For a projectile projected at a certain angle from horizontal, at the highest point its speed is not equal to zero that means only a part of its initial kinetic energy is utilized to raise the potential energy of earth-body system. Here is the derivation of escape speed that is given in my book:  Initial K.E. imparted to body to escape earth's gravitation is given by       $\frac{1}{2}mv^2 = \frac{GM}{R} $ (Here all letters have there usual meaning)  But in case of projectile, only a part of its initial K.E. is utilized.it means that escape speed for a projectile projected at an angle with horizontal should be more than escape speed calculated from above formula.But my book says that escape speed is independent of angle of projection.Why is it so?

Q: The escape velocity for a body projected vertically upwards from the surface of earth is 11 km/s. If the body is projected at an angle of $45^\circ$ with vertical, the escape velocity will be?   My Approach:  The new vertical velocity will be $u * \sin(45^\circ)$ = $u /\sqrt2$  Calculating expression for escape velocity:  $$\frac{1}{2} mv^2 = \frac{GMm}{r}$$ $$\frac{1}{4} mu^2 = \frac{GMm}{r}$$ $$u = 2\sqrt\frac{GMm}{r}$$  Hence the new escape velocity = $\sqrt2 * 11$km/s.  However, the Correct Answer is 11km/s.


Lets say we have a delegate  public delegate void MyEventHandler(string x);   and an event handler  public event MyEventHandler Something;   we add multiple events..  for(int x = 0; x <10; x++)   {    this.Something += HandleSomething; }   My question is .. how would one remove all methods from the eventhandler presuming one doesn't know its been added 10 (or more or less) times?

Take the following C# class:  c1 {  event EventHandler someEvent; }   If there are a lot of subscriptions to c1's someEvent event and I want to clear them all, what is the best way to achieve this? Also consider that subscriptions to this event could be/are lambdas/anonymous delegates.  Currently my solution is to add a ResetSubscriptions() method to c1 that sets someEvent to null. I don't know if this has any unseen consequences.


There's a Stack Exchange website that provides a lot of value to me, but they are at a situation which, in my opinion, the 5:10 reputation ratio is not fair because providing an answer is much more difficult than asking a good question.     Moreover, specific tags are even less populated by answerers and perhaps getting more reputation would motivate them. Maybe it would be a good idea to let the website administrators tune the number of reputation that people get rewarded for a question upvote in proportion to bonus for getting an answer upvoted?

A recent question on  reminded me that there is a  about awarding 10 rep per question upvote. This is mainly due to the relative difficulty and usefulness of asking/answering being different on the site (or appearing to be, at least).  The highly voted answer on PPCG is "Yes, we should do that," but it's been well over three years since it was posted. The answer there said that (at least at that time) meta.so had this implemented already, so it wouldn't/shouldn't be hard to do.  Given that it's been quite some time, I don't know if that's (still) true. I know that meat has undergone changes since then, but as long as I've been actively participating, meta.se (and meta.so before the split) has given 5 points per question upvote, not 10.  My question is: What would the process to change it look like? It's been discussed on meta.ppcg and agreed upon, so what's the next step? Or is it not feasible at all?


I found this javascript regex to validate the different format the US phone numbers can be written. But it has problem: it fails to match the second rule in this group:     The first group of three digits, know as area code start with a number   2–9, followed by 0–8, and then any third digit.   It accepts 9 whereas it should only accept numbers from (0-8). This regex show it all:   /^(1[- .]?)?(\([2-9]\d{2}\)[. -]?|[2-9]\d{2}[. -]?)[2-9]\d{2}[- .]?\d{4}$/gm

I'm trying to put together a comprehensive regex to validate phone numbers. Ideally it would handle international formats, but it must handle US formats, including the following:   1-234-567-8901 1-234-567-8901 x1234 1-234-567-8901 ext1234 1 (234) 567-8901 1.234.567.8901 1/234/567/8901 12345678901   I'll answer with my current attempt, but I'm hoping somebody has something better and/or more elegant.


I see questions  and , but does not answer on how to do the money transfer from India to USA. For USA to India transfer there are many websites/and Bank.   I left India about 25+ years ago and has been always sending money. Now I may get some money from parental properties( after sibling distribution and if left any thing for me), but what I remember India was a one way street for money transfer, one can send money there but cannot bring money from India as government controls it. So I am looking for tools that can help me bring it legally and does not take too much time( like visiting government offices/bank multiple times). As Time is money.

My daughter is a US Citizen. We (parents)are also planning to permanently settle in US. We will go their as Permanent Resident,as per US Law. We have a house here in India worth Rs.2 Crores.  We want to sell it and take money with us. We have ordinary savings Bank account here in India.  My US Citizen Daughter is a Income Tax payer.  Now your advises are required as under:   What are the routes to take money from India to US and our tax liabilities Can I gift this whole amount to my US Citizen Daughter or what is the maximum limit of Gift amount.  What will be the tax liability on me and on my Daughter in case of Gift   Whether I have to show it in my Income Tax Return or in my Daughter's Tax Return. What US Income Tax Laws says. What will be the procedure to send money as Gift to my Daughter. Will the money will go directly from my Bank Act.to my Daughter's Bank Account. Will there will be wire transfer from bank to bank Can I send money through other money sender Certified Companies also.    Please advise. If there is something more on the subject to make me understand, please advise. Thanks,


I was checking the following Euler's theorem exercise:     What are the possible remainders when the $110^{th}$ power of an integer is divided by $121$?   I've started working from calculating $\phi (110) = 40$  Now I'm thinking about applying $\mod 121$ but I'm unable to. So now I'm maybe in the wrong way. Any help or clue will be really appreciated.

How do I efficiently compute $a^b\bmod c$:  When $b$ is huge, for instance $5^{844325}\bmod 21$? When $b$ is less than $c$ but it would still be a lot of work to multiply $a$ by itself $b$ times, for instance $5^{69}\bmod 101$? When $(a,c)\ne1$, for instance $6^{103}\bmod 14$?  Are there any other tricks for evaluating exponents in modular arithmetic?  This is being asked in an effort to cut down on duplicates, see  and .


While reviewing suggested edits, I can across one for  which, as the tag wiki currently states, is clearly the result of a typo.  There are no questions tagged with this, and the tag edit was approved nullifying my attempt to disapprove it.  Neither is there any way to flag the edit for moderator attention.  Is there a way for this to be removed, and if so, could somebody with sufficient power do so?

If a tag wiki becomes inaccessible due to a tag being eliminated, is the data destroyed? Or would it be able to be recovered by just recreating the tag?  On Gaming we had one tag for a particularly difficult case that a wiki entry was written for. There has been some debate as to what we should keep the tag as, which has led to the only instance of the tag being renamed a few times and eventually left on a new tag. The nightly script eventually cleaned out the original tag, and the wiki is inaccessible. So would I be able to retrieve this by reverting to the original tag, or is a rewrite of the wiki necessary?


Assuming that you can't reach the internet nor reboot the machine, how can I recover from  chmod -x chmod   ?

Today I was told a tale by a Unix trainer where the root password got leaked to the students, and one of the fellas removed the execute permission from /usr/bin/chmod itself. How do you recover chmod in this case and make it executable again? Let's say getting it from an external source or recompiling it is not a preferable option, is there some smart hack that can recover this chmod itself?   Note that this happened a long time ago and I'm not looking for a solution for some current problem, just curious about what ways Unix provides us around such an issue.


Example:  Public class a<T> where T: containsStatic {     public void func()     {         T.StaticMethod();     }  }   Is it possible? And if not is there another way to do it?  EDIT:  it gives me the error: "'T' is a type parameter, which is not valid in the current context." why is that? is there a way to fix this?

I was hoping to do something like this, but it appears to be illegal in C#: public Collection MethodThatFetchesSomething<T>()     where T : SomeBaseClass {     return T.StaticMethodOnSomeBaseClassThatReturnsCollection(); }  I get a compile-time error:  'T' is a 'type parameter', which is not valid in the given context.  Given a generic type parameter, how can I call a static method on the generic class?  The static method has to be available, given the constraint.


I installed kali on my acer predator helios 300 alongside Windows 10. I couldn't get past the login screen because it gets stuck after entering the credentials. So I googled it and found the issue was with some graphic drivers and so I ctrl+alt+f2 ed at the login screen and got a terminal. My sources.list file  was like this  #deb cdrom:[Debian GNU/Linux 2018.4 _Kali-rolling -  Official Snapshot amd64 LIVE/INSTALL Binary 20181016-16:07] kali-last-snapshot contrib main non-free #This system was installed using small removable media #(e.g. netinst, live or single CD). The matching "deb cdrom" #entries were disabled at the end of the installation process #For information about how to configure apt package sources #see the sources.list(5) manual   So I added this line to the sources.list file to update apt and install Nvidia drivers.  deb http://http.kali.org/kali/dists/kali-rolling main contrib non-free   And when I run apt-get update it says  Ign:1 http://http.kali.org/kali/dists/kali-rolling main InRelease Err:2 http://http.kali.org/kali/dists/kali-rolling main Release  404 Not Found [IP: 192.99.200.113 80] Reading package lists... Done E: The repository 'http://http.kali.org/kali/dists/kali-rolling main Release' does not have a release file. N: Updating from suck a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.

root@Kali:~# echo -e "deb http://http.kali.org/kali sana main non-free contrib\ndeb http://security.kali.org/kali-security/ sana/updates main contrib non-free" > /etc/apt/sources.list  root@Kali:~# apt-get update  Ign:1 h t t p : / / http . kali . org/kali sana InRelease                                      Err:2 h t t p : / / http . kali . org/kali sana Release                                          404  Not Found [IP: 192.99.200.113 80] Ign:3 h t t p : / / http . kali . org/kali-security sana/updates InRelease Err:4 h t t p : / / http . kali . org/kali-security sana/updates Release   404  Not Found [IP: 192.99.200.113 80] Reading package lists... Done  E: The repository 'http://http.kali.org/kali sana Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://security.kali.org/kali-security sana/updates Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. root@Kali:~# apt-get update --fix-missing  Ign:1 h t t p : / / http . kali . org/kali sana InRelease                                      Ign:2 h t t p : / / http . kali . org/kali-security sana/updates InRelease                 Err:3 h t t p : / / http . kali . org/kali sana Release   404  Not Found [IP: 192.99.200.113 80] Err:4 h t t p : / / http . kali . org/kali-security sana/updates Release   404  Not Found [IP: 192.99.200.113 80] Reading package lists... Done E: The repository 'h t t p : / / http . kali . org/kali sana Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'h t t p : / / security . kali . org / kali-security sana/updates Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.  root@Kali:~# apt-get install tor Reading package lists... Done Building dependency tree         Reading state information... Done  Package tor 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 'tor' has no installation candidate


So is it possible? what is the simplest way to do this at this point, booth using the App store but also when installing pacakes through the terminal? thanks for the help, also i am on ubuntu 19.10

I have 2 HDD drives in my computer. At the moment second drive is mounted as /media/storage.  How can I move my user data from /home to /media/storage/home?  Can I just move the data over there and then simply symlink it back?


