I need to install eclipse for school, so that I could help with an Android project. Everyone else at my school uses Windows , so they cannot help me. I am using Ubuntu 18.04 and this fails to install the package: sudo apt-get update sudo apt-get upgrade sudo apt-get install eclipse  Here is the error I'm getting: Reading package lists... Done Building dependency tree        Reading state information... Done Package eclipse is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'eclipse' has no installation candidate  I've searched for an answer, but nothing seems to help. Would anybody mind helping me?

I want to install the latest version of Eclipse but the Ubuntu Software Centre contains an older version.  Is there a PPA or some other way to install latest Eclipse? Please describe the steps for full installation.


Did they chose this username, is this some kind of temporary account or they did not fill the username box?

It's been more than a month since I have started using . It has these users with user names in the format of "user-random number". I have observed them in some of the stack activities, most of the time asking questions.   Does the moderators create them for their own purpose. If yes what purpose do they serve?   I mean a user is free to have any user name. But it's just a hunch that such users are actually moderators. I may be wrong; just need some clarification.


That's not where my problem ends unfortunately, I'm running Ubuntu 20.04 and Ive never been able to boot into the grub menu. This means that I have no way to access recovery mode. All I can access is that weird gnu grub command line and a command line login screen that boots me out the moment I log in. If anybody has any suggestions please sling them my way.

I needed to edit a .config file (which I know for a fact is not creating these problems, just to clear that up) and it wouldn't let me save it, so I took ownership of /etc and all contents with the command chown -hR username /etc and that let me edit the .config file but now whenever I try to install any packages or use any sudo commands, it doesn't work  (I've checked for errors in the sudo file in sudoers.d and there was nothing wrong with that).   So how do I return it to the previous owner?


Using BeautifulSoup4 on Python3  Fired up my Ubuntu machine and got the following error.  My web scraping script runs BeautifulSoup4 and was working so far.   The only thing I did recently was install Audacity. Don't know how that could affect BeautifulSoup.    Traceback (most recent call last):   File "scrubNprint.py", line 1, in <module>     from bs4 import BeautifulSoup   File "/usr/lib/python3/dist-packages/bs4/__init__.py", line 30, in <module>     from .builder import builder_registry, ParserRejectedMarkup   File "/usr/lib/python3/dist-packages/bs4/builder/__init__.py", line 314, in <module>     from . import _html5lib   File "/usr/lib/python3/dist-packages/bs4/builder/_html5lib.py", line 70, in <module>     class TreeBuilderForHtml5lib(html5lib.treebuilders._base.TreeBuilder): AttributeError: module 'html5lib.treebuilders' has no attribute '_base'   The error from .builder import builder_registry, ParserRejectedMarkup, I have searched my directory list and I don't seem to find the script builder.  The error from . import _html5lib, the file seems to be there in the directory bs4/builder.  I don't understand why I am getting this error.  The last error  class TreeBuilderForHtml5lib(html5lib.treebuilders._base.TreeBuilder): AttributeError: module 'html5lib.treebuilders' has no attribute '_base'   is unclear to me. It appears to be in the script.  More importantly, I did not touch anything that I know of. But I might have done an update before installing Audacity.  However, I don't think updating Ubuntu should have affected BeautifulSoup.  When I do  pip3 --user uninstall beautifulsoup4  I get a message that --user is invalid.    I did pip uninstall, then tried a reinstall.  Still getting the same error messages.  beautifulsoup is installed.   the results of the command you asked for is;  python-bs4:   Installed: (none)   Candidate: 4.4.1-1   Version table:      4.4.1-1 500         500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages         500 http://us.archive.ubuntu.com/ubuntu xenial/main i386 Packages python3-bs4:   Installed: 4.4.1-1   Candidate: 4.4.1-1   Version table:  *** 4.4.1-1 500         500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages         500 http://us.archive.ubuntu.com/ubuntu xenial/main i386 Packages     100 /var/lib/dpkg/status   My python code is correct.  it was working for 5 months.  then, all of sudden I got the traceback error above.  which has not gone away, after deleting and reinstalling beautifulsoup (see .  There is a bug in the current release of the html5lib that causes the error, and it should be fixed in a few weeks.

I am using Ubuntu 14.04 64 bit Operating System .   I installed Beautiful Soup 4 using this command :  sudo apt-get install python-bs4   With Python 2.7.6 , I had no difficulty importing the bs4 module. But when I used Python 3.4.0 it showed me this error.  >>>import bs4 Traceback (most recent call last):   File "<stdin>", line 1, in <module> ImportError: No module named 'bs4'   I also tried to install it using pip.  sudo pip install beautifulsoup4   But again it didn't worked with Python 3.4.0.  Right now I have uninstalled pip and also uninstalled Beautiful Soup 4   sudo apt-get remove python-bs4 sudo apt-get remove python-pip   What should I do next to properly install Beautiful Soup 4 for both  Python 2.7.6 and Python 3.4.0 ??


When t<0 Components in circuit are Jt = 3 A, R1 = R2 = 2 Ω, R3 = 4 Ω ja L = 10 H      At t=0 switch K will be closed and i need to figure out what iL(t) is when t=4  So i tried to figure out iL(t) with  differential equation. First i combined R1 and R2 to get R12=1Ω  Then i transformed power supply from current to voltage Et=Jt*R12=3A*1Ω =3V Then i combined R12 and R3 to get Rz=5Ω Now i can create equation which is  $$E_t=L*\frac{di_L(t)}{dt}+R_ti(t)          $$ After adding constant i can start solving equation $$10*\frac{di_L(t)}{dt}+5i_L(t)=3          $$ $$           u(t)=e^{\int5dt}=e^{5t}    $$ $$           e^{5t}* \frac{di_L(t)}{dt}+ e^{5t}*i_L(t)=e^{5t}*3 $$ $$           \frac{di}{dt}(e^{5t}*i_L(t))=3e^{5t} $$ Then for integral in both sides $$           u=5t $$ $$           \frac{du}{5}=dt $$ $$           e^{5t}*i_L(t)=\frac{3}{5}e^{5t} +C$$ Then divide in both sides $$           i_L(t)=\frac{3}{5}+ C*e^{-5t}$$ Now i need to figure out what is iL(0) so that i can get C, but i don't know how.

When t<0 Components in circuit are Jt = 4 A, R1 = R2 = 2 Ω, R3 = 4 Ω ja L = 10 H      At t=0 switch K will be closed and i need to figure out what iL(t) is when t=4  So i tried to figure out iL(t) with  differential equation. First i combined R1 and R2 to get R12=1Ω  Then i transformed power supply from current to voltage Et=Jt*R12=J*1Ω =J Then i combined R12 and R3 to get Rz=5Ω Now i can create equation which is  $$E_t=L*\frac{di(t)}{dt}+R_ti(t)          $$ After adding constant i get $$J_t=10*\frac{di(t)}{dt}+5i(t)          $$ First i found the roots $$10r^t+5r=0 -> r=-\frac{1}{2}$$ So for homogeneous part i get $$y^h=C_1*(-\frac{1}{2})^t$$ And for nonhomogeneous part $$J_t=A$$ $$ \frac{dJ_t}{dt}=0 , \frac{d^2J_t}{dt^2}=0$$ So i get $$  10*0+5=A->A=5  $$  For complete equation i get $$ y(t)=C_1*(-\frac{1}{2})^t+5  $$ To figure out what is C1 i use t=0 $$ y(0)=C_1*(-\frac{1}{2})^0+5=4 ->C_1=-1  $$ And now for t=4 i get  $$ y(4)=-1*(-\frac{1}{2})^4+5=4.5   $$ I know this answer isn't correct but i don't know what went wrong Also sorry if its little bit hard to read this, i'm new to this


I happen to own two android devices, a Huawei P30 Pro and a Samsung Galaxy Tab S5e. Both devices came with a charger, the specifications can be seen here   I'd like to charge both devices with one charger, is this safe to do and which one should I use? Does it make a difference?

My friend and I both have droids and we often user each other's wall chargers out of convenience. I was told that it's possible that my phone might explode if it's charged with a charger that wasn't built specifically for my phone. How true is this across droids?


I have a pre-commit hook defined as follows in a pre-commit-config.yaml file located in the root of my repository - repos: -   repo: https://gitlab.com/pycqa/flake8     rev: 3.7.9     hooks:     - id: flake8  This works as expected and blocks any commit if I am now following flake8 rules. However, I want to do this for a git push and not for a git commit. One way I found is to add a pre-push file inside .git/hooks/ and do flake8 . from inside. This does the job but now I can't share that file with anyone through git since the .git folder is not tracked by git. Is there any file/config that I can put in the root of the repo that will act as a pre-push hook?

We'd like to make a few basic hook scripts that we can all share -- for things like pre-formatting commit messages.  Git has hook scripts for that that are normally stored under <project>/.git/hooks/.  However, those scripts are not propagated when people do a clone and they are not version controlled.    Is there a good way to help everyone get the right hook scripts?  Can I just make those hook scripts point to version controlled scripts in my repo?


I have a variable (var) which return value as VAR1 ($var has the value VAR1). There is an input file which has VAR1 defined (VAR1=ABCDEF)  How can I use echo to get the value ABCDEF using $var??  I tried echo $(echo $var) and many other options, but I always get output as VAR1 or echo VAR1 but never ABCDEF. I used source in file with VAR1 declared, tried in command prompt etc.

Given I have in a bash script  ev=USER   How can I get the environment variable value for $USER using ev?  Tried naively doing:  echo ${"$"$ev}   which results in bad substitution.  I'd expect to get back whatever the value of $USER is.


Plot Summary/Details  The story opens with the protagonist (human male, can't remember the name) en route to the starport on a remote, sparsely-populated world.  He's currently on foot, as his vehicle broke down sometime earlier in the journey.  The central idea of the plot as the story unfolds is whether or not there is some sort of deadly alien beast waiting out there in the darkness.  Early on, the protagonist recalls the tale he heard in the local bar from a fellow he knew.    This other man claimed to have seen some horrible creature, and to have narrowly escaped said creature.  He described the sound the creature made in the darkness.  I can't remember exactly how it was described, but I do remember it was compared to something familiar (i.e., "it was like the sound of X"), and I think it referred to a scraping sound made by the alien's claws or tusks. The man then claimed that the only thing that saved him was his flashlight.  The creature apparently fears light.     As the story progresses, the protagonist struggles to keep his fears in check.  He knows the other man is know for telling wild stories, but can't quite dismiss the idea out of hand.  The tension increases as his flashlight gives out, and he must continue the journey in total darkness.  The story ends with a somewhat predictable twist.  The man is in visual sight of the starport and can hear the comforting sounds of the machinery and routine activity of the starport off in the distance.  It is at that moment he also hears the telltale scraping sound of the creature.  The end being, just a few hundred meters short of safety, the alien beast turns out to be real, and has found him.  Publication Details/Timeframe  I read this one in an anthology either in the late 1970s or (more likely) early 1980s.  The feel of the story is such that it could be a much older offering, though I can't be for certain.

