TestCase.h  class TestCase {   public:     template<size_t N> TestCase(int (&arr)[N]) {       // Constructor code here, I iterate over the array of values.     }     // etc   private:     int var1;     // etc }   This is my header file for a class. The class takes in an array of any size using a template. This works great but I hate having the constructor code in the .h file. How can I move the constructor code into the .cpp file with the rest of the member functions? I can't use vectors or anything. Thanks :)


How can we prove that group of order 80 is solvable without using Burnside's theorem () ?


How to Teleport Players When They Enter a Certain Area/Coordinates

I am trying to teleport a player to certain coordinates once they enter an area.  The idea is that they walk into a really small building, but once they turn a corner, they get teleported into a larger building.   Please refer to the adventure map named '5 Cubed', if you need help understanding what I am asking.


Copying data from some columns of one table to some colums of another table

I have two table ex: student_old & student_new. I want to copy data from student_old to student_new. The table structures are in two different ways.  ex:  student_old  1. stu_id  2. stu_first_name  3. stu_middle_name  4. stu_last_name  5. stu_course 6. stu_class   student_new  1. student_id 2. student_last_name 3. student_first_name 4. student_address 5. student_dob 6. student_course 7. student_batch 8. student_class   Above is an example only. The table structures cannot be changed because it belong to an institute. There are 1000+ data in the old table. And there is no order between the two tables, as in data of column six of student_old should go to column eight in student_new. I need a SQL query to get data from the old table to the new.   I'm new to SQL. And i tried searching online, but i didn't get ant satisfactory answer. Hope you guys would help.


Prove that $a|p+1$ if and only if ${\frac{a}{p} = \frac{1}{n} + \frac{1}{m} }$ such that $n,m \in N$ and $p$ is prime

Let $p$ be a prime and let $n$ be a natural number such that $n \gt a$ . Prove that $a|p+1$ if and only if exists integers $n,m$ Such  that    ${\frac{a}{p} = \frac{1}{n} + \frac{1}{m}}$


I wanna combine two old PCs together to be one PC and I wish that if anybody can tell me any solution because it would be hard for me to buy a new PC atm


Can Convolution Neural Network be useful with encoded categorical features?

Convolution Neural Network (CNN) has been very successful in numerical features / inputs / independent variables, such as computer vision or or audio signal. And It can be viewed as extracting the useful information in frequency domain. (See )  But would it be useful in categorical feature. For example, suppose all of our features are categorical: a person's gender, race, education level, etc., what is the convolution mean on the data matrix (one-hot encoded) like that?    More background, my data are not images or audio, but more similar to , with the increasing popularity in deep learning and CNN, I am curious if it is also useful in non-images.


null object reference when calling a method from an extended activity

i am making a bluetooth service in android studio. i execute the service in a single activity successfully using some post in stackOverFlow like :  but when i want to send data from a second activity that extends first activity, to the bluetooth device i got a "null object reference". public void onClick(View v) {             sendToDevice(editSendData.getText().toString());         }  sendToDevice is a non-private method in MainActivity(first Activity): public void sendToDevice(String inMain){      printerService.sendingData(inMain);     Log.i("3","thread id:\n"+"send1"); }  //printerService is bluetoothService //sendData is a method in bluetoothService that uses bytes of "inMain" to send data using outputStream i do not know why but as i know, when second activity extends first activity(an activity is class), it also extends non-private methods of first activity. so why this error occurs? i did not find a question like this one but there was a question in the comment of another question simillar to my question but that wasn't answered. thank you a lot. any help would be appreciated.


What is the dot product and why do we need it?

I understand how to calculate the dot product of the vectors. But I don't actually understand what a dot product is, and why it's needed.  Could you answer these questions?


Calculate compound interest rate in Google Spreadsheet

Assume the PV=100, FV=150, yearly IR=X, number of period = 60 (5 years of interest and compounding is monthly basis)  Therefore:  FV = PV * (1 + X / 12)^60    How can I calculate X easily?   Technically I can use (root(FV/PV))-1)*12, where root(N) is the 60th root of N. But is there any existing function I can use such as PV and FV?


A doubt in the concept of potential energy

The concept of potential energy is best understood with examples, so let me give an example:    There lies a mass of $1~\mathrm{kg}$ on ground, I lift the mass to a height of $1~\mathrm m$. Since I have done a work (force times displacement) against the gravity, therefore, I have given potential energy to the mass.    Well, how can I know that the mass has gained any energy, if you say that “Let it fall and it will gain kinetic energy”. This argument shows that potential energy that I gave to the mass during the lift is now converting into kinetic energy, but I see it as the gravity doing work on the mass and therefore its kinetic energy is increasing.    Gravity is a force, so it can provide kinetic energy to a body by setting it in a motion and that’s exactly what’s happening in the above argument. Just imagine that I lifted that mass of $1~\mathrm{kg}$ and at when I reached to a height of $1~\mathrm m$ I just switched off the gravity. Now, will the potential energy convert into kinetic energy if I let the mass to fall (the word fall here refers only to my leaving it there). I think no, it will just remain there. So, it can be argued that energy-conservation is violated and hence the thought experiment is sloppy, but this contradiction of energy-conservation has come only from axiom of potential energy (the axiom that working against a field lets the object to gain some kind of energy called potential energy) So, why there is a concept of potential energy when it can be understood as the field is doing the work and supplying the kinetic energy rather than potential energy is getting converted to kinetic energy?    A Second View of the Situation: Let's take magnetic field  instead of gravitational field, imagine that I have two wires with current flowing in both of them in same direction, like this  According to the principles of magnetism, the two wires will attract each other, now if I take the violet wire far away (all I mean is doing the work against the attractive field) and then suddenly switching off the current in the red wire, would my violet wire accelerate towards the red one? If not where the potential energy has gone which I supplied it during taking it away.    We can also imagine this situation using electrostatic field (as @FGSUZ has said in his comment) by using parallel plate capacitors. We can do same thing in this setup too.     Thank you. Any help will be much appreciated.    Explanation of why I don’t think that my question is a duplicate: The question which was suggested to me as of which mine is a duplicate, I think that question is basically on work-energy theorem, there OP’s main problem was why potential energy came when work is defined as change in kinetic energy. My question is why do we say that potential energy converts into kinetic energy when it is the force(the gravitational force) which is supplying the kinetic energy?    Another defense against duplication: The question, to which my question is seemed to be of duplicate, says clearly in the last second paragraph above the EDIT as  "Secondly, the force done by us (the external agency), is along the direction of the displacement, the work done is positive and so the change in kinetic energy should be positive (by the work energy theorem?)" It says clearly that the OP wants to understand things in terms of energy theorem and doubts within it. My question deals with the interpretation of conversion of PE into KE and the work done by the field to supply KE.


I noticed that $$\frac{d^{n}}{dx^{n}} f(x)g(x)=\sum_{i=0}^n {n \choose i} f^{(i)}(x)g^{(n-i)}(x)$$ and it's had me scratching for a little bit. It's easy to see how the cross terms add up but can anyone draw a direct comparison between the behavior being exhibited here and the binomial expansion? It seems to work for the case equivalent to the multinomial theorem as well ($\frac{d^{m}}{dx^{m}} \prod_{k=1}^{n} f_k(x)$). Can someone produce a proof for this more general case (preferably by induction)? Any and all insights are welcome!


Minecraft crashes with "java.lang.IndexOutOfBoundsException" when loading on an older version

Whenever I try to run older versions of Vanilla Minecraft it won't allow me to create or load a world in Singleplayer. If I try, it will start to generate the world, then crash.  Error Message:  ---- Minecraft Crash Report ---- // Oh - I know what I did wrong!  Time: 2/1/16 10:14 PM Description: Unexpected error  java.lang.IndexOutOfBoundsException     at java.nio.Buffer.checkIndex(Buffer.java:540)     at java.nio.DirectIntBufferU.get(DirectIntBufferU.java:253)     at bls.a(SourceFile:270)     at bls.a(SourceFile:220)     at azd.a(SourceFile:1675)     at azd.a(SourceFile:1633)     at biv.a(SourceFile:113)     at gu.a(SourceFile:70)     at gu.a(SourceFile:13)     at ef.a(SourceFile:164)     at azd.o(SourceFile:1566)     at azd.ad(SourceFile:753)     at azd.e(SourceFile:704)     at net.minecraft.client.main.Main.main(SourceFile:103)   System Details:    -- System Details -- Details:     Minecraft Version: 1.7.2     Operating System: Mac OS X (x86_64) version 10.10.4     Java Version: 1.8.0_60, Oracle Corporation     Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation     Memory: 148530064 bytes (141 MB) / 285257728 bytes (272 MB) up to 1048576000 bytes (1000 MB)     JVM Flags: 5 total; -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn240M     AABB Pool Size: 18497 (1035832 bytes; 0 MB) allocated, 18497 (1035832 bytes; 0 MB) used     IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0     Launched Version: 1.7.2     LWJGL: 2.9.1     OpenGL: Intel(R) HD Graphics 6000 GL version 2.1 INTEL-10.6.31, Intel     Is Modded: Probably not. Jar signature remains and client brand is untouched.     Type: Client (map_client.txt)     Resource Packs: []     Current Language: English (US)     Profiler Position: N/A (disabled)     Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used     Anisotropic Filtering: Off (1)   Is this a system problem, is there a problem with my system settings that would cause this error? If so, what steps can be done to correct it. If not, what could be the problem?


My son doesn't want to share anything with other kids, and if some kid even so much as touches his toy, he pushes the kid. He shouts and cries at the same time, and tries to express his anger by pushing and hitting the kid. I feel so embarrassed in front of other parents.   And when he is at home with me and doing something wrong, I try to stop him, he tries to repeat my words and shouts at me. He is copying the behavior of others, whether it's a good act or bad...  Please help me how to stop him from being a bully.


Did Prof. Quirrell's body house two fragments of Voldemort's soul?

From HP :     J. K. Rowling revealed in Pottermore that Prof. Quirinus Quirrell served as a temporary Horcrux when Voldemort's soul possessed his body during Harry Potter's first year at Hogwarts. (source: )   QUESTION:  Seeing how at that point Quirrell was inhabited by the "main" fragment of Voldemort's soul (and that fact was something 100% clear and obvious from "HP&SS" book), does the statement above mean that somehow there actually were *two fragments of it in Quirrell, one "main" and one "Horcrux"?* If not, then what's the "reveal" part?


Some detail on @Username: why doesn't Stack Overflow write a link to the referred user?

