of light. Can space expand with unlimited speed?


I have been learning CPP lately, and I came across this question: Consider the below program: #include <iostream> using namespace std; class Hall {  public:  double cost; }; int main() {  Hall hall;  hall.cost=10000.50;  cout<<hall.cost;  return 0; } What will be the output of above coding?   The answer to this question is 10000.5, however, I couldn't understand why is it so ? In my opinion, answer should be either 10000.500000 as double has precision upto  6 decimal digits or it should print 10000.50 as it is the value assigned to hall.cost. Please explain.

In my  I was printing a double using cout that got rounded when I wasn't expecting it.  How can I make cout print a double using full precision?


I often pipe commands to less in order to read through the output (e.g. compiler errors).  MyCommand | less   This is great because it makes trawling through large amounts of output easy, but when I exit less the output is gone. How can I make the output still visible after quitting less?  This question differs from  because that question relates to output to a text file via tee, which, as far as I know, doesn't provide a facility to split output between less and stdout.

Relatively often, I find myself wanting to quit less but leave what I was viewing on the screen, to refer back to. Is there any way to do this? Workarounds?  (My current workaround is to quit, then use more. So any workaround that's better than that is welcomed. The ideal would be something I can use once I'm already inside less, perhaps with a shell setting or some scripting.)  My desktop is OSX, but I use RHEL and Ubuntu servers.


I am using Ubuntu 18.04 and I have found this weird bug in the default document viewer. When I click on text annotation, the annotation is completely offset. To open the annotation, I still have to click the required text, but the yellow highlight appears about five lines underneath the text.  I have attached a photo, where the problem is visible clearly. This happens in several pdfs that I have. What can I do?

This is an old bug, it seems to be not Evince's own fault but the bug is from Poppler.  The specific cause of the bug has been identified (it's the calculation of some coordinates) but as of 2019 it is still not fixed in Ubuntu.  This is an example:  I tried to highlight the second sentence of the first paragraph, but this is what I get:   That means all the users of Ubuntu cannot highlight PDF texts using Evince --- this is such a basic function.  Is there any way to update Poppler to the correct version such that Evince works?  Please do not mark this as a duplicate question UNLESS one can provide a specific way to upgrade Poppler and resolve this problem.


I was building and I must have clicked something because I couldn’t break blocks but I could place them. I don’t know if this means something but I was playing Crazycraft.   I tried looking through options but nothing seems to work and I can’t find any videos about this.

I'm playing on a Survival world with cheats on, "easy" difficulty, and at night in-game. I didn't have a sword or anything to make a sword with, and I was starving, so I switched to Creative to give myself a stack of food and a bed to set my spawn point. When I switched back to Survival, I couldn't destroy or place blocks. I'm on single player, and my Internet is fine, and I can destroy blocks still if I switch to creative. I've tried resetting the button one, and reloading the map, and it still doesn't work. I've even tried deleting everything I gave myself in Creative. This happened before on a different world and I ended up deleting it.  This only happens on this world. How do I fix it?  If I know I'm in the correct game mode, what else can cause this?  Are there different causes in multiplayer?


I am 19 years old, around 1.62 meters tall and a weight of 55 kilograms, and I want to increase my height.  Is it possible to do it at my age? If so, can I have a specific diet or use growth hormones?

I am an adult, and I want to be taller. I know about many medicines which claim to treat stunted height.  Is there any truth behind these?


Let $\Omega$ be a type (or signature, depending on your terminology), and let $\mathbf {\Omega Alg}$ be the category of $\Omega$-algebras. What is the coproduct in this category?  G. Bergman's "An invitation to general algebra and universal constructions" hints at this, but (unless I am overlooking something, it's a big book) doesn't provide an explicit construction for it. Where can I find an explicit construction of it? It should be noncommutative, nonassociative, etc. etc.

Suppose $S$ is a family of $L$-structures where $L$ is some collection of constant symbols, relation symbols, and function symbols.  Does the coproduct of elements of $S$ exist?  If not, how does one prove it?  If yes, how is the coproduct defined?  Are the maps from elements of S to the coproduct all monic?  Also, any references speaking about this would be appreciated; something that involves mathematical logic and category theory perhaps.  Thanks in advance for your answer.


We are using XeLaTeX and the longtable package to visualize information, one of those reports must have a colored cell. A single cell, not the entire row.  An example output is here:    Is there a way to color a single cell when using long tables?  Update: example code:  \documentclass[10pt,a4paper,onside,article,notitlepage, landscape]{memoir} \begin{document} \vspace*{-4cm}  \section*{Leverlijst per week}  \begin{longtable}{p{2cm}p{4cm} p{2cm}p{2cm} p{4cm}p{4cm} p{2cm}p{3cm}} Order ID & Referentie & Locatie & Klant & Tekeningnummer & Omschrijving & Leverdatum & Status \\ \hline 1234 & REFERENCE & Location & Client & Drawingnumber & Description & Deliveryday & Status \end{longtable} \end{document}

Possible Duplicate:          I tried to color only a cell of my table but I don't know how do it. I found the method to color an entire row.How could I color only a cell of my table of a precise color?