About fifteen years ago I read a short story about a man on a planet (possibly Mars or the Moon), travelling alone between bases. It's written in the first person and as he's walking across the planet, he's thinking to himself about this fearsome creature that preys on people. It sneaks up on them, makes some noise and then attacks them. Just as he turns the final corner of the canyon he was walking through and sees the door to the other base, he hears the creature behind him making its noise and the story ends.  It was in a short story collection but I don't remember the name of the story or the book it was in. Any help would be much appreciated.


Today I answered  on ELU and included as my suggestion of the correct answer the following line (taken from the OP's own example):     To his amusement, Jason realized that 'Madam Curie' is an anagram of 'Radium Came'   This was queried by another user, specifically my use of the present tense "is an anagram" as they felt the tense should match the tense of the comparison, i.e. "...was an anagram..."  In my explanation I replied:     Because 'Madame Curie' is an anagram of 'Radium Came' throughout the continuum of time. Jason only realised it in the past.   However I am not sure of my ground here and perhaps I am incorrect, so I have since scoured ELU to try and find a grammatical rule for handling this and I was unable to.  Am I using the correct tense (and for the right reasons)? Is there a rule for this?  Edit: Not a duplicate of  because that refers to a finite event in the past that does not continue into the present. I refer to something that was true then and is still true now, leading to the confusion about tenses.

Incident which happened a week ago:      Me to Kate: "Where are you going"?   Kate: "I'm going to the cinema".   Now today I happen to tell this story to Jim and I say,      "I met Kate a week ago."   Jim: What did she say?   Me: "Kate said that she 'is' going to the cinema".    My question is, is the usage of 'is' grammatically correct? Here, at the time of reporting after a week I don't know if she's still going to the cinema or not and even then I use 'is' will this be grammatically correct?


Let $W_1$ and $W_2$ be subspaces of a vector space $V$. Prove that $W_1 \cup W_2$ is subspace of $V$ if and only if $W_1 \subseteq W_2$ or $W_2 \subseteq W_1$  Attempt:  $\boxed {p\Leftarrow q}$   (Almost trivial): Assume $W_1 \subseteq W_2$ then $W_1 \cup W_2=W_2$  and since $W_{1,2}$  are subspaces proof of this side is over.  $\boxed {p\Rightarrow q}$  I couldnot do the direct proof so I wanted to assume otherwise, here is where trouble begins.  I don't know how to take negative statement of the $p\Rightarrow q$ as follows:  Otherwise statement of the  $\boxed {p\Rightarrow q}$   is $W_1 \cup W_2$ is subspace $V$ but $\boxed{\boxed{W_1 \subseteq W_2\; or\; W_2 \subseteq W_1}}$  is wrong.  How can I do the proof in the assumming otherwise, and can you give me hint to prove the theorem (hints or answers, of course, can be other methods.)

I'm having a difficult time understanding this statement. Can someone please explain with a concrete example?


I've already went through all possible advices and still cannot start my Atheros AR9285 wireless card.   I have a laptop Toshiba Portege Z830 where the WiFi already worked under Windows 7. But after migration on Ubuntu 12.10. I'm not able get it work.  This is what I see on command lshw  *-network UNCLAIMED             description: Network controller        product: AR9285 Wireless Network Adapter (PCI-Express)        vendor: Atheros Communications Inc.        physical id: 0        bus info: pci@0000:02:00.0        version: 01        width: 64 bits        clock: 33MHz        capabilities: pm msi pciexpress bus_master cap_list        configuration: latency=0        resources: memory:c0500000-c050ffff   This is what I see on command rfkill list  0: Toshiba Bluetooth: Bluetooth     Soft blocked: yes     Hard blocked: no 1: hci0: Bluetooth     Soft blocked: yes     Hard blocked: no   Any idea?

I've just decided to jump into the world of Ubuntu, so far I encountered no problems until I tried to connect to my wireless network. I'm running Ubuntu on my laptop, Acer Aspire 5333-2880, which has an Acer Nplify 802.11b/g/n wireless card.  After browsing for an answer, I think the problem is a missing driver. input:   lspci | grep Network   output:     02:00.0 Network controller; Atheros Communications Inc. AR9285 Wireless Network Adapter (PCI-Express) (rev 01)   I found a couple of answers that might be right, but I have problems with both of them.    It requires me to load the site in my laptop, but I can't do it without internet and I have no idea how to save this into a USB.  But I have no idea how to really run or use this, and I wouldn't like to screw it up.    Any advice or other possible solutions will be greatly appreciated!   EDIT.  Thanks a lot for your input Marko and Jorge. I am sure the problem was with one of the drivers, but I was too distracted, or tired yesterday to realize I didn't restart my computer after installing. As soon as I got turned on my computer again, it was working. Annoyingly, I am not sure what the problem was exactly nor what exactly fixed it.  But still, thanks a lot Marko for the intel on how to build packages, I am sure it will be very useful later on!


The question is whether we require a comma after 'Hi' or not.

Sometimes I see a comma after the proper name:     Hello Mr. Black,      In order to give you....   But my native language is not English and I think that the comma in this phrase should be placed before the proper name:      Hello, Mr. Black.      In order to give you....   What is the correct punctuation in English?


We are given that -  1) R is a commutative ring with unity. 2) I is a prime ideal of R.  We have to show that I[x] is a prime ideal of R[x].  MY PROGRESS SO FAR  My progress, so far, is simply that I multiplied two arbitrary polynomial from R[x] that give an arbitrary polynomial of I[x] and tried to show that since ALL the constants belong to I, somehow, since the constants are formed by product, i.e, either of the constants must belong to I.  For example   last constant = ab We must have either a in I or b in I Then I did a similar thing to the second last constant. However, I could never say with guarantee that one particular side belongs to I.

Prove that if $I$ is a prime ideal of $R$ then $I[x]$ is a prime ideal of $R[x]$.   This is homework. I have been trying to assume that there is an $fg$ in $I[x]$ such that neither $f$ nor $g$ is in $I[x]$. Hence $f$ and $g$ have at least one coefficient not in $I$. I was trying to show that $fg$ would then have a coefficient not in $I$, obtaining a contradiction. But I don't see how to control the terms. If $f$ and $g$ had only one coefficient not in $I$, then I think I could use the properties of the ideal to complete the proof. The problem is not being able to know for certain which if any of the coefficients of $f$ and $g$ are in $I$.  Perhaps my approach is wrong to begin. Please help. Even a hint in the right direction will much appreciated.


Part of the second law states that an object will accelerate in the direction of the unbalanced force.   However, I've been thinking about parachuting and skydiving a bit lately, and I know that when the skydiver opens their parachute, the air resistance becomes greater than the force of gravity.   How does the person not travel upwards, in that case?

If an object is moving at terminal velocity and then opens the parachute, the air resistance is higher than the weight so why doesnt he go upwards.


I am very new to r and statistics so excuse me if the answer to my question is very obvious. I have surveyed 64 people on their Facebook behaviour related to their political participation. One of my independent variables is how many Facebook friends the people have and i divided their answers into 3 categories: 0-500= 1, 500-1000= 2 and 1000+ = 3.The independent variable is whether or not they voted, coded 0= no and 1= yes. I have been trying to run this as a logistic regression but for some reason it is not working. This is my code:  #fit bivariate logistic regression model for amount of friends and voting fit3 <-glm(vote~as.factor(friends), family=binomial(link="logit"), data=politicalparticipation) summary(fit3) exp(coef(fit3)) abs(1-exp(coef(fit3)))*100 sjt.glm(fit3)   However, i continuously get the error message that there is a warning:  Warning messages: 1: glm.fit: fitted probabilities numerically 0 or 1 occurred   If someone could help me out, that'd be great!

If you have a variable which perfectly separates zeroes and ones in target variable, R will yield the following "perfect or quasi perfect separation" warning message:  Warning message: glm.fit: fitted probabilities numerically 0 or 1 occurred    We still get the model but the coefficient estimates are inflated.   How do you deal with this in practice?


I get the following error when trying to install gparted:  E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?   Please help. I need to install an extra hard drive. I have typed in all the stuff that everyone else has done and I still cannot get anything to do anything.

I get this error whenever I try to install programs using the terminal:  home@ubuntu:~$ apt-get install myunity E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?   Also I'm unable to install updates using the terminal.


I can interpolate different animations based on position, rotation, and scale.  I want to do the same for different sprites, automatically.  For example, lets say I have a soda can being crushed.  I have 2 sprites:  One is the soda can uncrushed, and one is the soda can fully crushed.  I want to only use those 2 sprites, and have Unity automatically transition from the normal can to the crushes can.  How can I do this without making a bunch of key frames in between?

For example, I'm looking to animate at 60 frames per second, but clearly my artist isn't going to hand-author 60 frames of art for every second of an animation clip and even if he could, it would only work properly in locked-timestep.  So given two successive frames in a sprite-based animation, I want to smoothly "interpolate" or "morph" between them at runtime to produce a smoother, and higher frame rate animation based on where the update time for the current frame lies between the two frames.  Another way to look at it would be to say that my animation is authored such that the frames occur at regular intervals, much less frequent then 60 FPS. Say I'm 30% between when frame N should appear and when frame N+1 should appear. I want to render an image that looks like it's a 30% the way through a smooth transition from the frame N image and the frame N+1 image.  , but am interested in other potential solutions I could look at for implementing this. Please do not recommend a tool as a solution.


EDIT: This question is different from  because I am not rendering a low-resolution texture into a high resolution image. I am rendering a high resolution texture into a low resolution image. The same solution to that question does not apply here. This is what the texture looks like:    I was hoping to use Blender to render sprites for a little game I am making. I started working on tiles and I noticed something weird.  In this example image, the left half is just a stretched out plane that has UV mapping to a texture. The right half is a completely separate object using the same material/texture, except that it is not UV mapped. You will notice that I am getting a pretty weird effect. Here is the un-edited raw rendered .png that I got from blender:    On the left half, the image is being blurred, blended, interpolated(?). The right side without the UV mapping seems confused, part of it is blurred but on the far right the image remains pixelated! The next image is blown up preserving the pixelation so it is easier to see:    Is there a way to intentionally get this effect? I tried turning off interpolation but that didn't seem to do the trick. After looking through the settings and googling around, I don't see anyone else having this problem. Note: Right now I am not using material/texture nodes. I am still a blender noob and not sure how to set those up let alone do advanced things with them...yet.  If there is an easy solution that does not require nodes, can I please have that solution first?  If I cannot avoid using nodes, would someone mind helping guide me to how I may get this done with the use of nodes?

