Why Does No One Remember Past Invasions In Doctor Who?

After watching the recent New Year's episode (Resolution), something has been bothering me. A Dalek is encountered on Earth in 'present' times and attempted extermination ensues. Nothing that shocking there, except that everyone aside from the Doctor reacts as if they have never seen or even heard of a Dalek before. Thinking about it more, this seems to happen on most occasions when a recurring threat shows up on Earth. Outside of the Doctor and perhaps a few government types, everyone reacts as though this is a completely novel situation. That in spite of the fact that the menace of the day has tangled with planet Earth within the living memory of these people (multiple times in the case of Daleks and some other popular foes).  I can understand smaller events that happen in isolated places or only affect a small group of people. Those could be covered up or simply dismissed as a hoax. In the case of the Daleks though, they have staged mass scale invasions on a global scale on multiple occasions. Kind of hard to forget millions of murderous pepper pots dropping out of the sky.  I understand why the show does this from a story perspective. Companions are the audience proxy, so they need to be in the dark to provide an excuse to explain things to the audience. Likewise, any serious efforts by Earth to protect itself from 'next time' would undermine the need for the Doctor to show up and save the day.  What I'm interested in is whether there has ever been an in-universe explanation? Do human beings just have the memory of a goldfish or is something else going on?


GeoJSON from react-leaflet doesn't render the layer over the map

I have a GeoServer running on my localhost also I have a react app which consumes a WFS service to get a GeoJSON data to render as a layer over the map.  These are my dependencies on my package.json  "axios": "^0.19.0", "leaflet": "^1.5.1", "react": "^16.8.6", "react-dom": "^16.8.6", "react-leaflet": "^2.4.0", "react-scripts": "3.0.1"   And this is my HomePage.js in my react app  // @packages import React, { PureComponent } from 'react'; import axios from 'axios';  import {     GeoJSON,     Map,     TileLayer } from 'react-leaflet';  // @constants const GEOSERVER = 'http://localhost:8080/geoserver/wfs';  const REQUEST_PARAMS = {     outputFormat: 'application/json',     maxFeatures: 250,     request: 'GetFeature',     service: 'WFS',     typeName: 'gaia:mining_titles',     version: '1.0.0' };  class HomePage extends PureComponent {     constructor() {         super();         this.map = null;         this.state = {             center: [6.217679, -75.570648],             data: null,             zoom: 8         };         this.handleOnMapMounted = this.handleOnMapMounted.bind(this);     }      componentDidMount() {         axios.get(GEOSERVER, { params: REQUEST_PARAMS })             .then(({ data }) => this.setState({ data }))             .catch(error => Promise.reject(error));     }      handleOnMapMounted(evt) {         this.map = evt ? evt.leafletElement : null;     }      render() {         const {             center,             data,             zoom         } = this.state;          return(             <Map                 center={center}                 id="home-page-map"                 ref={this.handleOnMapMounted}                 zoom={zoom}             >                 <TileLayer                     url="https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png"                     attribution="&copy; OpenStreetMap contributors"                 />                 <GeoJSON data={data} />             </Map>         )     } }  export default HomePage;   When the componentDidMount is called the data is set on the state but doesn't render anything and doesn't show errors it just nothing happens.  I already enabled the CORS configuration on my web.xml from my GeoServer  EDIT:  This is the response from the GeoServer  {"type":"FeatureCollection","features":[{"type":"Feature","id":"mining_titles.4133","geometry":{"type":"MultiPolygon","coordinates":[[[[689969.6239,566781.7359],[689969.6246,566381.7341],[690169.6234,566381.7345],[690169.6237,566231.7353],[689873.623,566283.7334],[689757.6244,566421.7352],[689757.6241,566621.734],[689835.6237,566781.7357],[689969.6239,566781.7359]]]]},"geometry_name":"geom","properties":{"id":4133,"objectid":1,"oid_":9918,"id_1":4133,"codigo_exp":"HCS-152","codigo_rmn":"HCS-152","codigo_ant":"HCS-152","fecha_cont":"2006-06-29Z","fecha_insc":"2007-05-17Z","grupo_trab":"PAR PASTO","estado_exp":"TITULO VIGENTE-EN EJECUCION","modalidade":"CONTRATO DE CONCESION (L 685)","minerales":"MATERIALES DE CONSTRUCCION","titulares":"(69021277) CLAUDIA CECILIA BETANCOURT YEPES\\ (12972275) GERMAN NAZARENO BETANCOURT PANTOJA","municipios":"ORITO-PUTUMAYO","fecha_term":"2037-05-16Z","shape_leng":1742.81141444,"shape_area":118628.3028,"grupo":null}}],"totalFeatures":8861,"numberMatched":8861,"numberReturned":1,"timeStamp":"2019-07-16T16:39:34.595Z","crs":{"type":"name","properties":{"name":"urn:ogc:def:crs:EPSG::3116"}}}


Using bootstrap modals, I keep running into the issue of having an info modal with content inside of it, but there's a need to have a "confirm your decision" modal/popup on top of the initial modal.   E.g. I have a page with a list of users. You can click on a user to open a modal with user info inside of it. Then there will be maybe a "remove user" button in the modal that requires a "confirm remove user" modal.  Is it ever a good idea to have a modal on top of another modal or am I using modals wrong? Should I use actual pages instead?


Is it possible to convert ArcGIS .mxd to QGIS .qgs without having ArcGIS installed?

I was reading .   It looks as though this only works with ArcGIS 10.   I would like to do this, but am unable to install things on the computer that has ArcGIS.   Is there a way to import to QGIS without using mxd2qgis (that requires ArcGIS 10)?


Pointwise convergence of $h_{n}(x)=x^{1+\frac{1}{2n-1}}$

The following statement appeared in my textbook:     Consider $h_{n}(x)=x^{1+\frac{1}{2n-1}}$ on the set $[-1, 1]$, for a    fixed $x \in [-1, 1]$, we have $\lim_{n \rightarrow \infty} h_n(x) =  |x|$.   Can someone explain why $\lim_{n \rightarrow \infty} h_{n}(x) = |x|$? Specifically, where did the absolute value sign come from? What limit laws/rules are used to obtain this result?  I would have thought $\lim_{n \rightarrow \infty} h_n(x) = x \lim_{n \rightarrow \infty} x^{\frac{1}{2n-1}} = x$?  EDIT: I had a look at the other question suggested, but my question is different because I want to know the exact limit laws used in each step of the justification that $\lim_{n \rightarrow \infty} h_n(x) =  |x|$.


I am a relatively new Ubuntu user having been using 16.04 on an ancient HP laptop.  I have now been bought a new Lenovo "Idea Centre" by my wife but would like to at least have Ubuntu installed as dual boot (initall) however I hae read some horror stories about issues with 17.10 and Lenovo pc's being irredeemably screwed up when Ubuntu is installed as a dual boot.  Has this issue been fixed ?  Am I safe to install 18.?? on my new Lenovo ?


Alex likes neither candy nor cake.   Alex don’t like candy and cake.      What is the difference in meaning between these two sentences?


What is the Alternate Universe's Fringe Division logo derived from?

Something seems very familiar about this logo, but for some reason I can't quite pin it down.  Is there a particular organization, real-life historical or fictional, from which this insignia might have been derived?  The particularly familiar-looking bits are large, red-on-black "F"s, back-to-back.  I'm not sure if they're familiar because they're opposing red letters, or because they resemble a pair of red wings outstretched, or perhaps they look like some other shape I've seen somewhere on some government or military organization's banner or insignia.  References from primary canon or official commentary or documentation are preferred, but I also welcome reasonable speculation.  Aside from simple demonstration or explanation of semblance, it would be good if any such speculation also included a logical reason for the similarity.


Constant sectional curvature and the Riemann tensor

I am trying to prove the theorem that:  Let $(M,g)$ be a Riemannian $n$-manifold of constant sectional curvature $C$. Then the curvature tensor is $R(X,Y)Z=C( \langle Y,Z \rangle X - \langle X, Z \rangle Y)$.  I can show by straight-forward calculation (using the definition of sectional curvature) that if the curvature tensor is as stated, then $M$ has constant sectional curvature.  But the other way around is giving me some trouble. Does anybody have a hint?


How to fix 'No matching function for call to 'strtok''

I'm trying to use the function strtok to tokenize an input from the user and then print out the result with new lines between each word. However, this error pops up.  #include <iostream> #include <stdio.h> #include <string.h>  using namespace std;  int main() {     string str;     char *tokenPtr;      cout << "Enter a sentence : " << endl;     getline(cin, str);      tokenPtr = strtok( str, " " ); // ERROR: No matching function for call to 'strtok'     while( tokenPtr != NULL ) {         cout << tokenPtr << endl;         tokenPtr = strtok( NULL, " " );     }      return 0; }


How did Lucius Malfoy know Sirius's Animagus form?

In Order of the Phoenix, Snape eggs on Sirius at Grimmauld Place:  ‘Tell me, how is Lucius Malfoy these days? I expect he’s delighted his lapdog’s working at Hogwarts, isn’t he?’ [Sirius] ‘Speaking of dogs,’ said Snape softly, ‘did you know that Lucius Malfoy recognised you last time you risked a little jaunt outside? Clever idea, Black, getting yourself seen on a safe station platform ... gave you a cast-iron excuse not to leave your hidey-hole in future, didn’t it?’ Order of the Phoenix - Chapter twenty-four, Occlumency - Page 460 - Bloomsbury  How did Lucius Malfoy know that Sirius was a dog Animagus? How did he know it was Sirius in the train station? Some facts to consider: According to the 's timeline, the characters who are considered to be of the Marauders era (born 1959) were only five years younger than Lucius Malfoy (born 1954), so Sirius and Snape, and the other Marauders-era students, and Lucius Malfoy, would have been at Hogwarts together for two years. Prisoner of Azkaban demonstrates it took Sirius, James, and Peter four to five years to master the Animagus transformation, which would have been at least two years after Lucius Malfoy would have left Hogwarts (Although we don't know when Lucius became a school governor.). A canon-based answer would be great; barring one, a speculative answer in the spirit of canon is welcome.


In the twin paradox from what I understand both observer see each other's time dilated so they always believe that the other frame is younger. Finally because the space ship frame has to make many accelerations it results that he will be younger. However, what if the frame in the space ship doesn't have to make any accelerations to come back to earth and could simply just come back like if the space was a looped or that there was a wormhole , so in this case who would be younger ?


I'm having trouble understanding why inductive proofs are logical

I am new to Mathematics, reading books in my free time. I have recently learned about proving Mathematical propositions by induction. I am having a bit of trouble understanding the process and why it is logical.  I have learned that if you have a statement $A$, and you assume $A_{n}$ is true, then you can prove $A$ is true for all numbers greater than $n$ by showing that $A_{n+1}$. I don't understand this because from my point of view it looks like you only proved $A$ is true for $n$ and $n + 1$.  Maybe I am missing something, or maybe I need a formal introduction to logic. I never read anything about philosophy or logic before learning Mathematics, but if reading about logic would help me understand proofs better I would be glad to.


How to delete gamer profiles from an Xbox 360?