I've read the post , but I am not sure I understood how to refer correctly to a user, for example, Sha Wiz Dow Ard. If I got it right, I have to write @ShaWizDowArd because spaces must be ignored.  Does it mean that there are no users called "ShaWizDowArd", "ShaWiz DowAr", because they wouldn't be unique usernames?  Talking about name + surname, does it mean that if there's a user called "John Smith" I can't register as "JohnSmith" or "John-Smith"?  How can I be sure my @referral is correctly written and interpreted? Is there a way to know if I referred to the right person? Why don't you write a link in "href style" to the user I'm referring to?


Define a function $\delta : \mathbb{Z}[i] \rightarrow \mathbb{N}$ by $\delta(a+bi)=a^2 +b^2$. Show that $\delta$ is a Euclidean valuation on the Gaussian Integers $\mathbb{Z}[i]$ i.e. For Gaussian Integers $a,b$ there exists Gaussian Integers $q,r$ such that $a=qb+r$ with either $r=0$ or $\delta(r)<\delta(b)$.  What I have so far: Let $a=a_{1}+a_{2}i$ and $b=b_{1}+b_{2}i$ be Gaussian Integers. Then $\frac{a}{b}=\frac{(a_{1}b_{1}+a_{2}b_{2})+(a_{2}b_{1}-a_{1}b_{2})i}{\delta(b)}$. Let $q$ be the Gaussian Integer which is closest to $\frac{a}{b}$ in the complex plane and $r=a-qb$. I then think I need to show that $r$ is suitably small, but I'm unsure how to do this. Any help would be greatly appreciated.


I'm trying to find out if there is a product out there to simulate Multiple Monitors on one large monitor/tv?  So take a screen and turn it into something like below...  -------------------------------- |               |              | |               |              | |               |              | |               |              | -------------------------------- |               |              | |               |              | |               |              | |               |              | --------------------------------   Something like this...even though in reality it's a single screen.  A software solution is perfectly fine as long as it functions like the built in Windows 8 functionality (Start screen only consumes the screen it was started on/etc).  If anyone is curious as to the reason.  I'm looking to get a treadmill desk since I'm a developer and don't like being sedentary all day.  So the two options that I see are having 4 monitors and mirroring them (I don't want to have to worry about forgetting to move the window that I need) or getting a large monitor/tv and putting it on an arm that I can simply swivel into place.  There are dual-monitor swivel mounts, but they are EXTREMELY pricey and the ones I've found don't appear to have the range of motion that I'm anticipating needing.  EDIT:  I found ... but I can't find the answer to the start menu question (I've sent the company a message on facebook).  Hoping I hear good news as this appears to offer many of the features I'm wanting.  So Fingers crossed there.


Will Mac Mini work with Dell Inspiron Laptop

I am interested in buying the new Mac Mini as I cannot afford a Mac book or Air. The laptop I have is Dell Inspiron 3537. So I wanted to know is it possible to connect Mac Mini with my Dell laptop. Any help will be appreciated.


Want to remove all printers but cant - printers keep returning

I have had many issues with printers - can never get the same result - sometimes they work - sometimes they dont - some times they print out blanks - just want to remove all printers but cant  - Tried removing them in settings/printers but they just keep reappearing. I want them purged from my computer if possible. I read where browsing can be turned off but I want them removed completely if possible. Thank you kindly


Laptop only using subwoofer rather then surround sound

I have a (still relatively new) acer predator laptop (G9-593-7757 15,6"/i7-7700/32 GB RAM/512 GB SSD/1 TB HDD/GTX1070) running 16.10 and noticed that the sound sounds far more hollow then when I use windows. It appears as if the laptop is only using the subwoofer rather then the 2 other speakers making the sound distorted.   Here is my /etc/pulse/deamon.etc file   # This file is part of PulseAudio. # # PulseAudio is free software; you can redistribute it and/or modify # it under the terms of the GNU Lesser General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # PulseAudio is distributed in the hope that it will be useful, but # WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # General Public License for more details. # # You should have received a copy of the GNU Lesser General Public License # along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.  ## Configuration file for the PulseAudio daemon. See pulse-daemon.conf(5) for ## more information. Default values are commented out.  Use either ; or # for ## commenting.  ; daemonize = no ; fail = yes ; allow-module-loading = yes ; allow-exit = yes ; use-pid-file = yes ; system-instance = no ; local-server-type = user ; enable-shm = yes ; shm-size-bytes = 0 # setting this 0 will use the system-default, usually 64 MiB ; lock-memory = no ; cpu-limit = no  ; high-priority = yes ; nice-level = -11  ; realtime-scheduling = yes ; realtime-priority = 5  ; exit-idle-time = 20 ; scache-idle-time = 20  ; dl-search-path = (depends on architecture)  ; load-default-script-file = yes ; default-script-file = /etc/pulse/default.pa  ; log-target = auto ; log-level = notice ; log-meta = no ; log-time = no ; log-backtrace = 0  ; resample-method = speex-float-1 ; enable-remixing = yes ; enable-lfe-remixing = no ; lfe-crossover-freq = 0  flat-volumes = no  ; rlimit-fsize = -1 ; rlimit-data = -1 ; rlimit-stack = -1 ; rlimit-core = -1 ; rlimit-as = -1 ; rlimit-rss = -1 ; rlimit-nproc = -1 ; rlimit-nofile = 256 ; rlimit-memlock = -1 ; rlimit-locks = -1 ; rlimit-sigpending = -1 ; rlimit-msgqueue = -1 ; rlimit-nice = 31 ; rlimit-rtprio = 9 ; rlimit-rttime = 200000  ; default-sample-format = s16le ; default-sample-rate = 44100 ; alternate-sample-rate = 48000 ; default-sample-channels = 2 ; default-channel-map = front-left,front-right  ; default-fragments = 4 ; default-fragment-size-msec = 25  ; enable-deferred-volume = yes deferred-volume-safety-margin-usec = 1 ; deferred-volume-extra-delay-usec = 0   here are my devices  $ cat /proc/asound/devices    1:        : sequencer   2: [ 0]   : control   3: [ 0- 0]: digital audio playback   4: [ 0- 0]: digital audio capture   5: [ 0- 0]: hardware dependent  33:        : timer  $ cat /proc/asound/cards  0 [PCH            ]: HDA-Intel - HDA Intel PCH                       HDA Intel PCH at 0x83620000 irq 134   Anybody got any ideas?


C++ Inheritence vs Using parent class as a field in children classes

I was wondering why to use inheritence, when you can easily come up with an alternative, which for me is more evident to use:  Let's say we have classes Parent, Child_1, and Child_2:  class Parent { public:     int x; }  class Child_1 { public:     Parent p;     string s; }  class Child_2 { public:     Parent p;     char c; }   How is this different, than:  class Parent { public:     int x; }  class Child_1 : public Parent { public:     string s; }  class Child_2 : public Parent { public:     char c; }   I understand that using inheritance allows us to use private, protected and public fields separately, but for me it complicates things more than being useful. To be honest, when I used private, it was more of a drawback, that I had to write getter and setter functions for private fields. Now I usually just put everything to public, for the sake of simplicity. Opinions?


For any three vectors $x,y,z\in\mathbb{R}^d$, we have $ \|y-z\|\cdot\|x\|\leq\|x-y\|\cdot\|z\|+\|z-x\|\cdot\|y\|$

Does anyone know a proof of the following problem?  Problem: Show that for any three vectors ${\bf x}, {\bf y}, {\bf z}\in \mathbb{R}^d$ the following holds, $$ \|{\bf y} - {\bf z}\|\cdot \|{\bf x}\| \leq \|{\bf x} - {\bf y}\|\cdot \|{\bf z}\| + \|{\bf z} - {\bf x}\|\cdot\|{\bf y}\|.$$  All of the norms are Euclidean 2-norm.


I am not sure if this sentence should have numbers of or number of. Here is the sentence "Right now, there are some impressive statistics on the numbers of women entrepreneurs in the US."


extracting from text blocks with stringr

I’m trying to use str_extract() from the stringr package to extract text from between square brackets using the pattern "(\\[){1}(.*)(\\]){1}". This works fine when the text between sets of brackets is separated by a new line (i.e. \n). Otherwise I get chunks of text that span multiple brackets.  So when:  my_text <- "[Sed ut perspiciatis]  [unde omnis iste natus] error sit architecto beatae vitae dicta sunt explicabo. \n [Nemo] sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt.  [consectetur], adipisci tempora incidunt ut \n [labore] et dolore magnam aliquam quaerat voluptatem. Ut consequatur, vel illum qui dolorem eum fugiat quo \n [voluptas nulla] pariatur?"  str_extract_all(my_text, "(\\[){1}(.*)(\\]){1}")   I get:  [[1]] [1] "[Sed ut perspiciatis]  [unde omnis iste natus]"                                                       [2] "[Nemo] sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt.  [consectetur]" [3] "[labore]"                                                                                [4] "[voluptas nulla]"          while I would like to obtain:  [[1]] [1] "[Sed ut perspiciatis] " [2] "[unde omnis iste natus]"                                                       [3] "[Nemo]"  [4] "[consectetur]" [5] "[labore]"                                                                                [6] "[voluptas nulla]"    How would I go about doing this?


Controlling and dependent picklist in lightning

I have industry and subindustry picklists in classic but i want to work these picklists in lightning component. I have created controlling picklist but not able to fetch related values of dependent picklist. Please help.  Code is-  <aura:component Controller="BPValueCalController">     <aura:attribute name="valueCalculator" type="Value_Calculator__c[]"/>     <aura:attribute Name="NewValueCalculator"  type="Value_Calculator__c"         default="{ 'sobjectType': 'Value_Calculator__c',                     'Name':'',                     'Picture__c' :'',                     'Industry__c' :''                  }"/>     <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>     <aura:attribute Name="value" type="String"/>
         <form class="slds-form--small">

                     <ui:inputSelect label="Industry" class="dynamic"                                      aura:id="InputSelectDynamic"                                      value="{!v.NewValueCalculator.Industry__c}"                                      required="false"                                     change="{!c.onSelectChange}"/>

                     <ui:inputSelect label="Sub Industry" class="dynamic"                                      aura:id="subIndustry"                                      value="{!v.NewValueCalculator.Sub_Industry__c}"                                      required="false"                                     change="{!c.handleIndustryChange}"/>

         </form>
 </aura:component>   Controller code-  public class BPValueCalController {     @AuraEnabled     public static List<String> getValueCal(){         List<String> options = new List<String>();         Schema.DescribeFieldResult fieldResult = Value_Calculator__c.Industry__c.getDescribe();         List<Schema.PicklistEntry> ple = fieldResult.getPicklistValues();             for (Schema.PicklistEntry f: ple) {                 options.add(f.getLabel());             }         return options;     }    }   Controller.js code-  ({     doInit : function(component, event, helper) {         var action = component.get("c.getValueCal");           var inputsel = component.find("InputSelectDynamic");          var opts=[];         action.setCallback(this, function(a){             for(var i=0;i< a.getReturnValue().length;i++){                 opts.push({"class": "optionClass", label: a.getReturnValue()[i], value: a.getReturnValue()[i]});             }             inputsel.set("v.options", opts);          });          $A.enqueueAction(action);       },      onSelectChange : function(component, event, helper){         var selected = component.find("InputSelectDynamic").get("v.value");         alert(selected);         console.log('selected');      },  })


Testing with the linux command line and pipe I tried to do echo {1..3} | touch and it doesn't work. I achieved the results with touch $(echo {1..3}). Why I can't pass the list generated by echo to touch using the pipe as in the first example?


