The four dot animation is endlessly running after Android 6 update in Nexus 5.

Last day I got the notification to download and install official Android 6.0 Marshmallow in my Nexus 5, which is not rooted, was running Android 5.1.1 and no custom ROM. As I downloaded and installed it, from that point its gone to boot loop state (the four dot animation is endlessly running).  I have already searched the web for solution like ,  and many more, but not tried. Because all those help seekers had tried to manually OS install or phone was rooted or already had custom ROM, but my Nexus 5 did not have any of those.  I had tried "wipe cache partition" and reboot, but it did not helped. As I don't had any data backup of my phone storage, the last thing I will be willing to do is "wipe data/factory reset". As my phone's usb debugging was enabled and I had adb in my desktop, so I have also tried to copy data from my phone using the "adb pull" command in boot looped mood. But also did not got any luck, may be "adp pull" command don't work in booting mood or I am doing something wrong with the command.  Any help to backup/recover the data or solution of the boot loop problem without "wipe data/factory reset" is appreciated. Thanks in advance.....


My new installed Kubuntu 16.04 with Plasma 5.5.5 takes very long time at login(~30s).  I read about a similar bug  , but I don't think this match my problem. Does anybody have similar problems?  System: Dell Latitude E7440 with WLAN and Bluetooth.  Edit: I think that the desktop is loaded while the KDE login wait-bar is on the screen. When I'm clicking ALT+TAB to switch between applications, it is possible to see the desktop for that moment.

My recent Notebook (Intel i3-6100 with SSD) boots from BIOS to the login of SDDM within 8s. After entering my credentials it takes 31s (no matter if I have autostart of Firefox and Thunderbird). While waiting these 31s the blue progression bar shows "100%" after very few seconds but stays the rest of the time at "100%".  If I reset my Plasma/KDE configuration it only takes few seconds as it was in Kubuntu 15.10 partly with NEON packages. My Plasma configuration is very basic with no bluetooth. There are no errors in ~/.xsession-errors and if I monitor the startup of Plasma with htop I see no activity. After the slow startup everything is fast.  The output of systemd-analyze blame is:  5.889s NetworkManager-wait-online.service   3.817s apt-daily.service   2.520s swapspace.service   568ms dev-sda1.device   224ms accounts-daemon.service   ...   Do you have an idea or how I can better monitor the cause of the slow startup of Plasma?


We (four people and luggage) need to get from King's Cross Station to Heathrow Terminal 2 for a 3:15 pm flight to Shannon.  Our train arrives from Edinburgh at 11:51 am.  What it the fastest way to get there and check in on time for our flight to Ireland?

My wife and I will be arriving in London via Heathrow Airport (LHR) and are staying at a hotel near King's Cross station. So, we were wondering what the best (which means fastest but also easiest when carrying two large pieces of luggage and two carry-ons) way to get from LHR to King's Cross?  I gather that, with only one changeover, we can take the Tube. However, in the interest of other passengers, we thought it would be best to take a taxi, or maybe a bus?  Thoughts?


I never know how to size my text...  Reason is that it depends on the font...14px Times new Roman is NOT the same size as 14px Roboto Slab for example...  What kind of units should I use for print, so it's readable for flyers and brochures?  I'm looking for an idea on size for:  H1 H2 h3 P   Ect...I'm a web guy, so no idea about print;)  I try to use Adobe AI for print, so to make things even more confusing...what if I change the text to outlines? What size then?

To avoid printing single letters at varying sizes and measuring how far away I can see it from a distance is there a formula for determining what size font for a particular read distance? Is it better to take the midpoint between the ascender line and x-height or to go purely off of the x-height (since going purely off the ascender line could leave lowercase letters difficult to read)? How does vertical height play into this? Would I need to then figure the hypotenuse distance instead of a straight distance?  For example if I'm shooting for a 20' read distance but the sign is to be placed about 30' up should I use a distance of  35' instead of 20'?  I'm shooting for a 20' read distance for the headline and then possibly a 10' read distance for additional content depending on how it all fits on the active area.


Can the equation $\ln(x)+ 1- x^2=0$ be solved without the Lambert W function ? (I didn't study Lambert W yet).  By inspection I can see that $x=1$ is a solution. Are there other solutions? And is there a systematic way to find them?  Note: I asked  concerning $\ln(x)-1+x^2$, however, the answer there cannot be used for the function here.

Can the equation $\ln(x)- 1 + x^2=0$ be solved without the Lambert $W$ function ? (I didn't study Lambert W yet).  By inspection I can see that $x=1$ is a solution. Are there other solutions? And is there a systematic way to find them?