I can't figure out how to delete gamer profiles off my Xbox 360. I have a few profiles that were duplicates and some that aren't used. Is it possible to delete them?


Intuition behind Lagrange's Theorem in Group Theory?

I'm taking an introductory unit on Group Theory at uni and very much enjoy the geometric intuition and interpretations behind the core ideas about groups, however I cannot wrap my head around Lagrange's Theorem, stated in our notes as      Let G be a finite group, and H a subgroup of G. Then |H| divides |G|.   The problem for me comes from the idea of cosets, and how they work. Our notes state that every element of G is in exactly one of the cosets, but if the cosets are the compositions of every element of H (which are therefore also in G) and an element of G then isn't every element in each coset an element of G? I can't convince myself of why an element of G can't be in multiple cosets. There is a proof provided showing that two cosets only intersect non-trivially if they are equal which I can follow without problem, but when I try to convince myself of why they don't intersect I can't explain it abstractly at all.  Any help would be appreciated.


Find all groups of order 121 up to isomorphism

Find all groups of order $121$ up to isomorphism.  if i'm right, all such groups are abelian groups, since this is $p^2$ for $p$ = $11$ and $11$ is prime.  there's only one, isn't there? isn't it just $\mathbb{Z}_{121} $ which is isomorphic to $\mathbb{Z}_{11} \times \mathbb{Z}_{11}$ ?


I've seen that my system has a two kind of rootkits: SHV4 / SHV5. (I'm going to add a log here)  I tried to remove it but I could not.   Can anybody recommend me any way to do it?  [ Rootkit Hunter version 1.3.8 ] Checking system commands... /usr/bin/md5sum                                          [ Warning ] /usr/bin/pstree                                          [ Warning ] /usr/bin/top                                             [ Warning ] /usr/bin/unhide.rb                                       [ Warning ] /sbin/ifconfig                                           [ Warning ] /bin/ls                                                  [ Warning ] /bin/ps                                                  [ Warning ] /bin/netstat                                             [ Warning ]  Checking for rootkits...  cb Rootkit                                               [ Warning ] SHV4 Rootkit                                             [ Warning ] SHV5 Rootkit                                             [ Warning ] Checking for possible rootkit strings                    [ Warning ]  Checking the local host...  Checking for root equivalent (UID 0) accounts            [ Warning ] Checking for passwd file changes                         [ Warning ] Checking for group file changes                          [ Warning ] Checking if SSH root access is allowed                   [ Warning ] Checking for running syslog daemon                       [ Warning ]  Checking the local host...  Checking for root equivalent (UID 0) accounts            [ Warning ] Checking for passwd file changes                         [ Warning ] Checking for group file changes                          [ Warning ] Checking if SSH root access is allowed                   [ Warning ] Checking for running syslog daemon                       [ Warning ]   Do you need other kind of log file?  Thanks in advance


How many possible combinations in 8 character password?

I need to calculate the possible combinations for 8 characters password. The password must contain at least one of the following: (lower case letters, upper case letters, digits, punctuations, special characters).  Assume I have 95 ascii characters (lower case letters, upper case letters, digits, punctuations, special characters).   lower case letters = $26$ upper case letters = $26$ digits = $10$ punctuations & special characters = $33$   The general formula for the possible passwords that I can from from these 95 characters is: $95^8$.  But, accurately, I feel the above formula is incorrect. Please, correct me. The password policy requires at least one of the listed above ascii characters. Therefore, the password possible combinations = $(26)*(26)*(10)*(33)*(95)*(95)*(95)*(95)$  Which calculation is correct?  EDIT: Please, note that I mean 8 characters password and exactly 8. Also, There is no order specified (i.e. it could start with small letter, symbol, etc.). But it should contain at least one of the specified characters set (upper case, lower case, symbol, no., etc.).


Is it possible to make sense of an unknown language by means of cryptanalysis?

I was wondering if it was possible to make any sense from an unknown language by using cryptanalysis. My premises are: suppose an analyst that knows nothing about a language (let's suppose chinese but it can be any other as long as it totally unknown to the analyst), but you do know it's a language (in order to avoid responses like ) and you can have as much samples of the language as you want (imagine literature, tweets, newspapers, ...)  EDIT: This question came to my mind because I read some time ago about how Americans in WWII used  speakers to carry coded messages, hence my interest in trying to solve the problem by cryptanalysis. Also, I'm aware that navajo isn't a written language, but I wanted to assume it in my example for simplicity


def multipliers():     return [lambda x: i * x for i in range(4)]   print([m(1) for m in multipliers()]) # [3, 3, 3, 3]   Why it's not [0, 1, 2, 3]? Can't understand. So, for some reason we have i = 3 in all lambdas? Why?


If I wanted to say: this folder contains the links to all the programs,  should I use: this folder contains the program links or this folder contains the programs links ?


Which of the following statesment are true?   there exists a finite field in which additive group is not cyclic $F$ is a finite field then there exist a polynomial $p$ over $F$ such that  $p(x) \ne0$ for all $x\in F$, where $0$ denotes zeros of $F$ Every finite field is isomorphic to a subfield of the field of complex numbers


How to prove the midpoint of a chord is also the midpoint of the line segment defined by the points of intersection of other two chords with it?

Bernhard Elsner, alias MathOMan, posted this exercise in plane Geometry,  on January $29$th, $2010.$  "Let $\mathcal{C}$ be a circle, $A,B$ two distinct points on $\mathcal{C}$ and $M$ be the midpoint of the chord $[AB]$. Take two other chords,$[PQ]$ and $[SR]$, that pass through $M$. Let $C$ (resp. $D$) be the intersection of $[AB]$ with $[PS]$ (resp. $[RQ]$). Prove that $M$ is the midpoint of the chord $[CD]$."    To prove it I've written the following (failed) argument, in the  of this post (translation of mine):    The figure is symmetric with respect to $M$: $\overline{AM}=\overline{MB}$, $\overline{PM}=\overline{MU}$, $\overline{RM}=\overline{MW}$, $\overline{QM}=\overline{MV}$, $\overline{QR}=\overline{VW}$, $\overline{SM}=\overline{MT}$. From $\dfrac{\overline{SC}}{\overline{DT}}=\dfrac{\overline{CM}}{\overline{MD}}=1$ follows that $\overline{CM}=\overline{MD}$.  Here is an extract of the author's reply (translation of mine):   "It is not clear that  $\overline{QM}=\overline{MV}$. Is the point $V$ on the line $(QM)$ defined by this equality or is $V$ defined as the intersection point of the lines $(QM)$ and $(WC)$? Why are both definitions to give the same point?  Let $C^{\prime }$ be the intersection of $(SP)$ and $(VW)$, and $D^{\prime }$ the intersection of $(TU)$ and $(QR)$. (...)  One still has to show that $C^{\prime }=C$ and $D^{\prime }=D$."   I have agreed with these objections.  Until now no proof has been posted. The author considers that the "proof is not quite simple".  Q. What is the theorem this exercise refers to? Or how does one prove it?


My son turns one in five days. Since yesterday he has started turning his head and blocking our attempts to bring a spoon or fork up to his mouth.   Sometimes he will open his mouth and let us put food in it. This is quickly followed by him pushing all of the food out of his mouth and grabbing what he can with his hand. He then drops the food on the floor.   I thought he was wanting to feed himself, but handing him the food results in a similar trip to the floor.   My wife took him to the pediatrician today because we thought he might be sick but the doctor didn't find anything (our son was happy and playful for him) and used the opportunity to do his one year checkup. He said everything was fine, but our son still doesn't want to eat.   He drinks from his sippy cup for a few seconds before pushing it away, too.   I think this may be my fault as I fed him a bite if my food last week during dinner that had Tapatio sauce on it. I wasn't trying to hurt him, but he was visibly uncomfortable with the bite. If I'm the reason this is happening, I'm ready to receive my "Worst Dad of the Year" mug.   Why won't he eat?


Allow non-root process to listen on port 80 without doing anything drastic

For reasons beyond my comprehension, GlassFish refuses to play ball with iptables. That is, with all the correct redirection rules in place, it won't receive any redirected traffic. So I'm at plan B which is to bind GlassFish to ports 80 and 443 rather than 8080 and 8181.  As I don't want to run GlassFish as root for security reasons, I need to grant the user account that is running it with sufficient privileges to bind to ports 80 and 443. From a security point of view, it's not risky because iptables is blocking all the other ports.  In Centos 6.4, what command(s) do I execute to allow a specified non-root user to directly listen to ports < 1024?  Please don't suggest drastic solutions that involve downloading (and compiling) stuff from random locations. I need something reproducible, so if any dependencies need to be brought in, they need to come from Centos's package repository.


I want to really understand the Euclidean Algorithm. A key component in the algorithm is fact that common divisors of two integers are common divisors of their difference. I can see from the perspective of symbolic manipulation that for all common divisors of $a$ and $b$: $d|a \land d|b$ means $a = kd \land b = ld \therefore a - b = kd - ld = (k - l)d$. The trouble is, this doesn't convince me. I need am image or some way of grasping this beyond just the symbols. The same for the rest of the algorithm. I get that the division/modulo version is really just applying subtraction multiple times, so understanding the subtraction part should help with that. Then there is the issue of the last non-zero remainder being the GCD. Again, I can kind of understand via algebraic proof, but it's not convincing for me. I wouldn't bet much money on being able to convince an expert that I really understand. So, any and all visual proofs, intuitions etc. that don't rely on that vertical list of divisors becoming dividends and remainders become divisors would be much appreciated.


I tried to install mysql server and mysql workbench with Ubuntu software center but It could not install them. Then I used command line to install mysql server and I run the following code repectivly:  sudo apt-get update && sudo apt-get upgrade sudo apt-get install mysql server   But,I got the following error after the last command:  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: mysql-server : Depends: mysql-community-server (= 5.6.24-1ubuntu14.10)   but it is not going to be installed E: Unable to correct problems, you have held broken packages.   How can I solve this problem? IS there any simple way to install mysql server and mysql workbench?  These are all mysql version on my computer:  `apt-cache search mysql|egrep '^mysql'  mysql-client-5.5 - MySQL database client binaries  mysql-client-core-5.5 - MySQL database core client binaries  mysql-server-5.5 - MySQL database server binaries and system database    setup  mysql-server-core-5.5 - MySQL database server binaries  mysql-client-5.6 - MySQL database client binaries  mysql-client-core-5.6 - MySQL database core client binaries  mysql-common-5.6 - MySQL 5.6 specific common files, e.g. /etc/mysql/conf.d/my-5.6.cnf  mysql-mmm-agent - Multi-Master Replication Manager for MySQL - agent daemon  mysql-mmm-common - Multi-Master Replication Manager for MySQL - common files  mysql-mmm-monitor - Multi-Master Replication Manager for MySQL - monitoring daemon  mysql-mmm-tools - Multi-Master Replication Manager for MySQL - tools  mysql-proxy - high availability, load balancing and query modification for mysql  mysql-server-5.6 - MySQL database server binaries and system database setup  mysql-server-core-5.6 - MySQL database server binaries  mysql-source-5.5 - MySQL source  mysql-source-5.6 - MySQL source  mysql-testsuite-5.5 - MySQL testsuite  mysql-testsuite-5.6 - MySQL 5.6 testsuite  mysql-utilities - collection of scripts for managing MySQL servers  mysql-workbench - MySQL Workbench - a visual database modeling, administration and queuing tool  mysql-workbench-data - MySQL Workbench -- architecture independent data  mysqltcl - interface to the MySQL database for the Tcl language  mysqltuner - high-performance MySQL tuning script  mysql-apt-config - Auto configuration for MySQL APT Repo.  mysql-client - MySQL Client meta package depending on latest version  mysql-common - MySQL Common  mysql-community-bench - MySQL Bench  mysql-community-client - MySQL Client  mysql-community-server - MySQL Server  mysql-community-source - MySQL source  mysql-community-test - MySQL Test Run MTR - The MySQL testsuite  mysql-server - MySQL Server meta package depending on latest version  mysql-testsuite - MySQL Testsuite meta package depending on latest version  mysql-workbench-community - MySQL Workbench


Lockscreen widget default to expanded on Android 4.3 or upcoming 4.4

Does anyone know if there is a configuration to allow the lockscreen widget to default to expanded view on Android 4.3 or higher?  I have a Note 3 and have not yet received the 4.4 update.  I prefer NOT to use a 3rd party app.  My preference is to use the stock email widget, but have it in expanded mode by default.