I have a problem. I am going to make a minecraft animation in blender. But when I put a minecraft texture on a 3d cube that is 16x16x16 it is very low resolution is there a way to get the texture in a better resolution or is there a way to make blender make the texture better?  I hope you have an answer. Thanks in advance


im frequently using the modifire stack and was wondering if theres is a function as listed below: I like to add several modifires to the stack as a kind of preset (known from e.g. obj export), so when I press the corresponding Listindex, it automatically adds the modifires with my custom set values to the stack. I dont want to apply them to the geometry nor do I want to add all the modifires after finishing my modelling work. This would increase the efficency for me dramatically since its quite annoying to add them for each object I generate. Example: Mirror (Y Axis, Clipping), Solidify (Offset, Thickness..), Bevel (Segments, Thickness, Limitation...), Subdivision (View 2, Render 3...) and so on (do that for eg 100 objects and you know how time intense that actually is -.-). Is there maybe a tool/addon/hidden function I dont know about? Or is it maybe better to do that with a custom script? (I dont really know about scripting, so I cant say whether this is even possible. Best regards

I have a cube. I select a face of it, and do the following 3 steps:  Insert face Extrude face Resize face  Is there a way to save these 3 actions to be able to use on any other faces? Like a hotkey/macro to improve the workflow. What keywords to search for this? Thanks for your help!


At the beginning of DS9 Season 6, the Dominion (including the Jem Ha'dar and the Cardassians) took DS9. At this time Bajor was neutral and in a non-aggression treaty with the Dominion.   How was this justified? Given Kira's and Odo's (reluctant) initial acceptance of this occupation and willingness to collaborate with it, it seemed that this occupation was legitimate. How could it be? Shouldn't Bajor control the station? As a neutral power, doesn't giving access to an important base violate the neutrality? At best, the Dominion could only be a guest in the station, but it looks like they are running the station.

In "A Call to Arms" (DS9, episode 5x26), it is made clear that the Dominion has a non-aggression pact with Bajor, which would prevent the Cardassians from retaking Bajor.  However, since DS9 is under the control of Bajor (ever since the occupation ended) and only administered by the Federation, why did the Bajorans allow the Cardassians to take control of the station?  Shouldn't it be protected by the non-aggression pact as well?


I'm a long-time PC and Linux user. Recently, I was given a mac mini (Yosemite) for my job. I've still got my full-size PC keyboard (with number pad). There are several differences. The biggest one is control key is used as command on windows. The physical location of command (right below ZXCV keys) is physically discomforting for me to use.  It's just too tight of a space for two of my sausage fingers to fit in. So I remapped the ctrl-key to command. This works, and is comfortable, except when I need to use control, because I do a lot of terminal stuff (ctrl-X(background), D(EOF), C(break),O) I don't know where I remap actual control to.  I thought option as alt, but that does not work. Additionally I use home and end keys quite a lot in terminal or chrome, and these don't function as in windows. Hitting end while typing in this box, it takes me to the bottom of the page. Hitting end in terminal takes me to the end of the scroll-back buffer. Previously, on my PC it would take me to the end of the current command, not the top of the scroll-back buffer. Modifier keys (Sys Prefs: Keyboard: Modifier Keys):  CAPS: CAPS Control: Command Option: Option Command: Control  Right of backspace I have:  Ins Home PgUp Del End PgDn  Bottom Row of keys:  Ctrl Win Alt Space Alt Menu Ctrl  To recap:  Can I use Ctrl for both Option and Ctrl (when I set Ctrl to both Command and Control, it only does one)  How can I get home and end to work per line, not per screen   I' don't mind remapping the terminal key, is that is possible, though I am using iTerm as well as regular terminal. Many thanks!

I have a very nice and expensive mechanical keyboard. It was designed for a PC and not a Mac.  How do I set up the mapping, so it works like I am used to. For example, I want the Ctrl key on the PC keyboard to act like the Command key on the Mac, so when I press Ctrl-C to Copy, I get the action I am used to.


I have a textarea that when hovered, I would like the caret to follow the cursor. It would be like if I clicked the textarea every time I moved my mouse. Here is my current js:  $("textarea").on("mousemove", function() {     $(this).trigger("click"); });   I don't want to move the mouse, but the caret in the textarea.    Update   similar but  how I can use mouse's co-ordinates to set the carets position using this method. If I receive X:120 Y:244 how can I use this method to set the caret

How do you set the cursor position in a text field using jQuery?  I've got a text field with content, and I want the users cursor to be positioned at a certain offset when they focus on the field.  The code should look kind of like this:  $('#input').focus(function() {   $(this).setCursorPosition(4); });   What would the implementation of that setCursorPosition function look like?  If you had a text field with the content abcdefg, this call would result in the cursor being positioned as follows: abcd**|**efg.  Java has a similar function, setCaretPosition.  Does a similar method exist for javascript?  Update: I modified CMS's code to work with jQuery as follows:  new function($) {   $.fn.setCursorPosition = function(pos) {     if (this.setSelectionRange) {       this.setSelectionRange(pos, pos);     } else if (this.createTextRange) {       var range = this.createTextRange();       range.collapse(true);       if(pos < 0) {         pos = $(this).val().length + pos;       }       range.moveEnd('character', pos);       range.moveStart('character', pos);       range.select();     }   } }(jQuery);


I'm trying to install skype in Ubuntu software or terminal, but always showing unable to install Skype, snap "skype" has "install-snap" change in progress. or cannot perform the following tasks. How to fix this?

I want to install Skype, but I can't locate it in Software Center or by using Synaptic Package Manager. Can anyone help me?


So can anybody tell about what's the difference between the terms Electronics and Electrical ? How do we differentiate them from one another?

I want to know if the words electric, electrical, and electronic can be used interchangeably. They all seem to mean about the same thing... Any suggestions?


Let $S$ be a half-open interval $(0,1]$. If we define $d$ on $S$ by  $$d(x,y) := \left|{1\over x} - {1\over y}\right|\;,$$  then show that $d$ is a metric on $S$. Also, prove that $(S,d)$ is a complete metric space.  I think that this problem would begin by showing the $3$ properties of a metric space. And then show that it is Cauchy?

Let $X=(0,1]$ and $d(x,y)=\left|\frac{1}{x}-\frac{1}{y}\right|$. I've proven $(X,d)$ is a metric space but I don't know how to show its completeness. How can I do that?


mentions tipping cleaners:     Forgetting the cleaners      It seems ridiculous to you and me, but in the US, and Canada, and many   parts of the Middle East, hotel guests are expected to leave money out   – the equivalent of a few dollars per day – for the housekeeping team.   You'll never see these people, but the cleanliness of your room will   certainly increase with the more money you decide to leave.   How do you indicate what money is (and is not) intended as a tip to the cleaners in hotels and motels (in the United States if it needs to be narrowed down to a specific country)?  The question  more or less answers my question, but doesn't address whether cleaning staff may inadvertently interpret money left lying around that wasn't meant as a tip as one.

I just read a question and answer about tipping housekeeping daily (). But how should I physically give them the money? Obviously if I see them I can hand them the money but if I'm out for the day?   I guess I leave cash somewhere obvious, should I leave a note as well? What if it's a non-English speaking country (I'm not sure if you'd be expected to tip there, but maybe you want to). Is there some customary place to leave the tip?   As someone brought up in a generally non-tipping country I often have to work out how to tip, but in general you can just keep an eye on what everyone else does. Not in this case.


Windows is notifying me every 20 minutes that my processor (i7 7700k) isn't supported by Windows 7, yet according to Intel it is. This wouldn't have been an issue if the message appeared once a month, or even once a week, but the problem is that the message is appearing every 20 minutes or so. This is especially annoying when I work in Photoshop and my selection gets cleared right when the window switches to the warning.     Originally I tried uninstalling the update causing the issue (KB4012218), which didn't work as it installed itself again, and so I fixed it by only selecting to install important security updates, which worked for about a week or two, but then yesterday one "security update called "April 2017 Security Quality Update for Windows (KB4015546)" showed up in Windows Update again and unlike ALL the other security updates, the checkmark was checked and grayed out, so I couldn't uncheck it, and the "hide update" was grayed out as well. I installed it in an attempt to uninstall it, and after I restarted the computer, it said said "Configuring Windows Updates" and then into a really weird screen - it was the normal Windows 7 boot animation, but instead of "Starting Windows" it said "Applying registry operation 3/40 (HKEY/current)" and then "Applying update operation 2/5 (C/Windows/Syste...)", and at first I thought I may have accidentally made it upgrade to Windows 10, but luckily not. The computer boot up and the annoying pop-up appeared. After that was done I thought the problem could've been fixed by uninstalling the update that caused the problem, but even though the update was uninstalled, the issue still remained.  I don't understand why this is considered to be a security update, as this update blocks any and all installation of Windows Update, including important security updates. Was there recently a virus discovered that made the i7700k vulnerable to remote executions?  I reinstalled Windows 7 and after hours of investigation, I found out that another update was causing the check mark grey out of the "security update" was another update, one of the updates that gets installed with all the other thousands of updates.  The strange thing is is that Intel actually fully supports the Intel i7 7700k on Windows 7. Both the chipset and graphics driver is available for it, and does offer much better performance then the previous processor I had installed according to SiSoft.   I understand that Microsoft wants people to be using an OS built for the specific processor, and I appreciate that Microsoft is notifying me, but I would like a way to unsubscribe for these warnings and take the risks, as according to Intel, the i7-700k processor fully supports Windows 7. I called and confirmed with Intel and they confirmed that I should have no problem running Windows 7 on it. I think Microsoft made a mistake by confusing the arm-based Intel Stratix 10 with Intel i7 7700k, as ARM architecture would be the one incompatible with Windows 10. I called Microsoft and let them know about this, but they said that the i7-7700k is indeed incompatible and that Intel is saying the wrong information because their support is not knowledgeable about chipset design. I'm not sure whose right, but I do know that the processor box itself supports Windows 7, 8, 8.1, or 10. There must be confusion between the designers of the box or Microsoft employees.  Frankly, I don't want to upgrade to Windows 10 because all the times I upgraded I experienced at least 3 different bugs and annoyances, not to mention that I don't like this "Store" or "MSN" or the new "Start" screen, especially with its significantly lacking search functionality.  I kindly appreciate anyones help.