Today I started getting a black screen when resuming my computer from sleep. Completely unresponsive. Couldn't even switch to another tty. Are a hard shutdown everything worked fine, but the same behavior reappeared after every suspend.  Naive as I was, I thought that maybe an update would solve the problem. Now after completing the upgrade I experience the same behaviour on boot. Right after the GRUB menu, the screen goes black. Choosing recovery mode and dropping to a root shell works as it's supposed to.  I've checked boot.log, syslog and the systemd logs and I can't find anything that looks like a serious problem. Here's a link to my , in case it helps.  My computer runs the mini.iso release of Ubuntu 17.10.  I'm really stumped here an have no idea where to look right now. I'd really appreciate some help!  Thanks  EDIT:  So it turns out that the suspension and boot to black screen were two separate problems. I managed to fix the boot problem by changing the grub config; it must have been messed up by the upgrade. The problem still remains after resuming from suspend however (closing the lid or running systemctl suspend)  EDIT 2:  I found this error in my systemd logs: wlp4s0: failed to remove key (1, ff:ff:ff:ff:ff:ff) from hardware (-22) which led me to . I have now upgraded to kernel 4.15.0 but I'm still seeing the same issue.  It actually looks like the screen doesn't turn on at all. It's not just blank but completely black.


Random sums of iid Uniform random variables

Let $\{X_r : r\ge 1\}$ be independently and uniformly distributed on $[0,1]$. Let $0<x<1$ and define  $$N=\min\{n\ge 1 : X_1 + X_2 +\ldots+X_n> x\}$$  Show that $$P(N>n) =  \frac{x^n}{n!}$$ and hence find the mean and variance of $N$.  I cant see how $N$ can be greater than $n$, as each $X_r$ is less than or equal $1$, so if each $X_r= 1$, then the sum would equal $n$, but not be greater. I am obviously interpreting this wrong but I cant see where.


Why do certain commands not show up when you type "help" in cmd.exe?

For instance, netstat. This doesn't show up when you type help, but netstat /? does provide the information.  Are there any other commands that will not get listed?  Also, the command netstat /? > netstat.txt won't work. Any idea why? The netstat.txt file is created but remains empty.  I have write-permission on the map and the CMD.EXE is running as admin.


Do I have to give my mailing address to create a certificate?

So, ICANN seems to require a mailing address for my domain, but my registrar (like many others) offers to proxy the mail to me to provide privacy.  However, when I want to create an SSL certificate, that also requires a mailing address.  What's the most common and acceptable way to keep my physical address private when creating a cert?


Find the coefficients of the Fourier series that minimise the error.

I am having a little trouble understanding what I have to actually do here. What does differentiate with respect to bn? I thinks after differentiation I must use some calculus theorem about extreme but how do I get there?


Causes for name / image to be listed as "last modified" on question list

I recently added an answer to a post, only to find someone else providing nearly the same answer (theirs was a bit better) so I deleted my entry.  Now the main question page lists my entry as being the one to "Last Modify" the post.  This seems odd to me...   Here's image the post and the    Here's a shot of who modified the post:   So those who post answers (and delete them) are considered editors of the original post?  that seems very odd to me.


I'm running CentOS 7, but hoping there is a general Linux way of doing this.  So you can cd back and forth between the previous and current directory with this:   cd -   Is there I way can cd back multiple directories? So I keep going back previous directories instead of just the last one?  Does Linux or bash track your navigation history at all?


How badly does failing a core class and retaking it hurt your chances at grad school programs?

I'm sorry if this is in the wrong place. I'm an undergraduate majoring in biology. I think, this semester, I'll fail a class on Statistics (the class is titled "Statistics for Life Sciences"). While I have the option this semester to use "Satisfactory/Unsatisfactory" and protect my GPA, this is nonetheless a failure that will show up on my transcript. I know I messed up and I feel really bad... I could have taken an introductory Math class (an option available to those with only an AS Level in Mathematics) before taking this Statistics class and I stupidly chose not to (officially, an AS Level meets the prerequisite for this Statistics class, though most students taking it have a full A Level in Mathematics). But this is no excuse (it's officially allowed, and plenty of AS Math students succeed in this class) and I think in fact reflects worse on my judgement.  :( I fully intend to retake this course (I can't not take it anyway; it's a core class, plus Statistics is important in Biology) and do much better in it. How badly does this hurt my chances at a graduate school program in biology? Assuming my other biology-related classes are okay (A grades). I don't know how I'm going to explain it. I was hoping to take a research Master's, then a PhD. Am I screwed? Thanks for any input and and have a nice day.


break: To turn the block into the little floating thing that you can pick up.  destroy: To completely obliterate a block, not even leaving a little floating thing.    Given those definitions, the question is very simple.  I had read about TNT mining , but when I tried it, it exposed a solitary diamond.  I thought this was odd because I'd never seen one block of diamond ore by itself before, which prompted this question:  Do explosions destroy stuff?


What happens to the crew in The Lost World: Jurassic Park?

In The Lost World: Jurassic Park there is a scene where the ship which brings the T-Rex to San Deigo has no crew inside it. How come all the crew members are dead if the dinosaur was still inside the cage?


How can energy have inertia?    To my intuition, inertia is so closely associated with mass that my intuition says "Huh?"  Indirectly by mass energy equivalence it works fine, for example:  I have a closed system, and add energy. Now it has more mass according to $E=mc^2$, and the inertia associated with that mass increased.   I do not doubt it's right, but does it mean anything associated with physics, beyond being true?


How can I do mathematical operations with Date using just vanilla JS ? something like : today + 2 days const today = new Date(27/3/2020); const DayToAdd = 2;   return today + DaytoAdd //expected 29/3/2020


Quicklook all unassociated files as text QLStephen doesn't work

Currently some filetypes have their own quicklook associations already, e.g. .mp4 files quicklook with some lite quicktime player, and .jpg files quicklook as an image. How can I make every unassociated file quicklook as if it were text? Commonly I have lots of programming or markup sourcefiles that I want to quickly inspect contents of. I have installed QuickLook Stephen, but it only seems to work for the files it specifically says it works for (README, package.json,— it's NOT working for arbitrary unassociated files, in my case these are files like *.cs, *.csproj, *.yml)


Do I use "the" or "a"? How do I decide which article to use?

Do I need to put "the" in front of correlation and negative?     We performed a correlation analysis to measure a correlation between job satisfaction and the shortage of nursing. We found that a negative correlation between job satisfaction and the shortage of nursing was indicated.


Does "a [x] of [y]" take a singular or plural verb?

What kind of verb, singular or plural, goes with phrases like "a record of [singular or plural noun]", "the use of", "the time of"? Does the choice depend on the following nouns (a record of nouns) or on the 'first' nouns (record, use, time)? Or do these phrases obey the rule of proximity (as does "a variety of")?  I have found different example sentences on the internet (source: newspapers or magazines) with different uses. What is correct?  Examples:   there were a record of other issues; there were a record of 28,000 runners; there was a record of these statements.


Potential asbestos exposure from adding screws to drywall?

My father manually screwed in two self-tapping screws into drywall that most likely contains asbestos in the compound. It was in a garage in a house built in 1976. It was actually those hooks that you screw into the wall to hang stuff off of. He did not use any power drill. Is the risk of asbestos exposure low? I understand the drywall usually doesn't contain asbestos but the compound usually did. No idea where he screwed it in.


How do you get the UserName of the owner of a process?

I'm trying to get a list of processes currently owned by the current user (Environment.UserName). Unfortunately, the Process class doesn't have any way of getting the UserName of the user owning a process.  How do you get the UserName of the user which is the owner of a process using the Process class so I can compare it to Environment.UserName?   If your solution requires a pinvoke, please provide a code example.


I have a script that process a folder, and count the files in the mean time.  i=1 find tmp -type f | while read x do     i=$(($i + 1))    echo $i done echo $i   However, $i is always 1, how do I resolve this?


This question is inspired by ?  Aragorn is a half-elf, and if he chooses to move to the west together with all the elves, can he live on forever? Can Elrond make Aragorn immortal?


Why have whales and dolphins not evolved to have gills?

It seems at first glance that it would be an evolutionary disadvantage for a sea creature to have to come up to the surface on a regular basis in order to breathe, so why are there animals (e.g. whales and dolphins) which still need to do so?  If there is some advantage to breathing from the air instead of using gills, why haven't animals such as sharks (or indeed fish in general) evolved to do this instead?


Retrieve name of the active network interface only

How can I retrieve from the command line (or a shell script) only the name of the active network interface, in Linux? If there are several active interfaces, I want just one (selected arbitrarily).


Why is my App Store saying it needs my to give it my credit card?

So, I'm trying to get a make up cam for danTDM photos (lol) so I'm trying to get it and it's free and I haven't gotten a app in a long time and then it came up! GIVE US CREDIT CARD. And so I tryed it again and BOOM it asks again! So now I look at all these things saying what to do and yet again, I can't do it... It says press the "none" credit card... WITCH I DONT HAVE! WHAT DO I DO HELP!


I have my page encoding set to utf8 and even in the meta tag as utf8.  However, when i'm taking a value from a database it's putting a diamond with a question mark instead - im assuming doesnt know the character.  The character is a é. If i do a echo é; it displays as normal on the page. Also if i write it manually in html. However, when i grab the same value from a database call using PDO i get a �  I'm assuming its a PDO setting. I've tried:  $db->exec("SET NAMES 'utf8';");   but this doesnt resolve it.  Any suggestions?


Consider a random variable $X$ with the log-normal pdf $f(x) ={1\over \sqrt{2π}}x^{−1}exp^{{−0.5 (logx)^2}}$, $x>0$.  a) Find the mean and the variance of $X$.  I know that $\int_0^\infty f(x) dx=1$, but this says "consider the random variable $X$ with the log-normal pdf" so would I actually be integrating $\int_0^\infty x f(x) dx$ for the mean? The reason I ask (and I'm skeptical) is because the solution to that integral is disgusting and has $i$ in the solution and that doesn't seem to be applicable for what I'm doing. Any help is greatly appreciated.