Let $\Omega$ a bounded domain, connexe and regular, and let $f \in L^2(\Omega).$ Let the variational problem: Find $u \in H^1(\Omega)$ such  $$\int_{\Omega} \nabla u \nabla v dx + (\int_{\Omega} u dx)(\int_{\Omega} v dx) = \int_{\Omega} f v dx, \forall v \in H^1(\Omega)$$ 1- Prouve that this variational problem admits a unique solution in $H^1(\Omega).$  2- Deduce the boundary problem associate to this variational problem ( study the two cases $u \in  H^2(\Omega)$ and $u \notin H^2(\Omega)$.  I dont't understand in the question 2, why we mus study the two cases $u \in H^2$ and $u \notin H^2$?


Design a question (addressing the chronological order involved) which is answered by say 'Abraham Lincoln was the 16th president of the United States'

In my native language of Malayalam, we have a word 'എത്രാമത്തെ' which denotes the chronological number/position  of something. It crudely translates to 'How much'th'. As far as I know there is no English equivalent to this word. Can you design a question, whose answer would be the above? A question that addresses the chronological part (16th president); Feel free to be creative. The answer is NOT, "Who was the 16th president of the Unites states'' The closest that I have come with the intended meaning is Word to word Malayalam to English translation: 'Abraham Lincoln was the 'how much'th' president of the Unites States?' A more cohesive translation would be: 'Chronologically, what number does Abraham lincoln occupy, in the line of US Presidents'


Cryptographically secure PRNG from a hash function

Is it possible to get a secure random number generator from a secure hash function this way  First choose a natural number $n$ as seed, then if we are looking to generate random numbers from $0$ to $F$ (in hex), the first in the sequence is the last digit in the hash of $n$, the second in the sequence is the last digit in the hash of $n+1$, and so on. Does this  make a secure PRNG.


Showing that $\lvert H K\rvert = \frac{| H\| K|}{ |H\cap K|}$

I have seen a proof that for two subgroups $H$ and $K$ of a finite group $G$, $$ |H K| = \frac{| H\| K\rvert}{| H\cap K|} $$ The proof counts the number of elements $hk$ that are the same as $h'k'$ for $h,h'\in H$ and $k,k'\in K$. I got confused with this proof.  My question is if there is another way to make things like this more clear. For example, I know that if one has a surjective homomorphism $f:G \to H$ then $\lvert G\rvert / \lvert \ker f\rvert = \lvert H\rvert$. That is, one can count the number of elements in something by essentially finding the order of the kernel of a map. This looks like what is going on with the product $HK$. But I guess that $HK$ in general isn't a group, so one can't talk about a group homomorphism.  Is there a way to find the "kernel" of a general function and get something like the first isomorphism theorem? All I would be interested in is how this can be used to count things.


Why does "deleted recent questions" not appear for users who have asked only one question?

A user asks a question. It gets downvoted.(to oblivion) And then gets deleted by a mod.     This question should then be accessible to the user in the "deleted recent questions" link but this doesn't happen.    If a user has asked only one question (which gets deleted) then this link goes missing. Only after asking another question (which must not get deleted), is the user able to see that link.     Is this a bug or a new-user-restriction?


How do I install linux on my computer without using a usb or cd?

I want to give my computer to my friend. He doesn't know how to use Windows, only Linux.   I would not like to keep windows on the system. The computer's BIOS does not support USB start-up. Also, I don't have a disk that has a large enough space to have the ISO image on it.  Help anyone?  Thanks, djtravz


Integer overflow: Why doesn't something similar to "checked" from C# exist in C?

Integer arithmetics in C# can be set to throw an  using checked, as in the following example:   int a = foo(); int b = bar() int result = checked(a * b); // Will result in OverflowException if this overflows   I'm currently getting more into C programming and just found a bug that was due to an integer overflow - which would have been much more easier to find with something like checked - and I ask myself: Why is nothing similar implemented in C? Can someone explain it to me or point me out (some standard reference, etc.) where it is stated why such a construct is not part of the C language?   Or am I completely wrong and there is some built-in functionality to check for (integer) overflows on arithmetic operations?


Where can I find Frost, when I lost him? I last remember leaving him at Riften Stables, 8-9 days later I went back there and he was gone! So he isn't there, like I had so much weight on me I was at Hog Rock Redoubt near Markarth and I headed to Whiterun Stables and bought a horse and wanted to see if Frost was at Riften Stables - he wasn't. So can anyone please help me find Frost?


We are going to fly  this May to Russia From Canada,  Russian citizens.  We have 2 stops in China, Beijing and Harbin, on the way ther spend 14 hours in China, on way back 26 hours. From Harbin to Russia we have different travel providor. Do we need  transit visas  on our way there or back? now since 2019 you have to give your fingerprints taken in Toronto. Is this really needed for transiting through China?  Could  somebody give me the phone number in China with service in English, so I can hear the answer? so far as I called nobody spoke English


can my transit visa take me through munich and frankfurt?

I am going to Nigeria from Mexico but i do have an airport transit visa but i have to stop first in Munich then take a connecting flight to frankfurt before going to Nigeria,would that be possible?


How to return a value in Loop and condition in each iteration?

I have the following function check_overload(...) where I check my links if they get overload or not using the parameters shown below.  def check_overload(SR_path, Router_1, Router_2, Router_3, Router_4, step, capacity):     iterations_array = number_iteration_tunnels(SR_path)     load_tunnels = bandwidth_tunnel(SR_path, Router_1, Router_2, Router_3, Router_4)     global overload_point     overload_point = np.zeros(len(iterations_array))     for i in range(len(iterations_array)):         if load_tunnels[i] >= capacity - (iterations_array[i][1] * step):             print "Link is overloaded"             overload_point = load_tunnels[i] - step             return overload_point         else:             print "Link is not overloaded"             return 0   First of all, I calculate number of iteration for each element of SR_path in the function number_iteration_tunnels(..). Then, using the array created by this function iterations_array, I do a loop to navigate that array.  I aim to return in each iteration the overload_point if the condition is met, otherwise, I return 0. The problem that I am facing is that using this implementation, the function returns only ones which is obvious. I could not find a way where to do it as my aim is.


Given $f(x+T) = f(x) + a$, prove that $f(x) = \varphi(x) + {a \over T}x$, where $\varphi(x)$ is periodic with period $T$

For some function $f(x)$ there exist numbers $T \ne 0$ and $a$ such that for any $x \in D(f)$:       $$ x+T \in D(f) \\ x-T \in D(f) $$      and $f(x+T) = f(x) + a$.       $D(f)$ denotes the domain of $f$.      Prove that $f(x) = \varphi (x) + {a \over T}x$, where $\varphi (x)$ is a periodic function with period $T$.   Here is my try but I have strong doubts about its validity.  Assume that $f(x) = \varphi (x) + {a \over T}x$.  Lets see how $f(x)$ behaves in $x+T$:  $$ f(x+T) = \varphi (x+T) + {a \over T}(x+T) $$  Given $\varphi (x)$ is periodic, then $\varphi (x+T) = \varphi (x)$. Therefore:  $$ \begin{align} f(x+T) &= \varphi (x) + {a \over T}(x+T) \\ &=\varphi (x) + {ax \over T} +a \end{align} $$  But $f(x+T) = f(x) + a$ and then:  $$ f(x+T) = f(x) + a \\ f(x) + a =\varphi (x) + {ax \over T} + a \iff \\ \iff f(x) = \varphi (x) + {ax \over T} + a - a $$  So finally I arrived at where I started. Moreover the above shows that $f(x)$ is periodic which contradicts the initial statement that $f(x+T) = f(x) + a$  One may notice that $f(x + nT) = f(x) + na$ but I don't see how I could use that fact. What is the correct way of proving the above?   Please note that the restrictions in the question section is everything i'm given. So the function is just known to have some domain $D(f)$ and both $T$ and $a$ are not restricted to any particular set of numbers. Also that is from pre-calc section.


My motivation for studying Hopf algebras is twofold:      I'm interested in representation theory and the algebraic structure of group rings.   I will also take a course on algebraic groups soon and I think it would be helpful to know about Hopf algebras for that.   So I'm looking for a good introductory book on Hopf algebras for self-study and especially for one that has many examples and applications to the two topics mentioned above.  (As for my background, I know abstract algebra,  commutative algebra and non-commutative algebra at a basic graduate level, I'm familiar with the basics on representation theory of (mostly finite) groups and category theory (including monoidal and symmetric monoidal, but not braided monoidal categories) and have some rudimentary knowledge of algebraic geometry. I know almost nothing about Lie algebras.)


I guess as the root password is default user account password (if i am wrong correct me) in terminal when I type su it asks me password when I enter my password it says Authentication failure why is it happening??


What is the difference between photon torpedoes and quantum torpedoes?

It seems that quantum torpedeos are the next generation of photon torpedoes but I was wondering what made them better and what makes them 'quantum'.


In C# want to do something like this:  StringBuilder strBuilder = new StringBuilder(); strBuilder.append("123");   And then some code  //Outputs 321 (works for any text value)


can I process salad dressing for shelf life in a water bath or pressure canner and if I can how long is the process time, I can't find out anything about it please help.


Where are the settings modified by "unity-tweak-tool" stored?

Where are the settings as modified by "unity-tweak-tool" stored?  Can they be edited with a text editor?  Is there documentation, manual or help on the available options? Are there options not available in the GUI? which?  Where is the documentation available?  Are there system wide pre-sets possible? Are there automation guidelines?  This question is different from this  because unity-tweak-tool is not mentioned there, and thus that question and answer can not be found by simply search for unity-tweak-tool.


Consider the space $C([0,1])$ equipped with the uniform norm.   Find a sequence of functions $\{g_n\}$ in $C([0,1])$ so that $\overline{\{g_n\}}$ is compact, but $g_n$ does not converge uniformly.   I'm confused about $\overline{\{g_n\}}$ and how to prove its compactness  Thanks!