It appears Microsoft plans on antagonizing or punishing users who want to use Windows 7 and Windows 8 by . It appears the updates that accomplishes it are KB4012218 and KB4012219.  I still use Windows 7 and with an occasional Windows 8. I have not acquired a taste for Windows 10. I don't agree to the change in the terms of service, and I don't agree to throw away my investments and purchases. I would like to permanently block the updates.  How do I permanently block KB4012218, KB4012219, and other related updates?  I've got a feeling a Hide this update in the Windows Update control panel is not going to work as expected. We know a bit about how Microsoft is going to handle things from the  malware. That's why I am looking for a way to block "related updates", too.


So I'm implementing a Singly LinkedList in Java. However, my addLast() method kept throwing a NullPointerException. Here is the error message: Exception in thread "main" java.lang.NullPointerException: Cannot assign field "next" because "list.tail" is null at SinglyLinkedList.SLinkedList.addLast(SLinkedList.java:39) at SinglyLinkedList.SLinkedList.main(SLinkedList.java:98) Process finished with exit code 1  I don't understand why tail is null. Any help would be appreciated. Here is my code public class SLinkedList {     private SNode head;     private SNode tail;     private static int size;      private static class SNode {         String name;         SNode next;          //constructor         SNode(String name) {             this.name = name;             next = null;         }     }      public static SLinkedList insertNode(SLinkedList list, String name) {         SNode newNode = new SNode(name);         newNode.next = null;          if (list.head == null) {             list.head = newNode;         } else {             SNode last = list.head;             while (last.next != null) {                 last = last.next;             }             last,next = newNode;         }         size++;         return list;     }      public static SLinkedList addLast(SLinkedList list, String name){         SNode newNode = new SNode(name);          list.tail.next = newNode;         list.tail = list.tail.next;          size++;         //return the list         return list;     }      // a method that add head to the list     public static SLinkedList addFirst(SLinkedList list, String input) {         SNode newNode = new SNode(input);         newNode.next = list.head;         if (list.head == null) {             list.tail = newNode;         }         list.head = newNode;         size++;         return list;     }      //a method to remove the head of the list     public static String removeFirst(SLinkedList list) throws Exception {         SNode temp = list.head;         // edge cases         // size 0         if (size == 0) {             throw new Exception("The LinkedList is empty.");         }          list.head = temp.next;         temp.next = null;         size--;          // edge cases         // size 0         if (size == 0) {             list.tail = null;         }          return temp.name;     }      public static void printSList(SLinkedList list) {         SNode current = list.head;         System.out.print("Singly LinkedList is: ");          while (current != null) {             System.out.print(current.name + " ");             current = current.next;         }     }      //driver code     public static void main(String[] args) throws Exception {         SLinkedList list = new SLinkedList();          insertNode(list, "nuggie");         insertNode(list, "cloud");          addLast(list, "cotton");         // addLast(list, "jamie");         // addLast(list, "pot-roast");          addFirst(list, "kennedy");         addFirst(list, "hoegaarden");          System.out.println("The element removed is " + removeFirst(list));          System.out.println("Size of the Singly Linked List is " + size);         printSList(list);     }  }

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


I was interested in knowing in what class does one learn Fredholm theory (integral equations). Any textbook recommendations for learning how to solve integral equations?

Can anyone recommend me some nice books about ? I'm looking for complete references.


I installed Lubuntu 14.04 on my wife's old netbook. I cannot get the wireless to work.  I initially installed the STA driver, but it did not work. I then removed it and installed the b43 driver. Synaptic Package Manager shows that firmware-b43-lpphy-installer and b43-fwcutter are installed and that bcmwl-kernel-source is not installed.  Yet when I go to the Additional Drivers screen is says that Broadcom BCM4312 is not working and is using bcmwl-kernel-source (which I know is not installed).  It also shows "unknown device" and gives me the option to continue using manually installed driver  If I try to do so, nothing happens. There is also a grayed out option that says using non-free firmware for Linux kernel from linux-firmware-non-free.  Any help would be appreciated. I am at my wits end, and the wife is threatening to go buy a Windows computer.  OK, it is not a blacklist issue. Here is the result of the dmesg | grep b43 command:  [17.652124] b43-phy0: Broadcom 4312 WLAN found (core revision 15) [17.728574] b43-phy0: Found PHY: Analog 6, Type 5 (LP), Revision 1  [22.268301] b43-phy0: Loading firmware version 478.104 (2008-07-01 00:50:23

I'm having serious problems installing the Broadcom drivers for Ubuntu. It worked perfectly on my previous version, but now, it is impossible.   What are the steps to install Broadcom wireless drivers for a BCM43xx card?  I'm a user with no advance knowledge in Linux, so I would need clear explanations on how to make, compile, etc.    lspci -vnn | grep Network showed:   Broadcom Corporation BCM4322 802.11a/b/g/n Wireless LAN Controller [14e4:432b]      iwconfig showed:  lo        no wireless extensions. eth0      no wireless extensions.   NOTE: Answer below is updated every time new information is added and confirmed working.


I'm not sure, if I'm just overlooking a simple preference setting or if what I would like to achieve is possible at all...  Anyway, I recently created a LaTeX class file (it's based on scrbook from the KOMA-Script package, but that might be beside the point) that looks like that:  \NeedsTeXFormat{LaTeX2e} \ProvidesClass{MyBook}[2016/06/03 My Book Class]  \LoadClass[ paper=17cm:22cm, DIV=12, twoside, fontsize=9pt, toc=flat ]{scrbook}  (...skipping a few more adjustments...)   I then created a LyX layout file by simply copying the contents of the original file scrbook.layout:  #% Do not delete the line below; configure depends on this #  \DeclareLaTeXClass{MyBook}  Format 35 Input scrclass.inc Input numreport.inc  Sides                   2 PageStyle               Headings  NoStyle Abstract   Style Chapter     LabelString          "\thechapter"     TocLevel 0 End   # Equations are numbered by chapter Counter equation     Within chapter     LabelString "\thechapter.\arabic{equation}" End   Style Bibliography     TopSep                4     LabelString           "Bibliography"     LabelFont       Series              Bold       Size                Largest     EndFont End   I put the files into the correct directories, reconfigured LyX and so far, everything is working perfectly.  ...well, except for the fact that LyX seems to ignore both the paper size (set as 17cm:22cm) and the margins (defined by setting DIV=12). Instead LyX always uses A4 for the paper size and standard margins (not sure how big). I'm assuming that LyX takes these from its own set of preferences, instead of honoring the class settings.  I could, of course, define the paper size and the margins in the preferences of the LyX document itself. However, I would like to give the class definition to several authors, without them having to do any further adjustments in the preferences. So, I would really prefer to define the paper size and the margins in a more central place.  Is this possible? Any help would be much appreciated. Thanks in advance!

I want to write several classes, most of them will use KOMA classes as base class.  However I stumbled upon the problem that some options (mainly concerned with layout) are not processed if given in the wrapper class:    \begin{filecontents}{test.cls}     \ProvidesClass{test}[2015/01/01]     \DeclareOption*{\PassOptionsToClass{\CurrentOption}{scrartcl}}     \ProcessOptions\relax     \LoadClass[paper=a5]{scrartcl}   \end{filecontents}  \documentclass{test}  \usepackage{blindtext}  \begin{document}   \section{Test}   \blindtext \end{document}   This results in   LaTeX Warning: Unused global option(s):     [paper=a5]  If i give the option as \documentclass[paper=a5]{test} it is used correctly, because I pass the options to scrartcl. However I want to change the defaults for the layout.   How can I achieve this?


I am using Ubuntu 16.04. I have installed HPLIP from the Ubuntu repository using the command sudo apt install hplip hplip-gui as recommended in . However, when I run hp-setup I am told to install HPLIP. The program 'hp-setup' is currently not installed. You can install it by typing: sudo apt install hplip  This is circular since I have HPLIP already installed. Can anyone suggest what I should do next? Output of sudo apt install hplip: Reading package lists... Done Building dependency tree        Reading state information... Done hplip is already the newest version (3.16.3+repack0-1). 0 upgraded, 0 newly installed, 0 to remove and 27 not upgraded.  The output confirms it is installed. Output of dpkg -l hplip: Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name                        Version            Architecture       Description +++-===========================-==================-==================-=========================================================== ii  hplip                       3.16.3+repack0-1   amd64              HP Linux Printing and Imaging System (HPLIP)

Let's assume that one has some HP printer and/or scanner and checked its support status on the corresponding page of HPLIP site - .  So one have the following information: the device Model name, Min. HPLIP Version and Driver Plug-in need.   What should one install to make Ubuntu fully support the HP printer and/or scanner?


Note : I'm not asking why is 0.1 + 0.2 different from 0.3.  According to , 0.1+0.2 does not equal to 0.3, because 0.1 and 0.2 are already rounded to different numbers before comparing, which is different from rounded number from 0.3.  But my question is, why 0.1+0.2+0.3!=0.3+0.2+0.1?    console.log(0.1+0.2+0.3==0.3+0.2+0.1);     My assumption: inside computers, floating numbers would be rounded to a value :  0.1 is round to A  0.2 is round to B  0.3 is round to C  since rounded value is exact (can be represented by binary), so I think  A+B+C should be exactly equals to C+B+A, just like 1+2+3 exactly equals to 3+2+1. But now the result is different. What wrong with my assumption?

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


Should I use     You are granted the choice to either be my friend or my enemy.   or     You are granted the choice of either being my friend or my enemy.   ?  It's for my poem and I want to double-check.

Some verbs are followed by ing, e.g. I enjoy swimming. We can't say I enjoy to swim. Likewise, some verbs are followed by to, e.g. I decided to make a plan.   Which particular verbs are followed by ing and to? Can you please provide a list for that?  Moreover, which verbs can be followed by both without having the meaning changed?


How to prove generalized DeMorgan's Law that $$\neg(A_1 \land A_2 \land \cdots \land A_n) = \neg A_1 \lor \neg A_2 \lor \cdots \lor \neg A_n.$$  Or in the set theory language, $$\Bigg(\bigcap_{i\in I}A_i\Bigg)^c = \bigcup_{i\in I}(A_i)^c.$$

Let $X$ be a set and $\{Y_\alpha\}$ is infinite system of some subsets of $X$. Is it true that: $$\bigcup_\alpha(X\setminus Y_\alpha)=X\setminus\bigcap_\alpha Y_\alpha,$$ $$\bigcap_\alpha(X\setminus Y_\alpha)=X\setminus\bigcup_\alpha Y_\alpha.$$ (infinite DeMorgan laws)  Thanks a lot!


Currently I am using nmtui for selecting a spot.  I would like to connect to a wifi spot from command line.  I expect there might be a tool that would work this way  connec2wifi -s somessid -p ****   Where -s is ssid and -p is password  or even like this?  connec2wifi  somessid *****   Also, if there is no such tool. What would be the best way to implement it?