The description of the 1st-level spell  (PH 282) states the following:     [...] Additionally, if the target is a creature, it must succeed on a Strength saving throw or be pushed 10 feet away from you and knocked prone.   How is a creature defined? Without this spell, I would have defined literally everything as a creature, but then why would this distinction exist? Just so you can't push a boulder away, which 99% of DMs wouldn't allow this spell to do anyway? That seems odd to me.  I couldn't find anything online that defines creatures as something other than , so I came here hoping that someone would have an answer.

In the Starter set and Basic Rules, it mentions "character", "non-player character", "player character", "monster", "creature", and maybe other terms I've missed.  Which of these terms are interchangeable?   Some examples from the Basic Rules PDF:   Page 105: Conditions Appendix refers only to creatures. Chapter 11: all spell descriptions refer to creatures, but occasionally other terms such as humanoids.


I'm trying to using a conditional statement to check if a value equals something prior to setting it using a setter. I am returned a StackOverFlowException error. I am using another .cs file to execute the code for general practice.  using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks;  namespace Job_Classes {     class Workers     {         public string Name         {             get { return Name; }             set             {                 if (Name.CompareTo("Admin") == 0 || Name.CompareTo("Admin") == -1) //Just trying out comparison with the input.                 {                     Console.WriteLine("Invalid Name."); //To see if an invalid input that is not "Admin" fails.                 }                 else                 {                     Name = value;                     Console.WriteLine("Done.");                 }             }         }         public Workers()         {             this.Name = null;         }         public Workers(string Name)         {             this.Name = Name;         }         public string Information()         {             return String.Format("Name: {0}", Name);          }                  } }   My execution code in another .cs is:  Workers Test = new Workers("John");

I know java and would normally put in getter/setter methods. I am interested in doing it in C# with the following code, but it throws a StackOverflow exception. What am I doing wrong?  Calling Code  c.firstName = "a";   Property Code    public String firstName; {     get     {         return firstName;     }     set     {         firstName = value;     } }


Evaluate $\frac{1+\frac{1}{2^p}+\frac{1}{3^p}+\frac{1}{4^p}+...}{1-\frac{1}{2^p}+\frac{1}{3^p}-\frac{1}{4^p}+...}$ where $p>1$.  Attempt: Observe that $B=\frac{1}{2^p}+\frac{1}{4^p}+...=\frac{1}{2^p}(1+\frac{1}{2^p}+\frac{1}{3^p}+\frac{1}{4^p}+...)=\frac{1}{2^p}(A+B)$. Rearrage top and bottom should give results. Are there any alternative solutions?

Let $p$ is real number which satisfies$\quad p > 1$  How can I simplify the fraction $$\frac{1+\frac{1}{2^p} + \frac{1}{3^p} + \frac{1}{4^p} + \cdots}{1 - \frac{1}{2^p} + \frac{1}{3^p} - \frac{1}{4^p} + \cdots}$$  Numerator is $\zeta(p)$ but I don't know the closed form of denominator.  Is there any idea to simplify this fraction?


There was a similar coding question at hacker earth. The challenge ends now. I don't have that question now but my code looked like this. I passed the test cases but my code was not accepted due to large input gives this error.  I have written the following code.  import java.util.*; class TripleStep{     public static void main(String[] args){         Scanner in=new Scanner(System.in);         int n=10000;         long[] memo=new long[n+1];         Arrays.fill(memo,-1);         long ans=StairOpr(n,memo);         Arrays.fill(memo,-1);         System.out.println(ans);     }     public static long StairOpr(int n,long[] memo){         if(n<0){             return 0;         }         else if(n==0){             return 1;         }         else if(n==1){             return 2;         }          else if(n==2){             return 3;         }         else if(memo[n]>-1){             return memo[n];         }         else             memo[n]= (StairOpr(n-1,memo)%1000000007+StairOpr(n-2,memo)%1000000007+StairOpr(n-3,memo)%1000000007+n*n*(n+1)%1000000007)%1000000007;             return memo[n];     } }   The code gives me the following error for the input value 10000.  Exception in thread "main" java.lang.StackOverflowError     at TripleStep.StairOpr(TripleStep.java:31)     at TripleStep.StairOpr(TripleStep.java:31)   What is the reason and what would be the solution? Since I write dynamic programming code but due to error the answer is not Submitted and I face the rejection.

What is a StackOverflowError, what causes it, and how should I deal with them?


I have one query related to name displayed on Air India website.  There is extra "MR" with my first name on website and "Title" field is empty.   Can you please suggest on this and whether it is fine? My name in passport is :  First Name: KAUSHAL  Last Name : KISHOR  Name on Air India website and ticket is displayed as KISHOR,KAUSHALMR. Will this be an issue??