Prove a challenging pseudo-cyclic inequality using basic inequalities

if a, b, c>0, then prove: $\frac{a+b}{\sqrt{a^{2}+a b+b^{2}+b c}}+\frac{b+c}{\sqrt{b^{2}+b c+c^{2}+c a}}+\frac{c+a}{\sqrt{c^{2}+c a+a^{2}+a b}} \geq 2+\sqrt{\frac{a b+b c+c a}{a^{2}+b^{2}+c^{2}}}$  I have spent several hours in proving the inequality above with Hölder inequality. But all my efforts were in vain since it turned out that Hölder inequality cannot match the square root form on the right side of inequal symbol. I hope someone could help me solve it at least could offer me some hints. Thanks for your time and efforts in advance.  Though this inequality has been posed in this website 5 years ago, no complete answer using basic inequalities is presented. I am expecting some hints to prove this inequality using some basic inequalities rather than methods of analysis.


Cite paper under review on a paper that is going to double-blind review?

I wrote a paper to a journal, which is still under review. Now I need to cite it in another paper that is double-blinded. Is this a problem?


Objects missing in render, light has no effect

I've been test-rendering a character I'm working on and I'm running into some problems. Not only are the eyes of my character not appearing in the render, but light seems to have no effect on objects at all.  In the viewport, all objects are visible and changes in light make changes to the image, but when I hit F12, I get the same thing every time.     [![enter image description here][2]][2]  This is what it looks like when I hit F12


SQL Server 2008.  I have several stored procedures.  I would like to execute them all in parallel, not serially. How can I do this?


Ubuntu 18.04 installed from USB boots straight to Windows 10

I have installed Ubuntu 18.04 downloaded from the Ubuntu website and booted to a USB drive. Then I formatted E: drive for Ubuntu and installed successfully, but when I start my laptop it boots straight to Windows 10.  What could be the problem and how can I fix it?


Proof that $\overline{P(z)} = P(\overline{z})$ for polynomial $P$ with real coefficients

Let $$ a_0, a_1, a_2, a_3, \ldots , a_n \quad (n \ge 1)$$ denote real numbers, and let $z$ be any complex number.  With the aid of $$ \overline {z_1 +z_2+ \ldots +z_n} = \overline z_1 +\overline z_2+ \ldots + \overline z_n $$ and $$ \overline {z_1 z_2 \ldots z_n} = \overline z_1 \overline z_2 \ldots  \overline z_n, $$ Show that $$ \overline {a_0 + a_1z+ a_2z^2+ \ldots + a_nz^n} = a_0 +  a_1\overline z + a_2\overline z^2+ \ldots + a_n \overline z^n.$$   I was also told to use $z$ is a real number if and only if $\overline z = z$ and is $z$ is either real or pure imaginary if and only if $ \overline z ^2 = z^2$  Any hints as to where to go?  Does this proof take mathematical induction? I was thinking I could factor out $a_0, a_1, etc)$ and then use the fact that $z$ is real if and only if $\overline z = z$  Then say by the other statement above about the sum of the conjugates of complex numbers the two must be equivalent.  I feel like this is right but it is not a very elegant proof.


I have searched and saw a similar question but i dont know if it's exactly the same. If I had a rope around earth, let's say a few meters above (and supposing a flat surface, and suddenly dropped it at the same time from all of the points, how would it fall? Or what would happen?  I know gravity’s pull is not exactly the same around earth, but if it was the case? If the rope is a few meters above ground, it's circumference is bigger than earth’s. Imagine it's a solid circumference and doesn't bend or whatever, it's pretty solid. How would it fall? It's supposed to fall all around earth at the same time but since its circumference is bigger, it can't touch surface all at the same time. If its just a rope, where does the circumference start deforming if gravity pulls equally? What parts of the rope touch the ground earlier?


Different terminal profiles for different directories/applications

I would like to have my terminal profile change based on either the current directory or the currently running program. Is this possible? If so, how would I accomplish this?


Will the Battery of my MacBook Pro 15" 2016 deteriorate if it is plugged in charging all day?

I am using my MacBook pro 15" 2016 everyday and attached to it I have got a DELL Monitor 25" QHD. In order to use the monitor as main screen my MacBook pro needs to be plugged in charging all the time.  Will the battery of the MacBook deteriorate because of this?  Thanks


Two Gates Active Simultaneously on the Same World

Related to questions:      Is it possible for two gates to be simultaneously active on the same world?  In the Stargate SG-1 episode Touchstone, it is revealed that the N.I.D. were using the second gate around the same time S.G. one were using theirs. Yet in episodes such as Stargate SG-1's Watergate, Stargate Command is unable to dial out due to another active wormhole.


Prove that $ND = DN$ where $D$ is a diagonalizable and $N$ is a nilpotent matrix.

Let $A$ be an $n \times n$ complex matrix. Prove that there exist a diagonalizable matrix $D$ and a nilpotent matrix $N$ such that  a. A = D + N  b. DN = ND  and show that these matrices are uniquely determined.   I think I've solved the part a but don't have an idea to continue. Here is what I've tried: Let $D = \begin{bmatrix} a_{11} & 0 \\ * & a_{nn} \\ \end{bmatrix}$ and $N = \begin{bmatrix} 0 & * \\ 0 & 0 \end{bmatrix}$. Since D is a lower triangular matrix, its determinant is equal to product of its diagonal entries and hence its characteristic polynomial is $(x-a_{11})...(x-a_{nn}).$ Then D is diagonalizable. Similarly, characteristic polynomial of $N$ is $x^n$ then by Cayley-Hamilton $N^n = 0$. Update: My assumption for D to be diagonalizable was wrong, eigenvalues need not to be distinct. Update after answers: Thank you all for your help. It was just a question asked in the end of the chapter "Canonical Forms". So I just know Jordan form, Rational form, etc. I don't know anything about the Lie Algebra, Semi simple matrices, Representation theory, Perfect field mentioned in the answers. Honestly, answers didn't help me to understand the solution but they seem useful so maybe they help other people. Thanks.


Scanner input= new Scanner(System.in);  int x=0;  String [] storage=new String[3];  while (x< 3){    storage[x]= input.nextLine();    x++;  }   This is my code so far. It is able to prompt the user to give the specified number of inputs. I am trying to check to see if the inputs really are being stored to the storage array. The current location of the print statement does not work because the array is "unreachable".


I spilled a juice on my MacBook-Pro keyboard. Consequently, some keys like 2, esc and tab don't work anymore on my keyboard.   Is there anyway to change those disabled keys with combination of some other keys, like Fn,Ctrl, Option+ something, using an app or a command?


How to allow snap applications to access /tmp folder?

Usually I'm avoiding snap-based applications, but sometime I need them. For example - Markdown Lint Tool is shipped only as Snap named  . It works great when files are in home folder - $ echo "# header" > ~/test.md $ /snap/bin/mdl ~/test.md ; echo $? 0  but it fails when file is located in /tmp directory: $ echo "# header" > /tmp/test.md $ cat /tmp/test.md # header $ /snap/bin/mdl /tmp/test.md /snap/mdl/140/lib/ruby/gems/2.4.0/gems/mdl-0.9.0/lib/mdl/doc.rb:57:in `read': No such file or directory @ rb_sysopen - /tmp/test.md (Errno::ENOENT)     from /snap/mdl/140/lib/ruby/gems/2.4.0/gems/mdl-0.9.0/lib/mdl/doc.rb:57:in `new_from_file'     from /snap/mdl/140/lib/ruby/gems/2.4.0/gems/mdl-0.9.0/lib/mdl.rb:75:in `block in run'     from /snap/mdl/140/lib/ruby/gems/2.4.0/gems/mdl-0.9.0/lib/mdl.rb:73:in `each'     from /snap/mdl/140/lib/ruby/gems/2.4.0/gems/mdl-0.9.0/lib/mdl.rb:73:in `run'     from /snap/mdl/140/lib/ruby/gems/2.4.0/gems/mdl-0.9.0/bin/mdl:10:in `<top (required)>'     from /snap/mdl/140/bin/mdl:23:in `load'     from /snap/mdl/140/bin/mdl:23:in `<main>'  For this particular application there are no options for snap connect: $ snap connections | grep mdl home                      mdl:home                             :home                                 -  Also I can't install it as classic: $ snap install mdl --classic  Warning: flag --classic ignored for strictly confined snap mdl  mdl 0.9.0 from Snapcrafters installed   What should I do to give Snap application full access to the /tmp folder? Does it happen by Snap design or not?


Sum of odd numbers always gives a perfect square.

$1 + 3 = 4$ (or $2$ squared) $1+3+5 = 9$ (or $3$ squared) $1+3+5+7 = 16$ (or $4$ squared) $1+3+5+7+9 = 25$ (or $5$ squared) $1+3+5+7+9+11 = 36$ (or $6$ squared)  you can go on like this as far as you want, and as long as you continue to add odd numbers in order like that, your answer is always going to be a perfect square.  But how to prove it?


I've lost Shadowmere - where can I find her?

So I own Shadowmere from the Dark Brotherhood.  However, I jumped on another horse for a few seconds, before fast travelling. I did a few quests, without even thinking about Shadowmere, and now when I need her, the horse that I rode for those few seconds appears.   Anyone have any idea where I can get Shadowmere back?


Sorry, my English isn't quite well.  Here is the problem.  When $n$ moves toward infinity $$ 1/(1^2)+1/(2^2)+1/(3^2)+\dots +1/(n^2)=? $$  Any ideas?


I have a Kenyan passport. Do I need a visa to transit in Brussels?. I have an ongoing flight 5 hours after I land in Brussels.


I'm trying to delete those ugly lines visible in the cylindrical shape of the lens. What is causing them is the added edge loops I made for the protruding detail with the switch. The problem is that if I delete those edges, it'll look even worse because of the n-gons. Any ideas?


I was messing around with some matrices and found the following result.      Let $A_n$ be the $(2n) \times (2n)$ matrix consisting of elements $$a_{ij} = \begin{cases} 1 & \text{if } (i,j) \leq (n,n) \text{ and } i \neq j \\ 1 & \text{if } (i,j) > (n,n) \text{ and } i \neq j \\ 0 & \text{otherwise}.  \end{cases} $$    Then, the determinant of $A_n$ is given by $$\text{det}(A_n) = (n-1)^2.$$   Example: $$A_2 = \begin{pmatrix} 0 & 1 & 0 & 0 \\ 1 & 0 & 0 & 0 \\ 0 & 0 & 0 & 1 \\ 0 & 0 & 1 & 0 \end{pmatrix}, A_3 = \begin{pmatrix} 0 & 1 & 1 & 0 & 0 & 0 \\ 1 & 0 & 1 & 0 & 0 & 0 \\ 1 & 1 & 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 & 1 & 1 \\ 0 & 0 & 0 & 1 & 0 & 1 \\ 0 & 0 & 0 & 1 & 1 & 0 \\ \end{pmatrix},$$ with det$(A_2)$ and det$(A_3)$ being $1$ and $4$ respectively. I was wondering if anybody could prove this statement for me.


Count occurencies number of special chars in string

I have some special chars declared that way.  private static readonly char[] Chars = "…".ToCharArray();   Also, I can check if that chars are present in given string like that way.  private static bool ContainsSpecialChars(string text)     {         return text.IndexOfAny(Chars) >= 0;     }   But I am stuck in counting how many occurencies are in the given string.  NOTE: I have array of chars


I am a n00b to physics. What physics I know comes from high school and popular science books.  At school we were taught about atoms and what make up atoms, but we weren't actually told what the particles were!  So sure an atom has electrons orbiting around a nucleus made of protons and neutrons, but what exactly is an ?  And if we don't know, how can we fire them from guns, like they do in experiments ... etc  Any clarification on this would be great.


MacOS 10.14 Mojave public beta public Wi-Fi problem

I can not connect to a single public Wi-Fi hotspot that does not require a password but instead shows a pop-up window pointed to captive.apple.com  The pop-up opens blank with the error "The web page couldn't be loaded"  Any idea on how to fix this?


Should acronyms be fully expanded words?

There are some acronyms which save time to those who write, but may not be known by few readers.  For example AFAICT, AFAIK, FWIK, IMHO. I think these are really widely known. And also widely used. If the reader doesn't know, she or he just a click away from looking it up, and will gain a knowledge he won't forget.  Should the posters avoid acronyms and write fully expanded words instead?  Note: This is not about auto-expanding. This is about expanding by posters.


What are the existing datasets of world maritime routes?

I have a list of cargo ports of all over the world and need to show some port-to-port trips on a map, and also to compute lengths of these trips.  For that, I need a dataset of actual maritime routes (even approximative) between important ports preferably free. Is there something available?


My Iterinary is as follows:   Italy - (4 days, 4 nights), Austria - (2 days, 2 nights), Switzerland - (5 days, 4 nights).   I am trying to book a Schengen visa appointment at the Italian embassy, but for some reason I'm not getting it. So alternatively I am also trying to book the appointment at the Swiss embassy. Is it ok if the Swiss embassy issues the visa for my travel, even though I am entering through Italy?


TAB does't work properly with `cp` command when using environment variables

Question When using cp command with environment variables, why pressing TAB for auto-complete doesn't work properly? Description I have a directory $HOME/Music; I want to copy a file from within this directory to the current directory. Therefore:  I Type cp $HOM and press TAB, so it reads cp $HOME ; There is an additional space after cp $HOME , therefore I delete it by Backspace and then type a slash:cp $HOME/; Now Press TAB creates cp \$HOME/ which has a spurious backslash at the beginning of $HOME. When writing further letters i.e. cp \$HOME/Mu for Music, TAB doesn't work for autocompletion.  OS: Ubuntu 20.04


I was recently in a bit of a quandary over which answer to accept to .  Of the answers I got, two were the clear leaders and, of course, I up-voted both. Choosing a 'winner' was more difficult though as their approaches were quite different.  Answer A addressed my question and provided a clear and well thought out response. I'd anticipate that this answer would be of most use to a user who found my question via a search. Selecting this would probably be the more community-focused way to go.  Answer B took a more lateral approach and made some guesses at the business logic behind my request, suggesting that I might be asking the wrong question. Their solution was based on this assumption - and they were spot on. Answer B formed the basis of my fix for the problem.  So... Best answer to the question or best solution to the problem - they may not always be the same thing.   I took the selfish approach and went with B. I'm not losing sleep over it, but I do wonder if I did the right thing?


How would I go about merging two cylinders in order to achieve a result similar to the joint in the highlighted part in this image?


I am trying to understand this proof, I think "$Q$ is lying above $P$" means $Q \cap P = R$, but I don't know why we can assume "$P=0$" or "$R$ is a field", can someone explain it to me?


Why does Rey know how to speak droid Binary?

Rey interacts with BB-8 vocally many times and appears to understand very complex topics within the language Droid Binary - such as the names of planets, coordinates, and short explanations about BB-8's mission secrecy.  It appears that Rey, who appears to have been living as a scavenger since her childhood, understands Binary.  Is there any in-universe (movie, novel, Disney accepted canon) explanation that would show when/where/why she learned this skill?  It isn't a widely known skill - Luke had C3PO translate for most of his earlier interactions, and then much of the communications between R2 and him occur in a cockpit with a display, though it's obvious he was able to pick up on the tone of the conversations R2 had and perhaps understand a little. Luke grew up on a desert planet with moisture evaporators and droids, but he obviously didn't understand the language at that time.    It seems like an odd thing for a young woman to have picked up on a planet where droids were apparently uncommon enough that they were routinely disassembled for parts and sold.


Is it possible to access the property of a javascript object using a string?  example: I have a javascript object "obj" that contains a property 'index'.  obj.index = 4;   Now let's say I have a string whose value is the same as a property name of my object:  var str = "index";   Can I use the value of the str variable to access the 'index' property of 'obj'?


Screen flickers / goes black for 1-2 seconds when redrawing on 16.04 - single monitor, R9 380

If I move the mouse or use the keyboard to do anything that would require redrawing the screen, it flickers, and then often goes black for a second or so. I found a number of similar problems, but I have not found this combination:   using a single monitor AMD R9 380 graphics card (not nVidia) independent of Google Chrome   I am using Legacy, not UEFI mode. I did not have this problem on 15.10 on the same machine. I have the same problem when booting into the 16.04 live CD. I installed the latest upgrades.  $ uname -a Linux <machine-name> 4.4.0-36-generic #55-Ubuntu SMP Thu Aug 11 18:01:55 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux  $ lsb_release -a No LSB modules are available Destributor ID: Ubuntu Description:    Ubuntu 16.04.1 LTS Release:        16.04 Codename:       xenial  $ lspci -nn | grep VGA 03:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Hawaii Pro [Radeon R9 290/390] [1002:67b1] (rev 80)  $ lshw -c video *-display      description: VGA compatible controller      product: Hawaii PRO [Radeon R9 290/390]      vendor: Advanced Micro Devices, Inc. [AMD/ATI]      physical id: 0      bus info: pci@0000:03:00.0      version: 80      width: 64 bits      clock: 33 MHz      capabilities: pm pciexpress msi vga_controller bus_master cap_list rom      configuration: driver=radeon latency=0      resources: irq: 128 memory:c0000000-cfffffff memory:d0000000-d07fffff ioport:e000(size=256) memory:dfd000000-dfd3ffff memory:dfd40000-dfd5ffff   I am a bit confused because  says for my graphics card, amdgpu is installed but the last command says driver=radeon. I tried installing amdgpu:   $ sudo apt-get install xserver-xorg-video-amdgpu libdrm-amdgpu1 xserver-xorg-video-amdgpu is already the newest version (1.1.0-1). xserver-xorg-video-amdgpu set to manually installed. libdrm-amdgpu1 is already the newest verison (2.4.67-1ubuntu0.16.04.2). libdrm-amdgpu1 set to manually installed.   Booting with nomodeset works fine, but I understand then I have no 3D acceleration which would be unfortunate. My mainboard is an ASRock H170M Pro4 with latest BIOS (2.20) in case it matters.  Any ideas what I could try?


Can I fail to deserialize with XmlSerializer in C# if an element is not found?

I am using XmlSerializer to write and read an object to xml in C#.  I currently use the attributes XmlElement and XmlIgnore to manipulate the serialization of the object.  If my xml file is missing an xml element that I require, my object still deserializes (xml -> object) just fine.   How do I indicate (preferably via Attributes) that a certain field is "required"?  Here is a sample method of what I am using currently:  [XmlElement(ElementName="numberOfWidgets")] public int NumberThatIsRequired {     set ...;     get ...; }   My ideal solution would be to add something like an XmlRequired attribute.     Also, is there a good reference for what Attributes are available to manipulate the behavior of XmlSerializer?


How to UPDATE with LATERAL Nearest-Neighbour query?

Say I have table gps like:  CREATE TABLE gps(    gps_id serial primary key,    measured_timestamp timestamp,     geom Geometry(Point,4326),    stop_id int --Null );   And I have a table of stops like:  CREATE TABLE stops(    stop_id serial primary key,    geom Geometry(Point,4326) );   If I want to do an UPDATE on gps to find the nearest stop to each point, is there a way to use a LATERAL query?  I tried something like  UPDATE gps SET stop_id = nearest.stop_id FROM LATERAL(SELECT stop_id FROM stops ORDER BY stops.geom <-> gps.geom LIMIT 1) nearest   but that told me   ERROR:  invalid reference to FROM-clause entry for table "gps"                                                ^ HINT:  There is an entry for table "gps", but it cannot be referenced from this part of the query.   So is the only way to do?  UPDATE gps SET stop_id = nearest.stop_id FROM (SELECT gps.gps_id, stop_id        FROM gps       LATERAL JOIN (SELECT stop_id FROM stops ORDER BY stops.geom <-> gps.geom LIMIT 1) stops) nearest WHERE nearest.gps_id = gps.gps_id   This feels like joining the same table to itself, which wouldn't need to happen with a SELECT INTO


How can I fix the error "GUI framework cannot be initialized" with TeXnicCenter and MiKTeX?

I don't know what I've done, but all of a sudden I am unable to compile any document which uses the geometry package. Minimal (non)-working example:     \documentclass[11pt]{article}      \usepackage{geometry}  \begin{document} test \end{document}   doesn't produce any output, and this is what I see in my error summary screen in TeXnicCenter:    The red arrow points to what seems to be the problem: something about the bundle "oberdiek" and its package "ifvtex" is causing pdflatex.exe (which, while I don't really know what it does, sounds pretty important) to "not be initialized". I , and it's relevance here is a mystery to me.  I've confirmed that all of my files without the geometry package compile just fine; however, that doesn't mean that the problem is with the geometry package - what seems more likely is that there is some hidden cause of the error, and geometry happens to be one way to induce that. By the way, I've tried compiling a document which includes the ifpdf and ifvtex packages separately, and they do just fine; it's only when I include the geometry package (which for some reason requires these ifpdf and ifvtex packages) that the error occurs.  I've tried the only things I can think of:   going into MiKTeX Package Manager (by the way I am using 2.8), and removing + reinstalling both geometry and oberdiek refreshing the file name database ("FNDB") deleting all automatically generated files, as well as simply starting over in a new document   So I'm stuck now. I've considered attempting to just get rid of all traces of MiKTeX and TeXnicCenter from my computer and starting over, but that seems a bit excessive - after all, the geometry package was working for me . I honestly am not sure what I did to cause this; I've spent today trying to make a better template file for myself, and so I've been trying out new packages, but if I'm not loading these new packages there shouldn't be any conflicts, right?   Actually, I've just now thought of something that I think I did between the last time it worked and now, so is a possible candidate for the cause: I had to install some package manually, as it wasn't available on MiKTeX, and so I created a folder and pointed MiKTeX to it (i.e. the second option ). The package didn't do what I wanted, so I deleted the folder and removed it from the list of folders I told MiKTeX to check. Perhaps it's still trying to reach it for some reason?


How to remove spikes from grid in SAGA GIS?

I tried to get a grid by interpolating LAS file using Ordinary Kriging. But the product grid has many pixels which values strongly stands out from average surface - I mean one pixel sinks nad spikes. I know that sinks can be easily filled with preprocessing modules, but I found removing spikes more complicated. Is there any automated way to remove them? For instance a module which could get rid of pixels with values that stands out from their neighborhood?


Explanation of the Fibonacci sequence appearing in the result of 1 divided by 89?


Coordinate system confusion of TikZ and PGFPlots

So, I'm drawing graphs using TikZ and pgfplots for my lecture notes. My question is about the two coordinate systems that are used in the following code: \documentclass{article}  \usepackage{tikz} \usepackage{pgfplots} \begin{document}  \begin{tikzpicture} \begin{axis}[axis lines = center, xlabel = $x$, ylabel =$y$, ymax=3, ymin=-1, xmax=5, xmin=-1 ,samples=500, ytick={1,2}, xtick={1,2,3,4}] % Code for the graph. \addplot[blue, domain=2.05:4.5, thick] {-x + 4}; \addplot[blue, domain=-0.5:1.95, thick] {x}; \draw[blue] (300,297) circle[radius=1.5pt]; \node[above right] at (300,297) {\footnotesize $y=f(x)$}; \end{axis} \end{tikzpicture}  \end{document}  Question: Why is it that the lines of the graph can be drawn with the coordinates of the axes, but the coordinates of the nodes have to be specified using some other system? Question: What is the other system? Is it easy to say where (0,0) in the "node system" is with respect to (0,0) on the axes? Ideally I would like to be able to use the axes coordinates for all aspects of the diagram. But, any help at all would be great! Thanks in advance.


We have an application that access the database (Sql server 2014 enterprise edition). The application calls a stored procedures to access the database. Everything was working fine until recently start sending the following error and stop the applications. Restarting the app fix the issue temporarily but facing the same error latter.     Error: A transport-level error has occurred when receiving results from the server. (Provider: TCP Provider, error: 0 - The specified network name is no longer available.)   I did a lot of research which most of them pointing out as a network issue but could not find anything to actually solve the problem.  Do anyone know what change I should have to make on the database side to resolve this issue.  I highly appreciate any suggestions.


A particular picture copies by itself multiple times in camera roll every day

I've been using iPhone for many years now but this is the first time I've this problem.    I received a picture from a friend, who is on Android. Since then that particular picture copies by itself multiple times during the day in my camera roll.  Any idea why this may be happening? A virus, malware?  I am on iPhone 6 with iOS 8.3.


The articles "a" and "the" in generic statements

This is intended as a generic statement:     *A madrigal is popular.   This means that being popular is a requirement for being a madrigal.    ...of course this conclusion is wrong, so I've marked the example with a star.     *A tiger is in danger of becoming extinct.       The tiger is in danger of becoming extinct.      Tigers are in danger of becoming extinct.      The Indefinite Generic a tiger is ungrammatical with the predicate become extinct, because that extinction can only happen to a species, and it means that every member is dead. In contrast, we we can use the Definite Generic because the predicate is characteristic of the species. We can also use a Plural Generic because we're speaking of tigers in aggregate.   I read those examples and explanations in a grammar book (or, more likely,  ).  Would anyone please explain those in a more simple way, so that I could get it? I cannot tell what the explanations mean very well.  Or could you possibly explain that with another example that is easier to understand?


After the scuffle between Mann (Damon) and Cooper (McConaughey) in Interstellar, our protagonist gets a hold of a radio and alerts his shipmates to Mann's duplicity. Then his ship explodes. What happened there?


I have an issue with accessing my ~/.bashrc file. I did and obtained the following:  yuve@YuveSys:~$ ~/.bashrc -bash: /home/yuve/.bashrc: Permission denied yuve@YuveSys:~$ sudo su root@YuveSys:/home/yuve# ~/.bashrc bash: /root/.bashrc: Permission denied   Can anyone help?  NB: I am using Ubuntu 14.04 LTS. Thanks.


Can $\sin(xy)$ be written in terms of trigonometric functions of only $x$ or $y$? I am tempted to say yes, because the double- and half-angle formulae exist, and these would be special cases of $\sin(xy)$.  I first looked at the Taylor series,  $$\sin(xy) = \sum_{n=0}^\infty\frac{(-1)^nx^{2n+1}y^{2n+1}}{(2n+1)!} = xy-\frac{x^3y^3}{6}+\frac{x^5y^5}{120}-\cdots$$  but as far as I know, neither $x$ nor $y$ can come out of the sum since they are not constants.


Why is task manager showing as using 66mbps when in Deluge it shows as only 6mbps?

In task manager Deluge shows as using 66mbps on the network, in the client however it only shows as 6mbps, how is this happening? Which speed is correct?


It is grammatical to use plural verb with police or the police. But when we say Delhi Police, London Police, California Police, etc., why do we use singular verb? I've seen this so many times in news.  Delhi Police asks motorists to avoid Connaught Place... Delhi Police has registered two cases...  Also the initial letter of Police is capitalized in this case. Why?


How to show cited references on the same page in beamer

I have created a presentation using Beamer template. The presentation is a bit long with lots of references. I believe audience will find more convenience in finding cited references on the same page (at the bottom) rather than looking at the end of the presentation, for example like this    References in standard beamer template appear like this    I couldn't find any beamer template that enables us to show references on the same page. I don't know how can we make such changes. Can anybody point me in the right direction, Thanks in advance


Weird, squished spacing with "Ask Question" on questions with responsive mobile

Update on August 22nd 2019: This glitch has come back:      I posted  yesterday, which got closed, with a very similar bug, but this is not a duplicate of that. This is a new problem, after that fix apparently got implemented.    The "Ask Question" button needs more legroom. It's a little cramped at the top of the page:    This just looks weird. I think it should just go back to being on the right, like it used to be:    Maybe the last active and posted times could move under it on small screens? It would still be at the top, but wouldn't need to push the button around.


Prove that if $A$ has a maximum, then the maximum must be the supremum

Prove that given $A\subseteq\mathbb{R}$, if has a maximum $a_0$, then $a_0$ must be the supremum.   In order to prove this, I have written the following:  Let $A\subseteq \mathbb{R}$, nonempty set because $a_{0}$ $\in A$ for hypotesis. Then, since $a_{0}$ $\in A$ is the largest element of the set $A$   (i.e. for each element $A$ of A we have that $ a\leq a_{0}$) $A$ is bounded above. Then, A has a supremum. Let $s$ be the least upper bound of $A,$ so we have that for each element $a$ of $A$, $a\leq s$, for being $s$ an upper bound. In particular, $a_0\leq s$, which implies that $s=a_0$.   Then, we have that $\sup(A)=\max(A)=a_0$, which is exactly what we wanted to prove.  Observation: this proof is true if $s \in A$   I'm not sure if my proof is correct. I will be thankful if someone tells me.


Compile TeX (directly) into SVG using the command line

Is there a way to directly compile TeX code into the SVG image format (rather than going the detour over TeX => PDF => SVG)?  I found this question:   But I don't want to do it online - it should be a command-line call.


Why does Hagrid say "cousin DON'T " instead of "doesn't"?

Hagrid: If that dolt of a cousin of yours, Dudley, gets up to any mischief, you could always threaten him with a nice pair of ears, to go with that tail.  Harry: But, Hagrid, we're not allowed to do magic outside Hogwarts.  Hagrid: I know that, but your cousin don't, do he?


Why is float value "++" operation different for 3.14?

Code  public class test{     public static void main(String[] args){         double first = 3.14 ;         first++;         System.out.println(first);     } }   Result  ubuntu@john:~/Desktop$ javac test.java  ubuntu@john:~/Desktop$ java test   Output : 4.140000000000001  I am getting expected answer for almost every other case... Eg : For 4.14 ,result is 5.14...  Why this case is special ?


Moderncv adding date of birth to personal information

I'm doing my cv with the moderncv package and I'm using the classic style. I would like to add a date of birth line directly above the adress. Does anyone know how to do this? I've tried various solutions but they all seem to be broken.


Why was my answer, a link to the documentation, deleted?

Kev deleted an answer that I wrote here:   I've tried to address his comment, though I still disagree with it.  Please undelete the answer.  Putting version specific snippets of a manual into an answer is MORE likely to result in bit rot.  While a link to the manual may suffer link rot, Google is still your friend and more likely to have the current best reference.  Thus, the name of the manual is the best answer as an indirect reference.


I am Creating a forget Password page when user click on forget password and enters his/her Email address a link is sent to his/her Email my code works fine but the email goes in Spam/junk folder.  can any one help me why this is happening??   Here is my code  <?php $remail = mysqli_real_escape_string($con,$_REQUEST['name']); if (!filter_var($remail, FILTER_VALIDATE_EMAIL)) // Validate email address { $message =  "Invalid email address please type a valid email!!"; } else { $query = "SELECT id FROM users where email='".$remail."'"; $r = mysqli_query($con,$query); $Results = mysqli_fetch_array($r); if(count($Results)>=1) { $encrypt = $Results['id']; $encrypt=md5(sha1(md5($encrypt))); $message = "Your password reset link send to your e-mail address."; $to=$remail; $subject="Forget Password"; $from = 'miniface'; $body='Hi,

Your Email is '.$_REQUEST['name'].'

Click here to reset your password http://link.com'.$encrypt.'&action=reset

--
miniface.com
Solve your problems.'; $headers = "From: " . strip_tags($from) . "\r\n"; $headers .= "Reply-To: ". strip_tags($from) . "\r\n"; $headers .= "MIME-Version: 1.0\r\n"; $headers .= "Content-Type: text/html; charset=ISO-8859-1\r\n"; mail($to,$subject,$body,$headers); else { $message = "Account not found please signup!"; } }  echo $message; ?>


Negative vote to close, prevent question from being closed, instead of only voting to reopen

I am looking at a valid question with 4 votes to close on a site. I think the collective conscious has edited the question to make it appropriate, and there are answers for that question now.  With one more vote that question will be closed, creating cognitive dissonance about acceptable questions on that site.  The current recourse is to wait for the question to be closed, and then begin voting to reopen.  Instead there should also be a way to negate a vote to close, with a vote to keep open.  Thoughts?


Find the limit,  $$L=\lim_{n\to \infty}\int_{0}^{1}(x^n+(1-x)^n)^{\frac{1}{n}}dx$$  My try:  $$ \int_{0}^{\frac{1}{2}}2^{\frac{1}{n}}xdx+ \int_{\frac{1}{2}}^{1}2^{\frac{1}{n}}(1-x)dx< \int_{0}^{1}(x^n+(1-x)^n)^{\frac{1}{n}}dx< \int_{0}^{\frac{1}{2}}2^{\frac{1}{n}}(1-x)dx+ \int_{\frac{1}{2}}^{1}2^{\frac{1}{n}}xdx$$  Now taking the limit I get that,  $$\frac{1}{4}<L<\frac{3}{4}$$  But, how can I get the exact answer!!  This is  from the American Mathematical Monthly.


Is that grammatically right if I use two predicates without using a conjunction to link them?

Is it grammatically right if I use two predicates without using a conjunction to link them? There are many sentences using this structure when I read a composition. Examples:   He became a teacher, established his own family twenty years later.  I saw nothing decent in him, saw nothing more than a selfish man.    Usage of conjunction:


How to prove that 𝑃(𝐴) Δ 𝑃(𝐵) ≠ 𝑃(𝐴 Δ 𝐵) for any 2 sets.

So the question is how can I prove that for any 2 Sets, A and B, the symmetric difference between the power set of A and the power set of B IS NOT equal to the powr set of A symmetric difference B. 𝑃(𝐴) Δ 𝑃(𝐵) ≠ 𝑃(𝐴 Δ 𝐵) I have been stuck on this question for a while and I can't find a way to prove it.


Calculate the integral $\int_0^1 \frac{x-1}{\log(x)} \mathrm dx$

Calculate the integral $$\int_0^1 \frac{x-1}{\log(x)} \mathrm dx$$ using $$\int_0^1 \frac{x^t-1}{\log(x)} \mathrm dx$$.


New mobile chat interfaces only partially scrolls on iPad

When I load chat on my iPad, it loads in the middle of the chat page. From there, I can scroll a little way in either direction, but I can't scroll all the way to the bottom or all the way to the top of the page.  This means I can't reach the input box at the bottom. I'm also unsure about whether there are supposed to be buttons at the top that I can see.  iOS 8 point something.


What are the non-diagonal screen dimensions of the Nexus 7?

Very simple question. I want to know the non-diagonal physical dimensions of the screen itself of a Nexus 7 (eg: 4" by 5" or whatever).  Every site I look it up on seems to just happily repeat that it's a 7" tablet with 1280x800px and so on.


This is a  about Securing a LAMP stack   What are the absolute guidelines for securing a LAMP server?


Acceleration of objects with speeds comparable to $c$. Can we find acceleration of the frame by treating $v$ in $1/\sqrt{1-v^2/c^2}$ as variable?

We know that the $v-t$ graph for constant acceleration is a straight line. But when the speed becomes comparable to $c$, the speed of light, relativistic effects come into play. Suppose if a rocket on earth starts from rest (A) with constant acceleration or (B) with increasing acceleration. Since, there is acceleration in both the cases speed will increase but it will never reach $c$ which means that acceleration has to decrease from somewhere. Then the graphs looks like these:    I tried to obtain an expression for the acceleration by using the inverse Lorentz transformation equations in STR.In STR the $v$ in $\gamma=\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}$ is constant. But in this rocket example this $v$ is itself changing and so I treated it as a variable. Let the rocket be $S'$ and the earth be $S$ and $S'$ be moving along $x$-direction. Now to see from $S$ how $S'$ is accelerating, I took a fixed position in $x'$-axis. For simplicity, I took its origin i.e., $x'=0$ so that $x=vt'\gamma$. Then I differentiated $x$ with respect to $t$, substituted $t'$, substituted $\frac{dt'}{dt}$ and tried to get an expression for $\frac{dv}{dt}$. But the result I got does not make sense.I am not familiar with GR so I thought this must be explained in GR and I searched in the Internet if there is any such formula but did not find any. Is it the wrong way I am going? If it is there in GR to which I am not familiar, I seek a brief explanation of how acceleration is understood in GR, if possible.


XAML combine styles with styles from toolkit

I use the  black theme for my styles and it makes all controls look great. Now, for a ListBox I need to add a custom style  <ListBox.ItemContainerStyle>        <Style TargetType="ListBoxItem">             <Setter Property="HorizontalContentAlignment" Value="Stretch"/>        </Style>  </ListBox.ItemContainerStyle>  but this removes some of the Adonis UI style from the ListBoxItem (the white font to be precise). I also tried adding the style to my ResourceDictionary: <ResourceDictionary>    <Style TargetType="{x:Type ListBoxItem}">       <Setter Property="HorizontalContentAlignment" Value="Stretch"/>    </Style> </ResourceDictionary>  and   <Application.Resources>     <ResourceDictionary>         <ResourceDictionary.MergedDictionaries>             <ResourceDictionary Source="pack://application:,,,/AdonisUI;component/ColorSchemes/Dark.xaml"/>             <ResourceDictionary Source="pack://application:,,,/AdonisUI.ClassicTheme;component/Resources.xaml"/>             <ResourceDictionary Source="ResourceDictionary.xaml"/>         </ResourceDictionary.MergedDictionaries>     </ResourceDictionary> </Application.Resources>  But that doesn't work at all. How can I combine those Styles?


Put bounties on other people's questions?

For whatever reason when I go to other people's questions that are eligible for bounty it appears that I can put bounty on them when they are not my own questions!  Is this supposed to happen?


"Unanswered" question sort order on profile pages

To help users keep track of (and hopefully get answers to) unanswered questions, it would be useful to have an "unanswered" sort order on a user's profile page.  It would order the list of questions with unanswered questions first.   This would be in addition to the "recent," "views," "newest," and "votes" sort orders.


ERROR: cuvid requested, but not all dependencies are satisfied: cuda/ffnvcodec

I am trying to compile FFMPEG with Nvidia Cuda support, on Debian 9.3. Parameters, what I am using:  --enable-cuda --enable-cuvid --enable-nvenc --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64 --enable-gpl --enable-libx264 --disable-x86asm --enable-libx265 --enable-libfdk-aac --enable-nonfree   Nvidia Cuda with drivers are installed. When I try to configure ffmpeg, it says:  ERROR: cuvid requested, but not all dependencies are satisfied: cuda   Newer ffmpeg will show a similar, re-worded message:  ERROR: cuda requested, but not all dependencies are satisfied: ffnvcodec   I absolutely don't know why I'm having this issue, because I am compiling ffmpeg on all of our trans-coding servers.


How to make "show settings" of a reference entity view affect the real field selection

In Drupal 8, I can manage to create an "Entity Reference" view. In the preview area, it shows multiple fields separated by a string separate, just as I configured. For example:    However, in the real form, a selector does not show the expected fields as by configuration, but rather shows only content title:    I tried clearing cache, but it did not help. What setting in the view editor should I use to let the live entity selector show fields the same as in the preview?


Can we have an easier way to set up a chat room from a post?

One of my sites has a persistent problem with comments -- chatty comments, proto-answers in comments, big long conversations in comments.  I suspect we're not the only ones with this problem.  While a conversation between two people will eventually trigger the "hey, you should do this in chat" notice, and while moderators can move comments to chat (after an auto-flag is raised), I'm looking for something that regular users can do, and sooner.  We currently ask people to , but the process is a little cumbersome:   You're on the site, on a specific post, and see a comment thread that's getting away from what comments are for. You leave the page or launch a new tab, navigate to chat, and find your way to "create a room".  You might or might not give this room a helpful name. Optionally you cut/paste existing comments there.  I include this theoretical step for the sake of completeness; it's not really a reasonable thing to expect. You go back to the post and write a comment linking to the chat room.   But the other commenters might just ignore you, might not even have privileges to chat, and have no easy way to move things there.  What can we do to make this easier?  It'd be great if we could at least create the room (with a canonical name pattern) and auto-generate the comment containing the link, all without leaving the post page.  A harder question is what to do about existing comments; we probably don't want any random user to be able to move a whole set of comments to chat, but there's something to be said for copying existing comments to the new chat room and then raising a moderator flag on the post so mods can review and decide whether to purge those comments.  (Ones that ask for clarification should remain, as usual, hence the need for human review.)  What can we do to make this process easier?


Is there a way to clone a hard drive to a smaller hard drive?

The Issue:  The issue I have is that I have several hard drives ALL 250GB, however, they vary ever so slightly on the amount of sectors. When cloning with CloneZilla on Parted Magic, I get the volume size error. The drive I am using as the master just happens to be the one with the most sectors.  What I need to do:  I installed Vista and ran all the updates which took a couple of days to do in total, and I don't want to have to reinstall everything again. I now need to copy this to the other drives.  I tried:  Resizing the partition of the OS to around 200GB, and doing a partition copy, however this will not boot.  I also tried other software but all give the same error. I did try to set the option to ignore the size difference but it gave other errors.


How can I "crop" an image in the shape of any alphanumeric character?

How can I punch cut an alphanumeric character, say, "A" out of an image, so that I have only the interior of a large bold "A" showing the contents of the image?


In our booklet it is written that :      A function is  continuous at every isolated point.   MY doubt:-  Let us consider an example: let $f:\mathbb N \rightarrow \mathbb{R} $ such that $f(x)=x$. As $\ \mathbb N =\{1,2,3,...\}$ and $1,2,3,..$ are all isolated points i.e $1,2,3... $ are not limit points of $\mathbb N $.  Now according to the above statement the function is continuous at every isolated point. But according to the definition of continuity, the continuity at point $a$ is $$\lim_{x\to a}f(x)=f(a)$$  Now take any number from  set $\mathbb N $ , for example take $ 2$ then $f(2)=2$ and $$\lim_{x\to 2}f(x)=\text{not  possible  to  determine or cannot be evaluate }$$  More precisely $2$ is not a limit point, so limit at $2$ cannot be calculated. So, the function is not continuous at all isolated points in this example.  How the function can be continuous at all isolated points? Can anyone tell me?


First of sorry for my english. I need some help here guys. I'm trying to boolean cut (operation: difference) a hole on a pipe-like shape with cylinder but doesn't work. I made two kind of this pipe-like shape one from a plane and another from a cylinder. Both failed.  Here's a screenshot of what i'm trying to do.   Here's a link to the file on my gdrive:


Is there any freely available pointcloud data?   I'm especially interested in dense clouds of small areas(5m to 100m radius) but anything else would be fine too.   I've found that these pages have very nice and easy to access point cloud data.


Does the artificer's Enhanced Weapon stack on top of hexblade's Improved Pact Blade?

I play a hexblade warlock with an Improved Pact Blade longsword. I like the idea of the eldritch tinkerer, who builds his patron's gifts into his gadgets, which fits in a warlock/artificer multiclass. The artificer's Enhanced Weapon infusion would be very nice with the warlock if it stacks with the Improved Pact Blade bonuses, but I can't tell if it does from the class descriptions. Do these features stack, or do I need to rethink this build?


Illustrator: Auto-sized Text box with shaded background?

I frequently create labels that follow the same format: white text on a 75% opaque black background, with 10px of margin around the text. Currently, I have to manually build these labels, which takes a lot of work.  In one method, I write the text, figure out its height and width, then create a separate rectangle and place it behind it. This takes a lot of clicking around for every label.  In the other method, I draw out a text box, select it directly, give it the correct background and margins, and then insert the text. However, I must then resize the box manually, meaning more clicking around and greater imprecision. There doesn't seem to be a way to directly select a text box once it has text inside it.  I tried using the script contained in  to resize the text box to the content, but it only resizes the box vertically, and removes my color and margins.  Does anyone have suggestions on how to resolve these problems, or for a better method? I'm using CS3.


I have a blend file, But when I am trying to import the only options I have are collada and alembic. FBX, OBJ etc are all missing.  I have enabled FBX add on in preferences. I have seen the options MANY times before, why is it missing all of a sudden?


I was wondering if reputation is meant more as a "resource to be used" or as something that should steadily increase as your experience grows? I ask this as recently on Stack Overflow my reputation has been dropping because I have been posting a lot of bounties.   Is this how I'm meant to use my reputation, or should I really be trying to get to those higher amounts of reputation?


If we solved the observer effect/problem, doesn't this mean Quantum superposition isn't actually real?

I am nowhere close to a physicist so please correct me anywhere I am wrong   From what I understand about the observer effect, when we measure one intrinsic property of an electron such as position, the mere act of observation instantly alters another property of that electron such as momentum, so we can never accurately measure both.  Continuing, the reason observing an electron changes one of these properties is because when we use electronic instruments to sense/measure these properties, we are shining light upon the electron which has enough energy itself to alter that electrons properties in that instant, so what was before the observation is different from what is observed in that moment.  So, my question is:   Isn't the problem that we just don't have the technology that could sense/measure the properties of an electron without disturbing it? Theoretically if we did have such a device as the aforementioned, doesn't this mean that a particle's state is determinable and particles don't actually exist in multiple states simultaneously?


Options for a functional-style enthusiast?

Senior programmer who has been coding in a functional style for years. I want to make an attempt on the indie games market, but I don't find any good, big platform that provides a good way to code using a functional style. And the fact Unity3D pretty much domains that market, I'm pretty much limited to C#. I wonder if there is another way?


How do programs detect home directory (other than $HOME)

I work at an organisation where the fileserver containing /home sometimes fails to start in the morning. I can still log in on the console but get an error message something like $HOME not available, using /. In this case my workaround is  cd /tmp mkdir home chmod 700 home export HOME=/tmp/home # wget a copy of my "emergency" rc files that I keep online # xinit, twm etc.    so I can still read e-mails through a web browser and if the file server is down for long, checkout my current projects from gitlab into /tmp and continue there.  Xterm and twm seem to respect $HOME and happily work in my temporary setting, cd with no parameters and ~ in bash work fine. chromium-browser does not and still complains about /home/organisation-specific-stuff/my-username not being available. (Chromium will run with --user-data-dir=/tmp/home/chromium but launching it still causes dbus to throw a fit about non-existent /home).  My questions:   What other ways besides $HOME are there for programs to reference the "home directory", and are there good reasons (for example security implications) why some programs choose one over the other? Is there a way to tell e.g. chromium, dbus to temporarily use /tmp/home instead? I cannot use the solution in [1] due to lack of root rights. For the same reason, chroot seems out of the question. Or is this a stupid/dangerous thing to do?   My system is Ubuntu "precise" if that makes a difference.  [1]


How to export UVMap to paint with external tools

I'm searching all over for a way to paint my UVMap in external tool, in my case photoshop, and them load it back to the mesh in render.  The problem is I want to use that blender export feature that creates a basic surface in the uvmap so it would be easy to identify the parts and paint in photoshop.  that this feature just exists in blender render as far as I searched.  any idea how to do that in cycles render?  I hope I was clear, thanks


Convert and ubuntu.iso file into a .dmg file

Can anyone help me figure out how to convert an iso into a dmg file..  I'm sure it has something to do with the dd command,  but I'm really not sure how to go about it..  I need to make a bootable ubuntu disk for an imac, and it is not reading any of the hundreds of burnt iso disks i have..  I'm at a total loss..  everything i can find about the process is done on a mac, and since my imac has been broken for about a year, I'm kind of stuck..  Thanks in advance. Max


I have a Kona Rove ST 2019.  only say "Spokes: Stainless Black 14g". How do I know the precise reference so I can buy some spare ones online?


Why doesn't C# allow generic types to be used as attributes inside the generic class?

This isn't a very important question, I'm only curious why it's not allowed. The error message is not helpful in explaining, because obviously 'Att' does inherit from Attribute.  public class Generic<Att> where Att : System.Attribute {     [Att] //Error: 'Att' is not an attribute class     public float number; }


Is it possible to get that typical chrome-like angled look using the Shader Editor? I see a lot of tutorials making chrome on all types of surfaces but not on a knob geometry like the one in the following image:  Q: Is there any way to get that chrome-like surface appearance procedurally or should I just use a texture to fake it?


Why do I receive Software Update notifications if there are no updates available?

I keep receiving the following notification about new updates:    If I then run the Software Updater, however, I don't receive any of these updates on Ubuntu 16.04.    Does someone have the same problem?


If I upgrade Ubuntu 12.04 to 14.04, will NS2 still be supported?  I am currently using NS2 on Ubuntu 12.04.


How do I ALTER a PostgreSQL table and make a column unique?

I have a table in PostgreSQL where the schema looks like this:  CREATE TABLE "foo_table" (     "id" serial NOT NULL PRIMARY KEY,     "permalink" varchar(200) NOT NULL,     "text" varchar(512) NOT NULL,     "timestamp" timestamp with time zone NOT NULL )   Now I want to make the permalink unique across the table by ALTER-ing the table. Can anybody help me with this?  TIA


Could dark energy just be another characteristic of the gravitational force?

Recent observations of the accelerating expansion of the universe have been quantified and for the time being given a name as to the cause: Dark Energy. And from what I've read from other, similar questions is that Dark Matter is a pressure that is causing this expansion, although we don't know the details of the mechanism yet behind this pressure.  But is there anything in our present theories of physics or observations that rules out gravity itself as the cause of this expansion? I'm thinking along the lines of an analogy: the nature of the strong nuclear force which, at close distance, tends to bind together nucleons, but at even closer distances repels them.  Couldn't this repulsive force we observe, this dark energy, just be the effects of the gravitational force on a larger scale of space?


What would a backdoor in symmetric key cipher look like?

Pretty much what the title says. DES was suspected of having one, but I couldn't imagine what it could possibly look like if only the NSA knew how to use it. Dual_EC_DRBG's backdoor is asymmetric, but it's not a cipher. Could one have a kletographic symmetric key cipher?


Sections (paragraphs) ordered different than in code

I need to write a task assignment (a paragraph ordered by enumerate) and attach a solution (possibly using hyperref technique). That's clear. But now I want the task solution to be placed at the end of the document in PDF but next to the assignment in the code.  What would be the best option to do so?  Example:  \begin{document}  \section{Tasks}  \begin{enumerate}   \item \label{Newton} How many apples fell on Newton's head?     %Here should be a code: How the hell should I know?   \item \label{Archimedes} How loud screamed Archimedes "Heureka"?     %Here should be a code: How the hell should I know? \end{enumerate}  \section{Solutions}  %Here should be an automatically created list of previously commented content.  \end{document}


Fedora automount external hdd where can I change the mount options

I've been pulling my hair to know where I configure the auto mount configurations for when I plug in my external harddrive. As I really don't want to have atime changed when I have my external hdd.  I've been using Fedora 26 and I need to know the location of configuration files to allow me to edit the rules for mount options.


Asus UEFI/BIOS options - How to boot from DVD?

I just bought a new PC and the default installed OS is Windows 8. I want to install Windows 7 but when I go into the boot options screen I only have one option:  Windows Boot Manager   I can't find my DVD drive. It is plugged in and visible under SATA options. How is it that I don't see it in the boot options menu?  The weirdest thing is that the drive is working perfectly inside Windows. So Windows 8 can detect it but the BIOS can't? I'm stuck with Windows 8... Any ideas?


How to move home directory to a new partition? And does it delete files?

I would like to move my /home/[user] to my partitioned drive that is currently /media/[user]/D.   I have been saving all of my pertinent files on the second drive, but I would like to make it a shorter path like ~.


I know that the integral looks like like the anti-derivative of $\arctan$, but i don't know how to use this fact so I tried to use a fraction decomposition to: $$\frac{1}{(x^2+1)^2}$$ to solve the anti-derivative : $$\int \frac{1}{(x^2+1)^2}\, dx$$ so :$$\frac{1}{(x^2+1)^2}=\frac{A}{x^2+1}+\frac{B}{x^2+1}\iff \frac{1}{x^2+1}=A+B$$ $$1+0x^2=(A+B)x^2+(A+B)1$$ Thus I got this system of equations: $$\cases{A+B=1 \\ A+B=0}$$ Which is impossible. I also tried to use substitution but it didn't help me.


Can we take negative numbers as base in taking log?

Can we take the negative numbers as base in taking log?    For example:$$\log_{(-2)}4=2$$ $$\log_{(-3)}81=4$$ etc.


Singularities in the punctured unit disc and square integrability

I'm having trouble with the following problem:  Let $f$ be holomorphic on the punctured unit disc, $D$. If $\int_D|f(z)|dA(z)<\infty$, then $z=0$ is either a removable singularity or a simple pole of $f$.  A similar problem is to prove or disprove that if $\int_D|f(z)|^2dA(z)<\infty$, then $f$ has a removable singularity at $0$.  I've tried using the Mean Value Property for $f$ and taking the limit as $z\to0$, but I didn't get anywhere.


today I was wondering why every sculpting app has the circle widget sticking to the surface normal and Blender does not, I find it to be a quite important visual aid  Retopoflow addon's widget does it already but, as far as I know, there is no sculpting plugin with a similar widget, and don't know if this functionality can be extracted from it being working modal. Is this sort of widget feature be even tackled by an addon (if it doesn't exist already)?  Blender it's already a really powerful tool for sculpting and 2.77 improvement are great, maybe it's just me feeling this need?


Ubuntu 15.04 intalled on older computer is running slow

I just installed Ubuntu 15.04 on an older computer because it could not handle many of the features included with Windows Vista. I thought I would try Ubuntu to improve performance. However it isn't running any better. Is there a way to remove some of the less important features of the Ubuntu O.S. to improve the performance of this older computer?


i have an array that i encode using '$args = json_encode($arr)' and then i create an sql command using $sql = "INSERT INTO log (/*...*/,`arg`) VALUES (/*...*/,'$args')";  which i then execute. It usually works very well, except when i have a string conating the character " like $name = 'Lore "Ipsum" dolor'; In the resulting sql command this looks like this: INSERT INTO... VALUES(..., '{"name": "Lore \"Ipsum\" dolor"}') which prosudes an Error


echo 1 > sudo /sys/block/sdX/device/delete command

I am trying to delete a scsi disk using below command echo 1 > sudo /sys/block/sdb/device/delete. When I try to lsscsi after the command, I am still able to see the disk.  That would be great if some one can point where I am going wrong.


localhost redirecting to https after Mojave upgrade

After the recent upgrade to macOS Mojave Safari started redirecting from http://localhost to https://localhost. The problem persists only in Safari, in Chrome everything is the same as before. Now I'm temporary using 127.0.0.1 as a replacement, but it's inconvenient due to some limitations of software I'm using.   I tried searching and found some similar questions, where accepted answers were to kill Safari and remove ~/Library/Cookies/HSTS.plist file, and in my case it didn't work.   I also tried , without luck.


I have tried to search around google, Bing, and Minecraft forums. I wand to ADD a NEW mob to the game. ------------ requirements for the answer -------  it has to be compatible for 1.16.4 it has to be how to add a new mob not change an existing no spam it cannot be a mod to add this to Minecraft I want it to be in my resource pack If I have to create a new pack, that is fine