I'm using latest version of Debian-based Linux Kali.  Maybe it is an , as the main problem is after I log in to the system I get a blank screen and mouse pointer. Somebody on the Internet recommend me to change window manager.  But I'm unable to do this as I can't connect to wifi.  I found tutorial how to do this   And I tried to do it step by step, but it doesn't work for me. In that tutorial that author wrote that I need use the command ip link set wlan0 ip to bring up the wifi interface. In his example the output looks like this:  root@kali:~# ip link show w lan0 4: wlan0: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN mode DORMANT qlen 1000   link/ether 00:60:64:37:4a:30 brd ff:ff:ff:ff:ff:ff  root@kali:~# ip link set wlan0 up  root@kali:~# ip link show wlan0 4: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DORMANT qlen 1000     link/ether 00:60:64:37:4a:30 brd ff:ff:ff:ff:ff:ff   On the other hand when I call:     ip link set wlan0 up    ip link show wlan0   I get:    4: wlan0: <NO_CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN mode DORMANT qlen 1000    link/ether 00:60:64:37:4a:30 brd ff:ff:ff:ff:ff:ff   and after running wpa supplicant with valid network details  wpa_supplicant -B -D wext -i wlan0 -c /etc/wpa_supplicant.conf   iw wlan0 link still returns Not connected.  How do I solve this problem and what shall I do next?


I am learning about photography and in process of that reading few books and online resources to get some basics.  Currently i am reading "Understanding Exposure" by Bryan Peterson.While going through book, i came across few sections where he first choose "shutter speed" in place of the "aperture".  I am not sure how relevant this question is  , but i am curious to know about these decision. Is there any thumb of rule for these decisions, when to go with aperture or when to go with shutter speed or it just a decision based on experience.  In All cases Camera was set in Manual mode

Under what circumstances would you use aperture priority vs. shutter priority and vice-versa?  I typically don’t use shutter priority (ever) and favor aperture priority to try to get a max aperture with the thinking that I’ll get more light and a better low light shot. But after getting almost all my shots being blurry and the help of a couple questions posted here I learned I should use faster shutter speeds to get clear shots.  What my question boils down to is me trying to get a firmer understanding when to use one over the other, and why.  Thanks all.


If we want to refer to "Lemma 3.4", we can write  " Lemma \ref{number9}". Is there a command that the word "Lemma" or "Theorem" or ... appear automatic too? (i.e we write ... and in pdf appear "Lemma 3.4")  Thank you for your help.

Sometimes when I work I write something like  \begin{proposition} \label{my new result} ... \end{proposition} ... blah blah in Proposition \ref{my new result} blah...   but then I realize that the Proposition should actually become a Lemma. So I change it to  \begin{lemma} \label{my new result} ... \end{lemma}   The problem is that I then have to hunt down all the places where I wrote Proposition and change it to Lemma, which is tedious and error-prone. Well, we have search facilities in editors, so it is not really that complicated, but still it feels the wrong way to do this. I would be happier to write  \begin{proposition} \label{my new result} ... \end{proposition} ... blah blah in \labelNameFor{my new result} \ref{my new result} blah...   where labelNameFor is a hypothetical magic command which outputs "Proposition". Then I could forget about all the places where I reference the result and just make any changes I wish.  Is there a way to do something like this? As far as I understand the label/ref mechanism is simply based on counters, so I do not see a straightforward way, but maybe someone more clever and industrious then I am has given the problem some thought.


How on earth do I pan fry fish without it turning to hell?  For the fish: Stainless steel pan Oil heated until it sizzles when droplets of water are thrown in Plain fish, skin side down first Try and flip, it falls apart...    Any advice on this?

Twice now I've tried pan frying fillets of white fish (Swai and Flouder) in olive oil and butter.  Both times the fish has disintegrated into unsightly mush.  Is there some technique I'm missing?  How can I pan fry without the fish falling apart?


When fighting against multiple of the Giant Spider creature and more than one manage to web you, do you need to break free from each web separately, or does just one successful escape check break you free from all webs?

The  () added the "Combining Game Effects" section which states (emphasis mine):  Different game features can affect a target at the same time. But when two or more game features have the same name, only the effects of one of them—the most potent one—apply while the durations of the effects overlap. [...]  The Essentials Kit has a further clarification on these rules in its "Effects with the Same Name Don't Stack" section (page 3, emphasis mine):  [...] But when two or more effects have the same proper name, only one of them applies while the durations of the effects overlap (a duration is a time span of 1 round or more). [...]  I'm unsure whether the further clarification will change my following examples but we do know for sure that with overlapping identical effects, one instance will be what I'd call "active" (will have effects) and the other will be what I'd call "inactive" (won't have effects). That all squared away, I think my question will make more sense with examples:  The  Fire Form trait:  [...] The first time it enters a creature's space on a turn, that creature takes 5 (1d10) fire damage and catches fire; until someone takes an action to douse the fire, the creature takes 5 (1d10) fire damage at the start of each of its turns.  If a creature is under the effects of multiple instances of Fire Form, and somebody uses their action to douse the fire, are both instances removed or only one?  The  spell:  [...] If the target willingly moves before then, it immediately takes 1d8 thunder damage, and the spell ends. [...]  If a creature is under the effects of multiple instances of booming blade, and they move, are both instances removed or only one?  The  spell:  [...] At the end of each of its turns, the target can make another Wisdom saving throw. On a success, the spell ends on the target. [...]  If a creature is under the effects of multiple instances of hold monster, and they succeed on a save, are both instances removed or only one?   Can an "inactive" effect end when its end-condition is met (letting them end simultaneously), or do these sorts of things always end one at a time? Or perhaps the answer is something in-between?  There is also the following related question:    Both answers there supports that if you are grappled by multiple creatures and you make a check to remove a grapple, you only remove one of the grapples. It's not perfectly analogous situation but it is somewhat similar.


How should I respond when someone ends their sentence with ', no?'. I can see this going two ways:  No  yes:  yes to the no. no:   no to the no.    Example: Q:  your day was good, no? A: No, it was good  or  Yes, I didn't have a good day   Sentence  yes:  yes to the sentence no:   no to the sentence    Example: Q:  your day was good, no? A: yes, it was good  or  no, I had a bad day  (if there was a , I would use it)

I know this is a duplicate, I couldn't get an answer from other topics.  Kids are bad, aren't they? yes they are, no they aren't.  Kids aren't bad, are they? yes they are, no they aren't.  Generally, do you answer the question tag or validate the truthiness of the sentence before question tag.


I am trying to find the value of: $$\sum_k (-1)^k {n \choose k}^2$$ The hint is that $(1-x^2)^n = (1-x)^n(1+x)^n$  I tried solving it using convolution but it didn't quite work.

Why is $\displaystyle\sum\limits_{k=0}^{n}(-1)^k\binom{n}{k}^2=(-1)^{n/2}\binom{n}{n/2}$ if $n$ is even ?   The case if $n$ is odd, is clear, since $\displaystyle(-1)^k\binom{n}{k}+(-1)^{n-k}\binom{n}{n-k}=0$ (we have $(n+1)/2$ such pairs.)  but if $n$ is even we have no symmetry, I tried to consider the odd and even terms separately but with no success.   Do you have an idea ? Thanks in advance.


I saw him .... off.  A.drive B.to drive C.driving D.driven  I chose C but the key is A. I don't know why. Can you help me explain the reason?

I saw him crossing the road.   I saw him cross the road.   Which one is correct and why?


The  app can be obtained . For people with Android devices that don't have Google Play access, is there another way of getting the app? For example, other app stores or a direct download of the .APK file.

I'm one of those exceptions that deviates from the norm: I run CyanogenMod without any Google apps.   Is it possible to download the Stack Exchange Android app .apk directly?


I have write the code of an slide in tex; the text is shown above the image  and the image is shown below the text.       What should I do; such that Image is in the left and the text in right?     begin{frame} \frametitle{History} The problem was first asked 200 years ago. \begin{center} \includegraphics[scale=0.3]{Image01} \end{center} \end{frame}   This code shows the text at top and shows the image in the bottom of the text.       What should I do to show the text in the right and image in the left?

I am new to Beamer and LaTeX itself. Right now, I want to create a simple slide with an image on the right and text and the sidebar (using the Hannover theme) on the left. I cannot figure out how to do that. Any suggestions?


Let $R$ be a commutative ring with a unity. Let $I_1,\dots,I_n,J\subseteq R$ be ideals, $I_3,\dots,I_n$ are prine and $J\subseteq I_1\cup\dots\cup I_n$. Show that $\exists k$ s.t. $J\subseteq I_k$.   Attempt:  If $n=1,2$ then it is easily shown. Suppose $n=3$. Not sure how to porceed.

Let $I \subset R$ be an ideal and $P_i$  $(i=\{1,...,n\})$ prime ideals with $I\subseteq\bigcup_{i=1}^nP_i$. Prove that then $I$ is contained in one $P_i$.   I don't know how to show this because I don't have any approach.  So I am looking for something to start with or something like a sequence of tips (Since I know this is a large proof)  Thanks in advance!


I installed QGIS 2.18.10 and then osgeo4w as you suggested it. I went to the Processing Provider options and entered the paths as you described it. But I do not still have OTB in my processing toolbox.  Can you help me? I don't have any other idea so far.

I had installed QGIS 2.18.3 using OSGeo4W and then the OTB standalone binary. In QGIS, I had manually entered the directory of the    OTB applications folder (C:\Program Files\QGIS 2.18\apps\OTB-5.10.0-win32\lib\otb\applications) and  Command line folder (C:\Program Files\QGIS 2.18\apps\OTB-5.10.0-win32\bin)   and I had checked the "Activate" button.  But nothing happens when I close the Processing window and there is no OTB menu appearing in the Processing Toolbox.  How can I resolve this issue?


Let $A, B \in M_n(\mathbb{R})$ such that : $AB-BA$ invertible and $A^2+B^2 = AB$ then prove that : $3 \mid n$.   I tried to manipulate or find some factorisation in order to be able to use efficiently eigenvalues...  but I dind't find anything.   Thank you !

The question is:     Are there square matrices $A,B$ over $\mathbb{C}$ s.t. $A^2+B^2=AB$ and $BA-AB$ is non-singular?   From $A^2+B^2=AB$ one could obtain $A^3+B^3=0$. Can we get something from this?  Edit:  $$A^2+B^2=AB\implies\\ A(A^2+B^2)=A^2B \implies\\ A^3+AB^2=A^2B \implies \\ A^3+(A^2+B^2)B=A^2B \implies \\  A^3+A^2B+B^3=A^2B \implies \\ A^3+B^3=0 $$


The (gold) Famous Question badge has the description: "Asked a question with 10,000 views."  Aren't all users who ask a question going to acquire this badge eventually? I mean, it would have to be something seriously obscure to not pick up a few pageviews every-so-often and even very mediocre questions will get significant pageviews just from people looking to avoid duplicates.  It seems to me, anything based on pageview counts should apply a rolling window to the criteria. So the badge description would be "Asked a question with 10,000 views in 60 days" or similar.