I have recently learned of the Monty Hall problem, where given three doors, you choose one with a 1/3 probability of choosing the correct door, and then switching to the other door changing the probability of choosing the correct door to 1/2. I am confused because wouldn't staying at the same door have an equal probability at 1/2 because by staying at that door you are effectively choosing that door in the smaller sample space?  Thanks for the help!

I was watching the movie 21 yesterday, and in the first 15 minutes or so the main character is in a classroom, being asked a "trick" question (in the sense that the teacher believes that he'll get the wrong answer) which revolves around theoretical probability.  The question goes a little something like this (I'm paraphrasing, but the numbers are all exact):  You're on a game show, and you're given three doors. Behind one of the doors is a brand new car, behind the other two are donkeys. With each door you have a $1/3$ chance of winning. Which door would you pick?  The character picks A, as the odds are all equally in his favor.  The teacher then opens door C, revealing a donkey to be behind there, and asks him if he would like to change his choice. At this point he also explains that most people change their choices out of fear; paranoia; emotion and such.  The character does change his answer to B, but because (according to the movie), the odds are now in favor of door B with a $1/3$ chance of winning if door A is picked and $2/3$ if door B is picked.  What I don't understand is how removing the final door increases the odds of winning if door B is picked only. Surely the split should be 50/50 now, as removal of the final door tells you nothing about the first two?  I assume that I'm wrong; as I'd really like to think that they wouldn't make a movie that's so mathematically incorrect, but I just can't seem to understand why this is the case.  So, if anyone could tell me whether I'm right; or if not explain why, I would be extremely grateful.


Is there any rule that regulates the word order in the negative infinitive form? If the infinitive follows certain verbs in a sentence, it's clear that it should be 'not+to+inf'. For example, We decided not to go to Paris. But in some dictionary explanations we can see a different word order: to + not+inf. Are these patterns interchangeable?

There is something that I often I meet in English.  It is the use of "to not", and I'm not sure about its correctness since I'm not a native English  speaker. For example:      I brought it to you in order to not give it to her.        He came from this way in order to not see you.   Is it correct to speak like that in English?


The Devil's Tongue trait from SCAG states:  Devil's Tongue. You know the vicious mockery cantrip. When you reach 3rd level, you can cast the charm person spell as a 2nd-level spell once with this trait. When you reach 5th level, you can cast the enthrall spell once with this trait. You must finish a long rest to cast these spells once again with this trait. Charisma is your spellcasting ability for them. [...]  It's pretty clear that the trait enables the Tiefling to cast the two later spells from the trait once per long rest without using spell slots (due to it saying with this trait, instead of with a spell slot). My Question My question is, could the Tiefling, who is also a Sorcerer, cast them using spell slots during the rest of the adventuring day? Questions I am not asking  I'm not asking "Can I cast a spell that isn't on my class' spell list?".  The general rule is that characters only have access to spells on their spell lists. The Devil's Tongue trait adds a specific rule that says you can cast this spell with this trait (which means you have access to it despite it not necessarily being on your class' spell list). This question is the next logical step, given that you have access to this spell from  can you also cast it using your class' spell slots?   I'm also not asking "Do I have to use spell slots to cast these spells?"  As mentioned in my question I regard this as obvious that you can

A 10th level Drow warlock (for instance) has the following Drow Magic racial trait (PHB p. 24), in addition to its warlock spellcasting abilities:  You know the dancing lights cantrip. When you reach 3rd level, you can cast the faerie fire spell once per day. When you reach 5th level, you can also cast the darkness spell once per day. Charisma is your spellcasting ability for these spells.  Can the Drow warlock cast faerie fire (which is not on the warlock spell list) using a warlock spell slot? Can it cast darkness (which is on the warlock spell list) using a warlock spell slot?  The  says this about the Magic Initiate feat:  If you’re a spellcaster, can you pick your own class when you gain the Magic Initiate feat? Yes, the feat doesn’t say you can’t. For example, if you’re a wizard and gain the Magic Initiate feat, you can choose wizard and thereby learn two more wizard cantrips and another 1st-level wizard spell. If you have spell slots, can you use them to cast the 1st-level spell you learn with the Magic Initiate feat? Yes, but only if the class you pick for the feat is one of your classes. For example, if you pick sorcerer and you are a sorcerer, the Spellcasting feature for that class tells you that you can use your spell slots to cast the sorcerer spells you know, so you can use your spell slots to cast the 1st-level sorcerer spell you learn from Magic Initiate. Similarly, if you are a wizard and pick that class for the feat, you learn a 1st-level wizard spell, which you could add to your spellbook and subsequently prepare.  But this specifically requires you to pick the feat for one of your classes to be able to cast the spell learnt using your class spell slots, and does not seem directly applicable. A Warlock can use warlock Pact Magic spell slots to cast spells learnt from levels of another spellcasting class, per the multiclass spellcasting rules (PHB p. 164):  If you have both the Spellcasting class feature and the Pact Magic class feature from the warlock class, you can use the spell slots you gain from the Pact Magic feature to cast spells you know or have prepared from classes with the Spellcasting class feature, and you can use the spell slots you gain from the Spellcasting class feature to cast warlock spells you know.  Similarly, if the warlock has learnt the invocation Mask of Many Faces (PHB p. 112)...  You can cast disguise self at will, without expending a spell slot.  ...Can the warlock cast disguise self using a spell slot, e.g. to decrease the chance it can be dispelled?


I'd like to legend only certain curves but \addlegendentry add an entry for each curve, in sequence.  \documentclass{article} \usepackage{tikz,pgfplots}  \begin{document} \begin{tikzpicture}   \begin{axis}[xmin=0,xmax=5]     \addplot {x};     \addplot {x^2};     \addlegendentry{square};   \end{axis} \end{tikzpicture}  \end{document}   How can I skip the legend for the first curve so that only the x^2 curve gets the "square" label.

In order to fill the area between two complex curves I use tables and the vertcat command (see ).   Now I don't want the plotted area to appear in my legend, just the two curves. Is there any command to prevent the yellow area plot from being added to my legend?  this could be a minimal example:  \documentclass{article} \usepackage{pgfplots}  \begin{document} \begin{tikzpicture}   \begin{axis}[area style,axis on top]     \addplot+[mark=none,fill=yellow,draw=none] {0.1*x^2} \closedcycle;     \addplot[mark=none,draw=red,line legend] {0.1*x^2};     \addplot[mark=none,draw=blue,line legend] {0.0*x^2};     \legend{red curve,blue curve};     % \legend{\empty,red curve,blue curve};   \end{axis} \end{tikzpicture} \end{document}   With this legend{...}-command the last plot is skipped, an additional \empty doesn't help, too.  Sadly, drawing the first to plots together with fill=yellow,draw=red is not an option for me. Does anybody know any inside hacks? As far as I know, there is no command shown in the manual. Thanks in advance.


Learning about joins and I understand the difference in what inner joins and left joins do,  returns rows when there is a match in both tables, and left join returns all rows from the left table, even if there are no matches in the right table. I get that. however in this example i am following along with, how they make the join confuses me: select * from person join car on person.car_id = car.car_id;  gives me every person in the db that has a car_id value that isnt null. select * from person left join car on car.car_id = person.car_id;  gives me every person in the db, regardless including those with a null car_id value; what I dont get, are why these two statements are identical (apart from the left join) but these two values are inversed: inner join: car on person.car_id = car.car_id; left join: car on car.car_id = person.car_id; can someone offer me a clear explanation as to why these statements are swapped about in the inner and left joins?

Also how do LEFT JOIN, RIGHT JOIN and FULL JOIN fit in?


You can check the form .Click on the for 1 button . There is validation for submitting it blank but I am not able to add validation for email. When I get the email validation working it just stops after the first input. I have tried a lot of ways but there seems to be some contradiction I am creating.

Is there a regular expression to validate an email address in JavaScript?


I'm a Linux newbie.  I partitioned my HDD and managed to install Ubuntu 15.04 along with my pre-installed Windows 8.1, but when I tried it, it kept crashing and restarting by itself, so I decided to uninstall it to try a different distribution.   I basically deleted the partitions required for Ubuntu (home, swap and root) from Windows, but when I restarted the computer I couldn't boot Windows any more. All I can see is the GRUB2 prompt, and I have no idea how to boot Windows.   Is there something I can do to use my laptop once again? Do I have to reinstall Windows, or can I boot the old OS and access the partition?

I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows.  How do I remove Ubuntu and reinstall Windows?    Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot.


I found a bug (or probably: unimplemented behaviour) in how the touchpad operates in GNOME 3. I'd like to report it in the appropriate channels (or at least check if it's already reported), but I have no idea with software is responsible for its behaviour. Who knows?  Note that I do not want to report an Ubuntu-specific bug, as described in , and the Wiki page  also does not describe which package is appropriate for the touchpad handling.

I found a problem with an application on Ubuntu.   Questions :   How do I best report the issue?  What sort of information should I provide?


Let $A$ is a commutative ring with $1$ and $a$, $b$ are the elements of $A$ such that $a+b=1$ and there is some $n>0$ , $(ab)^n=0$. Prove: $(1)=(a^n)+ (b^n)$.    I would say it's kind of easy one, but somehow I got stuck on it too long. Please help me !

Possible Duplicate:          On  it's a stated fact that if $I$ and $J$ are coprime ideals of a ring $A$, then $I^k$ and $J^\ell$ are also coprime for any integers $k,\ell$.   There's no proof given. Why is this fact true?