I recently booked tickets to travel by plane from the UK to Greece. The website I booked through (airfasttickets.co.uk) lists my name correctly, as "Mr Georgios [My surname]", exactly the same as in my passport.  When I log in to the airline's (Aegean Air) website using the booking number the above website gave me, my name is somehow listed as "Georgiosmr [My surname]" (the title "Mr" seems to have been appended to my first name).  Since I'm going to be travelling from the United Kingdom and my name is obviously non-english, I'm afraid they may have doubts about the "mr" at the end being a mistake instead of part of it and deny me entry.  I've sent two e-mails to Aegean but it's been more than a week since the last one and 2-3 weeks since the first and they haven't replied. Calling them would be too expensive since they're based in a different country than my phone provider and I'd rather avoid it.  Is there anything else I can do? Is it likely that they'll think "mr" is part of the name of the ticket's owner?


What does it mean when N-Fold coverage of read of sequence? Details will be much appreciated if a link provider with brief explanation.

Is that correct that a complete DNA sequencing (the whole genome) need only to be done once (per person)?   After that is done, it the complete genome can be stored and once the new genes (and their purposes are confirmed) are discovered, the scientist can simply go back to a previously sequenced data and to find it this particular person has this new gene or not.


Say I have a sequence that looks like this:  0 0 0 0 0 1 0 0 0 0 1 0 1 1 1 0 0 0 0 0 0 0 0 0 0   In general terms, I am interested in determining when there is an over-abundance of 1's in close proximity.  Not necessarily in a row, but within a sliding window.  In this example, the 0's and 1's represent whether a system is stable or unstable at regular time intervals.  Currently, I don't have any fixed notion of what exactly should constitute a significant or meaningful change in the sequence from 0's to more 1's, I am trying to work that out from some exploratory analyses.  I appreciate that this is somewhat general - however, if anyone has any ideas as to what literature to look at I would be grateful.

I have a sequence of binary samples and I want to model how this sequence is changing. The change should reflect whether it's a positive or negative change.  For example, sequence 1:  1 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1   is changing positively since we're confident in appearance of 1's before and become even more confident after some point. However, sequence 2:  1 1 1 1 0 1 1 1 0 1 1 1 0 1 1 0 1 0 1 0 0 0 1 1 0 0 0 0 0 0 0 0   is changing negatively since the number of 0's is increasing, as opposed to our prior confidence in 1. Is there a metric that models this behavior?  I've been looking into  but it seems to model change of frequency but does not distinguish positive and negative changes. The reason why I'd like to model this difference is I want to know whether there is a positive or negative effect on the underlying  that generates these samples so that I can detect these underlying changes. Thanks!


Let $T$ be a linear map from $\mathbb{R}^n \to \mathbb{R}^m$ , and let $L$ be a line in $\mathbb{R}^n$ . Show that $T(L)$ is also a line. (Is it not enough to just consider lines in the plane?)

I need help with this question:  Let $T$ be a linear map from $\mathbb{R}^n \to \mathbb{R}^m$, and let $L$ be a line in $\mathbb{R}^n$. Show that $T(L)$ is also a line (is it not enough to just consider lines in the plane).


I know that the limit below   $\lim_{(x,y)\to (1,0)}$ $\frac{xy-y}{(x-1)^2+y^2}$  does not exist. However, I haven't found a path that is not equal to 0. I have tried: $y=mx$, $x=cy^2$,$y=0$, and $x=0$.   Any suggestions?

Right now, I'm doing a question:   $$\lim_{(x,y)\to(1,0)}\frac{xy-y}{(x-1)^2 +y^2}$$  I know the limit doesn't exist, but I can't figure out how to prove it. I tried putting $x=1$, and getting $0/y^2$, and put $y=0$, got $0/(x^2-2x+1)$, but I don't think that does it.  (edit: this is not a duplicate; I'm having a hard time getting good explanations, hence why I asked)


I've  over a year ago and didn't quite get a satisfactory answer so it's been sitting there for a while.  I'm not very active on superuser so I'm not there all the time, I'll only check back if I ever get a notification that leads me there (e.g., comments, answers to questions, notifications, etc.).  I'm mainly active (to a degree) on stackoverfow and a couple other sites.  I recently  and got the usual notification so I went over to check it out.  To my surprise, I just noticed that my question has a bounty on it and has been there .  Had I known about it, I might have updated the question or left a comment regarding the status.  But alas, there was no notification or other indicator that there has been activity.  For virtually all  publicly visible post activities on the question itself, the asker receives notifications (exceptions: tweets, community bumps, and so on)... why not for bounties?  Can a notification be sent out to the asker if a bounty is placed on their question by someone else?

Placing a bounty on a question changes its last activity timestamp and bumps it to the front page, the same as posting a new answer or editing the question or one of its answers.  It would be nice to be notified when someone else is assigning a bounty on one of your own questions - it might be just a notification in the brand new notification tab of the  StackExchange™ MultiCollider SuperDropdown™ instead of a full inbox message.


I upgraded from 17.10 to 18.04 today and after a reboot, I noticed my password no longer works. I'm certain the password is correct, but I keep getting "bad passphrase or options". How can I fix this?

A few months ago I set full disk encryption during installation of Ubuntu 17.10. Now, I've decided to upgrade. The upgrade ran to the end without any problems. However, after reboot I am not able to log into my encrypted disk.  Where can be the problem? I am 100% sure I press the "right keys" on the keyboard, but technically I don't know what I am writing because of "*" characters and maybe after upgrade my keyboard layout changed. I use some characters which might be somewhere else on the keyboard. What language is default after upgrade?   By the way, I've already tried Caps-lock, but still no luck.  Help will be really appreciated. I am not a fan of installing my system and all backups over and over again.


Here is my code:          Piece grille[][] = new Piece[9][9];         grille[0][0] = new Piece(1,joueur1,0);         grille[8][0] = new Piece(1,joueur2,0);         grille[0][8] = new Piece(1,joueur2,0);         grille[8][8] = new Piece(1,joueur1,0);         grille[0][1] = new Piece(3,joueur2,1);         grille[1][0] = new Piece(3,joueur2,1);         grille[1][1] = new Piece(3,joueur2,1);         grille[7][0] = new Piece(3,joueur1,2);         grille[7][1] = new Piece(3,joueur1,2);         grille[8][1] = new Piece(3,joueur1,2);         grille[7][7] = new Piece(3,joueur2,3);         grille[7][8] = new Piece(3,joueur2,3);         grille[8][7] = new Piece(3,joueur2,3);         grille[0][7] = new Piece(3,joueur1,4);         grille[1][7] = new Piece(3,joueur1,4);         grille[1][8] = new Piece(3,joueur1,4);         grille[3][4] = new Piece(2,joueur1,0);         grille[5][4] = new Piece(2,joueur2,0);          for(int i=0; i<9; i++){             for(int j=0;j<9;j++){                 if(grille[i][j].joueur == null)                     grille[i][j] = new Piece(0, null,0); //0 correspond a case vide             }         }   My instance variables in Piece are :  public int type;     public Joueur joueur; public int param;   It seems that the error comes from this: grille[i][j].joueur == null  I get this error:     Exception in thread "main" java.lang.NullPointerException at Citadella.(Citadella.java:35) at Partie.main(Partie.java:8)

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?


Supposedly evolution was very efficient and evolved many human proteins over a few thousand generations. Yet obvious detrimental traits like wisdom teeth remained. Why?

If a trait would be advantageous to an organism then why hasn't it evolved yet?  Conversely, if a trait is not advantageous or mildly disadvantageous, why does it exist?  In other words why does evolution not make the organism more "perfect"?    This is a general question that would be applicable for any kind of trait. Please keep the answers precise and scientific.   Read this meta post for more information:


I'm trying to figure out what could be the most appropriate verb to use to describe a child grabbing firmly something in a shop, using a methaphor:     Mark was holding/tightening/squeezing the toy like if that was a raft   and he was adrift in the ocean.   Any seawolf out there :-) ? thanks a lot!

I need an expression to be a simile to gripping the wheel of a car tightly.


If Voldemort intends for wizards to rule the muggles does he also intend to reveal the magical world to the Muggles.  After Voldemort supporters takes over the Ministry of Magic and openly advocating that Purebloods should rule Muggles, he still has made no concentrated efforts to reveal the magical world to the muggles. No effort to finally reveal that Wizards are invincible and cannot be hurt or opposed by Muggles.     Deathly Hallows The Wedding      Then the Patronus’s    mouth opened wide and it spoke in the loud, deep, slow voice of    Kingsley Shacklebolt.       “The Ministry has fallen. Scrimgeour is dead. They are coming.”   There is no one in the Ministry to oppose Voldemort from revealing Wizard Superiority. The only thing stopping Voldemort is Voldemort himself.   Is this acknowledgement on Voldemort’s part about the wisdom of not revealing the magical world of the Muggles, does Voldemort recognize that muggles can be dangerous in their own way.  I am reminded of this Mythbuster episode of Jaime and a gun against a horde of slow moving zombies, Jaime was still taken down and disarmed. Taken down by nothing more than slow walking brainless teeth.                                 Why the hesitation to reveal wizards as masters of Muggles and reveal the magical world?     Deathly Hallows chapter Kreacher’s Tale       But Master Regulus had proper pride; he knew what was due to the name of Black and the dignity of his pure blood. For years he talked of the Dark Lord, who was going to bring the wizards out of hiding to rule the Muggles and the Muggle-borns . . .”    In Great Britain alone  One baby born every 40 seconds in Britain  For the rest of the world    Four births each second of every day   Nearly two people die each second   How many Muggles does Voldemort’s minions have to kill in a day, everyday 24/7 just to give Great Britain zero population growth?   I’ll let Voldemort do the math.