I'm no longer active on Stack Overflow, but it seems that any time I land on the site there's a notification that I've earned a badge for a question that has become  or . It seems literally only a matter of time before I "earn" a gold badge for having a  question.  Is there some time limit or other method to prevent questions from accumulating page views for the life of the site?  More importantly, is this a feature or a bug?  On the one hand, when I see the notification that I got a badge just for not deleting my account, I shake my head and think, "Silly system!  Don't you know about the ?"  On the other hand, I actually get a little  when I think that my question was one that other people were interested in reading. I feel like I helped someone who was searching for an answer.  On the third hand, who cares?


Recently, every time I hit a new page in stackexchange, whether it be the list of questions in a given forum, or a specific question, I am getting a pop-up like this:   Your privacy By clicking “Accept all cookies”, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Accept all cookies Customize settings  I am able to click "accept" and it will go away, but it comes back as soon as I reload the page or view a new topic.  UMatrix shows it's a script from cdn.cookielaw.org and that it's trying to set a 3rd-party cookie. My guess is that since I'm blocking 3rd-party cookies and scripts, it just keeps trying. Given how bad we know 3rd-party cookies are, and how they are used to violate privacy, track people across sites, etc., why on Earth would Stack Exchange do this?

I have a profile on AskUbuntu.com which is recognized on my StackEchange profile (). I have already asked and answered questions there. But even though I'm logged in stack exchange, Askubuntu does not see me as logged in. I have a long history of problems with that and though I have been able to access it up to end 2018, and I don't understand why it can't do it anymore. I have seen multiple questions about similar problems, but they all are older than 2018 and do not really helped me solve it. Amongst other, they proposed to log in with the same user and password, but using the same user and password on two different log in systems is a security hole. either your credential cookies are shared, or one should use different logging info. EDIT: it has been suggested to deactivate third party cookies blocking, but I do not want to ruin my browser's tracking protection.


I have to perform a load test on a env whose URL can be accessed as   When I access the URL from browser everything looks fine. However when I proxy it to use for Jmeter recording, I am getting error as below  javax.net.ssl.SSLHandshakeException: Received fatal alert: handshake_failure     at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)     at sun.security.ssl.Alerts.getSSLException(Alerts.java:154)     at sun.security.ssl.SSLSocketImpl.recvAlert(SSLSocketImpl.java:2023)     at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1125)     at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375)     at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1403)     at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1387)     at org.apache.http.conn.ssl.SSLSocketFactory.connectSocket(SSLSocketFactory.java:436)     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180)     at org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:294)     at org.apache.jmeter.protocol.http.sampler.MeasuringConnectionManager$MeasuredConnection.open(MeasuringConnectionManager.java:107)     at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:643)     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:479)     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:906)     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:805)     at org.apache.jmeter.protocol.http.sampler.HTTPHC4Impl.executeRequest(HTTPHC4Impl.java:517)     at org.apache.jmeter.protocol.http.sampler.HTTPHC4Impl.sample(HTTPHC4Impl.java:331)     at org.apache.jmeter.protocol.http.sampler.HTTPSamplerProxy.sample(HTTPSamplerProxy.java:74)     at org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1146)     at org.apache.jmeter.protocol.http.proxy.Proxy.run(Proxy.java:240)   I understand the env did not have the proper SSL setup needed. I tried some solutions suggested on how to bypass the SSL setup for recording but I haven't succeeded.   Any suggestions please

I'm using Apache JMeter 2.3, which now supports "attempt HTTPS spoofing" under the Proxy Server element.   I've tried this on several different servers, and have had no success.  Has anyone been able to successfully record from an HTTPS source with this setting?  Or barring successfully recording, can anyone share a work-around? When available, I simply have HTTPS turned off at the server level, but this is not always feasible. Thoughts?


If a Green Lantern can .   Can the Green Lantern then leave the new ring with that person indefinitely?  How long will the ring last?  Are there any example of this in any canon?

Suppose that a Green Lantern agent wants to assign a friend of his as his/her deputy for certain reason: for example, ensuring the safety of his home world while he/she is fighting crime several light years away. Could he/she use his/her willpower to create a copy of his/her ring?   Granted, the process might require a huge amount of power (from the ring and from its user), perhaps too much for it to be practical (conservation of energy), but could you make, at the very least, an imperfect copy in theory?  Just to get extraneous issues out of the way, let's assume this friend of agent is strong-willed enough to be a ring-bearer (perhaps even a prospective Lantern!), and the Guardians have sanctioned this experiment for the time being (out of sympathy or at least scientific curiosity).  Furthermore, I believe Jordan's Green power ring has been 'copied' in at least one comic story-line (Superman: Red Son), though I haven't really read it and don't quite know how that universe's Jordan accomplished it.


I want every filetype to open in Leafpad.  I tried to edit /usr/share/applications/defaults.list to associate file types. But I want all filetypes to open in a certain program, with maybe something like \*/*=leafpad.desktop  How to do it?

Ever since installing Bless Hex Editor, all unknown files and text files automatically open with Bless instead of gedit. How do I change it back? I don't want to have to manually associate files with gedit, I just want gedit to be the default if there's no other application set up to open the file.  Solution: modify ~/.local/share/applications/mimeapps.list  [Default Applications]  - text/plain=bless.desktop - application/octet-stream=bless.desktop + application/octet-stream=gedit.desktop


For integer $n$ greater than or equal to 2, let $A_n$ be $n^{th}$ order square matrix whose $(i,j)$ component is $|i-j|$. That is, \begin{align*}     A_n =\begin{pmatrix}      0& 1& 2& ... & n-1\\     1& 0& 1& ... & n-2\\     2& 1& 0& ... & n-3\\     .& .& .& ... & . \\     .& .& .& ... & . \\     .& .& .& ... & . \\     n-1& n-2& n-3& ... &0     \end{pmatrix} \end{align*} Find the determinant of $A_n$. We have two general tools for the determinant of $n\times n$ matrix, they are co-factor formula and the Leibniz formula but I tried to build an expression for the determinant of this matrix but failed, Any hints would be appreciated. Leibniz Formular : $\det A = \sum_{\sigma \in S_n}\bigg(\text{sgn}(\sigma) \prod_{i=1}^n a_{i,\sigma_i}\bigg) $ I can figure this out for $3\times 3$ matrices but it is hard to think for $n\times n$ matrices with these permutations $\sigma$. And how do we find these kind of problems on the internet? Any recommendations would be appreciated

Question states: "Let $D_n$ denote the determinant of the $n$-by-$n$ matrix whose $(i,j)$th element (the element in the $i$th row and $j$th column) is the absolute value of the difference between $i$ and $j$. Show that $D_n = (-1)^{n-1}(n-1)2^{n-2}$."  It seems like that I can get a recurrence relation (especially the question was from a book chapter dealing with recursion). In trying to get a recurrence relation, here is what I have done so far:  (Let $R_k$ denote the $k$th row and let $(i,j)$ denote the element/spot of $i$th row and $j$th spot)  1) replace $R_1$ with $R_1-(R_2+R_{n-1})$ to get $R_1^*$  2) replace $R_1^*$ with $R_1^*+R_{n-2}$  3) If I am not mistaken, I should have $-2$ on $(1,1)$, $2$ on both $(1,n-1)$ and $(1,n)$, and all other element in the first row as $0$.  4) take out $2$ from the first row, and expand the determinant about the first row  5) I should have $D_n=2(-D_{n-1}+(-1)^n B_{n-1})$, where $B_{n-1}$ is the determinant of a not-easily-reducible mayrix whose last column consists of $n-1$ ones followed by one $-1$.  How should I go about from now on? Once I get a recurrence relation, it would be pretty easy to get the explicit formula for $D_n$ using induction.  P.S. This question apparently is a question taken from 1969 Putnam Competition


How can I copy the text by click the div in the render function?  in the bellow you can see the div, I want to click it, then the clipboard can copy the text of it.    my code of render function is bellow:        h(          'div',          {slot:"content"},          [            h(             'ul',              params.row.ipv4s.map((item, index) => {                return h('li', [h('span', {}, index + 1 + '. ' + item.ip)])               })            )          ]        )   how can I realize my requirement?

What is the best way to copy text to the clipboard (multi-browser)? I have tried: function copyToClipboard(text) {     if (window.clipboardData) { // Internet Explorer         window.clipboardData.setData("Text", text);     } else {         unsafeWindow.netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");         const clipboardHelper = Components.classes["@mozilla.org/widget/clipboardhelper;1"].getService(Components.interfaces.nsIClipboardHelper);         clipboardHelper.copyString(text);     } }  But in Internet Explorer it gives a syntax error. In Firefox, it says unsafeWindow is not defined. A nice trick without using :


I have written this code but I want to delete the route[mini][minj] and route[mini+1][minj] I want it to find the minimum every time delete that and find the minimum in others.  class Test { public static void main(String[] args) {     int x=3;     int y=5;     double d=0;     double p=0;     double min=1000;     int mini=0;     int minj=0;     int b=0;     int[][] route = new int[][]{       {20,50,72,63,54,33,22,93,52,70},       {67,56,46,37,39,29,15,11,13,71},     };     int[][] distance = new int[10][10];     while (b<10) {     for (int i=0;i<route.length-1;i++) {         for (int j=0;j<route[0].length;j++) {             distance[i][j]=route[i][j]-x;             distance[i+1][j]=route[i+1][j]-y;             p=Math.sqrt((distance[i][j])*(distance[i][j])+((distance[i+1][j])*(distance[i+1][j])));             //System.out.println(p);             if (min>=p) {                 min=p;                 mini=i;                 minj=j;             }         }     }     b++;     } }   } I searched for it but none of the answers seem to work for my situation.

Given an array of n Objects, let's say it is an array of strings, and it has the following values:  foo[0] = "a"; foo[1] = "cc"; foo[2] = "a"; foo[3] = "dd";   What do I have to do to delete/remove all the strings/objects equal to "a" in the array?


I need to create a custom list in Sharepoint 2007 using JQuery (only!) using a custom list template. I'm using Sharepoint 2007. Is there any way to do it? I already know to create the list and update columns as said at

I need to create a custom list in Sharepoint 2007 using JQuery (only!). I'm using Sharepoint 2007. Is there any way to do it?


I have a site collection http://SPL-GT/sites/CP and would like to change it to a shorter version of http://SPL-Sharepoint. How this can be done?