This question is founded in . I originally solved the problem years ago but now I'm moving all the problems over to a new language. As I revisit this problem, I already know the answer but I don't know when to stop looking for the answer.  The task itself, minus lead up and notes, is      Find the sum of all numbers which are equal to the sum of the   factorial of their digits.   The task of summing factorials is trivial. What isn't obvious to me is how do I know when I've found them all? I don't want to give away the answer to the question but here's what I know:      I know that there are only 2 of these numbers: 145 as mentioned in the questions example and 40585.   When do I know to stop looking? How do I know that the biggest of these numbers is THE biggest and there won't be any more?


Why didn't Sauron make another ring to replace the One Ring?

When Sauron returned to Mordor, he had his forge, Mount Doom, and probably all of the tools that he has used to make the One Ring, so why didn't he just create a second Ring? Was it because he put too much of himself into the One Ring?


Split a python list into other "sublists" i.e smaller lists

I have a python list which runs into 1000's. Something like:  data=["I","am","a","python","programmer".....]   where, len(data)= say 1003  I would now like to create a subset of this list (data) by splitting the orginal list into chunks of 100. So, at the end, Id like to have something like:  data_chunk1=[.....] #first 100 items of list data data_chunk2=[.....] #second 100 items of list data . . . data_chunk11=[.....] # remainder of the entries,& its len <=100, len(data_chunk_11)=3   Is there a pythonic way to achieve this task? Obviously I can use data[0:100] and so on, but I am assuming that is terribly non-pythonic and very inefficient.  Many thanks.


How can I get my image's output cleaner?

I used a web safe red and I'm still getting a somewhat distorted output. I'm saving in .png format. I've noticed this happening a lot whenever a red color is used. The output looks HORRIBLE on Faceboook and Instagram. I have it at 300 dpi for printing. I'd like the image that appears on the internet to be just as clear as when I print it. I did a screenshot of it on Facebook and included it with this question.


Insert into MySQL using variable for columns through PHP

On the front end of my PHP, I want the user to decided what field to insert into among multiple fields.  I can do that with multiple 'if' statements like I have below, but that makes for a long code.  Can I use a variable for the field, i.e Song_id, Album_id?  I've tried doing something like "Insert into Song(?) values (?)" but that doesn't seem to work.      case "insert":     if ($table=="Song"){         if($field=="Song_id"){             $stmt = $db->prepare("INSERT into Song(Song_id) values (?)");             $stmt->bindValue(1, $_POST['value'], PDO::PARAM_INT);             $stmt->execute();             echo "done";}         break;}     if ($table=="Song"){         if($field=="Alubm_id"){             $stmt = $db->prepare("INSERT into Song(Album_id) values (?)");             $stmt->bindValue(1, $_POST['value'], PDO::PARAM_INT);             $stmt->execute();             echo "done";}         break;}   etc, etc, etc.  Thanks!


In my company we have 8 laptops that we use to deploy on the field. These machines get assigned to a user for a certain time and run Windows Vista. All the machines are the same model.  After the machine is returned, it is company policy to completely format the machine and go back to a predetermined configuration. Right now, what we do is we use the recovery utility in the laptop (we are a small shop so we use the OEM Windows license that the laptops come with) and manually uninstall and change the configuration in order to bring it to our baseline config.  I know that there are ways to create an image that gets copied to the hard drive with a specific configuration and with specific software installed (that's what OEMs do right?).  I'm looking for a tool or a tutorial or something that explains as simply as possible how to create such an image.


Pumping (going faster and faster) on a swing

How can we swing faster and faster without touching the ground? I mean, there's no external force on the swing + human system, right? Or is it because of gravity?  EDIT :  Another possibility : are we using the energy stored in our body (as food and everything) to increase the speed?


Why was Sirius Black not given a trial for the Potters' murder?

Sirius was their best friend and best man, and he was an important part of the Order of the Phoenix. Despite the fact that he was a Black, he should have been given a fair trial before Azkaban. Even criminals like Barty Crouch, Jr. got a publicised trial.  Why didn't Dumbledore or anybody else ever advocate this?


Setting Vista to send only some traffic through VPN

I use uTorrent to download files, and would like to do so with some level of encryption. I have signed up to  to use their VPN service, and have connected to it using the Network and Sharing center.  However when i connect to the VPN all my network traffic, web browsing and uTorrent, is routed through the VPN. Is is possible to set it up so that the uTorrent traffic is sent through the VPN, but all other traffic such as web browsing is not?


Stream network distance between specific paired points

I have a stream network dataset and am attempting to do a distance analysis between paired points located in two different layers. Ex. I have 500 points in layer A with given coordinates, and then 500 points with different coordinates in layer B. I plan to base the distance-pairing on a shared ID. Having looked at other questions related to this, I have often seen the OD Cost Matrix suggested as a solution, or tools that give linear distance. I don't think the OD Cost Matrix will work for me- I want the stream network distance between the points that share an ID, not the distance between Point A and all other points.


What enables protons to give new properties to an atom every time one is added?

How does adding one more particle to the nucleus of an atom give that atom new properties? I can see how it changes it's mass, that's obvious... But how does it give that new atom different properties like color?  A good example would be: start with a copper atom (Cu), with the atomic number 29, thus Cu has 29 protons, and you add one proton to the nucleus you are left with an atom of Zinc (Zn) with the atomic number 30, thus 30 protons. The first element mentioned is a totally different color than the second, and conducts electricity better etc.  Not only protons, but neutrons, which are the same type of particle (Baryon) affect the properties of the element in a much different and much less important manner. Adding a neutron only creates an isotope of that element, not a different one all together, unlike adding a proton.  Also, it is obvious that adding (or subtracting) electrons does not make a difference. For example, if you remove 28 electrons (I know that would take huge amounts of energy, but lets ignore that) that "orbit" the copper atom, we are still left with a copper atom, although a ion, but still a copper atom.  So, its apparent that only protons play a major role in "making" elements different from each other. How and why?  Also, the same can be asked about the protons themselves and quark flavor.


How to add empty arraylist to a ListView? Attempt to invoke interface method 'int java.util.List.size()' on a null object reference

@Override protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);     setSupportActionBar(toolbar);     NoteTaking_Activity noteTaking_activity = new NoteTaking_Activity();      arrayList = noteTaking_activity.getHeadlineArray();      ListView listView = (ListView) findViewById(R.id.List_Of_notes);     ArrayAdapter<String> adapter = new ArrayAdapter<String>( this, android.R.layout.simple_list_item_1, arrayList );      listView.setAdapter( adapter );   Executing the code shown above results in the error message   Attempt to invoke interface method 'int java.util.List.size()' on a null object reference.   The array list is empty at first, but then users may fill it.  What can I do to resolve this error?


meaning of letter "f" after year in financial report

It's a report chart showing the evolution of construction sector through the years . The titles of the columns read:  "2017", "2018f" and "2019f".   Does this mean the numbers below the titles are not final and could vary?  Thank you for your help!


What is the "show desktop" keyboard shortcut?

I just upgraded to 11.10 from 11.04. Previously the shortcut to show the desktop was Super +D (same as in Windows), But now it is not working. What is the new shortcut?


Is this possible to have negative number of reputations? What happens if you have zero reputations and someone downvotes one of your asked questions?


I just read about a guy that was beaten to the punch several times. I couldn't find a meaning of that using my dictionary or Google, so what does that mean?


How does a MOSFET gate resistor reduce ringing?

I desiged P-MOSFET for reverse voltage protection, without gate resistor. The reason that I tend to use it is protect from reverse DC voltage when someone connects the battery.  Do I need a gate resistor? (When someone connects the battery correctly it will be in the ON state, otherwise the PMOS will be OFF.) Second question: How does a gate resistor reduce ringing?


Program for translating English to Morsecode JAVA

I am having trouble on a program that is supposed to translate English to morse code.   public class MorseCode  {   private static String [] english = { "a","b","c","d","e","f","g","h","i","j","k","l", "m","n","o","p", "q","r","s","t","u","v","w","x","y","z","1","2","3","4","5","6","7","8","9","0"};   private static ArrayList<String> morse = new ArrayList<String> ();   public MorseCode(String fileName) throws IOException {     Scanner inFile = new Scanner(new File(fileName));      while(inFile.hasNext()){          morse.add(inFile.next());     }         }      public static void toMorse(String a)     {         String [] phrase = a.split("");           String translated = "";         for (String b : phrase)         {             for (int i = 0; i < 36; i++)             {                 if (b == english[i])                 {                  translated += morse.get(i);                  System.out.println(translated);                 }              }           }          System.out.println(translated);     }   }  Basically, I have an array of english letters/numbers in the String array [] English. The Array List morse contains a list of morse characters that is read in from a file. The English Array and Morse Array List are the same length and correspond in terms of translation.  In the toMorse function, I have a String array phrase[] that has each individual letter of the user inputted message that is to be translated.  For each letter in the message (each index in phrase[]), I go through each letter of the alphabet (english[]), and when I find a match, I take the same index of the match, and append the morse character of that index into a string.   I don't see any errors, but when I run the program there is just blank space after I type the message I want to be translated. I can't get the result to print out. I have made sure that most everything works, but I think there is something wrong in the for and if statements.   I have a separate class to run this:  public class MorseCodeTester {    public static void main (String args[]) throws IOException {     MorseCode m = new MorseCode ("morsecode.txt");     Scanner in = new Scanner (System.in);     System.out.println("Enter a message to translate to Morse Code: ");     String message = in.next();     message = message.toLowerCase();     m.toMorse(message); }   }  Any help would be much appreciated. Thanks!


Q. Let $P(x)$ be a non-constant polynomial whose coefficients are   positive integers. If $P(n)$ divides $P(P(n)-2015)$ for every natural   number $n$, prove that $P(-2015)=0$.   In one of the sources, the solution given is as follows: Note that $P(n)-2015-(-2015)=P(n)$ divides $P(P(n)-2015)-P(-2015)$ for every positive integer $n$. But $P(n)$ divides $P(P(n)-2015)$ for every positive integer n.   Therefore, $P(n)$ divides $P(-2015)$ for every positive integer $n$. Hence $P(-2015)=0$.  I am not able to understand that how $P(n)-2015-(-2015)=P(n)$ divides $P(P(n)-2015)-P(-2015)$. Please help me out.


How can I install Avro in Ubuntu 18.04 LTS release? I have tried with  but not working (previously worked in Ubuntu 16.04 LTS).  Edit: This question is not a duplicated version of . Seems like installing Avro in 18.04 LTS needs some additional steps.


I posted .  And wanted to provide a link to a comment. I can find a solution to provide a .   Apart from going to the user's profile and their activity, finding the comment and obtaining a link from there,  I there an easier way to a specific comment?