Im trying to display my result in asynctask using webview but i got nullpointExc any help will be appreciated.   @Override     //Display my result via webview     protected void onPostExecute(String result) { //where i get my result         setContentView(R.layout.paynamics_layout);         WebView myweb = (WebView) view.findViewById(R.id.paynamics_site);         myweb.loadData(result, "text/html", null); // i got error here         myweb.canGoBack();         super.onPostExecute(result);      }   Here is my error  java.lang.NullPointerException: Attempt to invoke virtual method 'void android.webkit.WebView.loadData(java.lang.String, java.lang.String, java.lang.String)' on a null object reference

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


Given $a_1,a_2,\dots,a_n \in \mathbb{Z}$ with $\gcd(a_1,a_2,\dots,a_n)=1$, is it possible to find $M \in GL_n(\mathbb{Z})$ with first row $(a_1,a_2,\dots,a_n)$?   Clearly for $n=2$ the result is true. For $a,b \in \mathbb{Z}$ with $\gcd(a,b)=1$, there exists $x,y \in \mathbb{Z}$ such that $ax+by=1$. Then the required matrix is $    M=   \left[ {\begin{array}{cc}    a & b \\    -y & x \\   \end{array} } \right] $. But I am not being able to extend it to general case. Even the converse of this result is true. For $M \in GL_n(\mathbb{Z})$ we can prove that every row and column has gcd 1.

Let $n \geq 2$. Let $a_1, a_2, \ldots, a_n$ be $n$ integers such that $\gcd\left(a_1, a_2, \ldots, a_n\right) = 1$. Prove that there exists a matrix in $\operatorname{SL}_n\left(\mathbb{Z}\right)$ whose first row is $\left(a_1, a_2, \ldots, a_n\right)$.   Since the gcd of the integers $a_1,\ldots, a_n$ is $1$, there exists weights $x_i \in \mathbb{Z}$ such that $a_1x_1+\cdots+ a_nx_n=1$. My two ideas are (a) to brute force construct an $n\times n$ matrix with first row $a_1,\ldots ,a_n$ and to construct the remaining rows such that the determinant is $\sum a_ix_i=1$ or (b) to use induction.  (a) (Constructive) This is tedious since once I find a way to construct the remaining $n-1$ rows to ensure that $a_1x_1$ appears in the determinant, I am not sure how to modify these $n-1$ rows to ensure  that only the terms $a_ix_i$ appear in the cofactor expansion. If such a matrix exists, I'd like to see it.  (ii) (Non-constructive) If I proceed by induction then the base case $n=2$ is settled since I can choose the 2nd row to be $-x_2, x_1$ so that the determinant is $a_1x_1-a_2(-x_2)=1$. However, I'm not sure how to use the inductive hypothesis to show that if I can construct such an $n\times n$-matrix then I can construct an $\left(n+1\right) \times \left(n+1\right)$-matrix with the desired property. In particular, if the gcd $(a_1,\ldots ,a_{n+1})$ is $1$, it is not necesarry that the gcd of any $n$ of these terms is $1$, so induction may not even apply here.  How can I construct such a matrix or prove that one exists (without necessarily constructing it)?


It can be that $R\cong R^2$ for some ring as wikipedia says, something like the column finite ring. In  the author proved in lemma 1.1 something different. But I could not find any mistakes in the proof. What is happening?

We're all aware of the theorem that says for a commutative ring $R$ with $1$, $I$ is maximal iff $R/I$ is a field. I'm currently working on a problem where I was asked to show commutative rings have IBN, and I used a lemma saying if $\psi:R\to T$ was a ring homomorphism and $R$ did not have IBN, then $T$ does not have IBN. I used this by sending $R$ to $R/I$, where $I$ is maximal, so $R/I$ is a field and must have IBN, so $R$ has IBN.   This made me wonder why this wouldn't work for any ring $R$. If I could just choose any maximal left ideal $I$ then send it to $R/I$, if $R/I$ is a division ring then I must have $R$ having IBN for the same reason. Therefore there must be a case where $I$ is a maximal ideal but $R/I$ is not a division ring. Does anybody know any examples? Is a "maximal ideal" even a well defined notion if $R$ is not commutative?


Is it possible to create password protected folders on the desktop?  Other people use my computer from time to time and it would be useful to have this facility.

Let's say that I have a folder, within my Documents folder, that has files I want no one to access without a password.  Is there a way to lock down that folder so that it's password protected / encrypted?  In fact, is it possible to password-protect any individual folder?


I need to prove that for a positive sequence $a_n$:  $$\sum_{n=1}^{\infty}{a_n} \text{ converges} \implies \sum_{n=1}^{\infty }\frac{\sqrt{a_n}}{n} \text{ converges}$$  How can I prove it with only basic tools such the comparison test? I've been struggling with this one for pretty long time and I'd be glad for some help.

Let $a_1,a_2,a_3,\ldots$ be reals. Prove that if $\sum_{n=1}^{\infty} a_n^{2}$ converges, then so does $\sum_{n=1}^{\infty} \frac {a_n}{n}$.   For this I have shown the case for when $ a_n^{2} \le\frac {|a_n|}{n}$ $\Rightarrow$ $ |a_n|\le\frac {1}{n}$ $\Rightarrow$ $\frac {|a_n|}{n} \le \frac{1}{n^{2}}$ and we know that $\sum_{n=1}^{\infty} \frac {1}{n^{2}}$ converges and hence $\sum_{n=1}^{\infty}\frac {a_n}{n}$ converges by the comparison test. Now considering $ a_n^{2} \ge\frac {|a_n|}{n}$ $\Rightarrow$ $\frac {|a_n|}{n} \le a_n^{2}$ $\rightarrow$ combining the two cases for any n we have: $\frac {|a_n|}{n}\le\frac{1}{n^{2}}+a_n^{2}$ Hence using the comparion test again we know that $\sum_{n=1}^{\infty} a_n^{2}$ converges and $\sum_{n=1}^{\infty} \frac {1}{n^{2}}$ converges hence the sum converges so we can conclude that $\sum_{n=1}^{\infty} \frac {a_n}{n}$ is absoluetly convergent $\Rightarrow$ convergent.  Not to sure if this is correct, any help would be much appreciated, many thanks.


I know $\pi$ is 3.141592653589793...... We all learn this at school.  But I haven't learned why pi is irrational number.  How can prove that pi is irrational number?  I would be grateful if you can explain it easily.  :)  Maybe I didn't understand it, but  didn't help me anyway.