EDIT: Originally I used the title "How do I find the Target of a MS-Office shortcut?" but have since changed it as the problem is not specific to MS-Office shortcuts.  I have MSOffice 2010 OneNote installed, the shortcut in the Start menu has the following properties:    As you can see the Target information is generic and the Find Target button is greyed out.   How do I find the file the shortcut is pointing to?  EDIT: I was looking for the Target of the shortcut so I could use it with one of the "Favourite" keys on my Microsoft keyboard. However, in getting caught up in wanting to find the location of the Target I forgot that I could just set the favourite to point to this shortcut, not the executable.  Although that solves my issue it still leaves we wanting to know how to find the location of the Target files in Advertised shortcuts.

Usually on Windows XP, if I wanted to know the location of an installed program, I would just click 'Properties' and it would show where the executable is located.  On Windows 7, I do the same thing and I get this:    How can I find out where programs are located based on the shortcut? I did however notice that for some programs it does show a shortcut under the 'Target', but not in the case with iTunes for example.


My email address was sold a while ago so I get a lot of junk mail.  I try to delete it and unsubscribe but some of it remains.  Recently, messages such as the image below have started appearing on my calendar.  Does this mean that I have a virus or that someone is accessing my iCloud account?  A while ago my email name changed without my knowledge leading to some interesting times!  is this related possibly?  Does anyone have suggestions on what this is, how to fix it, or how to prevent this in the future?

Today I've suddenly received spam calendar invitation for $19.99 Ray Ban sunglasses (never subscribed, checked, searched or visited any related site, so clearly spam) and it has other visible email accounts within the invitation. I'm wondering if I should be worried whether my accounts been compromised or a simple email from anywhere just plops this in my calendar without review. Questions to be answered:  What should I check/setup in order to make sure my iCloud account is safe? How can I delete this invitation without sending a notification to the sender, so as to prevent them from knowing my email address is live? How can I prevent these notifications in the future?  Here's an image:


If it was per unit length, I'd understand, but apparently it is a constant of the whole line.   Consider if I change the length of the transmission line, the impedance of the whole thing should increase since more power is dissipated, but the characteristic impedance doesn't change. So, what exactly is the characteristic impedance?

I am a licensed radio amateur, and find bewildering the many different explanations, which range from folksy urban myth to Maxwell-Heaviside Equations, of what happens at the termination of a transmission line or feeder. I realise that they all come to the same thing in the end (or should do, pun perfect), but none of them give me a gut feeling for what is going on.  I like diagrams, so an answer in terms of (graphical) phasors for the currents and voltages at the load would suit me best. How, for instance, does a step pulse down the line cause twice the voltage at an open circuit termination? Similarly for current at a short circuit. And how is the reflected step generated by the inductance and capacitance of the line?  Can anyone help, without getting all mathematical, and not telling any "lies to children"?


I want to assign a case record type to System Administrator. When I try to do this I get the error:      Please fix the following:      Permission Subscribe to Dashboards: Send to Groups and Roles depends   on permission(s): Subscribe to Dashboards   I can't change these settings because it's a standard profile. Is there any way around this?

When I try to change field access on System Admin profile I gets the following error      Please fix the following:      Permission Subscribe to Dashboards: Add Recipients depends on   permission(s): Subscribe to Dashboards   What should I change in the admin profile so that I can edit this profile without any problems?  I will only add that this field is not editable in the profile


I would like to do the equal of  net view /all   followed by  nslookup COMPUTERNAME   in a oneliner rendering something like  \\COMPUTERNAME1      192.168.1.1 \\COMPUTERNAME2      192.168.1.2   Can I? Or do I really need to script it like it's done ?

I know there is a single line of a command and its arguments that can help display all computer IP addresses (those that are being used) on a LAN, and my computer is also a client, as one of those displayed, but I forgot. What is it?


My income is too high to contribute to a Roth IRA, so my only choice is a Traditional IRA.  Is there some way I can in 2019 convert my 2018 Traditional IRA contributions into a Roth IRA? And then do that each year thereafter with the previous year's contributions?

Our household MAGI (Modified Adjusted Gross Income) does not allow us to contribute the full amount to a Roth IRA for 2010. In that case is converting some part of Traditional IRA to Roth to complete the gap, a good idea? Do the income restrictions only apply to direct contributions and not to conversions for the Roth IRA?   I know that we cannot claim any tax deductions for the contribution to a traditional IRA (due to MAGI limits), and that is okay with me. But, since I have already been adding post tax dollars to the traditional IRA, will I be taxed again if I convert it to a Roth IRA?


There is my source code.  \documentclass[conference]{IEEEtran} \usepackage{algorithm}  \usepackage{algorithmic}  %\usepackage{algpseudocode}   \usepackage[algcompatible]{algpseudocode} \usepackage{amsmath}  \begin{document} \begin{algorithm}[!b]       \caption{algorithm 1}       \label{alg}       \begin{algorithmic}[1]         \Require           INFORMATION         \Ensure           Model;         \STATE CALCULATE         \STATE END         \RETURN MODEL     \end{algorithmic}   \end{algorithm}  \end{document}   When I compile it, it looks like this. No matter what I modified the content, the zero is always there.

Can you suggest me what is wrong with using return command in algorithms. when I add  \RETURN $C   to my LaTeX document I get   return C =0,   what I need is just return C.  \begin{algorithm}                      % enter the algorithm environment   \caption{ lloyd's kmeans}         \label{alg1}                             \begin{algorithmic}[1]                    % enter the algorithmienvironment     \RETURN{$C$}   \end{algorithmic} \end{algorithm}   I get two extra characters =0. I wonder where its coming from. if it helps,there is  "Missing number, treated as zero",and  Missing = inserted for \ifnum. in the error log generated


I was wondering if a matrix $A$ can be PD, but still have complex eigenvalues (with nonzero imaginary part).  I know for example that any symmetric/Hermitian matrix has real eigenvalues, but for example $A=\begin{pmatrix} 1 & 1\\0 &1\end{pmatrix}$ is neither, yet is positive definite.   From linear algebra I also know that the following statements are equaivalent:  1) $A$ is PD if $z^TAz>0 \;\forall z \neq 0$.  2) $A$ is PD, then all eigenvalues $\lambda_i>0$.  3) $A$ is PD, then $z^TAz>cz^Tz$ for some $c>0$.  I'm mostly concerned abou the second statement, so if it would possible for a PD matrix to have complex eigenvalues, how does this relate to $\lambda>0$? Are we only considering the real part?   At this point I am wondering if these statements are even true for the complex case, since in classes you usually see examples like $z^TAz = c_1z_1^2+c_2z_2^2$, (considering some $A\in\mathbb{R}^{2\times 2}$) where $c_1$ and $c_2$ are some positive constants. This however works only for real $z$, since if for example $z = [i\quad 0]^T$, this argument already breaks down.  Looking at for example Wikipedia seems not very helpful, since this only considers Hermitian/symmetric matrices, which I am specifically not interested in.   Summarising  I am interested in the possibilities of having PD matrices with complex eigenvalues. I am not particularly interested in a simple yes or no (even though this would be a great starting point), but more in what the consequences of such a situation are. How does this relate to the above statements? Do I oversee some principles ideas which even contradict this being possible?

I found out that there exist positive definite matrices that are non-symmetric, and I know that symmetric positive definite matrices have positive eigenvalues.  Does this hold for non-symmetric matrices as well?


How can I prove by induction that $3^n ≥ 1 + 2^n$ for every $n\in\mathbb{N}$?

Use the PMI to prove the following for all natural numbers: $3^n ≥ 1+2^n$. I have already verified the base case but am having trouble doing so with the inductive case. Thanks!


"Would you give my extra points to whoever needs them the most?"  Should   whoever  be whomever?  My "opponent" in this discussion is using grammatical terms that I find unique.

On the subject of "whoever" and "whomever", I was reading this but I am still confused:   What is the correct use of whoever/whomever in the following sentence?     I like your copy, congratulations, whoever is writing it.   Whoever? Whomever?   Is there a difference between US and UK English?


Can someone tell me what this stamp means?

I am from Myanmar. I was on my way to Venice from Brussels while holding Schengen visa (single entry). I bought a British Airways ticket to fly from Brussels to Venice. Unfortunately, on that day, all BA flights from Brussels were canceled. British Airway's customer service centre told me to go to from Brussels to London by train, where I could catch my flight to Venice. I took a taxi to Bruxelles-Midi train station and bought a ticket to London. A Brussels immigration officer inspected and approved my passport.   Then I had to to through UK Border Immigration. There, they said I can't enter to get my flight. Although I explained the situation with the airline and made clear of my destination (I already reserved my hotels in Venice, Switzerland and France as described in my travel itinerary), they detained me for some hours and also took my fingerprints on paper and photo.   They asked questions concerned about my finances and gave me a refusal letter for not having a transit visa. So I had to re-enter Brussels where the immigration officer put the below stamp in my passport. As I had a single entry Schengen visa, I had to buy another airline ticket to Venice and complete my Europe trip.   What do the stamps below mean on my passport?   Can they affect me and, if so, how and why, when I apply for another Schengen visa?


I was wondering what the order of the group $Aut(Z_{p^a} \times Z_{p^b})$ is, where $p$ is prime and $a $ and $b$ are natural numbers, eventually equal. I had found a way on internet that was using matrices, but it looks like I cannot find that topic anymore, and I think I hadn't really understood that explanation, could someone please explain how to count them?  By the way, it seems that using matrices is the best option (as I clearly remember the explanation I had found wasn't very long and looked like it didn't require many calculations), but couldn't I just calculate how many  "good" possibilities there are? I mean, I would send the generator of $Z_{p^b}$ in another element of order $p^b$, then the generator of $Z_{p^a}$ in another element of order $p^a$. The problem is that the cyclic subroups generated by the images of the generators must have a trivial intersection. So I was hoping to find how many choices I had for the second generator, but here it gets tricky and I don't know how to proceed, how to count how many "good" choices I have.  Thanks for the help

Suppose I have $G = Z_{p^m} \times Z_{p^n}$ for $m, n$ distinct natural numbers and $p$ a prime. Is there a combinatorial way to determine the number of automorphisms of $G$?


Brother HL-L2305w Laser Printer for CUPS OS: Ubuntu 20.04.2 LTS, 64 bit GNOME: 3.36.8 Used linux-brprinter-installer-2.2.2-2 to install drivers. Printer and laptop are connected to the same WiFi SSID network. Test prints can be made directly from the printer but not from the laptop. Note: This printer was previously connected to a Windows machine and one test print indicates that the Windows drivers are still installed. $ avahi-discover Browsing domain 'local' on -1.-1 ... Browsing for services of type '_http._tcp' in domain 'local' on 3.0 ... Browsing for services of type '_ipp._tcp' in domain 'local' on 3.0 ... Browsing for services of type '_printer._tcp' in domain 'local' on 3.0 ... Browsing for services of type '_pdl-datastream._tcp' in domain 'local' on 3.0 ... Found service 'Brother HL-L2305 series' of type '_http._tcp' in domain 'local' on 3.0. Found service 'Brother HL-L2305 series' of type '_ipp._tcp' in domain 'local' on 3.0. Found service 'Brother HL-L2305 series' of type '_printer._tcp' in domain 'local' on 3.0. Found service 'Brother HL-L2305 series' of type '_pdl-datastream._tcp' in domain 'local' on 3.0.  $ avahi-browse -rt _ipp._tcp +   wlo1 IPv4 Brother HL-L2305 series                       Internet Printer     local Failed to resolve service 'Brother HL-L2305 series' of type '_ipp._tcp' in domain 'local': Timeout reached  Recent dmesg:   are the results of running the various commands suggested in  troubleshooting guide. It seems that the laptop and printer cannot "see" each other so printing from the laptop is not possible. Solutions?

I have 2 printers on a home WiFi network that are accessed by 2 desktops running Windows. I have a new laptop on which I am learning/trying Ubuntu 14.04.  How do I configure things to access these printers from the laptop?  There seems to be a lot of jargon that I don't understand or find confusing.  Step-by-step instructions would be helpful.


Note - To avoid duplication, I have referred the related .  Many a time, it happens that I put milk on the stove and forget about it while doing other work. So, milk always boils over. What can be done to prevent the milk overflowing the pan?

Many recipes call for first bringing milk up to boil.  I normally boil 1 quart (1 litre) of milk in a 3-quart stainless steel heavy bottomed pan:   use low heat keep scraping the bottom of the pan every 1-2 minute  Milk comes to a boil in about 40-45 minutes   In spite of my carefully watching the milk, at the end, when I pour of the milk, I see a "crust" form on the pan. This makes cleaning up a pain.  Further, it is hard to constantly watch and scrape the milk every 1-2 minutes.  Is there a more convenient way to bring milk up to a boil?  Looking for:   Unattended, fool-proof method Easy clean-up at the end.   Yes, I am aware of this other question:      However, my question is a bit different.


When I signed up, I gave my desired screen name in the place where John Doe was used as an example. Instead of that name, I got the wimpy user70330 instead.    How can I fix this?

How can I change (or remove / reset ) my name on a site in Stack Exchange network?


I have a database table that has the column and types defined. But it's a database table. I need a feature class so I can add spatial functionality, like add a SHAPE field. How do I create a feature class from a database table?  Update - I'm starting from a database table. The destination is an existing feature class in my enterprise SDE. I need to take some fields from the table and build a value for a SHAPE field. I also need to be able to use my fieldmappings to map fields from the source to the destination; hence the need to get this data into a feature class instead of a table.

Is there a way in ArcPy to create an empty polygon geodatabase feature class that will acquire the schema of a geodatabase table?  I know that it's possible in ArcCatalog (New -> Feature Class and then import all the fields from a table) but I wonder if it can be written in a Python script.  The CreateFeatureclass_management tool allows only Feature Layers as schema templates.


Does native iOS app uninstaller really remove all the data and footprints from the device, or should a person use some app cleaners like on OS X. I am wondering if leftovers cause any decrease in speed over time.

I'm trying to delete a few old apps from my iPhone but the best I can do is hide them. Does anyone know of a way to completely and fully delete the apps?  Thanks


What is the simplest solution to measure entire internet traffic at home? I have several computers connected to Internet via D-Link DIR-615.

I'm interested in finding a free piece of software for Windows XP & 7 that allows us to measure both incoming and outgoing internet traffic, but not traffic between users of the local network.  I live in a shared household with three others, and we're interested to see which of us is using the largest amount of our monthly internet quota. We're all happy to install the necessary software.  Any suggestions?


I have pages in path try/* and I would like to redirect to node/20. I tried path auto but using * is not allowed, I have to specify one by one.  Is there any module or way to redirect try/* to node/20

I have old links, for example the following ones.   index.php/event/nr1 index.php/event/nr2   If users are coming on index.php/event/*, they should be redirected to  /event.  How can I achieve this?


I am wondering why/how Stack Overflow is so fast.     "Stack Overflow is a programming Q & A site that's free. ... And fast. Very, very fast."   -

In the "About" section of SO, it says that it is "Fast. Very, very fast."  What is it that makes it so fast? DB? MVC? What?


I have submitted a paper and I received a request for major revisions.   The first time the status changed from "under review" to "with editor".  After that I submitted a revised version of the paper. Now the status has changed from "under review" to "required reviews completed".    Why first time it wasn't shown this status?  How many days does it usually take to change the status from "required reviews completed" to next status?

What steps does a manuscript typically go through from submission to publication (or rejection) in a typical journal? How are these steps referred to, in particular by editorial systems, and how long do they each typically take?  Note that this question is about the typical situation and hence not about:   Journals with an atypical workflow, e.g. those that allow for an instantaneous reviewer–author interaction. Exceptional steps or rare occurrences such as withdrawal or .   This is a canonical question on this topic as per . Due to its nature, it is rather broad and not exemplary for a regular question on this site. Please feel free to improve this question.


I accidentally signed out of my account and when I type in my details for Google it will take me to a page where there are Pokemon staring at me and it says, our servers are humbled etc. Why am I unable to sign back into the application?

Pokemon GO isn't working at all for me right now. I'm in one of the following circumstances and can't do anything:   My game is displaying a "Try Again" message I'm stuck on the Loading Screen When I sign in I get a message that the servers are experiencing problems. I see the map but nothing is loaded, and my team color is wrong The "loading" Pokeball just ends up spinning and I can't catch or interact with things When I try to catch a Pokemon, the Pokeball just sits on my screen doing nothing Gym opponents will drop to 1 HP and won't take any more damage or attack When I open a pokestop, the pokestop image and the name of the pokestop does not load.   What's causing this? Is there a way to fix it?


I intend to travel to Oslo next month from India to present a paper at an academic conference. The University won't pay me for this. Given that Norway doesn't have a provision for Conference Visa, should I apply for a Business Visa under short-term Visitor's visa? Should I specify the purpose of travel as 'Business' or 'Other', given that I am attending an academic and not a business conference?

I am planning to travel to Portugal to attend an academic conference and in that regard needed a short-stay Schengen visa. The visa application has a field "Purpose of Travel" with the following options:   - Business - Sports - Cultural - Other - Study - Visiting family or friends - Medical reasons - Official visit - Transit - Airport transit - Tourism   I am attending the conference to present the research I am conducting as a part of my PhD. So "Study" is the closest in my opinion. But I don't want the Embassy to misconstrue that it is for studying at a university in Portugal. In that case, would "Business" be the right option to choose?


I am having trouble working out how second argument in this code 'beer' is being passed to the anonymous function inside makeAdjectifier.  nicerizer is a variable that stores makeAdjectifier as a value, but how does 'beer' end up being passed to the parameter string?  Many thanks.  function makeAdjectifier(adjective) {   return function (string) {          return adjective + ' ' + string;      }; }  var nicerizer = makeAdjectifier('nice');  console.log(nicerizer('beer'));  // prints nice beer.

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


Problem: Suppose $\Phi : \mathbb{R}_{>0} \to [0,1]$ satisfies $\Phi(s+t)=\Phi(t)\Phi(s)$ for all $s,t \in \mathbb{R}_{>0}$. How can be proven that $\Phi(t)=e^t$? Actually I do not know where to start.

This is part of a homework assignment for a real analysis course taught out of "Baby Rudin."  Just looking for a push in the right direction, not a full-blown solution.  We are to suppose that $f(x)f(y)=f(x+y)$ for all real x and y, and that f is continuous and not zero.  The first part of this question let me assume differentiability as well, and I was able to compose it with the natural log and take the derivative to prove that $f(x)=e^{cx}$ where c is a real constant.  I'm having a little more trouble only assuming continuity; I'm currently trying to prove that f is differentiable at zero, and hence all real numbers.  Is this an approach worth taking?


This might be a silly question but i really want to know the internals.This is one of small table just to test as below    I have create a table as above and 'name' column is primary key and clustered index so it has sort all words in alphabetical order . Now when i create a non clustered index on column 'number' , the rows in 'name' column not anymore in alphabetical order as below    My question is, the name column should remain the rows in alphabetical order rite since it has clustered index and how come it changed after i add non clustered index on different column? i m sure there might be certain things i missed.Please let me know.Thank you

I have a developer that would like, when doing a select statement with no order by, the rows in a table to be in the order they were inserted. The developer suggested changing from a clustered to non-clustered index.   By changing the index from clustered to non-clustered, does this make any guarantees about the order in which rows would appear in the table?  This question is mostly for my curiosity; I am going to suggest using an identity column instead, but this request got me thinking. Timestamp could be used but there is a chance rows can be inserted simultaneously.   Thanks in advance for your help.


I want to do a fresh install on my computer. I have an intel 64 bit CPU. I am wondering can I install this version: ubuntu-14.04.2-desktop-amd64.iso  I really want to install the 64 bit version. But the name contains amd, so I am not sure if it's compatible with my machine. Thank you!

My processor is an Intel Core 2 Duo P8600 (2.40GHz). As far as I know that's a 64-bit processor - I'm a bit confused as the architecture is called AMD 64, is this a generic name given to 64-bit architectures? I've heard of x64 but can't see a release labelled with this.


Let $a$, $b$ an element of $\mathbb{Z}$ with $a$ and $b$ not both zero and let $c$ be a nonzero integer. Prove that $$(ca,cb) = |c|(a,b)$$

I need to prove that $z\gcd(a,b)=\gcd(za,zb)$.    I tried a lot, for example, looking at set of common divisors of the two sides, but I can't conclude anything from that. Can you please give me some advice how I can handle this problem? And $a,b,z \in \mathbb{Z}$.