MiKTeX and babel: missing file and useless package installation required

After not updating my MiKTeX 2.9 for a very long time, I did it a few days ago. I had  pdfTeX 3.14159265-2.6-1.40.16, LaTeX2e <2014/05/01>, babel <3.8m>,  and now I have  pdfTeX 3.14159265-2.6-1.40.17, LaTeX2e <2016/03/31>, babel <3.9r>.  Something (bad) happened in between: now, whenever I use the babel package (with any language), MiKTeX tells me that bblopts.cfg is missing and requires the installation of the arabi package - which actually contains that file.   Note that I don't even have arabic hyphenation in the format file and, after ignoring that request, the tex file is compiled without errors. Indeed, the rather weird fact is that bblopts.cfg is an optional file: it only appears in this line of babel.sty code:     \InputIfFileExists{bblopts.cfg} ...   Anyway.... To overcome the impasse, since I don't need the arabi package, I simply created an empty bblopts.cfg file. The very weird behaviour of MiKTeX follows:   If bblopts.cfg is in the tex path, e.g., C:\localtexmf\tex\generic\babel,    findtexmf returns the correct path C:\localtexmf\tex\generic\babel, MiKTeX includes bblopts.cfg, as the log file shows     * Local config file bblopts.cfg used   *   (C:\localtexmf\tex\generic\babel\bblopts.cfg).  but it still says that bblopts.cfg is missing and that I have to install the arabi package!  If bblopts.cfg is in the current folder,   findtexmf returns the correct path .\bblopts.cfg MiKTeX includes bblopts.cfg, as the log file shows     * Local config file bblopts.cfg used   *   (bblopts.cfg).  and no warnings or package installation requirements appear!    Does anyone have a clue? Is it just me or is it a MiKTeX bug?? If you want to try, be sure not have the arabi package installed and add the babel package to your tex file. A toy example could be:     \documentclass{article}\usepackage[british]{babel}\begin{document}.\end{document}   Just in case it matters: my OS is Windows 7 SP1 Enterprise...


How to stop the package \usepackage{parskip} disabling the paragraph indentation?

I would like to automatically insert vertical space between my paragraphs. Currently I am using \medskip before all my paragraphs. Example:  % proposal.tex % Based on http://www.latextemplates.com/template/simple-sectioned-essay \documentclass[12pt]{article}  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[a4paper, margin=2cm]{geometry} \usepackage[brazil]{babel}  \usepackage[utf8]{inputenc} \usepackage{mathptmx}  \usepackage{indentfirst}  \begin{document}  \section{Introdução}      In typesetting advertisement copy, a way of justifying paragraphs has     become popular in recent years that is somewhere between flushright     and raggedrightdddd setting. Lines that would stretch beyond certain limits     are set with their glue at natural width. This single paragraph is but an     example of this procedure; the macros are given next.      \medskip     Second paragraph.  \end{document}   Which generates:     I found about including the package \usepackage{parskip}. However after I do so, all my paragraphs indentations are disabled.     Therefore  I found I could use \setlength{\parindent}{30pt} to reset the paragraph indentation, however I am not sure this is a nice thing to do.  % proposal.tex % Based on http://www.latextemplates.com/template/simple-sectioned-essay \documentclass[12pt]{article}  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[a4paper, margin=2cm]{geometry} \usepackage[brazil]{babel}  \usepackage[utf8]{inputenc} \usepackage{mathptmx}  \usepackage{indentfirst}  \usepackage{parskip} \setlength{\parindent}{30pt}  \begin{document}  \section{Introdução}      In typesetting advertisement copy, a way of justifying paragraphs has     become popular in recent years that is somewhere between flushright     and raggedrightdddd setting. Lines that would stretch beyond certain limits     are set with their glue at natural width. This single paragraph is but an     example of this procedure; the macros are given next.      Second paragraph.  \end{document}   Which generates:    I would like to know whether there is a best way which I can include the package \usepackage{parskip} and keep the default LaTeX paragraph indentation, instead of overriding the overrode value with \setlength{\parindent}{30pt}.


I'm currently getting a panda data frame from alpaca - a stock trading platform.  The data I'm getting is for minute data and is giving me a timestamp that cant be converted to DateTime to make my functions easier. Heres an output for AMZN minute data                                 open       high        low     timestamp                                                                    2019-08-08 14:12:00-04:00  1826.8600  1826.9649  1826.1026   2019-08-08 14:13:00-04:00  1826.6500  1827.6520  1826.6500     Heres the data type:  print(type(AMZN.index[0]))  <class'pandas._libs.tslibs.timestamps.Timestamp'>   I'm trying to split this index into two columns where the day is the index and the time(minutes and hours) is the next column.  Or just getting it into all into datetime format together would work fine too.  I've tried finding a similar problem and using _datetime() but it doesn't seem to work.  I have the datetime library but it doesn't seem to register when I use the code as in other posts.  Overall Im just trying to find an easy way of iterating over a certain time on any given day and this format is giving me trouble.  If someone has a better way of dealing with time series of this type please feel free to share.


I have a button that when pressed it outputs a link in a rich text box. However, the link is highlighted in blue but when I click it does not open in my browser. Here is the code(Note that "" represents an actual link.):  using System.Data; using System.Diagnostics; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms;  namespace Project  {     public partial class Form2 : Form     {         public Form2()         {             InitializeComponent();         }         private void textBox1_TextChanged(object sender, EventArgs e)         {          }         private void button1_Click(object sender, EventArgs e)         {             richTextBox1.Text = "https://something.com/" + textBox1.Text;          }          private void richTextBox1_TextChanged(object sender, EventArgs e)         {          }     } }


Can we have the ability to change the reason of cast close vote?

I voted to close this question  as "Unclear what you're asking". However, I googled a bit and found a duplicate some time later.  I was wrong, so maybe it is a good idea to let the caster change the reason of his close vote?


Potentiometer for two 12V/1.1A fans in parallel

I recently bought a potentiometer to regulate the speed of two 12V/1.1A DC fans in parallel, powered by a 12V source. Its specifications are the following: Resistance= 10k Ohm, MaxPower = 0.2W. Can I connect the fans, the potentiometer and the power source in series, or do I need additional circuitry to avoid circuit damage? I feel like the potentiometer's maximum power is too low, but I may be wrong.


First off the word dream in most contexts does have positive connotations. When talking about dreams that people experience during sleep though the meaning becomes fairly neutral, at least as far as I'm aware.   The word nightmare means bad dream, of course. What, though, is the word for a good dream?


If photon experiences time in an instant, does it mean that it's predestined to be consumed?

That one bothers me a lot. If time is collapsed to an instant for the photon, and it experiences it's own end of lifetime, what should happen if photon is never going to be absorbed? Especially interesting in the context of constant expansion of the universe driven by dark energy, which allows more space to appear before photon's path, allowing it to move infinite time until time is not relevant anymore.  Update: Sorry, I don't think that this question is asked and answered in the linked one. The question is not about how photon perceives time (which I think was not answered in the related link), but about the paradox. If there is no paradox, then I would appreciate input on why (so for photon time is not one instant?). Link to a Feymann's interpretation of EM transaction is a good one, but it does not explain why photon should have a consumer in any way.


Amazon EC2 firewall settings not working

I'm new to AWS and set up an AMI instance. I then linked the instance to a "Test" security group to allow all incoming traffic.    When I'm logged in, I can see that the port is running  [ec2-user@ip-1-2-3-4 ~]$ sudo netstat -tnlp | grep :8545 tcp        0      0 127.0.0.1:8545              0.0.0.0:*                   LISTEN      2802/build/bin/geth    If I try to call the port from within the server using the IP that appears under IPv4 Public IP in the EC2 dashboard, I get a Connection refused:  [ec2-user@ip-1-2-3-4 ~]$ curl -X POST --data '{"jsonrpc":"2.0","method":"web3_sha3","params":["0x68656c6c6f20776f726c64"],"id":1}' http://11.222.333.444:8545 curl: (7) Failed to connect to 11.222.333.444 port 8545: Connection refused   All outbound traffic is allowed and I'm getting the same result on my local machine with the firewall disabled.  How can I open the port so I can make my second call from any machine?  Edit  I've added the iptables output:  [ec2-user@ip-1-2-3-4 ~]$ sudo iptables -L | grep policy Chain INPUT (policy ACCEPT) Chain FORWARD (policy ACCEPT) Chain OUTPUT (policy ACCEPT)


Conversion Failed From nvarchar to int even when all values in result set are int

Take the following SQL sample:  Declare @Table Table (Value int)  Insert Into @Table Select intValueAsVarcharType From OtherTable Where Category = 'Type1'   The OtherTable.intValueAsVarcharType contains a list of nvarchar values, all the records for Category = Type1 are castable to ints. Values for other categories cannot all be casted to ints.  When we run the select (without the insert) we get a list of values that are all numeric ints, as expected.  When we run it with the insert we get the following error:  Conversion failed when converting the nvarchar value 'aaa' to data type int.  Another interesting thing is that if we change the where clause to the below:  Where Category = 'Type1' and intValueAsVarcharType not like '%[^0-9]%'   The select statement returns the exact same result set, but this time the insert also works.  I can guess that this is likely caused by the way SQL optimises the query, and that it probably checks all that the values can be casted to int before it filters the result set.  What I'm not sure about is:   Why exactly does adding the second where condition allow it to work when it doesn't change the result set? It seems to have the same execution plan as the statement without it. What is the best way to resolve this issue properly? Adding the second where clause seems to work but it feels "hacky" and I don't know if it will continue to work under all circumstances


What is the largest perimeter rectangle inscribed in a right-angled triangle of 3 and 4 so that one side is over the hypotenuse?

Determine the rectangle with the largest area inscribed on it, so long as one side is over the hypotenuse. Does this rectangle match the larger perimeter rectangle under the same conditions? I've done the calculation for the largest area and found the value of the sides of the rectangle, using a derivative, and found the values of 6/5 and 5/2 but I don't know how to answer the final part of the question.


On average, how many times must a 6-sided die be rolled until a 6 turns up twice in a row?  This  a question from "a collection of dice problem", the original explanation I couldn't understant. Can someone explain it from the expectation (sum of an infinite series) point of view?


Best books for relearning precalculus maths the right way

I am looking for advice on the best texts to remind myself how to do math. I am 35 and an attorney (patent) but was once very good at math (best in my high school, 800 SAT) but then stopped completely after taking Calculus in college as that was all I needed for the MCAT. How I ended up an attorney is a long story...  Anyway, as I get older, I am drawn more and more to understanding simply for understanding's sake. I always enjoyed math because it required a lot of mental effort that led to a real, correct answer. I've gone back to math now and then for fun, took a class at a local college years ago but now I've decided I want to go back again and pick up where I left off but focus more on a rigorous understanding and not just the computational Calculus I took in high school and again in college. I searched online, including reading lots of threads on this site, and ultimately went with Apostol's Calculus Vol 1 and planned to look at the notes in MITs 18.014 class (Calculus w/ Theory).   Long story long, I received the book, got to the first proof in the introduction and realized I have forgotten just about everything. My arithmetic skills are still excellent as even as an attorney those get used day to day, but he might as well have been speaking Greek when he proved the area under the curve/method of exhaustion.  So, hence why I am here. :) I want to find the best book/books to re-ground myself in the mathematics needed to make a go at a rigorous study of calculus. There is no career goal in mind here, I just want to do it for the sake of it.   I came up with several ideas from reading threads here or reading Amazon reviews, including:  Gelfand (Algebra and Trigonometry)  Lang (Basic Mathematics)  Simmons (Precalculus in a Nutshell) Velleman (How to Prove It)  and I have Euclid already on the shelf, hah.  I am a perfectionist, fortunately or unfortunately, so if I am going to go through the effort, I want to do it well and with full understanding, not just blow through some Kahn Academy videos and on to Calculus. But, I also need to be efficient.   Does the list above make sense? Are they redundant or is anything missing? Any other recommendations?  Thanks very much.


Why do the deoxyribonucleotides use T and ribonucleotides use U?

We all know deoxyribonucleotides form DNA while ribonucleotides form RNA, DNA is double stranded while RNA is single stranded, and RNA can transcribe from DNA. We also know that DNA use A, G, C, T, while RNA use A, G, C, U and that it's the DNA that stores genetics information, not RNA.  My question is: how does the lost oxygen atom on deoxyribonucleotides 2' site of the sugar (turning it into a ribonucleotide), make such a large difference in function? It just an oxygen atom. Why don't they just all use U or all use T?     This answer may solve the question why is DNA double strand, RNA single strand, but it doesnt explain why does RNA uses U instead of T.


In the Miitomo Drop game, if you don't get one of the special items, you get 3 pieces of candy.   So far I haven't found anything that I can do with this candy - what use does it have in-game?


Is it possible that the zeroes of a polynomial form an infinite field?

Let $K/F$ be a finite field extension and suppose that $F$ is infinite. Is it possible to have a nonzero polynomial $p \in K[x_1,...,x_n]$ that vanishes in $F^n$?


Find the roots of $$z^4 + 2z^3 + 20z + 12 = 0.$$   I still haven't been able to solve it after hours of trying. There are no rational roots and factoring seems impossible. Who of you, mathematical geniuses, can help me? :-)


On the $\mathbb{F}_p$-automorphisms of a finite field $\mathbb{F}_q$

Let $\mathbb{F}_q$ be a finite field with $q=p^f$ elements. I know that for each $0\leqslant i\leqslant f-1$, the maps $\sigma_i(x)=x^{p^i}$ are $\mathbb{F}_p$-automorphsim of $\mathbb{F}_q$ (so $\sigma_i(x)=x$ for every $x\in \mathbb{F}_p$). Are there any other $\mathbb{F}_p$-automorphsim ? My Attempt: suppose that $g$ is a generator of $\mathbb{F}_q$. If $\sigma$ is an $\mathbb{F}_p$-automorphsim, then there exist a positive integer $k$ such that $\gcd(k,q-1)=1$ and $\sigma(g)=g^k$. Does $k$ must be a power of $p$ ?


A word that describes both "encoding" and "decoding"?

I am looking for a word that describes both of these activities, however the word coding does not seem to be suitable.   Likewise with encryption and decryption, cryption does not work well.


White cable with a Black Stripe and tons of unknowns

Currently installing a replacement power supply for my old 24V LED Strip lights in the kitchen. Almost got it fully connected, but on the DC end I hit a snag:  I made a small error in my wiring reference, the picture of the cables running from the PSU to the LEDs is from an angle that does not tell me which of the white cables is the V+, and which is the V-. I only noticed this after I disconnected the old PSU from the connectors. The new PSU is NOT the unknown, it has clear labels.  So in short: What polarity does White cable with a Black Stripe running along its side usually indicate?   I referred to  but this in-question had black wire with white stripes.   I have a suspicion that it is Positive, due to white cable with yellow or red stripe being the positive, but I am unsure because its black stripe.  EDIT: Adding to the issue:  A potential Answer would always be use a "multimeter": However how do you use a multimeter to distinguish is for an input cable? A multimeter doesn't really output power to power the strip.  Second problem is that the wires in the PCB do not seem to be the wires I am getting on the other side. So would the best course of action be disassemble half the kitchen to rewire everything?


I'm looking for a term to describe the phenomenon where a term with a once literal and direct meaning is carried on or borrowed to refer to something that is either only remotely related or completely unrelated to the original meaning.  This is mainly related to the process whereby technology is replaced or made obsolete by newer technology, but the terminology is reused to refer to elements of the newer technology.  For example, once upon a time, typewriters were the primary means of producing documents.  The paper would be fed around a drum, which sat atop a carriage that would advance from right to left with each keystroke in order to reposition the target on the page where the typebars would land.  When finished typing a line on a manual typewriter, the typist would have to manually return the carriage to its home position at the right.  After returning the carriage, the typist would have to feed the paper to the next line by turning the drum.  Automatic typewriters would accomplish this set of tasks with a single button, known as the "return" button.  The "shift" button would shift all of the typebars downward so that the uppercase letter embossed on each typebar would strike the ink ribbon instead of the lowercase letter.  Today, we don't use typewriters at all, and so we don't have any carriages to return, any physical pages to feed, or any typebars to shift, but we still have the terms "carriage return" and "line feed", which refer to specific ASCII characters, and the "shift" key.  For another example, once upon a time, carriages were the primary means of long distance transportation.  To protect the driver and passengers from being covered in mud dashed up by the pulling horses, carriages would have an angled board affixed to the front of the carriage.  This debris-blocking feature was known as a "dashboard".    As automobiles replaced carriages as the popular means of personal wheeled locomotion, the term "dashboard" came to be used to describe the board that sits in front of the driver and front passenger(s) in which the instrument panel and glove box are mounted.  Other than the fact that it is mounted somewhere in front of the riders in a wheeled vehicle, it has no relation to the original meaning of the word "dashboard".  Is there a term that describes this phenomenon?  Or rather, is there a term for a class of words such as these that have been orphaned, so to speak, from their original meanings?  (Something that would satisfy the statement "The terms 'carriage return', 'line feed', and 'dashboard' are all _______s.")  EDIT: While the term "holdover" certainly applies, it does not provide the level of precision that I'm seeking.  I'm looking for a term that describes these kind of terms using the kind of precision with which "skeuomorph" describes holdovers in user interfaces and aesthetics.  Perhaps the recently-coined term "skeuonym" would be most precise, were it to be commonly accepted.


I want a formula that highlight the dates that within next week.    I know how to highlight within the current week, with this formula:  =TODAY()-WEEKDAY(TODAY(),3)=$F6-WEEKDAY($F6,3)   (shown in the red highlight)  and I also know how to highlight within the 7 days after 7 days from today, with this formula:  =AND($F6-TODAY()>=7,$F6-TODAY()<=13)   (shown in the green highlight)  but what about highlighting all dates within next week, regardless being synchronous with today?  Notice that the green highlight does not cover next Monday as the 7 days are formulated to move synchronously with today date not limited to be within next week.


Is there any way to paint onto a bump map and diffuse map at the same time, so that the strokes match up? Like a multi-layer brush that uses a greyscale texture for the bump layer and a color texture for the diffuse color?  Here's a rough sculpt to demonstrate what I'm imagining:    The GIF above shows how such a brush could be made. The black and white height map would be the displacement brush, transferring its greyscale data to the bump map texture and the green one would transfer its color data to the diffuse map texture.  The resulting brush images:      Making the brush is one thing, but is it possible to use such a brush?


The WCAG (Web Content Accessibility Guidelines) provide a baseline for accessibility standards so various tools, such as screen readers, can provide a reasonable experience for those with accessibility challenges.  With regards to images, the guideline provides that all Image tabs  should probably (I say probably here for various reasons) have an ALT tag.  Is there any product/ .wsp file/ any custom solution that will add ALT tag to image.


\begin{table}[ht] \makebox[\textwidth][c]{     \begin{tabular}{ccccc}         \hline         \hline         [] & [] & [] & [] & []\\         [] & [] & [] & [] & []\\         \hline         \hline     \end{tabular} } \caption{test} \end{table}   I cannot run the above code, latex returned an error about missing number, but I can't see anything I am missing.  And the weirdest thing is that  \begin{table}[ht] \makebox[\textwidth][c]{     \begin{tabular}{ccccc}         \hline         \hline         [] & [] & [] & [] & []\\         \hline         \hline     \end{tabular} } \caption{test} \end{table}   This code works.  Anyone have any idea?


What is the difference between cd /  and cd //?  We can see that adding / to the end doesn't do anything. But when I do cd // and pwd, I found:  $ cd // $ pwd //     What is difference between / and //? An ls in both directories shows the same content. Why is // needed?


I always get confused between these two sentences:     Why are you making noise?      Why you are making noise?   Could anyone put light in the differences between the two?


Which video capture programs exists with this option: time and date displayed inside the video? I checked , but I didn't find nothing in this sense.


What does the -mtime option for find actually do?

I cant find any documentation surround this option in google. I assume it looks for files created within x amount of days? but a quick and precise definition would be appreciated.


What are the best question to ask a committee panel after a PhD interview?

I've a Skype interview for PhD application (it will make me miss  today.) I've been asked, in advance, to prepare a short presentation and then there would be some discussion with the panel (I guess.) I expect that they will ask if I have some questions so, I'm wondering what are the best (type of) questions one might consider?


I need change in a terminal all occurrences of the string path "/../path/file.extension" to "/path/file.extension" of my file using a sed command.  Notice that i just need replace "/../" to "/".  I have been tried something like this, but not work: sed -i \"s/..\//\//g\" myfile.php  edit  This config is for use in a package.json and I have some limitations beacuse this.


Can solar furnace achieve higher temperature than sun surface?  I guess not, but I'm not sure about that. Can you check my reasoning:  -------- My reasoning -----------  Consider Sun as a black body and (almost) Lambertian radiator. If there would be an optical system which can focus all radiation from one black body to an other body in such way, that you achieve higher temperature, it would be possible to make a Maxwell daemon, because you can than produce useful work by using one body as heater and the second body as cooler in an heat engine.  I think there is some theorem in optics which say that you cannot increase radiance by any focusing without loss of power.   However, I'm not quite sure how this theorem is called, and what is a background. As well I'm not able to make rigorous reasoning, how this limit the temperature of solar furnace.  Only what I can say that two black bodies of different size in elliptical cavity does not create Maxwell daemon, because of this radiance limit (You actually does not focus all the light from the bigger body to the smaller one ).  But what if I don't have to use all the light power from sun? For example you can limit the aperture by diaphragm. In this case you can increase radiance without braking second law of thermodynamics nor the radiance invariant. I'm not sure if in this case (if you sacrifice some power) you can get higher temperature?  If so, is it possible to formulate equation which connect power efficiency and temperature difference for this "optical heat pump"


I'm looking for a logical explanation of how we use the preposition "with" in the following context:  The company took the first place with their competition a distant second. North America had the greatest number of travellers over the 5-year period with Central and Eastern Europe showing a similar pattern.  I suppose my main question is how do I explain the phrase (it's not a clause) that follows the "with"? and how do I explain the function of "with" in these sentences?