This might sound like speculation, but can it be reliably predicted from canon what Voldemort would have done after he won, were he successful in defeating Harry and the Order?  Would he just rule over the wizard world and keep up the masquerade, or would he try to take over the whole Earth by starting a (dark-)wizard vs. muggle war?


Let $R$ be a ring without identity and $n$ be a positive integer. Prove that  the ring $R$ is simple iff $M_n(R)$ is simple.  When $R$ is unital ring (i.e. with identity) it is easy because we know the structure of two-sided ideals in $M_n(R)$. So we can consider the case, when $R$ is non-unital.

Let integer $n\geq 1$. I have obtained that for any field $k$, the matrix ring $M_n(k)$ is simple, i.e., $M_n(k)$ contains no nonzero proper two sided ideals. Now I want to prove that: for any ring $A$ (not necessarily commutative), the matrix ring $M_n(A)$ is simple if and only if $A$ is simple.   How to prove?


I have a  that I want to power using an  and control via one of the 4-pin fan terminals on an .    Not considering the wattage of the fan, I originally plugged it into a (known working) fan terminal but it of course would not turn (and the BIOS correctly reported the RPM as 0).  Connecting it directly to the PSU is simple enough, but this would result in it turning at full speed at all times.    I am curious if there is a "DIY" way that I can supply the fan with power from the PSU and control how much actually reaches the fan using the output of the motherboard (using something like an optoisolator to keep the motherboard safe).    The motherboard is able to control 4-wire fans using PWM, and 3-wire fans using DC voltage level.  Is there a product or combination of parts that will do this?  I originally asked this on Super User, but it was deemed more appropriate here due to the involvement of DIY electronics.  Thanks in advance!  EDIT: The 4-pin connectors on the motherboard are indeed keyed to force correct connection of 3-pin plugs.  The BIOS includes a Fan interface that allows you to plot desired RPM vs temperature.  Each fan output can individually be set to either PWM or DC voltage level control.  The motherboard auto-detects what is plugged in (4 or 3 wire) and selects the appropriate setting, but it can be changed manually if desired.  The fan was not purchased through DigiKey, and came terminated with a keyed 3-hole connector (F). It also shipped with a 2-wire (but 4-wide) molex connector (M), unterminated on the opposite end.

My computer's motherboard uses all four pin fan connectors with no support for speed controlling the older three pin fan connector. The problem is, all the PC fans that I have use a three pin connector. As fan as I know there are no premade solutions available, so I was thinking of building an adapter that sits in an unused drive bay.   I can't seem to find much information on how the four pin fan connecter works. Apparently, it looks something like this:   12 V 0V Tachometer PWM   The three pin header is numbered similarly:   Vcc 0V Tachometer   Could I simply use a logic level MOSFET to do the following?


I have a raspberry pi 4 and i have installed Ubuntu 20.04 LTS. When i am trying to install pip3 i am getting the following message :  Reading package lists... Done Building dependency tree Reading state information... Done Package python3-pip 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 'python3-pip' has no installation candidate This solution seems not working ( ) It is my fisrt time using rpi but i am very familiar with ubuntu os in general. Is there any particular way installing libraries etc to rpi due to its arm processor ? Silly question but i have stucked in a deadlock. Should i use a different version of OS ? I want to run Linux Containers on my rpi ( LXC/LXD )

What does the above Error mean? What is an installation candidate?  I was trying to do  sudo apt-get install munin-memcached     and I get this message:  Reading package lists... Done Building dependency tree        Reading state information... Done Package munin-memcached 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 munin-memcached has no installation candidate   I googled for the problem and someone said to do a apt-get upgrade but it still did not solve my problem.


I want to be able to default all new users created with the wp_login (register) box to have the user option: Show Toolbar when viewing site set to unchecked. I have the facility to then jump into wp-admin from within my website as and when required, but I don't want the black bar always showing. Its all works perfectly fine if the option is unchecked, but any new user is checked by default which means until I can manually uncheck it I have a problem. Thanks

In the profile.php admin page there is a checkbox for the Toolbar: Show Toolbar when viewing site.  I can't seem to find where this option is stored in the database.  I would have thought it would be in the wp_usermeta table ... but I don't see it.  My goal is to set the default value of this to "off" for new users.  Then, of course, they would have the option to turn it on if they wanted.


Suppose $Τ$ is an infinite set of propositional types and $\varphi$ a propositional type. Prove that if $Τ\vDash\varphi$, then a finite set $Τ_0\subseteq T$ exists, such that $Τ_0\vDash\varphi$.  I understand this is true based on my intuition but I cannot think of a strict mathematical way to justify it.   Any help would be appreciated.

Suppose $\Gamma$ is an infinite set of formulas in FOL. It is given that for a structure, $M$: If $\Gamma$ is satisfiable in $M$ then $\varphi$ is valid in $M$.  Why is it true that there's some finite $\Gamma ' \subset \Gamma$, such that $\Gamma ' \vDash \varphi$?   It reminds the compactness theorem in a way, but it's not quite the same.


Card karte; Stack <Card> kartenstapel;   public Standard52() {       /** this works*/      this.karte = new Card(Suit.HEARTS,13);                              /** this throws a 0-pointer exception when I try to initial*/       this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));      this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));      this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));      this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));  }   Why i get a null pointer exception when i try to inital it.  Its more theorie then practice but i do not undersstand my failure maybe some of you can explain me where my mistake is.

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


I set an static ip on my server  but after a day many unknown users created and unknown remote dekstop type softwares installed and sql server get unknown password.  Please help me to secure my server.

This is a  about Server Security - Responding to Breach Events (Hacking)   See Also:                  Canonical Version I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism:   What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", are there other initial considerations? How do I go about getting services back online? How do I prevent the same thing from happening immediately again? Are there best practices or methodologies for learning from this incident? If I wanted to put a Incident Response Plan together, where would I start? Should this be part of my Disaster Recovery or Business Continuity Planning?   Original Version       2011.01.02 - I'm on my way into work at 9.30 p.m. on a Sunday because our server has been compromised somehow and was resulting in a    attack on our provider. The servers access to the Internet   has been shut down which means over 5-600 of our clients sites are now   down. Now this could be an FTP hack, or some weakness in code   somewhere. I'm not sure till I get there.      How can I track this down quickly? We're in for a whole lot of   litigation if I don't get the server back up ASAP. Any help is   appreciated. We are running Open SUSE 11.0.            2011.01.03 - Thanks to everyone for your help. Luckily I WASN'T the only person responsible for this server, just the nearest. We managed   to resolve this problem, although it may not apply to many others in a   different situation. I'll detail what we did.      We unplugged the server from the net. It was performing (attempting to   perform) a Denial Of Service attack on another server in Indonesia,   and the guilty party was also based there.      We firstly tried to identify where on the server this was coming from,   considering we have over 500 sites on the server, we expected to be   moonlighting for some time. However, with SSH access still, we ran a   command to find all files edited or created in the time the attacks   started. Luckily, the offending file was created over the winter   holidays which meant that not many other files were created on the   server at that time.      We were then able to identify the offending file which was inside the   uploaded images folder within a  website.      After a short cigarette break we concluded that, due to the files   location, it must have been uploaded via a file upload facility that   was inadequetly secured. After some googling, we found that there was   a security vulnerability that allowed files to be uploaded, within the   ZenCart admin panel, for a picture for a record company. (The section   that it never really even used), posting this form just uploaded any   file, it did not check the extension of the file, and didn't even   check to see if the user was logged in.      This meant that any files could be uploaded, including a PHP file for   the attack. We secured the vulnerability with ZenCart on the infected   site, and removed the offending files.      The job was done, and I was home for 2 a.m.            The Moral   - Always apply security patches for ZenCart, or any other CMS system for that matter. As when security updates are released, the whole   world is made aware of the vulnerability.   - Always do backups, and backup your backups.   - Employ or arrange for someone that will be there in times like these. To prevent anyone from relying on a panicy post on Server   Fault.


I've started by letting the $\gcd = d$. With the goal of trying to prove $d$ must be equal to 1. Since $d$ divides both $n!i + 1$ and $n!j + 1$ then there exist integers $k$ and $m$ such that $dk = n!i + 1$ and $dm = n!j + 1$. By rearranging these equations and doing some substitution, I find that $d|i - j $and $d|j$ ai. Am I off base here?

I tried to prove this by induction but I got stuck, this is what I've got.  Base case: $n = 2$. $\gcd(2! + 1, 3*3!+1) = gcd(3, 7) = 1.$  Inductive step: assuming for $n = k$ that $\gcd(k!+1, 3k!+1) = 1$ holds. Let $n = k + 1$. We have to prove that $\gcd((k+1)! + 1, 3(k+1)!+1) = 1.$  From assumption we get that:  $\gcd(k!+1, 3k!+1) = 1$  Multiplying this by $k + 1$ we get:  $(k + 1) * \gcd(k!+1, 3k!+1) = k + 1$  Subtracting k from both sides:  $(k + 1) * \gcd(k!+1, 3k!+1) - k = 1$  Now $k+1$ can enter the gcd and we have:  $\gcd((k +1)! + (k + 1), 3(k + 1)! + (k + 1)) - k = 1$  Now I dont know where to proceed from here.


While it's been established that concentration spells can't overlap () this brings up the nitpicky question of 'how long is the gap between one concentration spell ending and the other beginning?  Example:  I cast Darkness on myself and that spell completely obscures me from sight for as long as I concentrate on it.       Magical darkness spreads from a point you choose within range to fill   a 15-foot-radius sphere for the duration. The darkness spreads around   corners. A creature with darkvision can't see through this darkness,   and nonmagical light can't illuminate it.   While I'm concentrating on the darkness spell, I cast      A creature you touch becomes invisible until the spell ends. Anything   the target is wearing or carrying is invisible as long as it is on the   target’s person. The spell ends for a target that attacks or casts a   spell.   So now I'm invisible.  It's well established that the spell effects from concentration spells can't overlap, so the darkness spell ends when I start concentrating on Invisibility.  But nothing mentions the amount of time that passes between each.  The Problem:  Say I'm trying to hide my identity, or otherwise pull a "mysterious force" scam and I don't want my opponents to see me at all.  Does the Darkness end when I start casting the Invisibility spell?  (in which case I'm visible, briefly, while the invisibility spell is cast)  Or does the darkness end as soon as the invisibility takes effect? (So I never actually become visible?)  And to be clear, I'm not asking about the converse (First cast Invisibility, then cast Darkness) because the act of casting any spell would end the Invisibility, and that strikes me as a potentially different case with potentially different rules in play.  And this seems different from the combat use case mentioned in the previous question; the spells don't overlap, and the amount of time they don't overlap doesn't matter in game mechanics. But in the case, it actually does matter because of what my opponents do, or do not, see.  Covered in RAW/Sage Advice/Etc. anywhere, or is this down to GM's discretion?

The book says:     Concentration. Some spells require you to maintain concentration in order to keep   their magic active. If you lose concentration, such a spell ends.   So what happens if, for example, you are already concentrating on a spell, and cast Witch Bolt without concentrating. Would you get the initial arc of blue energy, or would it not even go off?  I am asking if you can cast a spell that says concentration without concentrating for an immediate effect. This would be useful to avoid interrupting your existing concentration. In essence, if you are concentrating on thing A (doesn't have to be a spell since other things need concentration), can you cast a concentration spell getting an immediate effect without losing concentration on thing A?  Since the definition of concentration is to keep the spell active (meaning it is already active) I would think that you would get the initial effect (if it had one) without the need to concentrate on it.


It's been happening for the last few weeks in a small unix server (it doesn't have all standard unix commands, just the basics included in the BusyBox package) that I was configuring to backup files.   If we check the free space of the server it shows:   Filesystem             |   Size  |    Used | Available | Use%| Mounted on  /dev/hdc2              | 678.4G  |  416.6G |   261.8G  | 61% | /tmp/mnt/D  /dev/sda1              |  96.1G  |   36.0G |    55.2G  | 40% | /tmp/mnt/USB/USB_C   Now I am trying to copy either a 700MB files to USB_C or a 90GB files to /tmp/mnt/D where I can see that there's plenty of space available, however, I keep on receiving the followin error:  cp: Write Error: No space left on device   Any idea what the problem could be and how it could be fixed?  As mentioned, this is a small unix server with the bare minimum of unix commands, so most of the commands mentioned in other posts do NOT work for this box. Hence that I might need the help of someone who knows what I could try in this specific system to give us some clue...

It started happening today... all of a sudden, no apparent reason!  Here's the output from df:   assp:~# df -k Filesystem           1K-blocks      Used Available Use% Mounted on /dev/simfs             6291456   1378384   4913072  22% / tmpfs                  8202680         0   8202680   0% /lib/init/rw tmpfs                  8202680         0   8202680   0% /dev/shm  assp:~# df -i Filesystem            Inodes   IUsed   IFree IUse% Mounted on /dev/simfs           55781934   83005 55698929    1% / tmpfs                2050670       2 2050668    1% /lib/init/rw tmpfs                2050670       1 2050669    1% /dev/shm  assp:~# df -h Filesystem            Size  Used Avail Use% Mounted on /dev/simfs            6.0G  1.4G  4.7G  22% / tmpfs                 7.9G     0  7.9G   0% /lib/init/rw tmpfs                 7.9G     0  7.9G   0% /dev/shm   Here's an actual entry from /var/log/mail.warn:   Dec 11 17:55:37 assp postfix/smtpd[30614]: warning: not enough free space in mail queue: 0 bytes < 1.5*message size limit Dec 11 17:55:37 assp postfix/cleanup[30617]: warning: 4361D850D54: write queue file: No space left on device   .