I've a few questions in mind:   Why is $\pi$ irrational? If it is, then how can 2 rational quantities (circumference, diameter) can produce irrational number? How are we able to determine digits of $\pi$ accurately?


How would I render this title page in Latex?    So far, I have  \documentclass[titlepage]{article} \author{A.\,N.~Other} \title{Some things I did \\ Mathematics\\ Expiremental investigation} \date{October, November 2016} \begin{document} \maketitle \end{document}   I need a way to make the "signature of sponsoring teachers and signature of student" lines and the Adress Line.

The standard titlepage is quite simple. I am looking for a very  and need help customizing my title page.  It should match the  classicthesis doctoral thesis template  Below a minimal working example:   \documentclass[12pt,a4paper,footinclude=true,twoside,headinclude=true]{scrbook} \XeTeXinputencoding iso-8859-1 \usepackage[marginparsep=8pt,left=3.5cm,right=3.5cm,top=3cm,bottom=3cm]{geometry}  \usepackage[parts,pdfspacing,dottedtoc]{classicthesis}    \frontmatter  \begin{document}     \pagestyle{scrheadings}        %this is the place to set up my cover sheet.       %*******************************************************      % Abstract     %*******************************************************    %\renewcommand{\abstractname}{Abstract}    \pdfbookmark[1]{Résumé}{Résumé}   \begingroup    \let\clearpage\relax    \let\cleardoublepage\relax    \let\cleardoublepage\relax       \chapter{Résumé}     Résumé de la thèse en français\dots      \vfill      \chapter*{Summary}   Résumé de la thèse en anglais\dots    \endgroup             \vfill     \end{document}


I understand how it is calculated, but what does the determinant of a matrix mean and what is it used for? If you could explain it to me in simple words, thank you.

In my linear algebra class, we just talked about determinants. So far I’ve been understanding the material okay, but now I’m very confused. I get that when the determinant is zero, the matrix doesn’t have an inverse. I can find the determinant of a $2\times 2$ matrix by the formula. Our teacher showed us how to compute the determinant of an $n \times n$ matrix by breaking it up into the determinants of smaller matrices. Apparently there is a way by summing over a bunch of permutations. But the notation is really hard for me and I don’t really know what’s going on with them anymore. Can someone help me figure out what a determinant is, intuitively, and how all those definitions of it are related?


I now know the error of my ways and the stack overflow community has shunned my ability to ask a question but I am on my way to recovery. How do you suggest I bounce back? I have a question that I really need answered but I can't post and I can truly say that I regret having asked a few of my questions which were unclear.

If you are reading this, you may have been affected by one of our post quality bans. If so, it is important that you  to understand what has happened and how to regain the permissions that you lost. While trying to ask a question, one could see:  We are no longer accepting questions from this account. See  to learn more.  Likewise, for answers:  We are no longer accepting answers from this account. See  to learn more.   Why am I getting this message? Are deleted posts taken into account too? Is a question/answer ban the same as a suspension? How do I avoid getting a question ban? How long do I have to wait before I can post again? What can I do to release the ban? How can I reactivate my account? Can I simply create a new account? I'll just ask somewhere else on the SE network, and they'll migrate my question to the correct site! Will a ban on one Stack Exchange site affect my standing on other sites in the network? Does this apply to meta sites too? My account is in good standing. Why am I still blocked?


Are there any methods (mirroring, snapshot replication, change tracking, etc...) available in SQL Server 2k8 which would allow me to replicate production data to several individual development databases AND allow separate data to be written to each of those dev db?   In other words: Once a full copy of data is replicated to a dev database, replication would be turned off so new data can then be written to the dev database without impacting the production database.  Thanks in advance

I have a draft of requirements that look like this:   Production database should be copied in real-time to "Pre-prod" database The Pre-prod database should be available to read and update It should be possible to make schema and data changes to Pre-Prod Schema and data changes on Pre-prod should not effect Prod   The databases will be on the same SQL Server instance.  I'm wondering what approach to take? Transactional Replication seems the best option, but applying schema changes to a subscriber seems like a recipe for disaster.  Mirroring is out because the mirror will not be available; log shipping is out for similar reasons.  Are there any other technologies I should be considering?


I have an array of dictionaries:  LeaderBoard = [{'Driver':'Sebastian Williams', 'Car':1, 'Team':'Red Drink','Grid':2, 'Fastest Lap':'1:37.481','Race Time':'2:27:45.958','Points':10},                    {'Driver':'Tom Hamilton' ,'Car':44 ,'Team':'Mercidas' ,'Grid':6 ,'Fastest Lap':'1:37.176' ,'Race Time':'2:26:52.094' ,'Points':25 },                    {'Driver':'Danny Ricardo' ,'Car':3 ,'Team':'Red Drink' ,'Grid':8 ,'Fastest Lap':'1:38.459' ,'Race Time':'2:27:38.589' ,'Points':15 },                    {'Driver':'Walter Borras' ,'Car':77 ,'Team':'Lewis' ,'Grid':14 ,'Fastest Lap':'1:38.264' ,'Race Time':'2:27:22.229' ,'Points':18 },                    {'Driver':'Fernando Sonal' ,'Car':14 ,'Team':'Farrori' ,'Grid':16 ,'Fastest Lap':'1:38.587' ,'Race Time':'2:27:52.040' ,'Points':8 },                    {'Driver':'Jeson Smith' ,'Car':22 ,'Team':'McMilan' ,'Grid':3 ,'Fastest Lap':'1:38.284' ,'Race Time':'2:27:39.484' ,'Points':12},]   How do I sort them in order of quickest 'Race Time'?  I have tried everything I can think of. I used replace and split to make the race times individual numbers that I could compare easily, but I couldn't get the loops working.   This is for homework, where we need to use a sorting algorithm we have learned.  Using Python's sort or sorted is not allowed.  No other restrictions --- any way of sorting that array of dictionaries will be fine.