I have a site collection (of type enterprise KB) under the following URL http//servername/customer/questions where the customer is a wildcard managed path. now I want to change the site collection URL to be http://servername/customer/generalquestions.   so I am not sure how to change the site collection URL. I read that I can backup the current site collection, remove it,create a new site collection under the desired URL (customer/GeneralQuestion), restore the backup file on the new url.. but I am not sure if there is a more straightforward approach  to follow? using power shell or UI to accomplish this ?  Thanks


In the game World of Warcraft, I came across this game called "death rolling". (See similar post here ). The game has $2$ players. The first player types /roll $N_0$ which generates a random integer $N_1$  in the interval $[1,N_0]$. The second player similarly generates a random integer $N_2$ in the interval $[1,N_1]$. This process continues iteratively alternating between Player 1 and Player 2 until one of the players rolls $1$, and this player is deemed the loser of the game. What is the expected number of rolls $m$ in this game in terms of $N_0$? EDIT: I think this question is actually a duplicate with  . The answer provided there makes pretty good sense, but I don't quite follow the final step. Can anyone help me understand their justification for the final step?

Consider a game where one would roll a random integer between $1$ and $N_0$ where $N_0 \ge 1$. The newly randomly generated number is now the new "upper limit" of the game, the game continues by rolling a random number between $1$ and the randomly generated number. This game continues until the randomly generated number is 1. Here is an example of how it can look like. Consider $N_0 = 1000$ $$N_1 = Random(1, N_0) = Random(1, 1000) = 623$$ $$N_2 = Random(1, N_1) = Random(1, 623) = 366$$ $$N_3 = Random(1, N_2) = Random(1, 366) = 303$$ $$N_4 = Random(1, N_3) = Random(1, 303) = 190$$ $$N_5 = Random(1, N_4) = Random(1, 190) = 52$$ $$N_6 = Random(1, N_5) = Random(1, 52) = 13$$ $$N_7 = Random(1, N_6) = Random(1, 13) = 1$$ $$END$$ The Length of the example game was 7, it took 7 rolls to reach 1. Given the Starting Upper Limit $N_0$, what is the average amount of rolls needed to reach 1? I have tried to write Python code to help with this problem and it seems this follows a Logarithmic Pattern with the function to approximate the amount is $f(N_0) = 1.0168287465013466\ln(N_0) + 1.4731706151125865$


How do I get I into my account when I forgot email and password. My 4/ year old messed up my phone plz help

I won a Samsung Galaxy S6 Edge, signed into it with my Google account, played around with it, wiped it, and sold it.  Now the person can't get past setup because it's saying he must login with an account previously synced to the phone.   Is there anything I can do from my side to remove this lock?


Can any one help please? I tried to find some linear functions that satisfying $$f(x+y) = f(x) + f(y)$$ but the condition of scalar that says: $$f(ax)=a\cdot f(x)$$ does not hold in cauchy functional equation $$f(x+y)=f(x)+f(y)$$

Do there exist functions $f : \mathbb{R} \rightarrow \mathbb{R}$ such that $f(x+y)=f(x)+f(y),$ but which aren't linear? I bet you they exist, but I can't think of any examples.  Furthermore, what hypotheses do we need to put on $f$ before no such functions exist? I feel continuity should be enough.


I am confusing with the use of closure and self-revoking in Javascript. When I run this code, each time I click the Button the counter increases by 1. It seems that the function assigned to "add" is self-invoking function.        <!DOCTYPE html>    <button type="button" onclick="myFunction()">Count!</button>
0
          However, when I call the function like the code below, the counter value is always 1.    <!DOCTYPE html>    <button type="button" onclick="myFunction()">Count!</button>
0
          Could anyone tell me the difference between the two examples, and what goes under the hood? Thanks for you help.

I asked a question about Currying and closures were mentioned. What is a closure? How does it relate to currying?


Given this code:  #include <iostream>  class base { private:     char x; public:     base(char x) : x(x) {         std::cout << "base::base(char) " << this << std::endl;     }     base(base&& rhs) {         std::cout << "base::base(base&&), moving from " << &rhs << " to " << this << std::endl;         x = rhs.x; rhs.x = '\0';     }     virtual ~base() {         std::cout << "base::~base " << this << std::endl;     } };  class child : public base { private:     char y; public:     child(char x, char y) : base(x), y(y) {         std::cout << "child::child(char, char) " << this << std::endl;     }     child(child&& rhs) : base(std::move(rhs)) {         std::cout << "child::child(child&&), moving from " << &rhs << " to " << this << std::endl;         y = rhs.y; rhs.y = '\0';     }     virtual ~child() {         std::cout << "child::~child " << this << std::endl;     } };  int main(int argc, char* argv[]) {     { // This block enables me to read destructor calls on the console...         base o = child('a', 'b');     }     std::cin.get();     return 0; }   In the stack frame of main there's an area where child is being instantiated. After that the move constructor of base is being called with a reference to the newly created child. The (move) construction of base takes place in a different area in the same stack frame and copies the parts of child which are derived from base. From now on all that's left of child is the base parts, making it nothing more than base.  I know that polymorphism is not possible for objects on the stack and I think I understand why: Efficiency. No vtable lookups and such. The compiler can choose the methods to call at compile time.  What I don't understand is: Why is it possible to assign a child instance to a base variable (in a stack frame) when everything that makes up child gets lost? What's the motivation for that? I'd expect a compile error or at least a warning, because I can't think of a good reason to allow it.

Someone mentioned it in the IRC as the slicing problem.


Show that if a sequence $(x_{n})$ converges weakly for $x \in \ell^{1}$, then the sequence converges strongly. Can anybody help me?

Let $\ell^1$ be the space of absolutely summable real or complex sequences. Let us say that a sequence $(x_1, x_2, \ldots)$ of vectors in $\ell^1$ converges weakly to $x \in \ell^1$ if for every bounded linear functional $\varphi \in (\ell^1)^*$, $\varphi(x_n) \rightarrow \varphi(x)$ as $n \to \infty$. How may I show that weak convergence, in this sense, is the same as the usual convergence-in-norm? It's clear the weak convergence implies pointwise convergence, but that's not good enough to conclude strong convergence...  By linearity, it suffices to prove that if $\varphi(x_n) \longrightarrow 0$ for every $\varphi \in (\ell^1)^*$, then $\| x_n \| \longrightarrow 0$. Let $x_n(k)$ be the $k$-th component of the vector $x_n$. Then, $x_n(k) \longrightarrow 0$ for every $k$, so $\sup_n |x_n(k)| < \infty$ for each $k$, and this implies $$\lim_{N \to \infty} \lim_{n \to \infty} \sum_{k=1}^{N} |x_n(k)| = 0$$ This is almost what I want, but the limits are the wrong way around. The obvious next thing to try is to construct some clever functional, or even a family of clever functionals, but I can't think of anything useful here. I can see that pointwise convergence alone is not good enough — if $x_n$ is the standard basis vector, then $x_n \longrightarrow 0$ pointwise, but $\| x_n \| = 1$ for all $n$. The fact that it doesn't converge strongly can be detected by the linear functional $\varphi(x_n) = \sum_k x_n(k)$, but I'm at a loss as to how to generalise this.


Suppose two twins are put asleep.  One is put in a rocket ship and accelerated to 90 percent of the speed of light.  They are then both awakened, after which  they both train their telescope on each each other.  They both start dancing.  Will the twin in the rocket ship and the twin on the ground both see the other dancing at the appropriate rhythm; or will the twin in the rocket ship see the other twin dancing at a too fast rhythm and the twin on the ground see the other twin dancing in slow motion.

don't get upset but I'm a total layperson and I'm not really understanding the twin paradox and I'm just wondering: If the twin who left earth in a rocket so that he wouldn't age as fast had a walkie talkie of some kind to contact the twin on earth with, would the twin on earth hear the spaceship twin's voice talking veeeeeeery slooooowly, and would the rocket ship twin hear the other twins voice squeaky and sped up?


I tried to install dropbox and suddenly it couldn't finish installation. I tried from the terminal to do it manually and the same,it stucked at 100%. These are two of the problems are coming through terminal:  E: Could not get lock /var/lib/apt/lists/lock – open (11: Resource temporarily unavailable)  E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?   Also when i tried to do software update is coming this problem:  Software index is broken  It is impossible to install or remove any software. Please use the package manager "Synaptic" or run sudo apt-get install -f in a terminal to fix this issue at first.  I tried to fix it but is still the same problem. How can I solve these problems? Thank you

I get this error when trying to use apt-get:  E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?     How can I fix this?


Let $f$ be an integrable function on $\mathbb{R}$, and $g$ be an $L^\infty$ function on $\mathbb{R}$.  Then, the convolution $f*g$ is said to be continuous and bounded on R. I managed to show that it is bounded, but can't show that it is continuous. The convolution is defined as an integral, so it seems intuitively clear that it is continuous. Could anyone show me how to rigorously prove this?

Suppose $f\in L^\infty(\mathbb{R})$ and $K\in L^1(\mathbb{R})$ with $\int_\mathbb{R}K(x)dx=1$. Show that the convolution $f\ast K$ is a uniformly continuous and bounded function.  The definition of the convolution is $(f\ast K)(x)=\int_\mathbb{R}f(x-y)K(y)dy$.   There is the inequality $\|f\ast K\|_\infty\leq\|f\|_\infty\|K\|_1$, which yields that $f\ast K$ is bounded. But what about uniform continuity?


In my usage of Ubuntu, I have noticed a baffling array of different Linux kernel packages.  Some of them are listed below:   linux-generic linux-headers-generic linux-headers-generic-pae linux-headers-x.x.xx-xx linux-headers-x.x.xx-xx-generic linux-image-generic linux-image-generic-pae linux-image-x.x.xx-xx-generic linux-image-x.x.xx-xx-generic-pae linux-image-extra-x.x.xx-xx-generic linux-image-extra-x.x.xx-xx-generic-pae   My question is, why are there so many different kernel packages, often for the same version number (e.g., 3.5.0-24), and what are the differences between them?  Edit to deduplicate: This question is not asking about the differences between generic, server, and virtual kernel packages; instead, it is asking about what all of those packages (as well as the ones in the list) are.

I'm getting new VMs built for development and staging environments, and was wondering whether there are compelling reasons for or against using the linux-virtual package on all of these images.  Do the -virtual kernels have different tuning? Do they have tools that make the suspend/wake-up better/safer?


EDIT: the question is answered here    Using integrals, I managed to prove that $$\displaystyle \forall m, \sin(\ln(m+1))\leq \sum_{n=1}^m \frac{\cos(\ln(n))}{n}\leq 1+\sin(\ln(m))$$ and I noticed that $\sin(\ln(m+1)) - \sin(\ln(m)) \to 0$  I tend to believe that the series diverges, but I  can't prove it with the previous inequality.