Can you have more than one co-advisor as well ? I yet have to check with my department but wanted to see the pros and cons of it.   I did read  but wanted to see if someone else has opinions as well ?

Are there any advantages or disadvantages in having two supervisors instead of one? Why would a graduate student want to do this or avoid this?  The context is in an MA where students usually have one supervisor and two committee members (examiners).


$010$ can be generated. If $s$ is a sequence which can be generated by these rules, then $01s, 10s, 0s1, 1s0, s01$, and $s10$ can all be generated.   *Prove, by induction, that in any sequence generated by these rules, there are more $0$'s than $1$'s.    PART 2 Again. consider sequences of $0$'s and $1$'s, this time generated according to the following rules: $10$ can be generated.  $01$ can be generated.  If $s$ is a sequence which can be generated by these rules, then $0s1$ and $1s0$ can be generated by these rules.  If $s$ is a sequence which can be generated by these rules, then the sequence $ss$ ($s$ followed by another copy of $s$) can be generated.  If $s$ is a sequence which can be generated by these rules, and $s$ is of the form $t00$ or $t11$ for some smaller sequence $t$, then $t$ itself can be generated.  Prove that no sequence with an odd length can be generated by these rules.

010 can we generated. If s is a sequence which can be generated by these rules, then 01s, 10s, 0s1, 1s0, s01, and s10 can all be generated.   -Prove (by induction?!) that in any sequence generated by these rules, there are more 0's than 1's   Without using the principle of induction my best guess was that rule 1 is the base case hence there will always be one 0 more than 1. The order in which the sequences are displayed do not matter because they just add one 0 and one 1 to the sequence s. BUT the question demands induction.. I can't see any other way to explain it rather than the way I just did.  PART 2 (if you're bored :p) Again, consider sequences of 0's and 1's, this time generated according to the following rules: 10 can be generated.  01 can be generated.  If s is a sequence which can be generated by these rules, then 0s1 and 1s0 can be generated by these rules.  If s is a sequence which can be generated by these rules, then the sequence ss (s followed by another copy of s) can be generated.  If s is a sequence which can be generated by these rules, and s is of the form t00 or t11 for some smaller sequence t, then t itself can be generated.  Prove that no sequence with an odd length can be generated by these rules.


I have a script like the following:  #!/bin/bash  declare -A aaa  while [ "$1" != "" ]; do         case "$1" in                 -e|--env)                         if [ ! "$2" == "" ] && [ ! "$3" == "" ]; then                         aaa[$2]="$3"                         fi                         shift                         shift                         shift                         ;;                 *)                         echo "Error"                         shift                         ;;         esac  done  for K in "${!aaa[@]}"; do         str="$str --build-arg $K=\"${aaa[$K]}\"" done  #echo $str  ./test_args.sh $str   It is called like:  ./multi_args.sh -e arg1 "Hello Man!" -e arg2 Bye   in the second script test_args.sh, I get the built string str and print the arguments.  test_args.sh:  #!/bin/bash  while [ "$1" != "" ]; do         echo "$1"         shift done   it supposed to printed like this:  arg1 Hello Man! arg2 Bye   but it prints:  arg1 Hello  Man! arg2 Bye

In bash one can escape arguments that contain whitespace.  foo "a string"   This also works for arguments to a command or function:  bar() {     foo "$@" }  bar "a string"   So far so good, but what if I want to manipulate the arguments before calling foo?  This does not work:  bar() {     for arg in "$@"     do         args="$args \"prefix $arg\""     done      # Everything looks good ...     echo $args      # ... but it isn't.     foo $args      # foo "$args" would just be silly }  bar a b c   So how do you build argument lists when the arguments contain whitespace?


While trying to install Docker with the command sudo apt install docker.io, I got the following error: $ sudo apt install docker.io  Reading package lists... Done Building dependency tree        Reading state information... Done The following additional packages will be installed:   cgroupfs-mount containerd pigz runc ubuntu-fan Suggested packages:   aufs-tools btrfs-progs debootstrap docker-doc rinse zfs-fuse | zfsutils The following NEW packages will be installed:   cgroupfs-mount containerd docker.io pigz runc ubuntu-fan 0 upgraded, 6 newly installed, 0 to remove and 49 not upgraded. 2 not fully installed or removed. Need to get 0 B/63.7 MB of archives. After this operation, 319 MB of additional disk space will be used. Do you want to continue? [Y/n]  debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable Setting up libpam0g:amd64 (1.1.8-3.6ubuntu2.18.04.2) ... debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error processing package libpam0g:amd64 (--configure):  installed libpam0g:amd64 package post-installation script subprocess returned error exit status 1 Errors were encountered while processing:  libpam0g:amd64 E: Sub-process /usr/bin/dpkg returned an error code (1)  How can I fix this and install Docker?

I'm trying to install the flashybrid but when I enter the apt-get install flashybrid command, I get this error:  root@user-desktop:/home/user# apt-get install flashybrid Reading package lists... Done Building dependency tree Reading state information... Done flashybrid is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 1 not fully installed or removed. After this operation, 0B of additional disk space will be used. debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable Setting up flashybrid (0.15+nmu2) ... debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error processing flashybrid (--configure): subprocess post-installation script returned error exit status 1 Errors were encountered while processing: flashybrid E: Sub-process /usr/bin/dpkg returned an error code (1)   I also tried this one to find what is already using that file:  root@user-desktop:/home/user# lsof | grep /var/cache/debconf/config.dat lsof: WARNING: can't stat() fuse.gvfs-fuse-daemon file system /home/user/.gvfs Output information may be incomplete. dpkg-prec 4672 root 4rW REG 8,6 39658 1697827 /var/cache/debconf/config.dat   But I don't know how to fix this.


The title says all. I tried several syntax, all failed. Maybe this is not possible with a single shoot... Of course, search engines didn't help, nor the manual that is difficult to understand, nor the info command. All lack an example with a range of "kind of" preselection

In a file with lots of lines I want to delete lines that starts with HERE IT IS.  How can I do this using only command-line tools?


Hey guys I am long time Windows user I love Ubuntu but I need help with installing Ubumtu on my ASUS Laptop I need someone walk me through it pherphas via Skype  I would really appreciate it   Specs I5 Processer  256 GB SSD  8 RAM Bluetooth 4.1  Wireless built in of course

I'm absolutely new to Linux. I would like to know how to install Ubuntu alongside the pre-installed Windows 8+ OS.  Should I do it with Wubi, or through the Live USB/DVD?  What steps do I need to take to correctly install Ubuntu?


** Definition: ** Let $ J_n = \{1,2,3, \ldots, n \} $. We say that a set is finite if its cardinality is equal to that of $ J_n $.  To demonstrate that I gave the following function. Let $ \varphi: \Bbb N ^ {J_n} \to \Bbb N ^ n $ defined as follows: for $ f \in \Bbb N ^ {J_n} $, let $$ \varphi (f) = (f (1), f (2), \ldots, f (n)). $$ I already proved that this function is bijective. But I'm getting a bit out of the exercise, and I want to know what the inverse of this function is, and how to get it out. Can someone help me with that?

Is the finite Cartesian Product of Countable sets countable?  If possible, could you give a bijection that would work for any example?  Any help would be appreciated.


A few days ago, I told my friend that I wanted to learn trigonometry by the end of $2018$. His immediate reply was that I should go on if I could solve this mathematics problem:      a and b, given that $a\text{ and } b \in \mathbb N$ and $\left( \left( a^2+b^2 \right) \div \left( ab+1 \right)\right) \in \mathbb N$, then prove that $\sqrt{\frac {\left( a^2+b^2 \right) }{ \left( ab+1 \right)}} \in \mathbb N$   Over the last few days, I went about trying to see if I could prove it. (My friend has a tendency to occasionally trick me with unsolvable math problems) this is what I proved:   If $a \text{ xor } b=0$, it works. If $b=a^3 \text{ and } a \neq 1$, it works. Besides $n=0$, $x^n=a \text{ and } x^{n+2}=b $will work   To recap, one number must be $2$ powers greater than the other (i.e. $32$ and $128$. [$2^5$ and $2^7$]).    Or, at least what I thought...    When I sent an email to him, he said that I missed 2 very seldom noticed things and that everyone he had ever asked the problem missed it.  Which either means he intentionally made the problem too hard for my intelligence ( which is -spoiler alert- very low, compared to you people), or he is just making fun of me for not noticing his problem is impossible. Either way, a plethora of mathematicial geniuses whom are much more experienced than me at algebra could solve this easily. Could someone tell me what I'm missing??  Thanks in advance.   (And DON'T tell my friend about this!!)

Let $a,b$ be positive integers.  When $$k = \frac{a^2 + b^2}{ab+1}$$ is an integer, it is a square.    Proof 1: (Ngô Bảo Châu): Rearrange to get $a^2-akb+b^2-k=0$, as a quadratic in $a$ this has two values: $a$ and $kb - a = (b^2-k)/a$. (The second root is determined in two different ways from the expansion $(x-r_1)(x-r_2) = x^2 - (r_1 + r_2)x + r_1 r_2$.)  Now suppose we have $a,b$ such that $k$ is an integer but not a square, by the investigation about roots we have that the second root is a nonzero integer since $k,b,a$ are integers and $k \not = b^2$, futhermore it is positive which is easily seen from its defining equation.  WLOG assume $a \ge b$ so that the second root is strictly smaller than $a$. This leads to a decent, replacing $a$ with the second root.    Proof 2 (Don Zagier): Apply reduction theory (specifically, Sätze 1 and 2 of Section 13 of my book on quadratic fields) to the quadratic form $x^2 + kxy + y^2$, which is the unique reduced quadratic form in its equivalence class.    Note that Proof 2 is pretty much the same as Proof 1 when written out in explicit detail, but I could not read Zagier's book because I cannot read German.  I would like to know more approaches to this and other alternative proofs of this result if possible! Thanks in advance.  I would also be interested in related problems (especially easier ones of a similar nature) and texts which cover the reduction theory in English.


I made a mistake and deleted a 6/7GB file on an external hard drive with NTFS and now I'm trying to undelete / recover it.  I tried with Recuva and the file is there but with filesize 0. it seems NTFS handles big files differently so I need a recovery software that knows how to deal with this, any tips?  Searching, I found this post:  that explains why big files in NTFS are deleted differently but offers no solution.  In case this is relevant (I see some recovery programs looking for signatures of files) the file was a truecrypt mounted disk, with extension .iso.  So, what's the solution?

I've accidentaly deleted outlook.pst (6.7GB) file, while there was only 400MB free space left on primary NTFS partition (winxp).  I've tried several recovery tools to get this file back. "Ontrack Easy Recovery Pro" found 0 pst files (complete scan mode), while "Recover My Files" in sector scan mode found 5 pst's, but 4 of them of sizes from 3 to 28 KB, while the 5th one - 1Gb.  I've managed to succesfuly recover 1Gb pst file, which was 1 year old copy (the one used after the latest windows reinstall).  Now, I'm frustrated and confused   Why 1 year old file was succesfuly recovered if there were only 400MB left on primary partition? Where's 6.7GB file gone? I did some reading (), and it seems that there's almost no probability to retrieve the file I'm looking for, but wait - none of recovery tools i've used found zero-sized pst file, moreover - if due to fragmentation a file might be corrupted - we could use scanpst.exe to fix some errors and survive with 10 or 100 emails missing - whatever. Could you please recommend some more sophisticated recovery tools for this particular task?   Appretiate your help - thanks in advance


when on the  page, I noticed that the drop-down was not functioning correctly. When selecting , the drop-down keeps showing Stack Overflow:    I noticed the same behavior for some other sites, but not all. Even some weird combinations show up:

In the , if I select any site in the site switcher it will be set as Stack Overflow or some random site in the drop down list's selected site name.  For the Stack Overflow, Super User, Server Fault and Meta Stack Exchange, the site switcher is set to the selected site name, but the remaining do not retain the selected site name. For English Language and Usage, it changes to Physical Fitness for some reason. All the others I've tried  switch to Stack Overflow.  It can be replicated in Chrome and Firefox.  GIF for the same:


Im creating a hotel reservation program.  I need to store the array which have the details into a txt file and load it afterwards when running the program again..  my data is not storing into the hotel array  public static void Write(String[] hotel){      //storing information of the array into a text file      Scanner sc=new Scanner(System.in);      System.out.println("");      System.out.print("Do you want to write the data to a file(y/n) - ");      String SaveTheFile=sc.nextLine();      if(SaveTheFile.equalsIgnoreCase("y")){                     try{              FileWriter file  = new FileWriter("Hotel.txt");              PrintWriter pr = new PrintWriter(file);              for(int x =1;x<=10;x++){              pr.println(+x+":"+hotel[x]+":");              }              pr.close();              System.out.println("Write Successful");              System.out.println("");              Menu(hotel);          } catch (IOException e) {              System.err.println("Error!!!");          }       }else if(SaveTheFile.equalsIgnoreCase("n")){      //if the user entered 'n' going back to menu          Menu(hotel);      }else{      //if the user entered any other, displaying an error message          System.err.println("Please Enter 'y' or 'n' !!!");          Write(hotel);      }    }  public static String[] Load(String[] hotel){     String line = null;     String numSt,name;     int num;      System.out.println("");     Scanner sc = new Scanner(System.in);     try {         FileReader fr = new FileReader("Hotel.txt");         BufferedReader br = new BufferedReader(fr);          String str;         while ((str = br.readLine()) != null) {             String[] token = line.split(":");                             numSt = token[0];                             name = token[1];                                                         num = Integer.parseInt(numSt);                                                             hotel[num]=name;           }         br.close();       } catch (IOException e) {         System.out.println("file not found");                                              }             catch (NullPointerException f) {         System.out.println("Null pointer here...");                      }             return hotel;      }   I found out the answer......          String line = "";         int counter = 0;          while ((line = br.readLine()) != null) {                             numSt = line.split(":")[0];                             name = line.split(":")[1];                                                       counter = Integer.parseInt(numSt);                                                             hotel[counter]=name;                             counter++;   Thank u for spending your valuable time for helping me to sort this out :)

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?


When I search for images on Google, mostly it gives results related to stock websites with watermarked images. I want these sites to be ignored when I perform a search—is there any possibility to do it?

I often Google Image Search for simple images to add to my blog. For example I just searched 'lots of coffee'.   However, for certain terms (like the aforementioned one) it produces a lot of results from stock image companies, that are all obnoxiously watermarked.   I'm not interested in paying for the stock images so I'd rather just not have those results show up.   Is there a google-hack I can do avoid these images?


I'm working on an assignment for my IB biology class and some assistance would be highly appreciated. I've read several articles and I still haven't quite gotten the answer I'm looking for. I have to write a one page summary on whether or not Mitochondrion are alive or not.

In , the subject of mitochondria is raised at 2:58. At 3:12, the narrator says "[mitochondria] are not alive any more: they are dead."  What currents of thought lead to this affirmation?  When I search for  on Google, I get many links about the role of mitochondria in cell death, but I don't see anywhere that the assertion in this video is discussed.


I'm running Android 4.2.1 and recently the Play Store app updated to version 4.8.20 and since then I'm facing icon issues within the store.    Click for larger version  As you can see, there's a weird black background for every app icon, this is the case for every page within play store, all the icons have this kind of background. I once tried un-installing Play Store updates and fell back to pre-installed version 4.1 of Play Store, which solved the icon issues (but left me with older version of Play Store). And obviously, the Play Store again updated itself to latest version and I again have same issue.  Note that there isn't any such problem on my different Android phone (which is running Android 4.2.2 but has same Play Store version, 4.8.20).  I've tried clearing Play Store cache, App Data, and as said earlier, uninstalling updates (which momentarily solves the problem), but nothing seems to solve the problem with this version of Play Store, only option I haven't tried is hard resetting my phone, which I want to avoid.  Is this a known bug with this version of Play Store? what are the options I have to fix this?

The past few days I have noticed that the Play Store icons have a black background. I've even done a Factory Reset. I am facing the problem with every icon in the play store. Is there any way to get rid of it?


I have an international flight with an extended stop (8hours) at DFW. Is it possible to add luggage during the layover?

A common desire among some travelers with long layovers is to leave the airport for a while, and perhaps do some shopping, or even buy goods in the airport.  But this then often necessitates the ability to check additional luggage during the layover, for the remainder of the journey.  There might be other reasons to want to check luggage mid-journey as well.  Are there any general rules one can use to determine whether this is an option in a given airport when traveling with a given airline, and the associated costs (when it is possible)?


In Star Wars Episode 1: The Phantom Menace, when Darth Maul kills Qui-Gon Jinn, Obi-Wan Kenobi starts a saber duel with Darth Maul, and Darth Maul uses Force Push on Obi-Wan Kenobi. Obi-Wan hangs on that deep and dark big pipe. Then, Darth Maul kicks Kenobi's lightsaber into that hole. After that, Obi-Wan uses Qui-Gon Jinn's lightsaber to defeat Darth maul.     My questions are   Where Is Obi-Wan's Lightsaber? Does he build a new one or retrieve it from somewhere like from bottom of that big pipe or etc.? What about Qui-Gon Jinn's lightsaber? Where it is ?

They thought the Sith were gone for a thousand years, yet one shows up and kills Qui-Gon Jinn. So how come they did not bother to search his body and find out as much as possible about him?  To forestall easy guesses, keep in mind there is on-going debate on whether Obi-Wan retrieved his lightsaber after the duel (the one he carries in later events is identical to the one in TPM).  I prefer canon answers, but good conjectures are usually great reads, so I won't discourage 'em.


I'm trying to learn about casts and how they work. I have this   (Defined in the Header file)  typedef struct {     int code;     char* name;     float concentration;     int quantity; } Farmacy;   In the .c file when I'm creating a new object when should I use:  Farmacy* f= malloc(sizeof(Farmacy));   or  Farmacy* f= (Farmacy*)malloc(sizeof(Farmacy));

In , someone suggested in a  that I should not cast the result of malloc. i.e., I should do this: int *sieve = malloc(sizeof(int) * length);  rather than: int *sieve = (int *) malloc(sizeof(int) * length);  Why would this be the case?


I use the following method to break the double loop in Python.  for word1 in buf1:     find = False     for word2 in buf2:         ...         if res == res1:             print "BINGO " + word1 + ":" + word2             find = True     if find:         break   Is there a better way to break the double loop?

Given the following code (that doesn't work):  while True:     #snip: print out current state     while True:         ok = get_input("Is this ok? (y/n)")         if ok.lower() == "y": break 2 #this doesn't work :(         if ok.lower() == "n": break     #do more processing with menus and stuff   Is there a way to make this work? Or do I have do one check to break out of the input loop, then another, more limited, check in the outside loop to break out all together if the user is satisfied?


We are trying to deliver a LAS file with NIR values added for each point.  The NIR comes from a raster captured at the same moment as the LiDAR, and is stored as an 8bit number along with RGB in 8bit.  We have brought this into FME and managed to import the RGB and NIR values into a LAS file, though in the transfer the RGB becomes 16bit and the NIR stays at 8bit.  However, when our customer views the LAS file (I think in GlobalMapper) they do not see the NIR values, though they see the field.  We tried bringing the LAS file into ArcMap and there we see RGB fields, but all values are 0 and no NIR field.  Wondering if this maybe has something to do with FME's LAS attribute being called color_red, colour_green, colour_blue and ESRI's attributes being called red, green, blue.  Nonetheless we don't see the NIR field in ArcMap but we know it is there if we look at the same file in either FME (displays all properly) or GlobalMapper (shows field but with 0 values).  Ultimately the client wants a CSV so we are trying to generate one from FME for the LAS file that has all the information we know FME can see, but so far having issues there as well.  Anyone have any advice on what is needed to get NIR values into a LAS file that something other than FME can see?

Is there any tool available for extracting the X, Y and Z coordinates from a .las file and exporting them to a .csv or similar file?


This question may not apply to most people on Photo.SE, but my question is directed towards those who have an undergraduate degree in photography or a closely related field:   What experience as part of photography school do you feel you could not have acquired without having gone to school? Could you imagine an idea you were impressed upon in school that others who have not been to school for photography would have missed? Lastly, considering the ubiquity of photographic wisdom on the web, do you feel in hindsight formal school was a worthy investment?

What do students learn in a photography degree that they can't learn by themselves? Most amateur photographers (and many, many pros) are self taught.  A bit of reading, experimentation, practice, practice, practice, and reflection goes along way in photography education. Does a photography degree just fast track you through the initial stages of the learning curve, or do you get something extra?  I guess that access to expert criticism is major part of photo school, which certainly can't be self taught, but what else does the formally educated photographer learn that is difficult to pick up on your own?  I hope this doesn't sound like I am anyway dismissive of going to school, I'm just curious.


Suppose G is a group with x and y as elements. Show that $(xy)^2 = x^2 y^2$ if and only if x and y commute.  My very basic thought is that we expand such that $xxyy = xxyy$, then multiply each side by $x^{-1}$ and $y^{-1}$, such that $x^{-1} y^{-1} xxyy = xxyy x^{-1}$ , and therefore $xy=xy$.  I realize that this looks like a disproportionate amount of work for such a simple step, but that is what past instruction has looked like and that is perhaps why I am confused. Moreover, "if and only if" clauses have always been tricky for me since I took Foundations of Math years ago, but if I remember correctly, the goal here should be to basically do the proof from right to left and then left to right, so to speak. Anyhow, I think that I am overthinking this problem.

Prove that if in a group $(ab)^2= a^2 b^2$ then the group is commutative.  I am having a hard time doing this. Here is what I have so far: Proof:  $a^2 b^2= a^1 a^1 b^1 b^1$ =$aa^{-1}bb$ =ebb Hence,$aa^{-1}=e$  I am stuck, I do not know if this is the right process in proving this


I have to prove that the harmonic sum: $$\sum_{n=1}^\infty \frac1n$$   converges when we remove all the terms $\frac1n$ where the decimal expansion of $n$ contains the digit $9$.  I have a hint but don't know how to use it; how many terms of at most $k$ digits are there?

I know that the harmonic series $1 + \frac12 + \frac13 + \frac14 + \cdots$ diverges. I also know that the sum of the inverse of prime numbers $\frac12 + \frac13 + \frac15 + \frac17 + \frac1{11} + \cdots$ diverges too, even if really slowly since it's $O(\log \log n)$.  But I think I read that if we consider the numbers whose decimal representation does not have a certain digit (say, 7) and sum the inverse of these numbers, the sum is finite (usually between 19 and 20, it depends from the missing digit). Does anybody know the result, and some way to prove that the sum is finite?


How many 5-card poker hands are there containing at least 3 of the 4 suits? There are 52 cards in a deck and 13 cards of each suit.  Please check over my work and point me in the right direction for the last 2 parts.   The first card can be any suit (out of 4) and any card (out of 13). So 4 × 13. The second card be be any suit (now out of 3) and any card (out of 13). So 3 × 13. The third card be be any suit (now out of 2) and any card (out of 13). So 2 × 13. I don't know how to find the possibilities for the fourth and fifth card.

How many 5-cards poker hands are there containing at least 3 of the 4 suits?  I don't how know how to properly handle this question.  There 13 ranks of each card, and 4 suits  My Attempt:  Begin with the first 3: C(13,3) X 4 ways to choose suits  Then pick last 3 cards of anything:  C(49,2)  My solution: 1,345,344  Thanks,


I recently went on holiday to Japan for 3 weeks. I knew my passport was getting close to expiry, but my trip was entirely within the validity period, and I read that Japan didn't have minimum validity requirements ().  I got through immigration with no worries. I looked at my landing permission sticker and was mildly interested to note that the 90-day period of stay ended exactly when my passport expired - clearly they'd just cut down the period to match my passport validity. Except they didn't. I checked my partner's sticker and it had exactly the same period as mine, and she has years left on her passport. By sheer luck, I had exactly 90 days left on my passport.  Not that I ever intend on doing this again, but I was wondering what would have happened if I had less than 90 days on my passport? Would the period match my passport validity, or would something else happen?

I'm planning to travel to Japan and I just realised my passport will have less than six months validity at the time I travel.  I know some countries require at least 6 months validity for entry. Is this likely to be a problem for Japan?  (As an Australian citizen I don't require a visa for short term tourist entry)


Does "–" between methods and documenting have any function in this sentence? What is it trying to say?     Moreover, multi-lingual texts, like vernacular works, have traditionally had strong affinities with realist methods – documenting speech forms as they are spoken – but avant-garde, musical, parodic, sci-fi, psychic-interiorist, artificial/invented, machine, and digital multilingual works have also long followed non- and anti-realist logics.

I generally know how to use a hyphen, but when should I use an en-dash (–) instead of an em-dash, or when should I use a hyphen (-) instead of an em-dash (—)?


I've tried setting $p^{\dfrac 1k}= \dfrac a b$, and then raising $p^{\dfrac 1k}$ to the $k^\text{th}$ power, but I'm stuck.


Would particles behave the same way as a satellite orbiting earth, only far more compact and rapid correlating to the gravitational force of the black hole?

Black hole theory involves space (or space-time), itself, being sucked into the black-hole, with the event horizon marking the point at which space/space-time is moving faster than the speed of light. I find it really hard to picture how this could be happening while objects maintained a reasonable stable orbit around black holes. If we take the stars that orbit the super massive black hole at the centre of the Milky Way, the orbital dynamics are used to calculate the mass of the black hole, in the normal way. In other words not taking account of the fact space is rushing at some speed inwards toward the black-hole.  I appreciate I'm missing some knowledge here. That's the motivation for asking the question.


Let $\phi$ be a misurable function in [0,1] such that the linear trasformation $A\colon f\to \phi*f$ maps $L^2[0,1]$ in $L^2[0,1]$.Prove that $\phi\in L^{\infty}[0,1]$. Calculate t e norm of the operator A. When A is surjectiv,invertible,the inverse of A is continous?

If $\psi:[a,b]\to\mathbb C$ is a (measurable) function such that $\psi h$ is in $L^2[a,b]$ for all $h\in L^2[a,b]$, then must $\psi$ be essentially bounded?  The converse direction is clear: If $\psi$ is essentially bounded, then $\|\psi h\|_2\leq \|\psi\|_\infty\|h\|_2$ for all $h\in L^2$, and thus the multiplication operator $M_\psi:h\mapsto \psi h$ is defined and bounded.  The question here is whether, without prior assumptions on $\psi$, simply having $M_\psi(L^2)\subseteq L^2$ implies that $\psi$ is bounded.


I killed the Wall of Flesh, he dropped the Breaker Blade and the Sorcerer Emblem but didn't drop the Pwnhammer and I'm still in normal mode, not in HARDMODE. Can anyone help me and what can I do?

What items do I need to make my world Hard Mode?


I am aware of he uniform distribution density function however I am not entirely sure how I would find out the distribution of X.  Thanks very much, any help or hints in the right direction would be gladly appreciated.

For $X$ and $Y$ random variables; $X$ follows the uniform distribution.  (1): if $Y=-\log X$  (2): then it can be shown that $-\log X$ is distributed as $\exp(1)$ {i.e. exponential with mean 1}.  Why is this so? Intuitively statement (2) make sense to me. But i'd like a mathematical proof.  -Probably wrong working:  (1) seems to imply $\exp(-Y) = X$ (which is like saying $X$ is exponentially distributed, which is a contradiction, since its actually uniform!); or is it incorrect for me to do this since $X$ and $Y$ are random variables?  Ultimately how do I prove (2)?  Thanks


I have a professor that pulls slides from the internet to fill his lectures. He does occasionally attribute the slides to the original author (in class, not on the slide itself) but the majority of the time his slides are either scans from a book with zero attribution or slides that can easily be found on Google with either a text or image search, again, with no attribution. His latest homework assignment is copied directly from another college's . He is not a good educator in any sense of the word and seems to be teaching just to fulfill a teaching requirement. He comes to class, reads from his notes for 2 hours and leaves. If anyone has a question in class, he repeats what he just said and tells the person to read the book. While I obviously can't say for sure that he does not have permission from the content creators to use their lecture material without attribution, his in-class behavior lead me (and others I've spoken to in the class) to believe that is not the case. Is this the kind of thing that should be brought to an administrators attention or should I just keep my head low and deal with another bad professor?

I have a professor at my university who uses content from an un-cited textbook that he has never referenced anywhere, including his green sheet (syllabus), as an additional resource. At least some slides he has used include parts of content that have been re-worded and others that are 100% the same. I noticed this by Googling for textbooks on the material we're studying in class and found that examples given in one that I found were exactly the same as what he has provided.  Would this technically be plagiarism? Should he be given the benefit of the doubt in this situation?


So far, I'm actually pleased with Unity in 14.04. My only issue is the AppMenu.   And no, I'm not talking about the Unity launcher. I'm talking about the top panel's global menu.  Is there a way to remove the autohide function?  And I don't want to see any comments related to CCSM- The option doesn't exist in 14.04.  Thoughts?

Will there be a way to disable auto-hide behavior of global application menu in Unity. While I would prefer to have this behavior disabled by default (as it is bad UX), it looks like it's here to stay, so I'm wondering if, as a user, I will be able to turn it off.


Clarification: while this question is very much related to other questions regarding Windows 10, it also covers specific aspects relating to using Parallels Desktop. These aspects are not covered in other questions; therefore, this question is not a duplicate.  I have Windows 7 Ultimate running on my Mac (OS X 10.10.4) via Parallels Desktop 10.2.0.  I want to upgrade to Windows 10, but I don't seem to have the upgrade icon in the system tray. I've run Windows Update multiple times, but no joy. I've also tried everything at  and at .  I can confirm that GWX.exe is present in C:\WINDOWS\System32, but when I try to run it (either via the command line or through the GUI) nothing happens.  What should I try next? I'm confident I've tried all the standard troubleshooting steps for this, so is there perhaps something about Parallels that means the upgrade process will work differently?

I want to get Windows 10, but I do not see this icon in the notification area (tray):    How do I get the icon to get Windows 10?


I'm looking for a way of execute command which I can execute some command only under sub directory not command affect to current directory. find -name ":RUN" -exec rm -rf {} \;  If I got a directory name is level0 which has sub directory the name is level1. and I run the above example command at level0 directory then not only level1 directory but also level0 affected by command. How do I handle with that command only affect to level1 directory at level0 execute?

I am using the find command of bash, and I am trying to understand it since it is part of a code that I am using. In the code, the command in question is -   find -L $RAW_DIR -mindepth 2 -maxdepth 2 -name "*.bam" -o -name "*.sam" | wc -l  I have been trying to understand this command by searching its components. In esence, I thinking it is trying to find the number of files that end with .bam or .sam. I think -maxdepth 2 means to search for these files in this folder and its immediate subfolder.  What I do not understand is what mindepth -2 does in this case. I looked up mindepth, and the explanation given everywhere is -  "Do not apply any tests or actions at levels less than levels (a non-negative integer). '-mindepth 1' means process all files except the command line arguments."  To me this explanation is not very clear. Just like maxdepth -2means search for subfolders upto a depth of 2, what does mindepth -2 correspondingly mean, in simple language?  Also, if mindepth is just the opposite of maxdepth in terms of the direction (which would make intuitive sense), then how do I understand the fact that executing the command above on a folder that does have a .bam file leads to the output  0, whereas omitting the mindepth part of the command leads to the output 1 ?


I want every string inside $this->translate('') or $this->translate(""), I've come up with    grep -oe "\$this\->translate(\(['\"].*['\"]\))" -r dir/path   but this is bringing results like   $this->translate('Something?').'\');">'.$this->translate('Something else')   Each translate should be shown in separate lines. I tried using non-greedy/lazy but didn't work out.  Input samples  $this->translate('Something?').'\');">'.$this->translate('Something else') <?= $this->translate('random text');?>   Expected output  Something Something else random text   Any thoughts?

I am trying to extract a value from a long string that may change over time. So for example the string could look something like this  ....../filename-1.9.0.3.tar.gz"<....   And what I want to extract is the value between filename- and .tar.gz, essentially the file version (1.9.0.3 in this case). The reason I need to do it this way is because I may later run the command and the value will be 1.9.0.6 or 2.0.0.2 or something entirely different.  How can I do this? I'm currently only using grep, but I wouldn't mind using other utilities such as sed or awk or cut or whatever. To be perfectly clear, I need to extract only the file version part of the string, since it is very long (on both sides) everything else needs to be cut out somehow.


Yes, I know that there are tons of solutions of this up here, but I, essentially, wanted to try it a different way and ah, well.  Let $|G| = p^2$ for some prime $p$.  Consider $x \in G$. So, $|x| = p, $ or $ p^2$. If it is the latter, then, we are done.  So, if $|x|= p$, then, let, $H = [h|  h=x^i, i \in Z] \Rightarrow |H|= p$.  As $p$ is the smallest prime dividing $|G|$, $H$ is a normal subgroup.  Now, consider some $y \in G$, but not in $H \Rightarrow y^p= e$. Then, its easy to show that $G = \langle x,y \rangle$.  Now, consider a homomorphism $f:G \rightarrow \operatorname{Aut}(H), g \to c_g $, wherein $c_g$ represents conjugacy by $g$. So, for example, $c_g(x) = gx g^{-1}$.  Then, it is clear that, $H \subset \operatorname{Ker}(f) $, as it is cyclic and therefore abelian. So, we need only look at $G/H$.  Basically, I am asking for a hint as to why $c_y(x) = yxy^{-1} = x = c_e(x)$, where $x$ and $y$ are the generators of $H$ and $G/H$, respectively?  Because, if I establish it for the generators, then it follows that it applies for for all elements, i.e, that $\operatorname{Im}(f)$ is trivial and therefore that $G$ is abelian.  Thank You!

I have a group $G$ with $p^2$ elements, where $p$ is a prime number. Some (potentially) useful preliminary information I have is that there are exactly $p+1$ subgroups with $p$ elements, and with that I was able to show $G$ has a normal subgroup $N$ with $p$ elements.   My problem is showing that $G$ is abelian, and I would be glad if someone could show me how.   I had two potential approaches in mind and I would prefer if one of these were used (especially the second one).   First: The center $Z(G)$ is a normal subgroup of $G$ so by Langrange's theorem, if $Z(G)$ has anything other than the identity, it's size is either $p$ or $p^2$. If $p^2$ then $Z(G)=G$ and we are done. If $Z(G)=p$ then the quotient group of $G$ factored out by $Z(G)$ has $p$ elements, so it is cylic and I can prove from there that this implies $G$ is abelian. So can we show theres something other than the identity in the center of $G$?  Second: I list out the elements of some other subgroup $H$ with $p$ elements such that the intersection of $H$ and $N$ is only the identity (if any more, due to prime order the intersected elements would generate the entire subgroups). Let $N$ be generated by $a$ and $H$ be generated by $b$. We can show $NK= G$, i.e every element in G can be wrriten like $a^k b^l $. So for this method, we just need to show $ab=ba$ (remember, these are not general elements in the set, but the generators of $N$ and $H$).   Do any of these methods seem viable? I understand one can give very strong theorems using Sylow theorems and related facts, but I am looking for an elementary solution (no Sylow theorems, facts about p-groups, centrailzers) but definitions of centres and normalizers is fine.


In Windows, when adjusting ClearType text, following the option to turn on/off ClearType & ensuring the monitor is set to native resolution, one is supposed to follow 5 steps. I've already tried various combinations but none of them yielded the satisfying result. While the 3rd step makes the user choose between subpixel or grey-scale rendering (I think), I'm wondering what exactly other steps do?

I noticed that there are many posts on Super User about , but none seems to address the question I have.  I am on Windows 7 and I find fonts very fuzzy. To be specific, some letters are more fuzzy than others, and it's not specific to the letters, it's more about positioning. If I move my Windows to a slightly different position, then different sets of letters are fuzzy.  I tried to do the ClearType tuning, but I can't find a selection that looks sharp. I tried to turn off ClearType altogether, but it gets worse. I turn off antialiasing in systemspropertiesperformance.exe and it doesn't help much.  My prior experience is with Windows XP. And fonts look fine there. I think I prefer having jagged edges over anti-aliasing. Trying to round the edges just makes my eye sore.  I'm using a 17 inch monitor, 1280x1024. My friends who are also on Windows 7 using laptops still have fuzzy fonts, but they are a lot better. I think it's because their resolution is much higher with respect to their screen sizes.  EDIT: Interestingly the problem might not be font settings after all. I screenshot the text, same thing also happens to the screenshot!! Even though some letter are still fuzzier than others. I should hook the monitor up to a computer with Windows XP to check again.  EDIT2: Same monitor on Windows XP looks fine. Comparing text screenshots made in Windows XP and Windows 7 on Windows XP I do find Windows 7 fonts fuzzier than one on Windows XP. However, even when viewing screenshot from Windows XP on Windows 7, it looks very fuzzy! And this is specific to Windows 7 since I'm using the same monitor.  EDIT3: Problem solved. Posted under Bobince's reply. Thank you all. :)


In RoTS, Ani just wanted to 'save Padmé's life'. When he met Obi-Wan on Mustafar, he truly believed that he was in the right and that his friends were the traitors to the Republic (thanks to Palpatine's exquisite web of manipulation). So, after he harmed/killed so many beings, why didn't he figure out that something was dreadfully wrong and Palpatine was just seeking personal power? Was it that after discovering the power that came with the dark side he became addicted/wanted power for himself?

In the prequels, the primary reason Anakin was willing to become  is because he wanted to save Padmé;     ANAKIN: I will do whatever you ask.       PALPATINE: Good.       ANAKIN: Just help me save Padme's life. I can't live without her. If she dies, I don't know what I will do.      PALPATINE: To cheat death is a power only one has achieved, but if we work together, I know we can discover the secret.       ANAKIN kneels before PALPATINE.       ANAKIN: I pledge myself to your teachings. To the ways of the Sith.   Given that he didn't manage to save her, why did he still become a Sith?


I would like to insert multiple rows into table, but value of each row will be got from subquery.  Here is pseudo code what do I want:  INSERT INTO Entries VALUES                 (                     @Date,                     (SELECT Users.ID                      FROM Users),                     @Enter,                     @Leave                 )   Where Users has multiple rows of course.  How can I do it?

I'm trying to write a query that extracts and transforms data from a table and then insert those data into another table. Yes, this is a data warehousing query and I'm doing it in MS Access. So basically I want some query like this:  INSERT INTO Table2(LongIntColumn2, CurrencyColumn2) VALUES   (SELECT LongIntColumn1, Avg(CurrencyColumn) as CurrencyColumn1 FROM Table1 GROUP BY LongIntColumn1);   I tried but get a syntax error message.  What would you do if you want to do this?


I'm trying to create a rolled up . I thought I could use the cloth simulator and run a physics animation to make a subdivided mesh roll itself up but I couldn't get it to work. Everything I tried just resulted in a cloth that was bent in lots of different directions.  So then I thought maybe I could run an animation to make the mesh roll itself around a cylinder. I guess for this to work I'd need to be able to pin the mesh to the cylinder, and then animate the cylinder rotating a few times. I guess I can rotate the cylinder by creating keyframes with 0 degrees of rotation then say 10 * 360 degrees rotation. But how can I parent one end of the mesh to the cylinder in the first place?  Or is there a better way to do this?  I'd also like to be able to have the corners of the mat slightly curled up when it's flat (e.g.  but less pronounced) which makes me think perhaps physics is the way to go after all?

Currently I am working on an animation that requires a scroll opening up. I added a Curve Modifier with a spiral curve to both parts of the scroll mesh, then I added another Curve Modifier with another curve to the mesh. The result is this when it's only a bit open (good):    The result is this when it's halfway opened (bad):    How would I keep the wrapped-up part to stay circular like in the first image? Thanks in advance!


my camera (Nikon D3200) taken black pictures even if the room is light enough. I have it on manual mode, if i turn on flash it takes perfectly fine pictures. also if i put it on auto mode it takes black pictures, only normal ones with flash. I tried to change aperture, shutter speed and ISO but nothing works. Help!! I tried changing the settings but nothing helps

I'm having an issue with my Canon 6D. Whenever I shoot photos inside my house they turn out so grainy! I've tried turning the ISO down but anything lower than 6400 and my photos are basically black. Mind you this is mid-day, lots of light in our house, and yet the ISO on my camera will not go below 6400 and it is making my photos look terrible because they are grainy instead of sharp! Please help!!  Lens is 24 - 105mm f4.0. I shot at 24mm, f5.0, shutter 1/160th, ISO 6400 (this is on auto, but only because anything lower I set it at makes the photos black!).  I'm still kind of new to this, but I do understand ISO, aperture, and shutter speed need to be in certain places for light to come in!