I have a list of dictionaries and want each item to be sorted by a specific value. Take into consideration the list: [{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]  When sorted by name, it should become: [{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]


I got a problem when I build a class to use its own module like VB.net, because I don't want to initialize the Button's Label and TextField a lot of line in everyday, but I got an error when button didn't initialize it.   When I try to build the program below, I get the following error:      Exception in thread "main" java.lang.NullPointerException at java.awt.Container.addImpl(Unknown Source) at java.awt.Container.add(Unknown Source) at EmployeeGUI.AddLayout(EmployeeGUI.java:57) at EmployeeGUI.(EmployeeGUI.java:28) at EmployeeGUI.main(EmployeeGUI.java:89)   Here is class code:  import java.awt.Button;     public class Init{         public static void initButton(String btntxt,Object...btn){             String[] btnT = btntxt.split("\\\,");             for (int i = 0; i < btn.length; i++) {                 btn[i] = new Button(btnT[i]);             }         }    }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I built a website by copying content from other sites.  Is that OK from an SEO perspective?

This is a general, community wiki question regarding duplicate content.  If your question was closed as a duplicate of this question and you feel that the information provided here does not provide a sufficient answer, please open a discussion on .     What does Google consider to be duplicate content? Will the way I am presenting my content result in a duplicate content penalty? How can I avoid having my site's content treated as duplicate content?


I have a machine which has a port connected to a monitor port on a switch. Thus, many packets from different sources and destinations are arriving at its interface. However, I cannot seem to filter based on certain IP addresses.  For example, I try to do this, but I see no traffic:  # tcpdump -n -nn -i p2p2 host 239.31.80.152   tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on p2p2, link-type EN10MB (Ethernet), capture size 65535 bytes ^C 0 packets captured 0 packets received by filter 0 packets dropped by kernel   But if I do a simple grep, I can see packets come in:  # tcpdump -n -nn -i p2p2 | grep 239.31.80.152 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on p2p2, link-type EN10MB (Ethernet), capture size 65535 bytes 20:32:26.535506 IP 10.232.4.7.41724 > 239.31.80.152.10502: UDP, length 38 20:32:26.635546 IP 10.232.4.7.41724 > 239.31.80.152.10502: UDP, length 38   If I dump the packets to a pcap file, I cannot filter based on that host, either.  But I can filter on another host or network as I wish:  # tcpdump -n -nn -i p2p2 src net 50 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on p2p2, link-type EN10MB (Ethernet), capture size 65535 bytes 21:01:05.104011 IP 50.93.139.140.60745 > 233.90.130.137.13090: UDP, length 20 21:01:05.140072 IP 50.93.139.140.60745 > 233.90.130.137.13090: UDP, length 75  # tcpdump -n -nn -i p2p2 dst host 233.90.130.137 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on p2p2, link-type EN10MB (Ethernet), capture size 65535 bytes 21:01:17.940104 IP 50.93.139.140.60745 > 233.90.130.137.13090: UDP, length 460 21:01:17.954007 IP 50.93.139.140.60745 > 233.90.130.137.13090: UDP, length 20 21:01:18.000084 IP 50.93.139.140.60745 > 233.90.130.137.13090: UDP, length 59   What is peculiar about that host 239.31.80.152?

I have a server that is receiving traffic from a mirror port on a switch. The interface that is connected to this mirror port is in promisc mode. When I use just a plain catch all tcpdump on the interface, like   tcpdump -nn -i eth1   I see a ton of traffic.  I can even grep this for certain things like, say, port 443.  tcpdump -nn -i eth1 | grep 443   obviously this shows anything that has a 443 in it, not just port 443. I have visually inspected it and I do see stuff like this:  15:08:08.112550 IP 12.34.56.78.1430 > 87.65.43.21.443: . ack 35124 win 32768   But I want just port 443 so...  tcpdump -nn -i eth1 port 443 ... 0 packets captured   Weird. I am not seeing any traffic when I use a filter. I have tried "ip port", "dst port", and a few other filters. I have also tried filtering by the IP instead of port. Nothing.  eth1      Link encap:Ethernet  HWaddr 00:24:81:A5:AD:7A             inet6 addr: fe80::224:81ff:fea5:ad7a/64 Scope:Link           UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1           RX packets:4114781478 errors:0 dropped:1 overruns:0 frame:0           TX packets:17 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000            RX bytes:2240970313430 (2.0 TiB)  TX bytes:15155497 (14.4 MiB)           Interrupt:98 Memory:fa000000-fa012800    This interface has seen a ton of traffic. And my filter is valid, right? Why do I not see anything?


The output of this string should be sorted as follows. The output of this string should be sorted as follows.  public static void main(String[] args) { String input="";  List<String> items = Arrays.asList(input.split("\\s*,\\s*"));    System.out.println("items: " + items);    Collections.sort(items, new Comparator<String>() {        public int compare(String o1, String o2) {            String o1StringPart = o1.replaceAll("\\d", "");            String o2StringPart = o2.replaceAll("\\d", "");             if (o1StringPart.equalsIgnoreCase(o2StringPart)) {                return extractInt(o1) - extractInt(o2);            }             return o1.compareTo(o2);        }         int extractInt(String s) {            String num = s.replaceAll("\\D", "");            // return 0 if no digits found            return num.isEmpty() ? 0 : Integer.parseInt(num);        }    });     for (String s : items) {        System.out.println(s);    }} }

I need to write a Java Comparator class that compares Strings, however with one twist.  If the two strings it is comparing are the same at the beginning and end of the string are the same, and the middle part that differs is an integer, then compare based on the numeric values of those integers.  For example, I want the following strings to end up in order they're shown:   aaa bbb 3 ccc bbb 12 ccc ccc 11 ddd eee 3 ddd jpeg2000 eee eee 12 ddd jpeg2000 eee   As you can see, there might be other integers in the string, so I can't just use regular expressions to break out any integer.  I'm thinking of just walking the strings from the beginning until I find a bit that doesn't match, then walking in from the end until I find a bit that doesn't match, and then comparing the bit in the middle to the regular expression "[0-9]+", and if it compares, then doing a numeric comparison, otherwise doing a lexical comparison.  Is there a better way?  Update I don't think I can guarantee that the other numbers in the string, the ones that may match, don't have spaces around them, or that the ones that differ do have spaces.


trigger UpdateContactField on Contact (after update) {     Contact con;     for(Contact c:Trigger.New){         con=new Contact(id=c.id);         con.Current_Company__c=c.Current_Company__c;         con.Previous_Company__c=c.Current_Company__c;         update con;     } }   I am new to Apex. While doing this i am getting following error:     Error:Apex trigger UpdateContactField caused an unexpected exception,   contact your administrator: UpdateContactField: execution of   AfterUpdate caused by: System.DmlException: Update failed. First   exception on row 0 with id 0032800000Lg9fQAAR; first error:   CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY, UpdateContactField: maximum   trigger depth exceeded Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ] Contact trigger event AfterUpdate for   [0032800000Lg9fQ]: []: Trigger.UpdateContactField: line 7, column 1   Basically What my requirement is, For the first time when i create a new record in contact, i enter a value for Current_Company__c field. when the second time i want to update the Current_Company__c field to some other value, then the previous value which was present in Current_Company__c should be updated to Previous_Company__c field.  Please help me. Thanks and regards KS Kumar

What are recursive triggers? How can we control them, or prevent infinite recursion?  Are these any risks inherent in them, and any limits that we should be aware of?  Please explain with an example.


I have the following bar-chart with 5 sets of 2 bars. For some of the individual bars, there is a margin in the (upper) value. I would like to express this similar to a boxplot, with a 'whisker' on top of the bar. Is there a way to specify a value and plot a whisker in this graph, or do I need to resort to manually drawing the lines? \documentclass{article} \usepackage{pgfplots}  \begin{document} \begin{tikzpicture}     \begin{axis}[         width  = 0.65*\textwidth,         height = 7cm,         major x tick style = transparent,         ybar=2*\pgflinewidth,         bar width=14pt,         ymajorgrids = true,         x tick label style  = {text width=1.8cm,align=center,font=\small},         symbolic x coords={Scenario 1,Scenario 2,Scenario 3,Scenario 4,Scenario 5},         xtick = data,         scaled y ticks = false,         enlarge x limits=0.25,         ymin=0,]         \addplot[pattern=dots, style={mark=none}]             coordinates {(Scenario 1, 1500) (Scenario 2,1610) (Scenario 3,1620) (Scenario 4,1590) (Scenario 5,1660) };                      \addplot[fill=gray, style={mark=none}]             coordinates {(Scenario 1, 1520) (Scenario 2,1625) (Scenario 3,1650) (Scenario 4,1605) (Scenario 5,1660)  };              \end{axis} \end{document}

I have this figure in Excel that I want to replicate in LaTeX.    So far, I have these.    Can anyone help me to get as close as possible to the first figure please? Also, I want to add a legend to the error bars to let the reader know its magnitude.  My MWE:  \documentclass[11pt,paper=a4,BCOR=15mm,bibliography=totoc,DIV=9,final,headings=optiontohead, listof=chaptergapsmall,listof=totoc,numbers=noenddot,openright,parskip=half,titlepage,twoside,]{scrreprt} \usepackage[ngerman,english,]{babel}  \usepackage[onehalfspacing]{setspace}        \usepackage{graphicx} \usepackage{tikz,pgfplots} \usetikzlibrary{intersections, calc} \usepgfplotslibrary{units}   \begin{document}  \begin{figure}[h!] \centering \begin{tikzpicture} [scale=1.23] \begin{axis}[       ybar,         bar width=7pt,         xtick={1,...,9},     ylabel= y values,     xlabel=y values,     enlargelimits=0.05,     ybar interval=0.7,     %       x unit=-,     %       y unit=\si{\frac{kg}{h}},      ]    \addplot     coordinates {(1,4473.317111) (2,7394.47646) (3,6886.499957)      (4,9836.193336) (5,8098.401475) (6,8308.855452) (7,9983.205801)      (8,7617.506648) (9,9617.462814)}; \addplot+[error bars/.cd, y dir=both,y explicit]     coordinates {(1,4342.7395) +- (0,0.05)                 (2,7381.3423) +- (0,0.05)                 (3,6837.375) +- (0,0.05)                 (4,9964.5747) +- (0,0.05)                 (5,7624.083) +- (0,0.05)                 (6,7843.0192) +- (0,0.05)                 (7,9665.1374) +- (0,0.05)                 (8,7266.0779) +- (0,0.05)                 (9,9393.7355) +- (0,0.05)                 }; \legend{x data,y values} \end{axis} \end{tikzpicture} \caption{Figure Caption} \label{fig:plot1} \end{figure}  \end{document}


I assume that if we had two people named Ben and Jerry who made ice cream together, then it would be Ben's and Jerry's ice cream, yes? Now if "Ben and Jerry" were the name of a company, then it would be grammatically correct to call it Ben & Jerry's ice cream, but are there any problems here with the name of the company in its current form in terms of English grammar?

Which option is grammatical?        There will be readings from Nikki Giovanni’s and Alice Walker’s writings.   There will be readings from Nikki Giovanni and Alice Walker's writings.      Saying it out loud the latter sounds right, but looking at it the former looks better.


I have been looking in to arranging a short backpacking trip  around South Africa later this year. From what I have read both on the internet and in travel guides, and talking to South Africans it's making me think twice, it's giving me the impression that it seems  almost certain I will be involved in some sort of incident, which I hope is not the case.  What are likely to be the main safety threats on a three week holiday, flying into Cape Town and out of Nelspruit (via Johannesburg). We will be travelling internally by foot, hire car, and 2 internal flights (George to Durban, and Durban to Nelspruit).

As, the above link shows, other countries have similar murder rates but they are not in the radar of international travelers.  For example, as seen in the list, Puerto Rico has similar statistics. But, personally, I never heard of Puerto Rico to be a dangerous place to travel.  Why is it considered so dangerous to travel in South Africa? Is that due to the incompetent law enforcement agencies?


Some contractor says PP is safer (the arguments is it is used in food packaging...) and PVC will degrade and release toxic materials after 10+ years. But in  there is no such thing.  Is PVC safe to be used as air duct in home for a long time like decades?  (Only health safety is considered, fire safety etc is not considered)

I have not had a problem for nine years and never noticed what my plumbing pipes used. My hot and cold water feed away from heater use "Bristol 1120 Schedule 40 PVC.  480 PSI 73 deg." Is there strong evidence that I have been using this type of piping in danger to my family's heath. Should it be removed immediately?


For a real valued function $f(x,y)$ on $\mathbb{R}^2$ which is in $L_2$, show that $f(x+ε,y+ε) → f(x,y)$ in $L_2$ when $ε → 0.$  Not sure how to go about this problem.  I tried Fubini.  But that didn't seem to work well.  I tried doing t straight from the definition.  It seems the point is that it epsilon is changing the $x$ and $y$ coordinate at the same speed.

can anyone help me show that if $f\in L^p(a, b)$ then $$ \lim_{t\to 0^{+}}\int_{a}^b|f(x+t)-f(x)|^p\ dx=0.$$ Thanks, any help will be useful..


Kind of a longshot, because I have fuzzy memories of this at best, really only the beginning of it. A man from our Earth somehow gets transported to a desert world where buildings are made out of salt because there's so little water. He thinks he's entirely human until he tries to urinate and finds that he excretes crystals instead, all water being retained in his body. I want to say that he compares himself to a kangaroo rat at that point.  I read this in middle school or so, so it's late 80s at the least, and probably older. I read it as a paperback in my brother's sci-fi/fantasy collection.

Some time around 1998 I read a book (which is surely older) suggested by one of my friends. Since this is the first time posting for me I'll do my best to give all the details I can recall.  The main protagonist is a white male (who I believe has cancer and/or is very old) on a boat that gets hit by a comet or meteor or some kind of astronomical event. He wakes up in the body of a young dying male in a desert and meets a telepathic cat that was bonded with the dying male.   The beginning of the book is about the protagonist learning to navigate his body, the bonds with the people his body knew and the telepathic cat. The two have to learn to trust one another. The "bond" is a two-way lifelink, if one dies so does the other.  We learn later that others on that boat suffered much the same fate shifting into new bodies in this parallel dimension including a female he had fancied or met back on the boat. Her body is also bonded to a telepathic "riding" cat. While I can't remember if anyone else on the boat also switched over, I feel like at least one other person did who was an antagonist but I can't verify it in my brain.  The protagonist is trying to find "something", but I can't remember what. I seem to recall jewels or gems and an important sword. Like, a hilt that's important and has an invisible blade? I remember certain scenes but without enough information for them to feel useful.  Such scenes as:   They end up in a huge palace with a verdant garden that they later escape from, for some reason. The protagonist gets super injured at one point and the cat struggles with him so they both survive. He keeps having flash backs to the incident on the boat. For a long while the cat hates this guy who basically has supplanted his master/friend, but it's okay since that guy dying would have killed the cat.   The only thing I can recall about the title is "The [blank] cycle(s)" and all my searching has come to naught. It was a series of books, I know that.  The cover showed the main protagonist, the female "love interest" and their cats in the sun bleached desert. I recall that the female has very short cut dark hair. The protagonist is wearing a white "turban" of some sort.


How can I run objective c on Unix systems?

I finished building the GCC 4.7.2 with C, C++ and Go compilers on my Ubuntu 12.04. I now want to add the Objective C compiler, is it possible to add it to the previous build? If so, how should i proceed?   Thanks.


I am using Ubuntu 12.04. What software do I need to so I can install Windows programs from CD or flash drive? Is this software in the Ubuntu Software Center or do I download it from a website? At one point I saw a program called Wine for running Windows applications in Ubuntu?  Currently the CD/DVD drive isn't recognized. Also how can I install and use my Lexmark all-in-one printer? The Lexmark website doesn't list Ubuntu 12.04 for downloadable drivers.  I hope my Windows programs are not all garbage because I have Ubuntu and Windows 7 has been deleted.

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


I don't want this prompt to use my default ubuntu login, I would like this to match the password I would use either on a chromebook, mac, or windows. In other words, similar behavior to the other operating systems.  How would I make it so that I typed in my chromebook login, for example?    Text of the prompt:   "Enter password for keyring 'Chromium' to unlock" "An application wants access to the keyring 'Chromium', but it is locked"

Whenever Ubuntu boots up, a dialogue pops up asking me to unlock my default keyring. Is there some way this can unlock automatically through PAM or some other magical way?


In his  to  @Jeff Berry posted how can we can programmatically stop and start ArcGIS Server 10.0 map services using Python.   How do I stop services in ArcGIS 10.5?   I couldn't find AGSSOM there.

Is it possible to programmatically stop and start ArcGIS Server map services using Python?


How can i solve this?  the exercise is:     $$\tan{20^{\circ}}\cdot\tan{40^{\circ}}\cdot\tan80^{\circ}$$     I  have to define the exact answer. I have no idea how to start this exercise so please help. I think that would be so easy if I just multiply them. Thank for your help.

How can I find the following product using elementary trigonometry?  $$ \tan 20^\circ \cdot \tan 40^\circ \cdot \tan 80^\circ.$$  I have tried using a substitution, but nothing has worked.


I have an application which takes the information of a mysql database(a music-db) and shows it via echos in a div. Everything works fine.  Now I wanted to add a search bar so you can search the database for a specific song.   The search bar just loads a php file with a mysql query. The word or the letters you want to search for are passed via a varbiable in the link(for example test.php?searchvalue=it).  Now my problem: I get the following Mysql-error:     You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1   The quotes in the error are single quotes!  The Query is:  $searchvalue = $_GET["searchvalue"];  $query = mysql_query("select SongID, Songtitel, artwork, duration, SCID from tMusic where Songtitel LIKE '%$searchvalue%'") or die(mysql_error());   Why is this wrong?  Thanks for help.

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


My laptop (Ubuntu 14.04) is taking too long showing a message "Waiting 60 more seconds for network configuration"

This problem happens sometimes when ubuntu starts up. You can't really boot to the interface sometimes.  Splash Screen with the 5 dots and a message saying:     waiting for network configuration   followed by:     waiting an additional 60 seconds for network configuration


I am looking for a book (a small book or course pdf or videos  ) for study the riemannian geometry  for the beginning i need just  a basic understanding of Riemannian geometry  thank you for any suggestions

Could you recommend some beginner books for Riemannian geometry to me?  I am completely new to Riemannian geometry, but have some basic knowledge of differential geometry.   I am looking for a book in Riemannian which is similarly as light as Tu's "Introduction to Manifolds" for differential geometry. I know that the classical reference is the book of do Carmo, but I have heard some students complaining that its not a book for the absolute beginner.  For the moment, I am just looking for a source to introduce me Riemannian metrics, Riemannian manifolds, curvature, geodesics in a way as clear as possible.  Thank you


The file system on an older Mac mini (early 2009, latest supported OS 10.11) , and disk utilities ended up in an infinity verify-can't-repair loop. Thanks to a  I could mount it on a different machine and restore my files. (I physically removed the disk and mounted it with a USB-to-SATA cable).  I proceeded to reformat the disk, and now want to install a bootable macOS on this disk.  The best action seems to follow the Apple guide "", which requires me to download macOS 10.11 (El Capitan). It's normally hidden in the App Store, but I found the . Unfortunately, I can't seem to download it on my new Mac: It gives me a warning "OS X can't be installed on "MyNewMac" because the version of macOS is too new.". I know, but don't want to run it, just install on the disk for the older Mac, so I can run it on the early 2009 Mac mini.  How to proceed?

Sometimes it's hard to search for older versions of macOS & OS X  on the App Store.  This is an attempt to provide the canonical QA for this issue, as per the Meta QA -  I expect it to be modified over time to hopefully become a complete information resource.  How can I get any older version of a Mac OS to be able to run as a VM, or to reinstall on my Mac?


Which one is correct?  What item are you looking for?  or  What item you are looking for?  In British English if it's important.

I was wondering if you let me know which group of the self-made sentences below grammatically is corect:  A)        Where in the world are you?    What in the world are you doing here?    Who in the world do you think are you?       B)        Where in the world you are?    What in the world you are doing here?    Who in the world do you think you are?       I don't know which one ("are you" OR "you are") grammatically is correct in above constructions. I would be thankful if you somehow explain me the words order in "wh" questions like those.


How can i check convergence of $$\sum_{n=1}^{\infty} \frac{a^n}{n!}$$ ?  I tried some of the tests for checking if it's convergent , but it's does not work.

I have figured out a way to show that     $$e=\sum_{i=0}^\infty {1\over i!}$$   I am wanting to formally show that     $$e^x = \sum_{i=0}^\infty {x^i\over i!}$$   I have been looking at power series/Taylor series for a long period of time (absolute convergence) and have seen multiple proofs that I look past because something seems illegitimate with radius of convergence. If someone explains the general proof behind Taylor series/power series absolutely converging so there is no gray area, that would work as well. I will probably ask some questions in the comment area if this is the case. There must be something I am missing.


It has for many years been popular to use RSA keys that have lengths that are powers of two. E.g. 1024-bit, 2048-bit and 4096-bit key lengths are all popular for use with OpenPGP implementations such as GnuPG, and with OpenSSH, etc, and these key lengths are often either defaults in the software generating the keys, or are recommended by organisations whose participants are required to generate keys (e.g. ).  I have heard it said that, because cryptanalysts in practice will have devoted more resources towards breaking keys with popular lengths, and because popular lengths are powers of two, choosing a key length that is not a power of two would provide a practical security advantage, even if this means choosing a slightly shorter key length than one would otherwise desire (e.g. 4093-bit key instead of 4096-bit).  Is there any sense in that saying? Put another way, what (if any) are the reasons for which a cryptanalytic attack that would succeed against a 4096-bit key would fail or take significantly longer against a shorter key whose length is not a power of two?

I know that other bit sizes are possible, e.g. this HTTPS server seems to have a 9000 bit key , but it's very rare that one sees a key not of size 1024, 2048, 4096, etc. bits in common usage - what is the reason for this? Is it just customary, or is there a cryptographic advantage?


What im trying to do it's to have a non capital E at the end of the scrip:   % arara: pdflatex \documentclass{article} \usepackage{acro} \DeclareAcronym{CNO}{ short = CNO , long = Clasificador Nacional de Ocupaciones } \DeclareAcronym{e0}{ short = \ensuremath{e_0} , long = Esperanza de vida al nacer , sort = e_0 }  \begin{document} \Ac{CNO} foo. Pero si \ac{e0} bar. \end{document}   I want this text Clasificador Nacional de Ocupaciones (CNO) foo. Pero si esperanza de vida al nacer (e0) bar. Without 'Esperanza' with the capital E, just the e....

For a phrase that is not a proper name, I want to have the first letter of each word uncapitalized except when it starts off a sentence, in which case the very first letter of the phrase is capitalized. But that its not working with acro. This code is the one below.   \documentclass{article} \usepackage{acro}  % class `abbrev': abbreviations: \DeclareAcronym{CNO}{   short = CNO ,   long  = Clasificador Nacional de Ocupaciones ,   class = acro   }   % class `nomencl': nomenclature \DeclareAcronym{e0}{   short = \ensuremath{e_0} ,   long  = Esperanza de vida al nacer ,   sort  = e_0 ,   class = nomencl   }   \begin{document} \section*{List of acronyms} \addcontentsline{lof}{section}{List of acronyms}  \ac{evn} Si yo vengo escribien y el \ac{CNO} aperece primero y luego \ac{CNO}, \ac{ONU} and \ac{evn} are abbreviations whereas \ac{e0}.  \printacronyms  \printacronyms[include-classes=abbrev,name=Abbreviations]  \printacronyms[include-classes=nomencl,name=Nomenclature]  \printacronyms[include-classes=acro,name=Acronimos]  \end{document}


In what circumstances should you configure multiple DHCP servers on the same subnet?  My understanding of using more than one DHCP server is that your clients will use the nearest DHCP which could be unpredictable.  However I have read a suggestion of using 2 dhcp servers where one provides 80% of the addresses and the other 20% but I don't see what the advantages of doing this.

This is a  about Redundant DHCP Servers.   Is it possible to have more than one DHCP server on the same LAN? What are the implications of doing this?    What happens if there is more than one DHCP server available? How do my clients know which one to use?  How can I have DHCP servers supplying addresses to more than one subnet\network segment? How can I configure multiple DHCP servers to supply addresses for the same subnet.


Let's assume we are sending signal $\mathbf{x}$ (which is a vector $N\times 1$) through channel $\mathbf{H}$ (a $M\times N$ matrix). Our model is $\mathbf{y}=\mathbf{Hx}+\mathbf{n}$. Note that the matrix $\mathbf{H}$ is given at the receiver and $\mathbf{n}$ is a normal distribution with $\mathbf{n}\sim \mathcal{N}(\mathbf{0},\sigma^2\mathbf{I}_M)$.  We wish to estimate the vector $\mathbf{x}$ by using the maximum likelihood method. How we can do it?  My solution was to calculate $P\left(Y|X\right)$ which is a normal distribution with mean $\mathbf{Hx}$ and variance $\sigma^2\mathbf{I}_M$ and then maximize it. I don't know where to go after this.  Thanks

This question is inspired from the long discussion in comments here:    In the usual linear regression model, for simplicity here written with only one predictor: $$      Y_i = \beta_0 + \beta_1 x_i + \epsilon_i $$ where the $x_i$ are known constants and $\epsilon_i$ are zero-mean independent error terms. If we in addition assume normal distributions for the errors, then the usual least squares estimators and the maximum likelihood estimators of $\beta_0, \beta_1$ are identical.  So my easy question: do there exist any other distribution for the error terms such that the mle are identical with the ordinary least squaeres estimator?  The one implication is easy to show, the other one not so.


Is there a way that a bash script detects the path directory in which it's running?  It is like if the script is aware of where is it. In order to use files that are in the same location as the script. I'd like to change the directory to where the Bash Script is.  This Bash script is used to trigger few actions (other python scripts, apps... etc.) but I want to switch the operation directory to his root one.

Suppose I have a bash file called myBash.bash. It resides in:    /myDirect/myFolder/myBash.bash   Now I want to use the string /myDirect/myFolder (the location of myBash.bash) inside the script. Is there a command I can use to find this location?  Edit: The idea is that I want to set-up a zip-folder with code that can be started by a bash script inside that zip-file. I know the relative file-paths of the code inside that zip-file, but not the absolute paths, and I need those. One way would be to hard-code in the path, or require the path of the file to be given as a variable. However I would find it easier if it was possible for the bash-file to figure out where it is on its own and then create the relevant paths to the other file from its knowledge of the structure of the zip-file.


I am trying to avoid the ajax url called while page load so that I can maintain of log of posted data from ajax only.  if ($this->_request->isXmlHttpRequest()){   # do the code }

How can I detect which request type was used (GET, POST, PUT or DELETE) in PHP?


I've played a Rogue character in a few campaigns. At level 5, Rogues gain the Uncanny Dodge feature, described as follows:     Starting at 5th level, when an attacker that you can see hits you with an attack, you can use your reaction to halve the attack’s damage against you.   In practice, this has never been an issue, as my DMs have always allowed me to choose whether to use Uncanny Dodge after damage has been rolled... But I recently came across someone asking whether it had to be done before or after damage was rolled, and I realized I wasn't sure.  So obviously, Uncanny Dodge can only be used after a successful attack roll by the enemy, but according to the rules, does Uncanny Dodge have to be decided upon before or after damage is rolled? (Both RAW and RAI answers are welcome as long as they are properly supported.)

In D+D 5e, there are many effects that enable AC, attack rolls, or damage rolls to be modified after being rolled but before the hit is resolves. Examples are the Shield spell and the "Parry" Battle Master maneuver.  When the opponent makes an attack roll against you, is the DM supposed to roll and say, e.g. "does an 18 hit your AC", or are you supposed to tell the DM your AC in advance and he just tells you if it hit or not? This is relevant because in the first case, you will always know if a Shield spell (for instance) would avoid the attack.  Same thing with damage rolls - do you know how much damage was rolled before you decide whether to use a Parry?