I'm struggling to prove that $$\sum \limits_{n=1}^{\infty} \frac{\cos(\log(n))}{n}$$ diverges.   Does anyone have any idea how to prove it? Breaking it into smaller pieces din't work. Maybe I should bound it with another series? But how?


In Agents of SHIELD Season 2,      Episode 22 ("SOS Part Two"), Grant Ward is shown taking over Hydra, with a couple goons giving him their allegiance.   Then, in Ant-Man,      former SHIELD bigshot Mitch Carson is revealed to be a Hydra agent, and it is assumed that he has been for some time. He's clearly more of a power broker than a former specialist with a couple goofy henchmen. Also, it's unclear what he could do with the Yellowjacket serum without a team of researchers behind him, so he's probably not a lone wolf.   What's going on here? What's the status of Hydra and who is in charge?

In Ant-Man, some Hydra members come to buy Cross' suit. However, Age of Ultron and Agents of S.H.I.E.L.D. stated that Hydra is in disarray, with all of the top ranking members either dead or imprisoned. So who are the Hydra members in the film? Who sent them?  Additionally, Cross states this:     We're anticipating 15 billion   How could Hydra afford to pay that much?


Some files are compressed using their own compression scheme and some aren't.  If I try Max compression on an already compressed file, I'll get 1%-2% better compression at most.  The amount of time wasted compressing those files are worthless.  I want 7zip to use the Store or Fast level of compression instead of Max for those already compressed files, while using Max on the uncompressed files.  I can do this if I go into the directory and make 2 different 7z files for multiple different kinds of file types stored in that folder.  But is there a way to store these differently compressed files inside the same 7zip file?  The files that aren't already compressed will be compressed and the ones that are will just be stored.  Has anybody found a way to do that?

Is there any way to selectively prevent certain file types from compression in 7-zip, like in WinRAR?  I'm trying to compress a huge folder (many gigabytes), and I don't want the already-compressed files (e.g. ZIP files) to be re-compressed -- they should be stored without compression.


So I got bored one weekend so I thought I would make a login system in python. I then realized if I wanted to reuse the accounts I made I had to store the account details locally. I realized I had to use some sort of encryption. I looked around for what is best for passwords and I chose to use use a SHA512 hash(I know it isn't encryption, but still). Now a few weeks later I discover about SHA3. I hear this is more secure so implement it in my code. Reading on the tutorial on the SHA3 module I am using to add SHA3 to my code, I see there is such thing as SHAKE. With searching all I can find is Weed growing forums. So I want to know:  What is Shake? Is it like a SHA hash?  Is there an algorithm that is used to make hashes? Or are hashes made some other way?

defines 2 functions, SHAKE128 and SHAKE256, as extendable-output functions (XOFs) that can have variable output length. But in Appendix A.2 marks:     it is possible to use an XOF as a hash function by   selecting a fixed output length. However, XOFs have the potential for generating related   outputs—a property that designers of security applications/protocols/systems may not expect of   hash functions   Later it describes a theoretical use case (and explicitly discourage such uses):     For example, a naïve (and non-approved) way   for two parties to agree to derive a 112-bit Triple DES key from a message designated as keymaterial would be to compute SHAKE128(keymaterial, keylength), where keylength is 112.   However, if an attacker is able to induce one of the parties to use a different value for keylength, say 168 bits, but the same value for keymaterial   So what is the use case for these functions? Is there any reasonable use case where these functions should be used instead of standard (fixed-size output functions) SHA-3 functions?


Does anybody know how I can read all the files in a specific folder and use the filenames in my LaTeX document?  I want to automatically create a seating chart with the fotos in a folder.

Assume I have many TeX files. For the sake of simplicity, also asssume they are in a single folder or directory.  I want to input all files from within my main LaTeX document. Actually I can create a list of those files using C# in advance.  To enrich my view about LaTeX or TeX, could you tell me whether or not this job can be done only by using pure TeX or LaTeX?


Consider you have the following text:  yada yada  yada yada 1 ;   <Hello.There>yada:EGHKJHKG, Source:QWEKGHGHJGKGHJKGHJKVMVNMVMVMVMVMVMVMBTDFHG, </Hello.There> yada2 yada3   I want to be able to take the information after Source: and before , only.  I've managed to do it with this  , and matched the source value My regex expression is: <Hello.There>.+Source:(.+?),\s*</Hello.There>  My python code is:  match = re.match(r'<Hello.There>.+Source:(.+?),\s*</Hello.There> I get None for match after this line, any ideas? (I tried many more regex options without success)

What is the difference between the search() and match() functions in the ?  I've read the  (), but I never seem to remember it.  I keep having to look it up and re-learn it.  I'm hoping that someone will answer it clearly with examples so that (perhaps) it will stick in my head.  Or at least I'll have a better place to return with my question and it will take less time to re-learn it.


I have 2 different height divs side by side:   .box {       color: white;       display: inline-block;       }        #box-a {         background-color: black;         height: 90px;         width: 100px;        }         #box-b {         background-color: blue;         height: 50px;         width: 100px;        }

 div a

 div b

    Now I want something like this  and no matter how hard I have tried and researched I can't get it to work.

I have a div with two images and an h1. All of them need to be vertically aligned within the div, next to each other. One of the images needs to be absolute positioned within the div. What is the CSS needed for this to work on all common browsers?

testing...


Given $X_{n}\sim N(\sin(n\pi),1)$, how could we prove $X_{n}=O_{p}(1)$? Thanks!

If $X_{n}\sim N(\sin(\pi n),1)$, then how do I show $X_{n} = O_{p}(1)$? $X_{n} = O_{p}(1)$ means that for every $\epsilon$, there exists an $M$ such that $\sup_{n} P(|X_{n}|>M)<\epsilon$. I am trying to fix an $M$ in terms of $\epsilon$, but I'm not sure what choice would make sense given the oscillating sine wave. Thank you.


Can you use prepared statements with a * and ORDER BY?  Because I can't figure out how to do it. I've been trying for awhile now. I've looked at a few other threads but haven't found out how. If not, how could I go about getting a mysqli query like this and prevent sql-injection?  Would appreciate any ideas or critiques.  Thanks, Matt  <?php     require ($_SERVER['DOCUMENT_ROOT'].'/db-connect.php');     $conn = new mysqli($servername, $username, $password, $dbname);     if ($conn->connect_error) {                     die("Connection failed: " . $conn->connect_error);     }      if ($stmt = $conn->prepare("SELECT * FROM websites ORDER BY ? DESC LIMIT 1")){     $id = 'id';      $stmt->bind_param('s',$id);      $stmt->execute();      $stmt->store_result();      $result = $stmt->get_result();      $row = $result->fetch_assoc();      echo $row['title'];       $stmt->free_result();      $stmt->close();      }  $conn->close();  ?>

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


I had an old Ubuntu installation (version 13), which had a partitioned drive, with /home mounted on a partition, and /data on another partition which I used to store my files. I wanted to install Ubuntu 14.04, but I accidently clicked on the "Erase entire disk" option, and now the old partitions are gone. I didn't proceed with the installation, so I except it to be recoverable. How can I recover what I had on /data?  Note that unlike a , I'm not sure what filesystem /data was. It could have been NTFS, but more probably it was ext4.  Thanks.

I had Ubuntu 14.04 LTS installed on my Laptop. After a while I had some troubles starting it up. I decided to reinstall Ubuntu.  I had 3 ntfs partitions, 2 ext3 partitions the mount point for the first was / and for the second was ./local and a swap partition. During the reinstallation I chose the option: "erase Ubuntu 14.04 and reinstall".  During the reinstallation the power cut off. After it worked again I turned my laptop on to try to restart the installation process. I couldn't find any options other than:   Erase disk and install Ubuntu Something else   When I chose Something else I couldn't see my partitions. Instead I found this:  Device                         Type     Mount point     Format?     Size      Used     System     /dev/mapper/ubuntu--vg-root  /dev/mapper/ubuntu--vg-root   ext4                                 631381 MB unknown  Linux device-mapper (linear)(631.4 GB) /dev/mapper/ubuntu-vg-swap_1  /dev/mapper/ubuntu-vg-swap_1  swap                                 8493 MB   unknown /dev/sda  /dev/sda1                     ext2                                 254 MB    27 MB  /dev/sda5                                                          639877 MB unknown   At the Testdisk phase I have this:


The sample covariance is defined as $\hat{\sigma}_{xy}:=\frac1{n-1} \sum_{i=1}^n (x_i -\bar{x})(y_i-\bar{y})$. What is the intuition for using the correction term $n-1$ instead of $n-2$. Because we have estimated $\bar{x}$ and $\bar{y}$, my intuition is that we lose two degrees of freedom.

The denominator of the (unbiased) variance estimator is $n-1$ as there are $n$ observations and only one parameter is being estimated.  $$ \mathbb{V}\left(X\right)=\frac{\sum_{i=1}^{n}\left(X_{i}-\overline{X}\right)^{2}}{n-1} $$  By the same token I wonder why shouldn't the denominator of covariance be $n-2$ when two parameters are being estimated?  $$ \mathbb{Cov}\left(X, Y\right)=\frac{\sum_{i=1}^{n}\left(X_{i}-\overline{X}\right)\left(Y_{i}-\overline{Y}\right)}{n-1} $$


I'm looking for a book where outcasts from Earth settle on some planet and eventually form seven or so guilds/families/kingdoms/nations. Each nation was known for some special trait. One nation could regenerate almost any wound. Another nation was of spies and could go invisible (?). One nation controlled time to an extent... etc. The name of the book was something like 'outcast' but not that word, only a similar word.

I read a book 10+ years ago where the world was ruled by various factions, each one had a special ability of some sort. The main characters faction had regenerative ability. Another faction had the ability to speed up or slow down time. I am not sure of the plot, but I know at one point he is injured so badly he starts growing a clone which he attempts to kill, but comes back later in the story.    Any ideas?


I wonder why the circle on the top has weird outline. My zoom is set to 100%. I am working in CMYK color mode and this is my settings.

I'm trying to make a document with one color black  (c:0,m:0,y:0,k:100) background with red text on it. However in CMYK the text has this weird grey white-ish edge. In RGB it doesn't show but in CMYK it shows. I'm wondering will this show when printing or do I need to use different methods? ie. using rich black etc.  Here's the RGB and CMYK comparison


I am installing Ubuntu and I want to do it on "free space" on my disk, but I don't know how.  This is what I have:   Please help me to figure this out.

I'd like to see the full How-To on how to use manual partitioning during Ubuntu installation. The existing guides (at least those I found here) cover only automatic part and leave untouched the manual part (or extremely short and contain no pictures).  I'd like to cover such situations:     If your disk contains other systems: