How to learn Gravitation after 20 years?

I have a B.S. in physics but I graduated nearly 20 years ago. All this time I’ve kept a copy of Gravitation by Misner, Thorne, and Wheeler thinking that I would, one day, get around to going through it. I would now like to do that but I think that I need to first brush up on my math. Actually, I remember that the math in this one was a bit above me as an undergrad so I might need more than just brushing up. Any suggestions on books and/or online courses that would prepare me to really understand Gravitation?


I broke my laptop and had to buy a new one with a new keyboard that I am struggling to get familiar with, especially with the keys like home, page-up, page-down and end, which aren't standardized at all.  I found myself doing this for like the 5th time in the last several years, and I think it is really annoying.   Is there an app that can reliably map one key to another?  By reliably I mean that key mapping works with Shift, Alt, and other modifiers.  UPDATE  Windows 7, Samsung Chronos 7


How did Google, Comscore and Grapeshot learn of a secret page

I have a secret web page, let's call it something123.php, and looking through my Apache webserver access.log I waas surprised to see that two entities have learned of this page.  Google Grapeshot.co.uk Comscore  I have the page in my bookmarks, but I noticed something especially odd. In one case, 20 seconds after I accessed the secret page, Google did too. In another case, 4 seconds after I accessed it, Comscore did too and then 5 minutes later, Grapeshot did. I am curious to learn how this could be. I use Firefox, and my extensions consist of only one: UBlock Origin. I have a theme installed from Mozilla for dark mode. That's it. I may have been running Ungoogled Chromium at the same time as Firefox but I would think it wouldn't leak information. It feels like I have spyware on my computer.


Making a logic circuit with only NAND GATES?

I am trying to create a logic circuit using only NAND Gates for this expression: (NOT Q AND P) OR R   This question has really gotten me stuck! Can somebody please help?


==>> What are the most useful Unix shell "one-liners" that you use? <<==  Here are a couple of mine to get the conversation started:  1. Repeat the previous command with a substring replacement:  Syntax:  ^before^after^   Example:  You entered:  git clonr https://unbelievablylongurl.org/projectdirectory/evenmoreprojects/project.git   Use this:  ^clonr^clone^   And your command will be re-run with the replaced substring:  git clone http://unbelievablylongurl.org/projectdirectory/evenmoreprojects/project.git   2. Repeat the previous command with an additional string/character  Shell Idiom:  !!   Example:  You ran a command that requires superuser privileges on your box.  Re-run the command without retyping it like this:  sudo !!


Proof of “The product of two quotient maps need not be a quotient map”

Problem: The product of two quotient maps need not be a quotient map  I started proof by followings  Let $X=\mathbb{R}$ and let $X^*$ (obtained from $X$) be the set identifying the subset $\mathbb{Z}^+$ to $a$ point $b$ And let $\mathbb{Q}$ be rational numbers  Claim : 1)  $p$: $X\to X^*$ be the quotient map.  2)  $q$: $\mathbb{Q}\to\mathbb{Q}$ be identity map then $q$ is quotient map 3)  $p\times q$: $X\times \mathbb{Q}\to X^*\times\mathbb{Q}$ is not quotient map  I want to know how to prove $1$, $2$, and $3$ In particular, why $p$ is surjective


Word similar to stigma, but without negative connotation

I'm trying to describe the way in which generally, ignorant football fans will talk highly of players without having any sense or proper understanding of football or that player.  When it comes to the awarding of "Man of the Match" awards, I am trying to say there is a "stigma" around certain players wherein they will almost automatically receive such awards just because they are "stigmatised" to be deserving of the award, even if they don't perform particularly well.  What would the word be to replace "stigma"/"stigmatised"? Thanks.


How can you protect a fragile object like bottle of champagne in your baggage against breaking?

I tend to bring something quite fragile with me as cabin luggage. On my next journey I want to bring a special bottle of champagne (because of sentimental reasons). Unfortunately you can't bring a bottle with you as cabin luggage.  I already know that it is okay to bring a bottle of  as check-in luggage (even confirmed by .)  I am wondering how you can transport a bottle of champagne in your luggage in such a way it doesn't break easily.


Does the unit generate the additive group in a unital ring with cyclic additive group?

Let $R$ be a unital ring with cyclic additve group $(R, +,0)$. Is it the case that $1$ generates the additive group $(R,+,0)$?  Thoughts: Maybe classifying the unital rings with cyclic subgroups is possible.


Minecraft LAN World - 2 Users 1 Account (1.8 New Launcher)

Me and my brother have always shared a Minecraft account, and we recently got a new laptop and want to play on a LAN world together.


After they had their supper, Father went into the living-room to watch TV.   Why use Father not father?


Writing a word into every txt file in a folder

How can I write the word "cat" into every .txt file in a folder?


Classification of prime ideals of $\mathbb{Z}[X]$

Let $\mathbb{Z}[X]$ be the ring of polynomials in one variable over $\Bbb Z$.  My question: Is every prime ideal of $\mathbb{Z}[X]$ one of following types? If yes, how would you prove this?  $(0)$.  $(f(X))$, where $f(X)$ is an irreducible polynomial.  $(p)$, where $p$ is a prime number.  $(p, f(X))$, where $p$ is a prime number and $f(X)$ is an irreducible polynomial modulo $p$.


How can I change Unity sidebar to bottom?

How can I make changes to my sidebars to bottom, and the theme etc.   thank you


Arranging equations (short and long ones) in a presentable way

Say I have 8 equations all of different length including equations that are 3 lines long on an A4 paper. When I type them on Latex, I can separate the long sentence by using "$$$$" to break it and it then continues on the line below. What disturbs me though is that the calculations do not look neat. They look like:  (x+y)+(x+z)+(f+p)+e^s+ ....+p^y=0  l+p+i+....-(i+d)^y+(fg+1)^7....+   \hspace{2cm}6+0+9-(io+8)^7+(54)^i+xvy+....+p^s+kope^x =0    where {what I wrote} is any algebraic data you would like to insert and the \hspace is what my latex is giving me without me intending to put that space. How to make those looks neater. To start from the same point and each broken line to start directly under the line before it without me going and studying where to put the "$$$$" and breaking it so as it looks neat and then it turns out that it does not and so on and so forth... Maybe if you have another idea for how to structure those in a nicer way than the one I asked about, I would be thankful.


Why can arbitrary two qubit density matrices be expressed in this form?

In the paper "Violating Bell inequality by mixed spin 1/2 states: necessary and sufficient condition" () by three Horodecki siblings, it is stated that an arbitrary two qubit density matrix can be written in the following form:  $\rho = \frac{1}{4}(I \otimes I + r \cdot \sigma \otimes I + I \otimes s \cdot \sigma + \Sigma_{i,j=1}^3t_{ij}\sigma_i \otimes \sigma_j)$  where $r$ and $s$ are some vectors.  I understand how $I$ and $\sigma_i$ for $i=1,2,3$ form a basis for operators on a single qubit so taking pairwise cross products of each forms a basis for operators on two qubits. But why does the coefficient of the $I \otimes I$ have to be $\frac{1}{4}$?  As a side question, the paper also says $t_{ij}=tr[\rho\sigma_i \otimes \sigma_j]$. Why is that the case?  Edit: The other page linked doesn't answer either of my questions. They say that $I,\sigma_i$ form a basis, but don't explain why $\frac{1}{4}$ is the coefficient. It also doesn't mention my second question.


Does $\varphi(x)\le\int_0^x\varphi(t)dt$ for all $x\in[0,\infty)$ imply $\varphi\equiv0$.

Let $\varphi$ be a nonnegative and continuous function on $[0,\infty)$ and such that $$\varphi(x)\le\int_0^x\varphi(t)dt$$ for all $x\in[0,\infty)$. Can we infer from here that $\varphi\equiv0$.  By taking limit on both sides, I got $\varphi(0)\le 0$. As $\varphi$ is nonnegative, I can say $\varphi(0)=0$. But what then. I could have progressed if I could show that $\varphi(x)\le \varphi'(x)$, but it is not quite evident from the given condition.


I would like to know if there is a $\bbar$ command to produce the symbol    just as there is a $\hbar$ command for the symbol


Why is this code gives an Debug Assertion Fail?     std::string query;    int ClientID = 666;    query = "select logged from login where id = ";    query.append((char *)ClientID);


We all know that $\sqrt[3]{3}\not\in \mathbb{Q}({\sqrt[3]{2}})$ intuitively. We even know that $\sqrt[3]{p}\not\in \mathbb{Q}(\sqrt[3]{q})$ for two distinct primes $p, q$. However, I don't know how to prove these things rigorously. In case of $\sqrt{p}\not\in \mathbb{Q}(\sqrt{q})$, we can just set assume $\sqrt{p}=a+b\sqrt{q}$ for some $a, b\in\mathbb{Q}$ and deduce a contradiction. However, in cubic case, expansion of $(a+b\sqrt[3]{2}+c\sqrt[3]{4})^{3}$ is very complicated and even I expand this I couldn't get any contradiction by this.  To be specific, it gives us 3 diophantine equations  $$a^{3}+2b^{3}+4c^{3}+12abc=3$$ $$a^{2}b+2b^{2}c+2c^{2}a=0$$ $$ab^{2}+2bc^{2}+ca^{2}=0$$  and I don't know how to check solvability of this kind of diophantine equations (over $\mathbb{Q}$). Even if there exists a way to check solvability, I cannot convince that it can be used to prove $\sqrt[3]{p}\not\in \mathbb{Q}(\sqrt[3]{q})$.   So I tried to use Galois theory, but actually I don't know where to go. I assumed $\mathbb{Q}(\sqrt[3]{3})=\mathbb{Q}(\sqrt[3]{2})$ and take a Galois closure, i.e. $K=\mathbb{Q}(\sqrt[3]{3}, w)=\mathbb{Q}(\sqrt[3]{2}, w)$ where $w^{3}=1$ then tried to use field norm maps. We can check that $\beta=\sqrt[3]{3}\cdot\sigma(\sqrt[3]{3})\cdot\sigma^{2}(\sqrt[3]{3})\in \mathbb{Q}$ when $\sigma\in Gal(K/\mathbb{Q}), \sigma(\sqrt[3]{2})=\sqrt[3]{2}, \sigma(w)=w^{2}$. But I cannot get any information from this.   Edit : It would be great if there is a simple algorithm to check whether $\alpha\in K$ or not for a given algebraic number $\alpha$ and a number field $K$.


I know that sound waves can be described as pressure waves. Now, let's consider the case of reflection of a sound wave from an open end, as in an organ pipe. My textbook says that, in case of reflection from an open end, the reflected wave suffers a phase change by $π$ radians. In other words, a compression pulse becomes a rarefaction pulse, and a rarefaction pulse becomes a compression pulse. I can't understand (from the explanation given) why that occurs. Does the external medium (that in which the sound wave isn't travelling) has a role to play? I found a slightly similar question  as well as , but I couldn't really understand what's going on.


Can I use a Vittoria Zaffiro 700 * 25c road bike tyre with a hole in outer rim of the tyre?

My road bike tyre got punctured couple of days ago and I just noticed that it resulted in a hole in the outer wall of my tyre. How can I close this hole? I rode just 500kms on this tyre so I am not sure if I need to replace it with a new one


New Criteria of Isomorphism + Abelian Group

The following questions were suggested by my friend, while we were studying fundamental group theory. We had no exact ideas of the way to approach the problems. Questions  (1) Let $G$ and $H$ be groups such that $|H|=|G|$. If we can make a bijection $\phi:G\to H$ such that for $\forall a\in G$, $ord(a)=ord(\phi(a))$, then does $G\cong H$?   (2) Let $G$ be a group. If all of the elements in $G$ except $e$ have the same order, then is $G$ an abelian group?  Both suggestions were not easy to find the counter-examples. So, we wanted to prove these statements instead, but again too difficult. We also failed to find these types of questions on the internet. Is there theories or propositions related to the problems? Thanks.


What is first class object in java and why arrays are considered as first class objects?

Unlike C++, arrays are first class objects in Java. For example, in the following program, size of array is accessed using length which is a member of arr[] object. the above statement from the geek for geek website is what made my question.


How many physical CPU Cores does Windows support? (Asked in 2021)

How many physical CPU Cores does Windows (amd64, not arm) support? So with "physical CPU Cores" i mean that a CPU with 4 Cores and Hyperthreading counts as 4 and not 8 Cores. Also with "Windows" i mean the Versions (Workstations and Enterprise too) that target normal peoples consumer PCs, not Servers nor modified versions. (i dont want to know the maximal thread count a process can have) Question 1:I found a Table on Wikipedia which says the maximum would be 256 Cores and 4 CPU Sockets, but it is not noted that the maximum of 256 Cores is related to 1 CPU Socket or if its an overall limit? (so does it mean limit is 256 or 1024?) Question 2:Related to Hyperthreading, is Windows counting a CPU with 128 Cores and Hyperthreading as 256 Cores and with that reaches the limit? (so do i have to disable Hyperthreading if i install 4 CPUs with 64 Cores?) Link to Wikipedia:


C# Lambda expressions: Why should I use them?

I have quickly read over the  documentation.  This kind of example has helped me to understand better, though:   delegate int del(int i); del myDelegate = x => x * x; int j = myDelegate(5); //j = 25   Still, I don't understand why it's such an innovation. It's just a method that dies when the "method variable" ends, right? Why should I use this instead of a real method?


Is Wrestling such as WWE Faked as the moves that the Wrestlers do seem to be well rehearsed and they don't seem to get hurt


I own a MBP 2019 and iMac 2017 5k. Mostly I use the MBP for my programming as it is having an SSD. Is there any way to use the iMAC as a secondary display or mirrored display using the type c cable or other cables? I do not prefer wireless methods as it may get slow. Both are running in Big Sur


Better proof of inequality $x - (1 + x) \log(1+x) \leq -\frac{x^2}{2(1+x)}$ for $x > 0$

The following inequality is valid for all positive real $x$, $$ x - (1+x)\log(1+x) \leq \frac{-x^2}{2(1+x)}. $$ It is possible to show that this is true by considering the function $$ f(x) := x - (1+x)\log(1+x)+ \frac{x^2}{2(1+x)}. $$ By differentiation it is possible to check that $f(x)$ attains it maximum on the nonnegative reals at $x = 0$. However, is there a cleaner, more obvious way to see that this is true? Specifically, I would like a solution that does not require me to analyze the monotonicity of $f$ via differentiation if possible. I tried Taylor expansion, but do not get this inequality.


Why does Shamir's Secret Sharing Scheme need a finite field?

I read ampersand's question , where he asked why Shamir's Secret Sharing Scheme uses arithmetic in a finite field of prime order.  The answers to that question explain that a prime field is not necessary for Shamir's scheme, but, rather, that any finite field can be used.  However, they don't really address the other part of the question, namely why do we need a finite field at all?  Couldn't we just use, say, ordinary integer arithmetic instead?  Can someone please explain (in the simplest possible manner) the reason that Shamir's Secret Sharing Scheme uses finite field arithmetic?


I was changing the  bashrc file based upon the following video  but suddenly when I type sudo su I get the following error      bash: export: `/home/mala/WRFinstall/Build_WRF/LIBRARIES/mpich/bin:/home/mala/WRFinstall/Build_WRF/LIBRARIES/netcdf/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games': not a valid identifier   I tried to edit the bashrc file by typing nano ~/.bashrc  but I can't find the file I edited. I only get content of a normal bash file.


I am making my first object in blender (a bow) its very simple started with a cube, thinned and / extruded / scaled / rotated / extruded / scaled / rotated / etc. to create half the bow about 5 pieces, I then simply mirrored if for the other half added a string then placed a single bone on the string (parent) another bone on the main bow (child) them) parented them, tested the mechanic, pulled the sting bone pulled away from the body bone okay.  Then selected the entire bow, and parented it to the bones with auto weights.  Now here is the problem.  In pose mode when I go to pull the bow string, it does pull back but instead of the string just pulling away from the bow frame, the string pulls back and the bow frame kind of pulls apart at all of its vertices. It just kind of falls apart.  I am following a tutorial that explains little to nothing other than just watching someone do it, so I don't know what he did that kept the bow in tack when he pulled the string, I tried groping the bow pieces all together but this didn't help.  Any help would be greatly appreciated.


Deleting LARGE number of files (exec, loops..)


Does $$\lim_{(a, b) \to (0, 0)} \ \sqrt{\frac{a^2b^2}{a^2 + b^2}} = 0 \ ?$$   I'm trying to show that $$\lim_{(a, b) \to (0, 0)} \ \sqrt{\frac{a^2b^2}{a^2 + b^2}} = 0 $$  but I am getting stuck. I was thinking that as a starting point I could show that $$\lim_{(a, b) \to (0, 0)} \ \frac{a^2b^2}{a^2 + b^2} = 0 $$  and then conclude that since $$\lim_{x \to 0} \sqrt{x} = 0$$ and $\frac{a^2b^2}{a^2 + b^2} \to 0$ as $(a, b) \to (0, 0)$ we arrive at $$\lim_{(a, b) \to (0, 0)} \ \sqrt{\frac{a^2b^2}{a^2 + b^2}} = 0.$$    Firstly is my approach above a correct one. Secondly how can show that $$\lim_{(a, b) \to (0, 0)} \ \frac{a^2b^2}{a^2 + b^2} = 0. $$ Because I don't see any way to show the above (apart from perhaps proving it from the definition directly, which I would like to avoid if there is an easier way to do it). Also it could be the case that the initial limit doesn't even exist.


I thought interfaces couldn't be instantiated in java

I'm working on some JPA stuff and i'm a little confused with some of the start up code that you have to write.   EntityManagerFactory factory = Persistence.createEntityManagerFactory("sample"); EntityManager manager = factory.createEntityManager(); EntityTransaction transaction = manager.getTransaction();   Those three variables all have an interface as their type. How can we do things like  manager.persist() transaction.commit()   etc if interfaces cannot be instantiated?


For any prime $p > 3$, why is $p^2-1$ always divisible by 24?

Let $p>3$ be a prime. Prove that $24 \mid p^2-1$.   I know this is very basic and old hat to many, but I love this question and I am interested in seeing whether there are any proofs beyond the two I already know.


gnome-terminal: can't access url from the terminal by single click

I want to access the url that is printed on the command line. For example, if I see the man pages for dropbox, there are some url links with underlines (i.e. https://www.dropbox.com/)--     The only way to access this url is to do right click and copy the link.  Is there anyway I can access it using a single click?


What provides aptdcon for Ubuntu 16.04? Which package do I install?

How do I install the aptdcon command to script aptitude package installation?  Someone else had a similar question here:


Why is the reflection of a vector on a line, twice the projection of the vector minus the vector?

I am working through a linear algebra text and I am doing exercises in a chapter dealing with linear transformations and linear functions. I am trying to come up with the transformation matrix for a vector reflected on a line in two-dimensional space. Please try to the answer the question without change of basis or eigenvalues as I have not reached that chapter. I am confident this does not warrant complicated trigonometry either.  So far I have projected the basis vectors of the space onto the line and found an orthogonal line in search of a solution. I am not sure where to go from here. Thank you


Toolbar options are not displaying in Edit Profile - About me section

Toolbar options are not displaying in  page About me section.  Issue can be reproduced in all the Stack Exchange sites.        Seeing the following error in Google Chrome console:     Uncaught TypeError: Cannot use 'in' operator to search for 'showLowRepImageUploadWarning' in undefined   at new StackExchange.MarkdownEditor (wmd.en.js?v=50f41773693e:2)


When does Janna's extra AD from her shield take effect?

Janna's E is a shield that also grants the shielded champion bonus AD.   If a champion uses a skillshot and gains the shield after the skillshot is fired but before it hits an enemy, does the skillshot have the bonus AD or not?


Falling then rising of an effervescent tablet dropped into a glass of water

If you drop an effervescent tablet into a glass of water. The tablet first sinks to the base of the glass and effervesces energetically - producing a rising column of bubbles, i.e. a bubble plume - as it dissolves. Later the partially dissolved tablet (of reduced mass compared with the original tablet) rises to the surface of the glass on a cushion of bubbles.  What is(are) the reason(s) for this phenomenon?


My Mechanics textbook claims that the sum of the work by internal forces is not generally zero.  translated to English the paragraph reads:     Notice about the work by internal forces: the work by the internal forces is in general not equal to zero although the sum of the internal forces is always equal to zero. Since the work also depends on the relative displacement of the two pointmasses in the material system, the work provided by these 2 internal forces will generally not be equal to zero.   Other sources claim that the work done by internal forces is always zero.  (answer by Mark Eichenlaub)     Then I didn't do any work on the system at all since, by definition, only external forces can do work.        the net work done by internal forces is zero since they do not cause motion of the object.   To me it would seem that these sources contradict eachother. Do they? If so, which one is correct? If not, please explain why they don't contradict eachother.


Do I have to protect my SQL queries if the URL protects my query anyway?

Please note, this is purely for educational purposes only and I ALWAYS protect my SQL queries no matter what they are used for, it would be a majorly bad idea not to! This question specifically focuses on $_GET requests and NOT $_POST requests.  So I have recently experienced a brute force attack on one of my accounts and thought it was probably for the best to check my scripts in case I had missed anything (Luckily the attack was unsuccessful).   I came across this script from one of my older accounts:  if(isset($_GET['del'])){     $user_id = $_SESSION['userid'];     $id_pho = $_GET['del'];     $sql = "DELETE FROM new_user_favourites WHERE `user_id` = '$user_id' AND `photo_id` = '$id_pho'";     $conn->query($sql); }   I thought before I protected this script, that I would give it a bit of a test and found that even if I attempted to cause a problem to this script, using the URL, that the URL added encoded spaces %20 or speech marks %27 and these would not allow the script to process any further code?  For example, I tested:  mysite.co.uk?del='; UPDATE new_users SET account_type='1' WHERE email_address='test@test.com   Which should have sent:  $sql = "DELETE FROM new_user_favourites WHERE `user_id` = '' AND `photo_id` = ''; UPDATE new_users SET account_type='1' WHERE email_address='test@test.com'";   That would have given that user admin privileges to my site. Although because of the encoding, the result in the URL shows as:  mysite.co.uk?del=%27;%20UPDATE%20new_users%20SET%20account_type=%271%27%20WHERE%20email_address=%27test@test.com   And so the query would process like this, and fail:  $sql = "DELETE FROM new_user_favourites WHERE `user_id` = '' AND `photo_id` = '%27;%20UPDATE%20new_users%20SET%20account_type=%271%27%20WHERE%20email_address=%27test@test.com'";   Could this mean that my query is already protected from this kind of attack? Or is there a way around this for people who would wish to destroy my website? I've taken a look online for information about this but there doesn't seem to be anything?


Back to Questions when clicking physical back key (mobile app)

I'm not sure if there's a better place to ask this, but;  When viewing a question on the mobile Stack Overflow app, clicking the physical back key returns you to the tags menu. Should this not take you back to the list of questions instead filtered by your already chosen tag? I.e;  Current App Flow   load app Choose tags view Filter by tag (e.g., JavaScript) to show questions View question Press physical back key - returns you to step 2   Should step 5 not return you back to step 3? The only way to do so is to click the back arrow in the top left corner.  Not sure if it matters, but this is on Android. (Don't have an iOS device to see if the functionality is the same.)  Thoughts?


I have been an EE for over forty years and never did find out the right answer to this one....  How do power-stations and transformer switching stations ensure that the power they are feeding into the grid is in-phase with the existing power on the lines.  I know they are VERY serious about setting the line frequency to a ridiculously good accuracy. However, obviously, you can not connect a power line to another line that is 180degress out of phase. Even a small deviation would presumably cause a huge drain on the system and generate a rather strange, and out-of-spec AC waveform.  OK I can imagine a solution at the power station that uses the target line frequency to synchronize the alternators before flipping the switch perhaps. However, that switching station 100km away maybe switching onto a line from a different alternator that is much closer or farther away and consequently at a different point in the phase cycle...  How do they do that...   Note his is NOT the same as  That article only pertains to a local generator and is not, in my mind, the same as the main power grid and transformer switching.


Must $f$ be measurable if each $f^{-1}(c)$ is?

Suppose $f$ is a real-valued function on $\mathbb R$ such that $f^{−1}(c)$ is measurable for each number $c$.  Is $f$ necessarily measurable?


Trigonometric integration $ \int \sqrt{1-\sin2x}dx$

I could not figure out how to solve this problem. Can anyone give me a hint how to solve this: $$ \int \sqrt{1-\sin2x}dx$$


polygons to polygon conversion with attribute name

1) I have a polygon shapefile with 1000 multi-part polygons in it. Each Row of the table is a multipart polygon.  2) I need 1000 shapefiles with 1 multi-part polygon in each.  3) Each output shapefile with 1 multi-part polygon needs to be named with a name from the attribute table (1) unique to each input polygon.  Open to ArcGIS, ArcPy, Model Builder, OGR, QGIS solutions.


Assume that f is continuous on $[0,\infty)$ and $\lim_{x\to \infty} f(x)=0$ then f is uniformly continuous  since given  $\lim_{x\to \infty} f(x)=0$ then   $\forall \epsilon 0, \exists M>0, \forall x>M,|f(x)|<\epsilon $  i did't get any ideal any help .thank you...


How to use pagefactory in POM? why we pass parameters in pagefactory?

While developing a script using Page Object Model, we use PageFactory.initElements(driver,this) to initialize the webelement. How this is done and why we pass parameters 'driver' and 'this' ?


Canon Prime Lens for Fashion Street Photography (Full Frame)

I shoot mainly Street Fashion and need something with fast focus, large aperture and small to carry with me. I've narrowed down my options to 35L vs 50L.  I am wondering since the 50L can be used easily on a full frame for both scenarios (portraits and full body shots), if it's a better candidate and might replace my 35mm needs. The 35L though, has faster autofocus and it's a great walkaround lens. I am also somewhat afraid in regards the shift-backfocusing issues on the 50L.  Which one would you pick if you could only get one?  Here's a few samples of what Focal Point - Style I am looking for:


How can we use wrapper class to change the value of a variable from method?

I was going through javaTpoint about wrapper class in java and it states that  "Change the value in Method: Java supports only call by value. So, if we pass a primitive value, it will not change the original value. But, if we convert the primitive value in an object, it will change the original value"   As first use of wrapper class in java, how can we demonstrate it? I've tried but it didn't worked Heres my snippet class demo {     void change(Integer a) {         a += 100;         System.out.println("Value in change: "+a);     }      public static void main (String [] a) {         Integer a = new Integer (10);         demo obj = new demo();         System.out.println("Value before change: "+a);         obj.change(a);         System.out.println("Value after change: "+a);     } }


"I'm avoiding traveling" or "I'm avoiding to travel"

Is it correct to use two present continuous verb successively? For example  I'm avoiding traveling  Or it should be  I'm avoiding to travel


How to change table numbering scheme at a new section?

I am trying to implement a style to name tables and figures depending on the section for a thesis and can't figure out how to do it with LaTeX.  In the end it should look like this:   and my document:  \documentclass{article}  \begin{document}  \section{Start} Start text \section{Middle} Middle text \begin{table}[h]     \centering     \begin{tabular}{l}     first table\\     \end{tabular} \caption{A normal table} \end{table}  \section*{Supplemental}  \begin{table}[h]     \centering     \begin{tabular}{l}         table in supplemental part\\     \end{tabular} \caption{This should read: ``Table S1: caption text''} \end{table}  \end{document}      I don't want to change the naming permanently, it should continue normally in the next chapter. Is there any easy way to accomplish something like this?


Does PostgreSQL optimize adding columns with non-NULL DEFAULTs?

When adding NOT NULL columns with a DEFAULT value - does PostgreSQL optimize this operation?  In case the table has n rows, a not-optimized alter-table-add-column would yield n writes of the default value - which could be very painful, obviously. With the optimization the DB would instantaneously create the new column, store just one copy of the default value which would be returned when no non-default value is found for that column in a suitable index data structure.  For example  such an .


Java Incremental operator query (++i and i++)

I have the following code:  public class Book {     private static int sample1(int i) {         return i++;     }     private static int sample2(int j) {         return ++j;     }      public static void main(String[] arguments){          int i = 0;         int j = 0;         System.out.println(sample1(i++)); //0         System.out.println(sample1(++i)); //1         System.out.println(sample2(j++));//1         System.out.println(sample2(++j));//2         System.out.println(i);//2         System.out.println(j);//2     } }   My expected output is in comments. The actual output is below:  0 2 1 3 2 2   I'm getting confused with the function calls and incemental operator. Can someone kindly explain the actual result?


I have a string like &#70;&#101;&#101;&#108 and I want to decode it to its ascii representation - feel. Is there any library in C# that does it, or I have to do it manually?


I am writing a remote terminal application and i use pipes to take data from a child process' stdout/stderr to then send it to a client. Specifically, I am running Linux, and I don't really care about portability (if the solution is Linux-only, it's OK).  I need to know how many bytes have currently been written to, but not yet read from, the pipe. I was Googling for a long time and couldn't find an answer. I need to read as many bytes from the pipe as possible without blocking.  Is this possible? Thank you for help.


Suppose a package provides whatever.service file so certain events (including whatever.socket) cause a daemon to start with a certain configuration.  I want to disable this completely. In particular, I want the old socket and any other unit files that might refer to this service by name to be unable to start the daemon.  Instead, I want to create my own unit files for this daemon with a different .socket unit and different environment variables. I also want my override to automatically take account of possible upstream updates to the original unit file (which my current solution of copying whatever.service as whatever-modified.service and editing it unfortunately does not provide).  If I create the following symlinks and files: /etc/systemd/system/whatever.service → /dev/null /etc/systemd/system/whatever-modified.service → /usr/lib/systemd/system/whatever.service /etc/systemd/system/whatever-modified.service.d/fix.conf  systemd considers the new service to be masked as well and refuses to start it. How to avoid this?


Error with \include: Improper \prevdepth

I get this error:  ! Improper \prevdepth. \newpage ...everypar {}\fi \par \ifdim \prevdepth                                                    >\z@ \vskip -\ifdim \prevd... l.17 \include{base_var}  ? ^D ! Emergency stop.   With file test.tex being:      \documentclass[a4paper]{article}                                  \usepackage{float}                                                % For \midrule                                                   \usepackage{booktabs}                                             \begin{document}                                                  \begin{table}[H]                                                 \centering                                                        \begin{tabular}{lccccc}                                           \hline                                                            \include{base_var}                                                 \end{tabular}                                                     \caption{Co-variance matrix of variables.}                       \label{table_base_var}                                           \end{table}                                                       \end{document}    and base_var.tex:              &         esg&        esge&        esgs&        esgg&       \_cons\\    \midrule                                                     esg         &    1.89e+07&    1.73e+07&    1.89e+07&    1.97e+07&    363792.8\\ esge        &    1.73e+07&    1.66e+07&    1.75e+07&    1.75e+07&    328833.6\\ esgs        &    1.89e+07&    1.75e+07&    1.92e+07&    1.94e+07&    365736.2\\ esgg        &    1.97e+07&    1.75e+07&    1.94e+07&    2.11e+07&    379999.8\\ \_cons      &    363792.8&    328833.6&    365736.2&    379999.8&        7147\\   However, if I inline the included file manually, it works. Odd. I don't know what causes it, nor how to work around or fix it. The data file is generated from Stata.  I encountered this in Overleaf first where the compile times out (and here reproduced on my Mac).  Any idea how to fix this?


What is the smallest font size that is still legible on mobile phones?

I am working with a designer who wants to cram a lot of content into the mobile version of his website and who has provided a design at 750px physical width rather than at a more average device width.    As he designs in Photoshop, I want to be able to go back to him and say "show me a version which is 320px wide and has fonts no smaller than X pixels" in order to try and emphasise quite how little space we actually have on an average phone, and why his template needs to be simpler.  The smallest fonts will be only used for small print t&cs and so just have to be legible rather than optimised for easy reading.  The likely font is going to be Open Sans.  What font size is the smallest possible in this case?


On invertibility of a special matrix - Hilbert matrix

I want to know how to prove that the below matrix is invertible   \begin{pmatrix} 1 & \frac { 1 }{ 2 }  & ... & \frac { 1 }{ n }  \\ \frac { 1 }{ 2 }  & \frac { 1 }{ 3 }  & ... & \frac { 1 }{ n+1 }  \\ ... & ... & ... & ... \\ \frac { 1 }{ n }  & \frac { 1 }{ n+1 }  & ... & \frac { 1 }{ 2n-1 }  \end{pmatrix}  and that the inverse matrix has integer entries.


Show that {$x_n$} is a convergent sequence if $d(x_{n+2}, x_{n+1})≤ rd(x_{n+1}, x_n)$

Let $(X, d)$ be a complete metric space, $r∈ (0,1)$ and $\{x_n\}$ be a sequence in $X$ such that   $$d(x_{n+2}, x_{n+1})≤ rd(x_{n+1}, x_n),$$ for every $n∈ℕ$.  Show that $\{x_n\}$ is a convergent sequence.


Do conjugate priors just lead to a posterior that is a modification of the parameters of the prior?

We know, for example, that the conjugate relationship between the classic beta-binomial is as follows:  \begin{align}  y &∼ \mathcal{Bin}(n,\ θ)  \\  θ &∼ \mathcal{Beta}(α,\ β)  \\ θ|y &∼ \mathcal{Beta}(y + α,\  n − y + β) \end{align}  Notice how the posterior is just a change in parameterization compared to the prior. Is the posterior of conjugate priors just a change in parameters?


Are 'accuracy' and 'precision' interchangeable nouns?

The dictionary for accuracy says:        The quality or state of being correct or precise.   The ability to perform a task with precision.      And for precision:        The quality, condition, or fact of being exact and accurate.   Marked by or adapted for accuracy and exactness      Are these nouns interchangeable? If not, how to decide whether to use one or another?


Cannot install eclipse due to broken packages

Trying to install eclipse, I get the following error:  XXX:~$ sudo apt-get install eclipse Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  eclipse : Depends: eclipse-jdt (>= 3.8.0~rc4-1ubuntu1) but it is not going to be installed            Depends: eclipse-pde (>= 3.8.0~rc4-1ubuntu1) but it is not going to be installed E: Unable to correct problems, you have held broken packages.   I have no idea how to solve it. I'm quite new to Ubuntu, but I don't think that I'm using a unstable distribution. But I have added the repository which is required to install Tomcat7. Could that cause the problem?


iMessage stopped working.. Contacts are shown as red now

This problem has been seen on mid-2012 MacBook Pros on Mavericks and on late-2014 Retina MacBook Pros on Yosemite.  One day while using iMessage on the Mac, all the contacts turned red and messages failed to send, immediately returning a "not delivered" error. It also reported when trying to resend the messages that the contacts were no longer associated with an iMessage account.  Things that didn't fix this behavior:   Deleting the com.apple.ids.madrid Removing the Apple ID information from my phone, turning off iMessage on both of the devices, and placing my iPhone in airplane mode for several minutes before turning it on logging in again.   Could someone help me figure out how to solve this?


Launching X11 application (Firefox) via crontab

I want to write a crontab that opens Firefox every minute (just to test it, I know it doesn't make any sense). My problem is that even though crontab is active nothing happens. This is how my crontab looks like:  SHELL=/bin/bash PATH=~/bin:/usr/bin:bin * * * * * export DISPLAY=:0.0 xhost localuser /usr/bin/firefox   Any idea why it isn't working?


How to efficiently slice a Python list into chunks of 20 + a slice for the remainder?

Given a list of URLs urls of unknown length, I want to divide it into slices of 20 urls (plus the slice containing the remainder, if there is one). So if it contains 96 URLS, I'll have a 4 slices of 20, and a slice of 16. Also if the length is less than 20, obviously the list itself is the only slice.  Given:   quotient = len(urls) / 20 remainder = len(urls) % 20   Then:  if len(urls) / 20 == 0:    slice = urls else:    numberOfSlices = (quotient + 1) if remainder !=0 else quotient   From here, I can start constructing the individual slices. But it's all starting to feel a little convoluted. Is there a more efficient (perhaps with NumPy) way of achieving this?


How can I get all of the packages repository for Ubuntu server 12.04 (Precise Pangolin)

I am new with Ubuntu.  I want to set up a local repository for Ubuntu 12.04 (Precise Pangolin), because I don't have Internet access on my laptop. I downloaded the repository using a local link (mirror ini Indonesia), but some of the repository is in error. What would be a link or similar for the download?


Ok guys, so I have this code:  var q=(function(){     var u,q,x;     x=616;     q=q_construct();     qp_construct();     return q;     function q_construct(){         var q,pro;         q={             a:1         };         return q;     };     function qp_construct(){         console.log('1 ⇒    ',q,x);         Object.defineProperty(Object.prototype,'q',{get:function(){             console.log('2 ⇒    ',q,x);             var r={b:2};             return r;         }});     }; })();   When I enter y={z:616}; y.q; into the console, I get:  1 ⇒  Object {a: 1} 616  y={z:616}; y.q;                 //  console entry point  2 ⇒  Object {a: 1} 616 Object {b: 2}   Yet if i change:  var r={b:2}; return r;   to  var q={b:2}; return q;   the result changes from:  2 ⇒  Object {a: 1} 616   to  2 ⇒  undefined 616   I can not find out why, when setting this variable name to q, the q from the inherent scope is redefined as undefined.  Something is niggling in the back of my head, saying I read something on "hoisting" that might help?


Use of capitals and full stops in bullet points

Possible Duplicate:          Let's say I have a bullet point list e.g:   Point 1. Point 2.  Point 3.    Notice I have put a capital letter for the starting letter of every bullet point and a full stop at the end. Is this the correct way to do it?  If not, what is the correct way to do it?  Do I put a capital letter and no full stop, or, the other way around, a full stop and no capital letter? Alternatively, do I not put a capital letter or a full stop? Is it only necessary to put a capital letter on the first bullet point and full stop on the last bullet point?  For reference, I'm from the UK so British-English grammar would apply.


Show that an ideal $I$ of $R$ is proper if and only if it does not contain $1$ iff and only if it does not contain any units. ($1$ is the identity element) I'll need to show 3 parts: (1) $\implies$ (2): Let $I$ be a proper ideal and assume $1 \in I$. I want to show that $1 \notin I$. (2) $\implies$ (3): Let $I$ be a proper ideal that doesn't contain $1$ and assume there are units in $R$. By the definition, units of $R$ are elements with multiplicative inverses. So I need to show that there aren't multiplicative inverses. (3) $\implies$ (1): Assume there are no units in $R$ and then show that $I$ is a proper ideal. For this part I was thinking of doing something like this- Let $u \in I$ such that $u$ has a multiplicative inverse. Let $x \in R$. Then \begin{align}u^{-1}x \in R;\\ x=u(u^{-1}x) \in I,\end{align} so $R \subseteq I$ which implies that $I = R$. But this is a contradition so therefore $I$ must be a proper ideal. I just need help completing the proof.


I was wondering of it is possible to kill the Golem pre-hardmode. If so please tell me how to do so and what kinds of gear you need to kill it (accessories, armor, weapons, arena prep). Thanks for the help.


How to extend lv without loss of data on other lvs within partition

I want to extend my logical volume mounted to /home:  lsblk NAME                     MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT sr0                       11:0    1 1024M  0 rom xvda                     202:0    0  125G  0 disk ├─xvda1                  202:1    0  500M  0 part /boot └─xvda2                  202:2    0 74.5G  0 part   ├─centos_jenslv05-root 253:0    0   48G  0 lvm  /   ├─centos_jenslv05-swap 253:1    0    3G  0 lvm  [SWAP]   └─centos_jenslv05-home 253:2    0 23.5G  0 lvm  /home   As you can see xvda has 125GB and xvda1 + xvda2 have only 75GB combined. The extra 50GB is what i want to add to centos_jenslv05-home logical volume.  PVS  pvs   PV         VG              Fmt  Attr PSize  PFree   /dev/xvda2 centos_jenslv05 lvm2 a--  74.51g    0   VGS  vgs   VG              #PV #LV #SN Attr   VSize  VFree   centos_jenslv05   1   3   0 wz--n- 74.51g    0   LVS  lvs   LV   VG              Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert   home centos_jenslv05 -wi-ao---- 23.45g   root centos_jenslv05 -wi-ao---- 48.04g   swap centos_jenslv05 -wi-ao----  3.02g   So basically i need to extend the partition dev/xvda2, add it to the PV, add it to VG and then to LVM which is mounted to home.  However, i don't want to loose data on root lv (/), which is on the same partition as the home lv (/home). Is there a way to extend only one logical volume, without touching other lvs? If it's not possible and i need to delete the partition and then recreate it with added space, will backing up all the files on /root and /home be enough? Can i recreate parition, then recreate lvs and copy the files back to lvs and will it start the server as it was? Is it safe?  I know that extending logical volume without touching others is possible on Windows, but not sure if it's as handy on Linux. The system is Centos 7.


I've been having this problem with several models and I can never figure out what the issue is.   Hard edges are appearing on the model in rendered view despite it being entirely smooth shaded. There are no overlapping objects, it's not the textures, I've recalculated the normals. I have no clue what is causing this.


Limit $\lim_{x\to \infty} \frac{\sqrt{x+1}+\sqrt{x+2}-\sqrt{4x+12}}{\sqrt{x+2}+\sqrt{x}-\sqrt{4x+12}}$

Using the equivalency, I got the answer equal to $1$, however the answer is given as $\frac34$.    also gives $\frac34$.  Could someone tell me that the given answer is wrong or I made a mistake!


My teacher describes absolute value confusingly: $|x|=\pm x,\quad \text{if}\enspace x>0 $.

He says (direct quote): "In higher mathematics the absolute value of a number, $|x|$, is equal to positive and negative $x$, if $x$ is a positive number."  Then he wrote:  $|x|=\pm x,\quad \text{if}\enspace x>0 $.  I think he misunderstood the definition of absolute value, or did I? From what I understand, absolute value of a number is the distance of a number from zero, so it is always positive. Am I wrong?


Originally posted on Stack Overflow:   Requirements to reproduce:  Windows 7 x64  Firefox 71.0 x64  Steps to reproduce:   Go to the ask question section Write something to the title field Start scrolling similar questions Change the title field Start scrolling the similar questions again


How do I insultingly describe an extremely ugly building?

The building is shaped like a matchbox. Or like a beehive. Designs of this sort need very little engineering and less imagination. It's mostly glass and concrete. More glass than concrete. It is a residential building.  In order to make room for it, an entire block of 19th Century buildings (very quaint and very much in keeping with the city's spirit) was mercilessly razed.   A handful of half-hearted protests from the neighbors followed. Those were ignored. The local media assessed the situation and found there was nothing worth reporting.  The monstrosity went up in no time. It now towers over the street, faceless and depressing.  Because the windows are walls, and the walls windows, it costs a fortune to keep the apartments warm in the winter and cool in the summer. Not that I think the tenants give a rat's ass: to those who can afford to rent a place in that building, the utility bill of any size is a trifling matter.  Ordinary pejorative words that people normally use to describe this type of architecture (matchbox, barn, etc) are way too weak. The monster is just too hideous, and the architects who designed it, contractors who built it, and tenants who live in it are too self-complacent and too dismissive of things that are beautiful and harmonious, as well as of the city's history, as well as of other people who live in the city.  To summarize. The building is neither a barn, shack, nor a matchbox. Those words are much too weak. Any suggestions?  Addendum: I once called the whole "ugly growth" phenomenon "a chancrous rash on the body of American architecture," but that's too general, I think. Nor is it an exclusively American thing either: London is chock-full of them, and so is any German city, and Paris is catching up pretty fast.  Before: buildings not unlike these:    ... and now:


Product of matrices of different order is not invertible

If $A$ is an $m \times n$ and $B$ is an $n \times m$ matrix with $n < m$ then prove that $C = AB$ is not invertible.  I am not getting any idea. May be I am missing vary basic point. $C = AB$ where both $A$ and $B$ are square matrices  will be invertible iff both $A$ and $B$ be invertible. I know it and its proof.  May be this question has been discussed earlier, but I am not seeing the link. Thank you for your help.


exit out of all SSH connections in one command and close PuTTY

Is there a way to back out of all SSH connections and close  in "one shot"?  I work in Windows 7 and use PuTTY to SSH to various Linux hosts.  An example of the way I find myself working:  SSH to host1 with PuTTY... banjer@host1:~> #...doin some work...ooh! need to go check something on host8... banjer@host1:~> ssh host8 banjer@host8:~> #...doin some work...OK time for lunch. lets close putty... banjer@host8:~> exit banjer@host1:~> exit Putty closes.   Per above, any way to get from host8 to closing PuTTY in one shot?  Sometimes I find myself up to 5 or 10 hosts deep.  I realize I can click the X to close the PuTTY window, but I like to make sure my SSH connections get closed properly by using the exit command.  I also realize I'm asking for tips on how to increase laziness.  I'll just write it off as "how can I be more efficient".


Prove that $d(x,M)=\frac{|\langle f,x \rangle|}{||f||}$

I want to show that for $E$ a normed space, $f\in E^*$ and $M=\{x\in E\,:\, f(x)=0\}$:  Write $M^\perp$ Show that $d(x,M)=\frac{|\langle f,x\rangle|}{||f||}$.  This is my attempt: For the second part: We have that $f\in E^*$ and for $x\in E$ and $m\in M$ $$\ |\langle f,x-m|\rangle \leq ||f|| ||x-m|| \Rightarrow \frac{|\langle f,x\rangle|}{||f||} \leq ||x-m||. $$ Therefore, $$ \frac{|\langle f,x\rangle|}{||f||} \leq \inf_{m\in M}||x-m|| =d(x,M). $$ The second inequalyty is that I can't prove, I think that any corollary of Hanh-Banach could help me to prove that  $$d(x,M)\leq \frac{|\langle f,x\rangle|}{||f||} $$ Does anyone have any idea and could check my proof? Update I found the same question in this link


Characterize all entire functions $f$ such that $|f(z)|=1$, whenever $|z|=1$.  I think either $f(z)=c$ or $f(z)=cz$ where $|c|=1$. But I am not sure, any hint would be great, thanks.


Stable Nuclei - Deviation from equal protons and neutrons

While studying the semi-empirical mass formula for nuclei, I came across an "asymmetry term" whose function, as far as I understand, is to build in the fact that nuclei "prefer" to have equal numbers of protons and neutrons. This is explained by the Pauli exclusion principle; the neutrons and protons are distinguishable, and hence have fill separate energy levels. Hence, if the number of neutrons and protons is close, the nuclei will have a smaller energy.  Yet, it is observed that large stable nuclei have more neutrons than protons. Why is this so? If nuclei prefer to have equal protons and neutrons, shouldn't the stable nuclei lie along the N=Z line? (in the image)


Is there this notation in mathematics $\mathbb{R^{\frac{1}{2}}}$ and is it meant the space dimension is $\frac{1}{2}$?

I'm not familiar with algebra theory, but I'm interested to know if there is an ensemble in mathematics for which the power of ensemble could be a real number, we take for example $\mathbb{R^{\frac{1}{2}}}$, Does this meant the space dimension is $\frac{1}{2} $?  Note:I want $\mathbb{R^{\frac{1}{2}}}$ have a metric space structure   Thanks for any comments


Installing Ubuntu on a separate hard drive from Windows

I want to install Ubuntu and learn Linux.  I've been using Raspbian a bit and really would like to get away from Windows as much as possible.  The only problem is some of the games I use requires Windows for now.  Also, I'm taking classes through Coursera and using online tutorials to learn Linux from and would like an operating system installed besides the Raspbian I have on my Pi.  I have a desktop computer with Windows 10 installed on a SSD (M.2 if it matters) and another HDD used to store files. I have a new 1 TB HDD I'd like to install Ubuntu on. My plan is to install it and place the GRUB bootloader on the new drive.  I can then point the UEFI to that drive as the primary boot drive and GRUB should allow me to choose Linux or Windows. My thought is if I do this, I can change the boot order in UEFI back to C:\ drive and have the machine boot directly to Windows as it does now. Then I have the option of having a dual boot system or a Windows only system. Is this viable?  Should I use the whole drive for Linux?    Also, I'm reading a couple different opinions on disabling Secure Boot and Fast Boot from the UEFI.  Any reason not to disable these in my plan above?  Any other advice is welcome. I appreciate the help!


If the denominator of a rational number contains only 2 and 5 as prime factors then the decimal expansion of the rational number is terminating.  How can I Prove this


In Smith's book about Godel's Theorems a proof is given of incompleteness of Robinson Arithmetic.  It's done by producing a special interpretation of the theory:   Domain is $N^* = N \cup \{a,b\}$, a and b are "rogue elements" Sum $+^*$ as follows: $$     a +^* n = a,  n \in N \\     b +^* n = b,  n \in N \\     x +^* a = b,  x \in N^* \\     x +^* b = a,  x \in N^* $$  From this he concludes  $0 +^* a \neq a$.  How is this reached?   Thanks for any guidance.


How to suppress polygon boundaries shared by objects of same type in QGIS?

Given polygons - like landcover in OpenStreetMap or street areas in cadastre - how can one suppress those polygon boundaries which are shared by objects (features) of same type in QGIS (see figure below)? AFAIK there exists no such symbolization rules in QGIS 2.6 (yet). It doesn't seem useful to aggregate (union) the geometries. But preprocessing could still be an approach, like splitting the common boundaries first, then "suppressing" these when rendering. Any ideas?


Can someone give me a roadmap or a routine to help me learn Blender?

I have been studying Blender on and off for a couple of months but I feel like I always hit a roadblock. I wanna start from the beginning(kind of). Can someone give me a routine they used to study or a roadmap which I can follow or just which concepts I should first(again)?


i personally have been on and off with ubuntu since... 9.04 i belive.  now i'd like to stay with ubuntu for good. i have settled in with 12.10.  the thing is, im not an expert in this field, i do not have professional knowledge on source coding not to mention programming language (basic c is all i've got, except all the pythons i played with in my calculator when i was in high school...)   ubuntu is always developing and there have always been problems and solvings people worked out. and i am more than greatful for this huge community.  now i want to contribute. not in a sence that i would donate money, but actually problem solving. I have been having so many stability issues with ubuntu which is why i have been on and off with it.  i am wondering how and where i should start with tackling problems if i encounter one.  any advice please, would be much appreciated, thanks!


Why do we need interface while we can do the same with class itself?

Consider my code below which serves to book flight ticket using interface  import java.io.*;  interface FlightDetails {     void getFlightDetails();     void book(Ticket ticket); }  class AirIndia implements FlightDetails {     public void getFlightDetails() {         System.out.println("Flight Details of Air India");     }      public void book(Ticket ticket) {         System.out.println("Ticket booked in Air India");     } }  class Emirates implements FlightDetails {     public void getFlightDetails() {         System.out.println("Flight Details of Emirates");     }      public void book(Ticket ticket) {         System.out.println("Ticket booked in Emirates");     } }  class Lufthansa implements FlightDetails {     public void getFlightDetails() {         System.out.println("Flight Details of Lufthansa");     }      public void book(Ticket ticket) {         System.out.println("Ticket booked in Lufthansa");     } }  class Ticket{  }  public class InterfaceFlight {     public static void main(String[] args) throws IOException {         FlightDetails flight = null;         BufferedReader br = new BufferedReader(new InputStreamReader(System.in));         System.out.println("1.Air India\n2.Emirates\n3.Lufthansa");         System.out.print("Enter choice = ");         int choice = Integer.parseInt(br.readLine());         if(choice == 1){             flight = new AirIndia();             flight.book(new Ticket());         } else if(choice == 2){             flight = new Emirates();             flight.book(new Ticket());         } else if(choice == 3){             flight = new Lufthansa();             flight.book(new Ticket());         }     } }   This above implementation could have been done without the use of interface by writing separate classes and creating object for the respective flights  Then Why do we need interface??  Thanks in Advance!


Prove that : $(a-b)(a-c)(a-d)(b-c)(b-d)(c-d)$ divisible by $12$, with $a,b,c,d\in\mathbb{Z}$.


I update 16.04 and I don't remember my username, can't open my computer how to know username please help.  I tried press and hold shift that didn't work, i also tried clrt+alt+f7 in that screen disappeared.  Please help


Will my sony erricson xperia pro support Ubuntu?


I just noticed that the default text in the "Add Comment" box seems to be unfinished:    I'm guessing this is a mistake, because "Avoid comments like" is pretty useless as a statement on its own ;) I haven't noticed it before, so either it's a new bug or I'm incredibly unobservant. (Or maybe we're advising users to avoid blank comments? I suppose that could be it ;)).


Detect if a Lightning component is opened from Chrome

I'd like to detect if a lightning component is opened from Chrome browser. I've tried using $A.get('$Browser')but it doesn't provide anything about detecting Chrome. Do you know how i could achieve this? Thanks,  EDIT : It's not about detecting any browser, os or device, it's about detecting when Salesforce1 is actually running on Chrome Mobile Browser or using Web-view specifically.


Null Pointer Exception when calling onCreateOptionsMenu()

I'm getting the following error,    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.SearchView.setOnQueryTextListener(android.support.v7.widget.SearchView$OnQueryTextListener)' on a null object reference   on this code:   public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {      inflater.inflate(R.menu.search_menu, menu);     final MenuItem item = menu.findItem(R.id.search);      final SearchView searchView = (SearchView) MenuItemCompat.getActionView(item);     searchView.setOnQueryTextListener(this);  }   I can't figure out how to fix it - does anyone have any suggestions? I understand what a nullpointer exception is, but I don't understand why searchView is null.


Which is the correct tense: "earth was/is round"?

Maybe it's very simple but I'm wondering which one is correct. Google search has showed me both forms are used.    "He said the earth was round."  "He said the earth is round."


I would like to be able to run the aliased commands I have defined for my current user in conjunction with sudo as well.   This does not work by default, because they would have to be defined for root instead of my current user in order to work with sudo.  An example is the ll alias:  $ type ll ll is aliased to `ls -alF' $ sudo ll / sudo: ll: command not found   A special problem would be nested aliases:  bytecommander@BC-AlkaliMetal:~$ type ls ls is aliased to `ls --color=auto'   So actually ll should evaluate to ls -alf --color=auto.  How can I run aliases defined for my current user as root with sudo properly?


I have a problem in this code The tv.setText(str); is working and the text for tv change to "LED1", but in if(str=="LED1") it's not working! What is the problem?  Handler = new Handler() {     @Override     public void handleMessage(Message msg)     {          byte [] data= (byte[]) msg.obj;         try {             tv.setText("");             String str = new String(data, "UTF-8");             tv.setText(str);             if(str=="LED1")             {                 tv.setBackgroundColor(getResources().getColor(R.color.red));             }         } catch (UnsupportedEncodingException e) {             e.printStackTrace();         }     } };


What happens when baker's, butcher's, etc. are in the plural?

If the singular it is:     The baker's and the butcher's are closed on Sundays.   Which one is the plural?        Bakers and butchers are closed on Sundays.     Bakers' and butchers' are closed on Sundays.


I have a question about Java:  I am trying to make a program that goes through files and checks something, but for that I need something to count the lines, does anyone knows a good method to do this?  I have never worked with files before so I dont really know something. Also I don't have code to show, because I don't know how to do it.


I have 40 mp4 files in a folder.  Every file starts with video_. Every file is of format video_*.mp4.  I need to rename all the files with video_ removed from the begining of every file. How can I do that from terminal?


Prove that every integer is a sum of two squares and a cube of integer.  Probably the only connected result I know, is the Fermat's theorem on sums of two squares. But I don't know how to prove that in other cases (for numbers not being of the form $x^2+y^2=x^2+y^2+0^3$) one can choose such two squares that the remainder will be a cube.


How does one remove a certificate authority's certificate from a system?

The ca-certificates package was just updated, and it caused the following changes on my Xubuntu 13.10 system:  Running hooks in /etc/ca-certificates/update.d.... Adding debian:CA_Disig_Root_R1.pem Adding debian:CA_Disig_Root_R2.pem Adding debian:China_Internet_Network_Information_Center_EV_Certificates_Root.pem Adding debian:D-TRUST_Root_Class_3_CA_2_2009.pem Adding debian:D-TRUST_Root_Class_3_CA_2_EV_2009.pem Adding debian:PSCProcert.pem Adding debian:StartCom_Certification_Authority_2.pem Adding debian:Swisscom_Root_CA_2.pem Adding debian:Swisscom_Root_EV_CA_2.pem Adding debian:TURKTRUST_Certificate_Services_Provider_Root_2007.pem Adding debian:Verisign_Class_3_Public_Primary_Certification_Authority_2.pem Removing debian:cacert.org_class3.pem Removing debian:cacert.org_root.pem Removing debian:Equifax_Secure_eBusiness_CA_2.pem Removing debian:TC_TrustCenter_Universal_CA_III.pem   I've decided I don't trust some of these CAs, and I would like to remove their certificates. How do I do that?


For example i have the domainname buyhouse.com The keywords "buy house new york"  buyhouse.com/new-york/   buyhouse.com/buy-house-new-york/   Whats the best url option for SEO?


Can't acces admin account, how may I fix it?

So when I try to log into the admin account i go right back to the log-in screen. And I've been searching around all over the internet trying to fix it, but then some other problems always comes along, how may I fix it?


Fantasy novel where first death is celebrated

I can't remember what this book is. In it, a particular culture of people (who may or may not be human) celebrate each individual's first death as a coming-of-age ritual. I think that the person is intentionally killed by members of the community as part of the ritual, since they all reincarnate in some way. This novel is probably aimed at middle-grade readers. I can't remember any other details.


Path integrals and Weyl ordering in Peskin and Schroeder

On pages 280-281 of "An Introduction to Quantum Field Theory" by Peskin and Schroeder, the authors discuss the path integral formulation for a general quantum system and briefly mention Weyl ordering. The presence of operator ordering issues seems clear. However, my question, details of which follow, is whether the requirement to use Weyl ordering in particular is the result of a (seemingly innocuous) choice made earlier in the calculation. Does making different choices lead to different ordering requirements?  In detail, after equation 9.9, the matrix element of a Hamiltonian term involving only the coordinates (and not the momenta) is given as $$ <q_{k+1}|f(q)|q_k> = f(q_k)\prod_i\delta(q_k^i - q_{k+1}^i) $$ which is then rewritten as $$ \tag{1} <q_{k+1}|f(q)|q_k> = f\left(\frac{q_{k+1} + q_k}{2}\right)\left(\prod_i\int\frac{dp_k^i}{2\pi}\right)\exp\left[i\sum_ip_k^i(q_{k+1}^i - q_k^i)\right]. $$ Here, the choice has been made to replace $f(q_k)$ with $f\left(\frac{q_{k+1} + q_k}{2}\right)$. I assume that one could have left $f(q_k)$ alone, or indeed replaced it with $f(q_{k+1})$.  The text then continues to show that if Hamiltonian $H$ contains only terms of the form $f(q)$ and $f(p)$ then its matrix element is given by $$ <q_{k+1}|H(q,p)|q_k> = \left(\prod_i\int\frac{dp_k^i}{2\pi}\right)H\left(\frac{q_{k+1}+q_k}{2},p_k\right)\exp\left[i\sum_ip_k^i(q_{k+1}^i-q_k^i)\right], $$ and tries to extend this to general Hamiltonians with products of $p$s and $q$s. The authors note that, due to ordering issues, this only works if the Hamiltonian is Weyl ordered, e.g. $$ <q_{k+1}|\frac{1}{4}(q^2p^2 + 2qp^2q + p^2q^2)|q_k> = \left(\frac{q_{k+1}+q_k}{2}\right)^2<q_{k+1}|p^2|q_k>. $$  Am I right to think that this particular ordering is required as a result of the choice made in (1) to replace $f(q_k)$ with $f\left(\frac{q_{k+1} + q_k}{2}\right)$? For example, would leaving $f(q_k)$ alone give a Hamiltonian matrix element (assuming only terms of the form $f(p)$ and $f(q)$) of the form $$ <q_{k+1}|H(q,p)|q_k> = \left(\prod_i\int\frac{dp_k^i}{2\pi}\right)H\left(q_k,p_k\right)\exp\left[i\sum_ip_k^i(q_{k+1}^i-q_k^i)\right], $$ and require us to order products involving $p$s and $q$s with the $q$s on the right, i.e. $$ <q_{k+1}|p^2q^2|q_k> = q_k^2<q_{k+1}|p^2|q_k>. $$    To conclude, am I right to think that Weyl ordering is, in effect, a choice, but one that was made when we decided to replace $f(q_k)$ with $f\left(\frac{q_{k+1} + q_k}{2}\right)$ in (1), and that other orderings are required if we leave $f(q_k)$ alone or replace it with $f(q_{k+1})$. If so, is there something special about Weyl ordering that makes it preferable to, say, placing all $q$s on the right?


Insect identification - is it a bed bug?

We were on holiday and got bitten by (most probably) bed bugs. We then carried them home, and I also saw a typical one: 4mm, flat, round, black. I thought it was pretty clear we had bed bugs. I smashed one:    Currently (2 weeks later) we have a lot of small insects in the house, like shown in the picture. But they don't really seem like bed bugs, do they? The big ones look like bed bugs, but the small ones don't?  What is it? It's around 2mm (others are much smaller, very tiny, less than 1mm). They can jump (or run really fast) 2cm if I try to squash them with a finger.    Update:  The small one is very similar to a ?!    Update 2:  They have wings.. I think they're psocids. What I also realized, I probably have two different larves. I take some more probes..


Is it possible to create a VPN link between AZURE VNET and AWS VPC?

As I found solutions on making site-to-site VPN between Azure and AWS using a software VPN server, I'm asking myself if it's possible to connect the VPN gateways (Azure VNET / AWS VPC) directly.  Is there a limitation that forbids it ?


I want to remove last character from a line:  [root@ozzesh ~]#df -h | awk  '{ print $5 }' Use% 22% 1% 1% 59% 51% 63% 5%  Expected result:  Use 22 1 1 59 51 63 5


I had experience that mt blender gone crashed, I try to open autosave file, but both original file and autosave file has gone corrupted, so I can’t open any of them, it happened sometimes when huge blender file got crash, autosave didn’t save it’s backup property. I notice that autosave only provide one back up file.  My point is is there any option I can save number of autosave version like zbrush?? or maybe script for it?


Write the code for large formula in terms of smaller chunks

I am wondering if it is possible that for large formulas in order to avoid confusion during code typing, we break it into variables. For example the formula below could be confusing during typing the code and sometimes it is a hassle to debug it. Is it possible that like all computer languages one writes the numerator into a variable and denominator into another one and at the end plugs those variables into the final formula and run it. thanks  \begin{equation} \hbar \omega_c = I_p+\frac{0.5I_p^{3.5}\lambda^2}{\big[\text{ln}\big(\frac{0.86I_p3^{2n^*-1}G_{lm}C^2_{n^*l^*}}{-\text{ln}(1-p_s)}\tau_p\big)\big]} \end{equation}


I created a table and I would like to put a figure next to this table (see picture attached.  The caption can be the same for both of them. I would probably need to increase the space between rows in order to align the table with the figure. The table can be positioned either right or left.  I leave you my code: \documentclass{article} \usepackage[utf8]{inputenc} \usepackage[super]{natbib} \usepackage{comment} \usepackage{graphicx} \usepackage{float} \usepackage{hyperref} \hypersetup{     colorlinks,     citecolor=black,     filecolor=black,     linkcolor=black,     urlcolor=black } \usepackage{amsmath} \usepackage{mathtools} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{caption} \usepackage{adjustbox} \usepackage{lipsum} \usepackage{lscape} \usepackage{multicol} \usepackage{longtable} \usepackage{chngcntr} \counterwithin{figure}{section} \counterwithin{table}{section} \captionsetup[figure]{font=small,labelfont=bf} \captionsetup[table]{font=small,labelfont=bf} \usepackage[justification=centering]{caption} \usepackage{eurosym} \usepackage{mhchem} \usepackage{relsize} \usepackage[table, dvipsnames]{xcolor} \renewcommand*\descriptionlabel[1]{\hspace\leftmargin$#1$} \usepackage{enumitem}   \usepackage{array,ragged2e} \newcolumntype{C}{>{\Centering\hspace{0pt}}p{0.1\textwidth}} \usepackage[output-decimal-marker={,}]{siunitx}  \usepackage{booktabs, makecell, tabularx} \newcolumntype{L}{>{\raggedright\arraybackslash}X} \newcolumntype{M}{p{\dimexpr 0.25\textwidth-2\tabcolsep}} \newcolumntype{P}[1]{>{\centering\arraybackslash}p{#1}}  \usepackage{longtable,array,ragged2e} \newlength\mylen \setlength\mylen{\dimexpr0.25\textwidth-1.5\tabcolsep-0.25\arrayrulewidth\relax} \newcolumntype{Z}{>{\RaggedRight}p{\mylen}}  \usepackage[export]{adjustbox}   % <--- \usepackage{booktabs, tabularx} \usepackage{array} \usepackage{booktabs,tabularx} \usepackage[export]{adjustbox}   \makeatletter \newcommand*{\rom}[1]{\expandafter\@slowromancap\romannumeral #1@} \makeatother \def\changemargin#1#2{\list{}{\rightmargin#2\leftmargin#1}\item[]} \let\endchangemargin=\endlist   \bibliographystyle{abbrvnat} \setcitestyle{authoryear,open={(},close={)}} \begin{document}  \begin{table}[h] \resizebox{0.5\textwidth}{!}{% \begin{tabular}{lcc} \toprule                     & Deterministic   & Stochastic \\                     \midrule Mean                & \euro430,96M        & \euro429,89M   \\ StDev               & \euro6,36M          & \euro5,44M     \\ n                   & 100             & 100        \\ \midrule Best SP result      & \multicolumn{2}{c}{-\euro4,40M}  \\ Worst SP result     & \multicolumn{2}{c}{+\euro2,89M}  \\ Average performance & \multicolumn{2}{c}{-\euro1,08M}  \\ t-test              & \multicolumn{2}{c}{3,87E-10}\\ \hline \end{tabular}% } \caption{Analysis of the comparison between the SP and the deterministic model.} \label{tab:my-table} \end{table}  \begin{figure}[H] \centerline{\includegraphics[scale=0.26]{SD5.png}} \begin{changemargin}{0.5cm}{0.5cm} \vspace*{-1mm} \caption{Analysis of the comparison between the SP and the deterministic model.} \end{changemargin} \label{fig} \end{figure} \vspace{-8mm}


I want to arrange pages of my presentation in a rectangular array.  I want to print on each page (what may be the equivalent of) a watermark which is a portion of a glyph.  For this discussion let us say the glyph is a katakana symbol for ka, spread across 6 pages.  When I am done, I should have an array of three rows and two columns of pages with print and with a light-gray water mark on each page, so when I step back some distance, I can look at the watermark(s) and make out the symbol for ka which is about two pages high and two pages wide, but centered so that part of the symbol is on all 6 pages.  I suspect I can use a TeX package for watermarking, but I am asking for an example (or pointer to an example:  I am a TeX beginner) that someone more adept than I can post that I can adapt.   It is my hope that I can for each page issue the same watermark command, using the same scale for the watermark glyph, but using different offsets for each page (which I am willing to input manually).  I am willing to compute the offsets myself to account for the physical space I will use in arranging the pages.  For this example, suppose I will have one inch vertically between sheet edges as well as one inch horizontally.  If there is a better package for this effect, I am willing to use it, but I am hoping the learning curve will be mild.


Sharing MySQL data folder between Windows and Linux

I have dual boot laptop with Windows 7 and Linux. I've been working for a long time on Windows programming in php / Apache / MySql. I share NTFS partition with Linux which is mounted using ntfs-3g, it is writable and works fine. I set up Apache on Linux with configuration that uses the same www directory as Windows. I have MySQL data in custom directory on Windows... what would happen if I install MySQL on Linux with configuration that points data path to the directory that I use on Windows - will this accually work? Thanks :-)


For implementing a hash function, we can use Davies-Meyer Construction. In Katz crypto book it is written:  Let $F$ be a block cipher with $n$-bit key length and $l$-bit block length. We can then define the compression function $h:\{0,1\}^{l+n} \rightarrow \{0,1\}^l$ by $h(k,x)=F_k(x)\oplus x$.  My question is what is the point of XORing $x$ with $F_k(x)$?


While running sudo apt-get install alien, there is an error: Unable lock administrator directory (/var/lib/dpkg/), is another process using it?  How do I fix this?


How should a stealthy attack start combat?

Say, a PC fires a longbow at an enemy without their knowledge before combat has begun, how should combat start?   Should there be a stealth/perception opposed check? Should a successful/unsuccessful opposed check give a benefit/failure to initiative? Should a successful opposed check cause an automatic hit or crit? When should initiative be rolled? Should there be a surprise round? If I whisper to my party what I'm doing, do they automatically fail to be surprised?


Why is SSMS inserting new rows at the top of a table not the bottom?

Whenever I manually insert a row into a table in SQL Server Management Studio 2008 (the database is SQL Server 2005) my new row appears at the TOP of the list rather than the bottom. I'm using identity columns and this results in things like   id  row 42 first row 1 second row 2 third row   When rows are fetched and not explicitly ordered. This results in a different appearance when the rows are fetched for the web app and changes what a TOP 1 query returns.  I know I can order by them, but why is this happening? Most of my data is inserted through a web application, all inserts from this application result in a First In First Out ordering, e.g. latest insert is at the bottom, so the ids are all in a row. Is there some setting in the server or Management Studio that causes this improper ordering?


I've installed a version of Java. How can we set the $JAVA_HOME environment variable correctly?


How do I toggle headset/headphone mode manually?

It seems that the hardware erroneously regard the headset as attached at all times (to the 3.5" jack). This makes me unable to make calls without headset or speaker mode.


Having read other questions on here I believe I would be right in saying that this error occurs when you are trying to modify the children of a node while iterating over it.  I saw a couple of methods I could use to overcome this issue, however when I was messing around with my code I noticed that by replacing my enhanced for loop with a regular for loop it solved the issue.  My first question is why does this work? It would seem to me that I am still modifying the children of a node while iterating over them, so I don't understand why this now works. Secondly, is there anything wrong with overcoming the error in this way?  Update  As requested, here is a snippet of code      ArrayList<Button> list = new ArrayList<Button>();     Button b1 = new Button();     Button b2 = new Button();     Button b3 = new Button();     Collections.addAll(list, b1, b2, b3);      //Error     for(Button b : list) {         list.remove(b);     }      //No Error     for(int i = 0; i < list.size(); i++) {         Button b = list.get(i);         list.remove(b);     }


linear mixed effect model splits variabel into two

I want to investigate if there is an interaction between "Group" and "Type" in my data. Type consists of "verbs" and "circumstantial information". "QCorrect" is performance.    Why does the model split Type up into verbs and circum (it is not supposed to do that)? Furthermore, what is the intercept?   I1 = lmer(Qcorrect ~ Group * Type + (1|ID), data = Sdata1)  summary(I1)  #Fixed effects: #                Estimate Std. Error         df t value Pr(>|t|)     #(Intercept)     8.095e-01  4.488e-02  4.140e+01  18.038   <2e-16 *** #Group          -2.381e-02  6.347e-02  4.140e+01  -0.375    0.709     #TypeVerb        1.190e-02  6.149e-02  3.200e+02   0.194    0.847     #Group:TypeVerb -1.057e-17  8.696e-02  3.200e+02   0.000    1.000


Create file in home directory from another directory

I know touch & echo for creating an empty file. But how can I create an empty file in the home directory in one line? I have tried touch ~/boo.txt but it's creating the file. I'm new to shell, I need to know two approaches of creating an empty file in Home directory from another directory. TIA


Let $a,b,c$ be positive real numbers such that $abc =1$

Let $a,b,c$ be positive real numbers such that $abc=1$. Prove that $$a^2+b^2+c^2\geq a+b+c$$. Also, state the condition for equality.  My Attempt,  $a,b,c$ are real and positive numbers,  then  $$(a-1)^2+(b-1)^2+(c-1)^2\ge 0$$ $$a^2-2a+1+ b^2-2b+1+c^2-2c+1\ge 0$$ $$a^2+b^2+ c^2-2(a+b+c)+3\ge 0$$.  I have made a start in this way, but I am not sure if this works. Please help me, with any simple and beautiful method.


How can I put a name's prefix in front in citations but *not* in the bibliography?

For my Dutch thesis I need to have the prefix to a name when using the \cite command but not in the bibliography. So basically what I need is     Cite: ‘De Jonge’      Bibliography: ‘Jonge, Marinus, de’   I cannot achieve this at the same time with biblatex, as it seems that I need useprefix=true for the citations and useprefix=false for the bibliography.  Can anyone help?


Give an example of a pair of real-valued function f and g defined on R for which f is not differentiable at 0, g is not differentiable at f(0)...

Give an example of a pair of real-valued function f and g defined on $\mathbb{R}$ for which f is not differentiable at 0, g is not differentiable at f(0) but for which $g \circ f$ is differentiable at 0.   I honestly can't even wrap my mind around this. So some hints would be helpful! Thank you!


No sound devices or input devices (Ubuntu 14)

So last night I turned my laptop off to go to sleep, I then turned it on this morning only to discover I have no sound devices (input and output).  I tried sudo Alsa force-reload and also tried reinstalling Alsa and Pulse Audio  Any ideas how to fix this problem?  edit: I think the problem is that pulseaudio wont load, any ideas how to fix it, tried reinstalling it already?


From where ls gets inode info in a deleted directory

I am not able to understand ls and cd behaviour in following case : Create directory a/b/c  $ mkdir a/b/c -p $ ls -lhRai .: total 324K 24512531 drwxrwxr-x  3 mayank mayank 312K May 22 16:23 . 24380771 drwxr-xr-x 34 mayank mayank 4.0K May 22 15:14 .. 25690305 drwxrwxr-x  3 mayank mayank 4.0K May 22 16:23 a  ./a: total 324K 25690305 drwxrwxr-x 3 mayank mayank 4.0K May 22 16:23 . 24512531 drwxrwxr-x 3 mayank mayank 312K May 22 16:23 .. 25690306 drwxrwxr-x 3 mayank mayank 4.0K May 22 16:23 b  ./a/b: total 12K 25690306 drwxrwxr-x 3 mayank mayank 4.0K May 22 16:23 . 25690305 drwxrwxr-x 3 mayank mayank 4.0K May 22 16:23 .. 25690307 drwxrwxr-x 2 mayank mayank 4.0K May 22 16:23 c  ./a/b/c: total 8.0K 25690307 drwxrwxr-x 2 mayank mayank 4.0K May 22 16:23 . 25690306 drwxrwxr-x 3 mayank mayank 4.0K May 22 16:23 ..   cd to innermost directory c  $ cd a/b/c   from another terminal, remove directory a, i.e.  $ rm -rf a   but ls is still getting inode info  $ pwd /home/mayank/Tmp/a/b/c $ ls -lai . total 0 $ ls -laid . 25690307 drwxrwxr-x 0 mayank mayank 0 May 22 16:23 . $ ls -laid  25690307 drwxrwxr-x 0 mayank mayank 0 May 22 16:23 . $ ls -laid ../ 25690306 drwxrwxr-x 0 mayank mayank 0 May 22 16:24 ../ $ ls -laid ../.. 25690305 drwxrwxr-x 0 mayank mayank 0 May 22 16:24 ../.. $ ls -laid ../../.. 24512531 drwxrwxr-x 2 mayank mayank 319488 May 22 16:24 ../../..   offcourse cwd file in /proc of bash is pointing to deleted dir  $ ls -l /proc/$$/cwd lrwxrwxrwx 1 mayank mayank 0 May 22 16:32 /proc/13125/cwd -> /home/mayank/Tmp/a/b/c (deleted)   Also, not able to understand cd behaviour  $ cd .. cd: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory     $ ls -li total 0 $ ls -lid 25690306 drwxrwxr-x 0 mayank mayank 0 May 22 16:24 . $ pwd /home/mayank/Tmp/a/b/c/.. $ cd .. cd: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory $ pwd /home/mayank/Tmp/a/b/c/../.. $ ls -lhid 25690305 drwxrwxr-x 0 mayank mayank 0 May 22 16:24 . $ cd ..     Tmp:$ ls -lhtrai total 320K 24380771 drwxr-xr-x 34 mayank mayank 4.0K May 22 15:14 .. 24512531 drwxrwxr-x  2 mayank mayank 312K May 22 16:24 . Tmp:$ cd - bash: cd: /home/mayank/Tmp/a/b/c/../..: No such file or directory   cd was not able to get parent dir info in c b , but a


Specification of my laptop are : CPU Intel Atom N450(1.66 GHz, 512 KB cache, 1 GB Memory. Which will be a suitable Ubuntu and how to install it?


I'm a little confused at the moment.  My back story in short, is that I'm trying to set up a Minecraft server on an Ubuntu server I've recently set up, obviously to do this I needed Java, but after googling for a short while I wasn't entirely sure whether it is possible (or legal?) to do so in Ubuntu 12.04 due to licensing type issues - so I installed open JDK instead which appears not to work properly with the Minecraft server software (I half expected this)  I'm now considering uninstalling open JDK and instead trying to get proper Java on there instead, my question is, is this possible? Is it Legal? And if so how do I go about doing it? Because I'm finding it very difficult to find any instructions on how to do so for 12.04 . . .


What are the implications of using /Zi vs /Z7 for Visual Studio C++ projects?

Background  There are several different  you can use with the Visual Studio C++ compiler. They are:   (none)   Create no debugging information Faster compilation times  /Z7   Produce full-symbolic debugging information in the .obj files using CodeView format  /Zi       Produce full-symbolic debugging information in a .pdb file for the target using Program Database format.  Enables support for minimal rebuilds (/Gm) which can reduce the time needed for recompilation.  /ZI       Produce debugging information like /Zi except with support for Edit-and-Continue    Issues   The /Gm flag is incompatible with the  (Visual Studio 2005/2008) If you want to enable minimal rebuilds, then the /Zi flag is necessary over the /Z7 flag. If you are going to use the /MP flag, there is seemingly no difference between /Z7 and /Zi looking at MSDN. However, the  states that you must use /Z7 to support parallel builds.   Questions   What are the implications of using /Zi vs /Z7 in a Visual Studio C++ project?  Are there other pros or cons for either of these options that I have missed?  Specifically, what is the benefit of a single Program Database format (PDB) file for the target vs multiple CodeView format (.obj) files for each source?   References


Is there any way to prevent an Android app from being removed?

Does anyone know if there's a way to either keep the user from uninstalling an app from an Android phone or reinstall it on removal? Before you flame me, please know that I have an app that's intended to be installed on the phone by a parent/employer/etc. and has a password-protected settings screen; the user would need to enter the password to remove the app.


How do I know if a moderator has checked an on-hold question after an edit?

If my question got put on hold and I edited my question, how do I know if the moderator checked the edited question and leaves it on hold, since it's still not amended to the extent it can fit into the scope of the site?


I have an HP 566 with Windows 8 installed. I removed it, and I wanted to install Windows 7. I have problems installing Windows 7.  In BIOS I can choose two boot modes:   Legacy boot mode   UEFI boot mode     If I chose the Legacy boot mode for some strange reason all of my Windows CDs stop booting at a certain point.  If I choose UEFI mode I enter the installation process, but cannot install Windows on the drives because they are GPT type. I tried converting them using diskpart, and I got an error that disks cannot be converted.   How to proceed? I am really stuck here.   If it makes things easier, Windows XP can also be installed.


What does the output of the command below mean? (result is positive integer)  echo $$


I was using wine while after a while tried to use an exe and outputted wine: Bad EXE format for Z:\"AN APP.exe" This is the only exe that did that, now I know it's because I need to use 32 bit version of wine, so I want to uninstall wine and install it as a debian package file instead of a tarball, deleted the .wine folder, tarball, everything and it didn't work. I already viewed tons of problems, and all the commands they suggest doesn't work, any help? I use kubuntu 18.04 by the way.


Prove $\frac{1}{n+1}\le \log\left(1+\frac{1}{n}\right)\le \frac{1}{n} ,\forall n\ge1$ if $\log x= \int_{1}^{x}\frac{dt}{t},x>0$

I know it is very simple but something is going amiss.  We can see here that $\log(1+\dfrac{1}{n})=\displaystyle \int_{n}^{n+1}\dfrac{dt}{t}$  if $t \in[n,n+1]$, $\dfrac{1}{n+1}\le\dfrac{1}{t}\le\dfrac{1}{n}$  I want to show that $\dfrac{1}{n+1}\le\displaystyle \int_{n}^{n+1}\dfrac{dt}{t}\le\dfrac{1}{n}$.  Can I straight infer that? If so what is the logic behind it? I was thinking of using $\displaystyle \Sigma_{i=1}^{n}$ and sandwiching $\displaystyle \int_{n}^{n+1}\dfrac{dt}{t}$ between. But confused !


I'm very new to Blender. I've used a loop cut and slide to make the shapes I want to indent in this object, then extruded them inward to get them how they look now, then dissolved the unnecessary leftover edges. I wanted to apply a bevel to some of the edges, so I used Tag Bevel in Edge Select Mode and marked the edges I wanted to Bevel, added the Bevel modifier and set the mode to weight.  On one side, it looks exactly how I want it:    On the other side though, some of the edges aren't being bevelled despite being tagged (the ones closest, on the left side):    Why is it working for every edge other than these ones? This is the wireframe of the object and it doesn't appear to be any different on the side that works to the side that does not:    And these are the bevel's settings just in case (I've tried fiddling with the width and it doesn't seem to have any effect. Incidentally, if I change limit method to None, those edges bevel fine):


Copy contents of one List into another List (not reference)

I have two List :  List<Object> listA = new ArrayList<Object>(); List<Object> newListB = new ArrayList<Object>();   How can i copy the contents of listA into newListB such as if i change one of the elements in my copied list, i dont want to change it in my original list.


Why $\mathbb Z_2\otimes_{\mathbb Z}\mathbb Z_3\cong \{0\}$?

I just stated tensor product, and I have problem to see how it works. So, why $$\mathbb Z_2\otimes_{\mathbb Z}\mathbb Z_3\cong \{0\}\ \ ?$$


Proving that $\mathbb{Z}_2\times \mathbb{Z}_2$ and $\mathbb{Z}_4$ are not isomorphic

How can I show that $\mathbb{Z}_2$$\times$ $\mathbb{Z}_2$ and  $\mathbb{Z}_4$ are not isomorphic?   I don't even know how to start  Thanks for any help


(I have a feeling that this question may be off-topic here because it is so utterly, enormously basic, and hardly related to engineering at all. Please bear with me...)  My phone came with a power cable that outputs 1 ampere. I have a different cable that outputs 2.1 ampere, which can be plugged in in a car's cigarette lighter socket. Is there a chance of damaging the phone in case I use the second cable? If not, why is this? Is it because an "overdose" in current simply does no harm, or because the difference is too small?


Common term or single word for someone who is embarrassingly over-complimentary

Does English have a word for someone who compliments another person in a way which is awkward or even embarrassing?    Someone who uses compliments which are overly-familiar and all but inappropriate, and praises someone they barely know in over-the-top fashion?


How to set bounties in the Stack Exchange app

I often use an app to access SE/SO. Sometimes I see some post on Stack Overflow that didn't get much attention, so I want to use my reputation to set the bounties while I am on an app (Android). I couldn't find the bounty button. Where is the bounty button?


How can I enable the wifi connection on HP Pavilion Notebook 8216 83.13?

I can't find the wifi option in my Ubuntu system.   $ iwconfig  lo     no wireless extensions eno1   no wireless extensions   I have tried:   Installing new Ubuntu updates. (This only enabled bluetooth access)  Tried additional-drivers: it has NVIDIA updates only.  I read somewhere to check rfkill list all command and it shows results for bluetooth only. So I couldn't do anything further I disabled secure boot, no change   Hardware:  $ lspci -knn | grep -iA3 net 03:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8101/2/6E PCI Express Fast/Gigabit Ethernet controller [10ec:8136] (rev 0a)     DeviceName: Realtek PCIe FE Family Controller     Subsystem: Hewlett-Packard Company RTL8101/2/6E PCI Express Fast/Gigabit Ethernet controller [103c:8216]     Kernel driver in use: r8169     Kernel modules: r8169 05:00.0 Network controller [0280]: Intel Corporation Device [8086:24fb] (rev 10)     DeviceName: Intel Dual BandWireless-AC 3168 802.11 ac 1x1 WiFi + BT 4.0 Combo Adapter     Subsystem: Intel Corporation Device [8086:2110]


For example I want to change  "'this text'" "that text" 'other_text'   into  'this text' "that text" 'other_text'   I tried  sed -e 's/^"\'/"/g'   but my quoting must be off.  Ubuntu.


I want to make an attendance sheet in Excel. If a child is present, the teacher will write P in a cell, or A for absent. I have to add l (which indicates  a latecomer) in addition to attendance. So an entry with both P and l must also be counted in total days present; I want to get the number of P and l in a range to calculate total number of days in the month each child was present.   How can I accomplish this?


Who is responsible to align all Warhammer 40k books or stories?

Given that Black Library offers an enormous number of books, I was wondering what the process looks like which ensures that all the stories do align nicely and do not contradict each other.  Is there a review board which checks new books? How does e.g. Dan Abnett know what to write and so it does not contradict what Guy Haley writes? Is there a committee which desires how certain stories will develop?


Validity of gauge fixing in classical electrodynamics

I am working through Griffith, and was confused by some of the restrictions he imposed on the potentials in introducing the Coulomb and Lorenz gauge.   It is easy to see that adding some arbitrary gradient field $\nabla\lambda$ to the vector potential and subtracting the derivative $\frac{\partial\lambda}{\partial t}$ from the scalar potential will not change the electric and magnetic fields. But following this introduction, he fixes the value of the divergence of A, not A itself, assuming at least without proof that there always exists a gradient field such that $\nabla\cdot\left(A+\nabla\lambda\right) = 0$. Is this always true? And furthermore, he never adds that $\nabla\lambda$ to any of the other occurrences of the vector potential in the equation, nor does he subtract the time derivative of the field from the scalar potential. If we're using the equation  $$\left(\nabla^2A -\mu_0\epsilon_0\frac{\partial^2 A}{\partial t^2}\right)-\nabla\left(\nabla\cdot A + \mu_0\epsilon_0\frac{\partial V}{\partial t}\right)=-\mu_0 J$$  To calculate the value of the vector potential, doesn't changing the value of A and the time dependence of V matter? Why are we not forced to solve for lambda?


Provided $f$ is continuous at $x_0$, and $f(x+y) = f(x) + f(y)$ prove $f$ is continuous everywhere.

My attempt...    By definition, whenever $|x- x_0| < \delta$ we have $|f(x) - f(x_0)| < \epsilon$. Observing that    \begin{align}  |f(x) - f(y)| &= |f(x -x_0 + x_0) + f(y)| = |f(x-x_0) + f(x_0) - f(y)|  \newline \newline &\leq \epsilon + |f(y) - f(x_0)| = \epsilon + |f(y-x_0)|... \end{align}      Here I need to choose a delta that can depends on $\epsilon$ and $y$ s.t. whenever $0<|x-y|< \delta$ then the above inequality is bounded by any $\epsilon$.     I'm also, in general, having trouble understanding this concept of continuity on an interval. I believe the structure of the definition is: for any $\epsilon> 0$ and any number $y$ in the interval, there exists a $\delta$ that depends on $\epsilon$ and $y$ such that for all $x$ in the interval and $|x - y | < \delta$ then $|f(x) - f(y)| < \epsilon$.     This definition makes me tempted to just choose y to be in the same delta neighborhood as $x$ in the given statement, but that constricts continuity to a small interval.    Edit: This question assumes no knowledge of Lebesgue measure theory.


Showing that only $(n+1)^{n-1}$ of all the possible $n^n$ choices assure a full car park

This exercise is taken from the site of Queen Mary University of London:  A car park has $n$ spaces, numbered from $1$ to $n$, arranged in a row. $n$ drivers each independently choose a favourite parking space in the park. As each driver enters the park, he drives to his favourite space. If it is empty, he parks there. Otherwise, he continues along the line and parks in the first free space. If all spaces between his favourite and $n$ are taken, he leaves in disgust. Show that, out of the $n^n$ choices of favourite spaces that the drivers can make, just $(n+1)^{n-1}$ lead to all drivers parking successfully.  Now, my question is whether my (attempt of ) solution is wrong and what a different approach could be. Here's my idea: proving the claim by (a kind of) induction. It is easy to verify truthfulness for $n=1$ and $n=2$, so having this base case, we shall prove that if the claim holds for all $1\le n\le k$, then it does also for $n=k+1$. Let us assume WLOG there is an already established order of appearance of the drivers, since a different order yields the same number of successful choices: it just suffices to swap the drivers. Let us call $d_m$ the space chosen by the $m$-th driver. Now, consider the cases in which $d_1=1$. By inductive hypothesis, the other drivers have $n^{n-2}$ successful choices. In fact, the same goes for all the other $n-1$ choices of the first driver, so that in total, as a "first outcome", we have $\color\red{n^{n-1}}$ successful choices. We somewhat can do the same reasoning with the second driver, but we must keep in mind that for each of his choices, we have already counted those in which the first driver occupies the other spaces. For example, we need to subtract the successful cases in which at the same time $d_2=1$ and $d_1=2$: that is $(n-1)^{n-2}$. This happens for all the spaces not chosen by the second driver, and so we actually need to subtract $(n-1)^{n-1}$. Finally, letting vary $d_2$ yields the "second outcome" $\color\red{n^{n-1}-n(n-1)^{n-1}}$. And so on, and so on. The final outcome would be the sum of all the red expressions. However I'm afraid no nice power would be a result of this. Is there a mistake in my reasoning?


I am working with ArcMap 10.3.  I have imported DEM files.  When I imported the files they had the extension of .DDF.  I would now like to be able to take a list of XY coordinates and, for lack of a better term, merge them with the DEM files so that I can get the elevation of any given point.  I imported XY Data and projected it with the NAD 1983 coordinate system.  But, I can't figure out how to "combine" the 2 layers to get the elevation of my XY points.  I can right click on the map and click "Identify..." and get the elevation, but that's about it.  Also, if there is a way to do this without the Spatial Analyst extension, that would be great.  I am supposed to have it on my license, but for whatever reason I don't and need to know if there is a way to do this without it.