I have seen people using "This one is Daddy's" with the word "one" before a form of the verb be. I am confused about which is more accurate, to use:     This is Daddy's.   or     This one is Daddy's.   Hope you can address my concerns, thank you.


What is reflection, is it the bouncing back of photon or re-emission of photon by first jumping to a higher energy state and then coming down due to interaction with incident photon?


Scientist or explorer goes to a tidal-locked planet with vicious creatures, accompanied by his wife

There is this short story about a (scientist?/explorer?) who goes to either Mars or Venus or a certain exoplanet (accompanied by his wife) which is in a tidal lock such that the dark side is very cold for a human being, and harbors vicious creatures. I think one of the two was a botanist. The sun side is too hot for a human, so they conduct their short time on the planet at the borderline of day and night, which is not a very broad strip. Anyone got a clue about this story?


The giraffe, who was the tallest in the zoo, towered over the other animals.  Is it correct to use the relative pronoun who to relate to "the giraffe", an animal?


Sum of convex function and increasing function

I have a sum of increasing function and a convex function over some domain. Can I say that the sum is also a convex function ? Or when can i say that sum of convex function with increasing function is convex and sum of convcave function and increasing function is concave? Functions are continous... Thanks a lot for helping...


Is that my problems? If travel agent didn't ask me to get transit visa?

As above picture - brought a return flight ticket from London to buenos aires and transit at JFK airport. I didn't know a transit visa is needs until I went to check in today at Gatwick airport. The travel agent didn't mention to me that I need a visa for transit with Argentina passport holder. I was so annoying and didn't know what to do for the last minute. I phoned the travel agent and he said nothing to do with him.  He is just selling ticket. If I need to change the date with the same itinerary with same airline and it will cost me £768 just to change the date. My question is there any help for this critical situation?


There is a yes command in unix/linux which basically infinitely prints y to the stdout. What is the point of it, and how is it useful?


Let $f(X)=X^6+X^3+1\in\mathbb Q[X]$. I need to find a splitting field $L$ for this polynomial and the degree of $[L:\mathbb Q]$.  $f$ is irreducible with $f(X+1)$ and $p=3$ to apply Eisenstein. I know that then $\mathbb Q[X]/(f(X))$ is a field in which $f$ has a root (how can I find out what the root is?). I'm supposed to inductively find more splitting fields and adjoin them in the end to get $L$, but how is that done concretely?


Can an Arcane Trickster or Eldritch Knight with the Magic Initiate feat (picking the wizard list) use spell slots to cast the chosen 1st-level spell?

A bard who takes the Magic Initiate feat and chooses the bard spell list for the feat can use spell slots to cast the 1st-level spell they learn from the feat. A wizard who takes the feat and chooses the wizard list can do the same. Can an Arcane Trickster rogue or Eldritch Knight fighter who takes the Magic Initiate feat and picks the wizard spell list also use their spell slots to cast the 1st-level spell they pick for the feat? Both the AT rogue and the EK fighter use the wizard spell list for their Spellcasting feature, so one could assume that they could use their spell slots to cast a wizard spell from the feat... But is that assumption correct?  This Q&A addresses the general case:  However, the Arcane Trickster rogue and Eldritch Knight fighter are a bit of an exception and aren't specifically addressed by that Q&A. Both the Arcane Trickster rogue and Eldritch Knight fighter use the wizard spell list, even though they are not themselves wizards. As a result, I'm not 100% sure if my assumption about their interaction with the feat is correct.


Given dominant morphism between irreducible varieties, prove that image of a proper closed subset is not dense.

Suppose $f:X\to Y$ is a dominant morphism between varieties such that $k(Y)$ is a finite field extension of $k(X)$, $S\varsubsetneqq X$ is a proper closed subset (subvariety) of $X$. Is it always true that $\overline{f(S)}\ne Y$?


I would like to typeset the top part of Pascal's triangle. To get the triangle with the names of the binomial coefficients, i.e., {n \choose k}, I used the following code  \begin{tikzpicture} \foreach \n in {0,...,4} {   \foreach \k in {0,...,\n} {     \node at (\k-\n/2,-\n) {${\n \choose \k}$};   } } \end{tikzpicture}   The result is this   Now I want to be equally lazy and do something like this for the values of the binomial coefficients, i.e., replace {\n \choose \k} in the node label with \CalculateBinomialCoefficient{\n}{\k} where \CalculateBinomialCoefficient is a hypothetical macro that calculates the binomial coefficient. Has anyone done something like that?  The result should look like this:


How to remove app icons in system tray on Ubuntu 18.04 with GNOME

How can I remove the apps in right top corner (Google Chrome, flux, TeamViewer)?  Before my update from Ubuntu GNOME 16 these were even more annoying in the left down corner.


I have an ASP.Net page that will be hosted on a couple different servers, and I want to get the URL of the page (or even better:  the site where the page is hosted) as a string for use in the code-behind.  Any ideas?


How to ensure that all traffic goes through VPN connection once it has been started?

I connect to the internet through a VPN provider along with other precautions in order to ensure privacy (against traffic analysis by agencies of a repressive government). I currently use  to configure and establish the VPN connection. Tunnelblick does not allow automatically connecting to the provider at or before login so I need to connect manually each time, and sometimes the connection is lost.  I need any and all traffic to go through the VPN connection at all times; whenever the VPN isn't connectable for whatever reason, I want the fallback to be no connection. I need to ensure   that OS X does not connect to the internet on my regular internet connection, or at all, during boot (until the login screen, for time synchronization and other possible "call home" stuff etc.). What services, if any, try to do this, and how can I practically analyze and change what's going on with networking during boot? Is there a way to connect to VPN earlier than right after login? that if my VPN connection is temporarily lost, applications do not continue to communicate over my regular unencrypted connection.    I basically want the system to act as if the network connection is lost altogether if the VPN connection fails, but currently they just continue to work as if nothing happened. What can I do to my system so that once a VPN is established, all traffic can only flow through that connection and no traffic can flow if the connection drops?


Override firstinits=true for some entries in bib

I have a bib entry that is just a forum name and the URL. The problem is that all the bibliography is generated using firstinits=true. For this one with firstinits=true biblatex shortens the company name.  Any idea?   @misc{UPNP,    author =       {{UP}n{P} {F}orum},    url =          {http://www.upnp.org},    urldate =      2014,  }   [For] U. Forum. Url:    If I left the author blank and put the content in organization/institution then the cite is only the year (BTW I'm using alphabetic IEEE).


Bounding box should rotate - Skews instead

I have a method to rotate a sprite's bounding box around the center of the sprite (the sprite rotates and I need the bounding box to rotate with it. The sprite is rectangular).  Instead of being rotated, the bounding box is skewing wierdly. When the angle is 0 - the bounding box is a perfect rectangle. But when the angle changes, the bounding box is getting gradually skewed.  All of this happens in the object's move() method. This method is called every cycle of the game-loop. What I'm trying to do is this:   Move the sprite in the direction the user chose. (x += dx, y += dy). Get the coordinates of the new center of the sprite. Get coordinates for the four vertices of the not-rotated-version of the sprite. Manipulate these coordinates, so they are now the vertices of the rotated sprite.   The coordinates that step 4 gives me, are used to create the bounding box (and temporarily draw it on the screen so I can see).  Somewhere, this fails. As I said, the bounding box doens't rotate. Instead, it skews (and maybe also rotates, not sure).  What could be the problem?  Code:  public void move(){  // Advance sprite. x += dx; y += dy;  // Get the new center point of the sprite. centerx = x + width/2; centery = y + height/2;  // Get the 4 vertices of the non-rotated version of the sprite. xcoo[0] = (int) x; xcoo[1] = (int) (x + width); xcoo[2] = (int) (x + width); xcoo[3] = (int) x;  ycoo[0] = (int) y; ycoo[1] = (int) y; ycoo[2] = (int) (y + height); ycoo[3] = (int) (y + height);  // Manipulate each vertex, so it fits the rotated sprite. for(int z=0;z<4;++z){      xcoo[z] -= centerx;     ycoo[z] -= centery;      xcoo[z] = (xcoo[z] * Math.cos(Math.toRadians(angle)) - ycoo[z] * Math.sin(Math.toRadians(angle)));     ycoo[z] = (xcoo[z] * Math.sin(Math.toRadians(angle)) + ycoo[z] * Math.cos(Math.toRadians(angle)));      xcoo[z] += centerx;     ycoo[z] += centery;  }  }   Help would be very appreciated. Thank you


Help with cluster analysis. Is this possible?

I'm working with the productivity of various government documents. In my data I have two variables (annual frequency and time of resolution) and each document gets its position in a Cartesian plane derived from these two variables (frequency on the vertical axis and time on the horizontal axis).   Now, I define that there are 4 possible groups (or clusters) knowing that the minimum frecuency and time are both 1:  -One group of "Productive and irrelevant" documents with a frequency higher than 1 but lower than the average frequency and a time higher than 1 but lower than the average time.  -One group of "Unproductive and irrelevant" documents with a frequency higher than 1 but lower than the average frequency and a time higher than the average time.  -One group of "Productive and relevant" documents with a frequency higher than the average frequency and a time higher than 1 but lower than the average time.  -And finally a group of "Unproductive and relevant" documents with a frequency higher than the average frequency and a time higher than the average time.  There is I way with the cluster analysis, or with another approach or tool, in Stata, SPSS or R where my clusters can be made? Furthermore, there is a way through I can see what are the minimum changes that an observation must do in its variables to 'migrate' from one cluster to another? Any idea?  Notes: All my variables are discrete. My complete data set is of 1800 observations.


Why hadn't SE had HTTPS for a long time?

I'm novice in security, but after reading the post  I'm confused. As in the answer of , having an SSL certificate is not expensive anymore, so I can't imagine why we hadn't had it for a long time. I mean, I had thought that there was always a green padlock whenever I visited Stack Exchange.  I would like to have an answer that contains not so much technical terms, unlike the  post.


I have recently converted my code into an asp.net format but am getting an this Uncaught TypeError with one of my JS functions. I have tested and it works when its not in the asp.net format.   The error comes when i interact with a button that i supposed to close a message. I have double checked syntax but still cant find the error.  This is the button -   <div id="main_modal" class="modal">     <button type="button" value="Exit Modal" id="exit_modal" onclick="exit_modal()">X</button> </div>   This is the function it calls onclick -   function exit_modal(){     document.getElementById("main_modal").style.visibility = "hidden"; }   This is the error received in Chrome dev tools when button is clicked -      Uncaught TypeError: exit_modal is not a function at HTMLButtonElement.onclick   I am new to using asp.net so any help would be very appreciated. Thanks in advance.


In previous Battlfields, there were many types of rocket launchers, explosives, and even weapons you can use to take out armor(armored vehicles, tanks, heavy planes, etc.) with relative ease. In Battlefield 1, this does not seem the case. As it seems the only class that has anything capable of dealing good damage to armor is the Assault with C4 equivalent and heavy AT grenades, but even then you have to get close and it's extremely high risk.  I get armor was a new thing in WW1 and they probably didn't really figure out how to deal with it effectively, but games (at least I would expect) would try to balance things as best possible.  How can I deal with the Armor in BF1 without rockets or Armor of my own?


I have this code but I can't figure out how to align it to the very center of the div, someone could help me? thanks  HTML:

     the css and the rest here:   Also the image is 30x30 pixels, just in case:) thanks guys!


Can an infectious diseases come from a plant?

Coronavirus, HIV, 1918 Flu, etc. They all come from animals. Do any infectious diseases (in humans) come from plants? More specifically, are there viruses that infect plants that can mutate to infect humans?


How do I download iOS 8.0 or newer for iPhone 4s

I have an iPhone 4s that is running iOS 7.04 and won't update. It requires iOS 8.0 or newer to install any apps.   How can I download iOS 8.0 or newer on my iPhone 4s?


Question: What if the author of a question can accept a comment?   The problem:  Time and time again, answers are posted as a comment.  Usually, the person who commented has the best of intention (e.g. it was a trivial answer [to the answerer], and they weren't sure if the OP would immediately edit the question after the comment).  But this leaves the frustrating situation of an unanswered question with a perfectly good answer.  This problem accumulates over the years.     Candidate solution:  The OP can just "accept" the comment, after which a duplicate of the comment is made an accepted CW answer, with a preface indicating that it was originally a comment, e.g. This answer was originally a comment posted by [[blah]] that has been accepted by the author of the question.   Comments on this scheme:   The author of the comment has indicated they're not interested in gaining/losing reputation through their comment (thus CW answer). The original comment is still there. If desirable, the "author" of the accepted question could be a "bot", so the answer is not attributed to a genuine account.  (I suppose it would already be technically possible for Joe Blow to create a script for a bot that creates an answer from a comment in the proposed way.)     A similar question was asked before  (over 3 years ago), and in numerous other questions which have been deemed "duplicates" (,  and ; see also ), so there seems to be demand for such a feature.  The answers to these questions seem (to me, at least) quite weak:   "ask the commenter to add the comment as an answer"   The OP already did this by asking the question in the first place.  And what if the author of the comment doesn't respond (or takes a long time to respond)?  This also adds more chit-chat irrelevant to the question.   "add an answer of your own, referring to the comment, and accept it."   A hacky workaround.  How could this possibly be better than accepting a comment?  (Yet, this is the most up-voted response.)  Moreover, this adds to the user's list of "answers" (thus making the user's page harder to look through).   "When i leave a comment, i do so because i want to leave a comment."   Great; now what about everyone else?  In the immortal words of the FAQ: "Other people can edit my posts?!"  And it's not even an edit, it's copying the post from one box to another (a more hacky version of which is regarded as the "accepted" method).


Prove that $\int_{0}^{\infty}\frac{\sin(x)}{x}dx=\frac{\pi}{2}$ using contour integral

Solving the following exercise I have some doubts. I want to show that \begin{equation*}     \int_{0}^{\infty}\frac{\sin(x)}{x}dx=\frac{\pi}{2} \end{equation*} I tried the following: Let $\gamma$ be the upper semicircle \begin{equation*}         \int_{\gamma} \frac{\sin(z)}{z} dz = 0     \end{equation*} how do we have to \begin{equation*}         f(x) = \frac{\sin(x)}{x} = \frac{\sin(-x)}{-x} = f(-x)     \end{equation*} Note that \begin{eqnarray*}         0 = \int_{\gamma} \frac{\sin(z)}{z} dz         & = &   \int_{-R}^{R} \frac{\sin(z)}{z} dz + \int_{C_{R}} \frac{\sin(z)}{z} dz\\         & = &   \int_{-R}^{R} \frac{\sin(x)}{x} dx + \int_{C_{R}} \frac{\sin(z)}{z} dz\\         & = &   2\int_{0}^{R} \frac{\sin(x)}{x} dx + \int_{C_{R}} \frac{\sin(z)}{z} dz\\     \end{eqnarray*} then \begin{eqnarray*}         -2 \int_{0}^{R} \frac{\sin(x)}{x}dx          & = &   \int_{C_{R}} \frac{\sin(z)}{z}dz\\         & = &   \int_{0}^{\pi} \frac{\sin(Re^{i\theta})}{Re^{i\theta}} Rie^{i\theta} d\theta\\         & = &   i\int_{0}^{\pi}\sin(Re^{i\theta})d\theta\\         & = &   -\int_{u(0)}^{u(\pi)}\sin(u)udu\\         & = &   -\left(u\cos(u)|_{u(0)}^{u(\pi)}-\int_{u(0)}^{u(\pi)}-\cos(u)du \right)\\         & = &   -\left(Re^{i\theta}\cos(Re^{i\theta})|_{0}^{\pi}-\sin(Re^{i\theta})|_{0}^{\pi} \right)\to -\pi\text{ when }R\to\infty\text{ ?}\\     \end{eqnarray*} I do not think this last step is correct, however I see it necessary, I do not know if my reasoning is wrong or I should approach the problem from another point of view. Is my reasoning correct? I have my doubts about being able to take the closed curve, because at $ z = 0 $ there is a singularity and it is located on the border of the region enclosed by my curve PD: This requires the use of contour integral, although another method is also welcome


Global Inbox -> Global RSS feed for all my questions across all the sites?

For me the distinction between sites is purely topical. I get that there's a right and a wrong place to ask questions, but I regularly ask questions across a number of sites. They all log me in (in a weird sort of way), and now there's the global inbox.  I've read that there's a feed  and that there's a  but neither of these are what I want.  What I'd like is to have an RSS feed from my global inbox, i.e. to include notification of updates to my public questions, answers, comments. Is this possible?


I'd like to have a group of debris fall from a ceiling onto the floor, but not have them drop all at the same time. Is there a way to set a keyframe that dictates when the object enters the simulation? For example, object 1 starts falling on frame 0, object 2 on frame 5, object 3 on frame 24, etc.


Necessary Condition for linear independence of functions

I am trying to prove the following fact, which seems intuitive to me, yet I cannot find a way to show it.  Consider the set of functions $\{f_1,\ldots,f_n\}$, $f_i:\mathbb{R}\rightarrow\mathbb{R}$. Suppose that this set is linearly independent, i.e. $$\sum_i f_ic_i=0\implies c_i=0\;\;\; \forall i$$  Then there exists numbers $(x_i)_{i=1}^n$ such that the matrix  \begin{bmatrix}     f_1(x_{1})       & f_2(x_{1})   & \dots & \dots & f_n(x_{1})  \\     f_1(x_{2})       & \dots  & \dots  & \dots & \dots  \\      \dots  & \dots  & \dots & \dots & \dots \\     f_1(x_{n})        & \dots  & \dots  & \dots & f_n(x_{n}) \end{bmatrix} has a nonzero determinat.  I have tried to reason by contraposition, assuming that the determinant vanishes for any choice of the $(x_i)_{i=1}^n$ but I didn't get anywhere.


Quadratic substitution question: applying substitution $p=x+\frac1x$ to $2x^4+x^3-6x^2+x+2=0$

By using the substitution $p=x+\frac{1}{x}$, show that the equation $$2x^4+x^3-6x^2+x+2=0$$ reduces to $2p^2+p-10=0$.  I can't think of anything that produces a useful result, I tried writing p as $p=\frac{x^2+1}{x}$ and finding areas to substitute but have come with no progress. Could someone offer a slight hint on how to proceed?  Thanks


Sufficient and complete statistic function for $\theta$ of geometric distribution

I am trying to find a sufficient and complete statistics function for $0<\theta<1$ of a sample $X = X_1, \dots, X_n$ from the Geometric Distribution.  We have $f(x;\theta) = (1-\theta)^{x-1}\theta $. Thus :  $$p(x;\theta)=\prod_{i=1}^n(1-\theta)^{x_i-1}\theta=\theta^n\prod_{i=1}^n (1-\theta)^{x_i-1}$$  $$=$$  $$\theta^n(1-\theta)^{\sum_i^n (x_i-1)} = \theta^n\exp\bigg\{(1-\theta)\ln\bigg(\sum_{i=1}^n(x_i-1)\bigg)\bigg\}$$  $$=$$  $$\theta^n\exp\bigg\{(1-\theta)\sum_{i=1}^n\ln(x_i-1)\bigg\}$$  This is an expression of the form of the Exponential Distribution Family and since the support does not depend on $\theta$, we can conclude that it belongs in the exponential distribution family. Thus, a sufficient and complete statistics function for $\theta$, is :  $$\sum_{i=1}^n\ln(x_i-1) \longrightarrow T(x) = \sum_{i=1}^n\ln x_i$$  Question : Is my approach and my conclusion correct ? Thanks in advance for your time.


std::map, pointer to map key value, is this possible?

std::map<std::string, std::string> myMap;  std::map<std::string, std::string>::iterator i = m_myMap.find(some_key_string); if(i == m_imagesMap.end())     return NULL;  string *p = &i->first;   Is the last line valid?  I want to store this pointer p somewhere else, will it be valid for the whole program life?  But what will happen if I add some more elements to this map (with other unique keys) or remove some other keys, won’t it reallocate this string (key-value pair), so the p will become invalid?


$a->b = 7.56704843521; $a->c = 7.56704843521;   But  $a->b == $a->c   returns false.  How can that be?  Even when doing floatval($a->b) == floatval($a->c) is false, and it should not be necessary anyway when using type-independent comparison "==" instead of "===".  Full code is  $a->b = 7.56704843521; $a->c = 7.06704843521+0.5;   Thanks!


What is Object Mocking and when do I need it?

Many people use Mock Objects when they are writing unit tests. What is a Mock Object? Why would I ever need one? Do I need a Mock Object Framework?