Example code:  var person = {   name: 'Sam',   age: 45 };  // This function is able to modify the name property function nameChanger (obj, name) {   obj.name = name; }  nameChanger(person, 'Joe');  // modifies original object   But trying to redefine the objection in a similar function doesn't work at all:  var person2 = {   name: 'Ashley',   age: 26 };  function personRedefiner (obj, name, age) {   obj = {     name: name,     age: age   }; }  personRedefiner (person2, 'Joe', 21); // original object not changed   This second example does not modify the original object. I would have to change the function to return the object, then set person2 = personRedefiner(person2, 'joe', 21);  Why does the first example work but the second example does not?

The primitive types (number, string, etc.) are passed by value, but objects are unknown, because they can be both passed-by-value (in case we consider that a variable holding an object is in fact a reference to the object) and passed-by-reference (when we consider that the variable to the object holds the object itself).  Although it doesn't really matter at the end, I want to know what is the correct way to present the arguments passing conventions. Is there an excerpt from JavaScript specification, which defines what should be the semantics regarding this?


this is for an assignment. I need to implement a queue using linked lists. I keep getting a null pointer exception while using my enqueue method for my listQueue Class. I'm not too sure what is going on. Below are my main class and listQueue Class.  public class Driver{      public static void main(String[] args) {          MyQueue<Integer> q = null;          boolean useList = true;  // make it false if you want to array implementation          if (useList)             q = new ListQueue<Integer>();   // default setting: use a list to implement the queue. You can change it.         else             q = new ArrayQueue<Integer>();          for(int i = 0; i < 1000; i++)  // add a large number of items onto the queue         {             q.enqueue(i);           }          System.out.println("Now, dequeue items!");         while(!q.isEmpty())           {             System.out.print(q.dequeue() + " ");           }         System.out.println("\nEnd of dequeueing");              // you should fully test/debug all methods!      }  }     public class ListQueue<T> implements MyQueue<T> {      private class Node {          T item; // public         Node next;  // null      }      private Node head = null;     private Node tail = null;     private int size = 0; //size of the list      public ListQueue(){}      /**      * is empty?      */     public boolean isEmpty() {         // your implementation here:         if (size == 0) {             return true;         }//end if         return false;     }//end isEmpty      /**      * @return the number of items in the queue      */     public int size() {         // your implementation here:         return size;     }//end size      /**      * enqueue: add an element at the tail of queue      */     public void enqueue(T item) {         // your implementation here:         if (size == 0) {             head = new Node();             head.item = item;             head.next=tail;             size++;         }//end if         else{             Node newNode = new Node();             newNode.item=item;             tail.next = newNode;             tail = newNode;             size++;         }//end else     }      /**      * dequeue: remove and return the head of the queue      *      * @return the deleted value      * @throws NoSuchElementException if queue is empty      */     public T dequeue() {         // your implementation here:         if(isEmpty()){             throw new NoSuchElementException();         }//end if         else{             Node temp = head;             head = head.next;             size--;             return temp.item;         }//end else     }//end dequeue      /**      * peek: view the head of queue without removing it.      *      * @return Null if queue is empty      */     public T peek() {         // your implementation here:         if(isEmpty()){         return null;         }//end if         else{             return head.item;         }//end else     }//end peek }//end ListQueue


I fully understand that  provides the complete information of a state of a quantum system, i.e. quantum phase space, while not violating Uncertainty principle. But can anyone tell me how this is derived and why it could work at the first place?  To me the mathematics isn't very simple to visualise. It looks like some convolution and fourier transform in place at the same time. It would be helpful if anyone can motivate the origin of the terms in the function?

Most sources say that  acts like a joint phase-space distribution in quantum mechanics and this is justified by the formula   $$\int_{\mathbb{R}^6}w(x,p)a(x,p)dxdp= \langle \psi|\hat{a}\psi\rangle$$  as this allows us to compute the expectation value for the operator $\hat{a}$ corresponding to the physical quantity $a$. However, without the knowledge of this formula, how did Wigner come up with this definition:  $$w(x,p)=\frac{1}{(2\pi)^3}\int_{\mathbb{R}^3}\psi\left(x-\frac{v}{2}\right)\psi^*\left(x+\frac{v}{2}\right)e^{iv \cdot p}dv \quad ?$$  I would be greatly indebted for any mathematical motivation that anyone could provide. Similarly, I also wonder at the mathematical motivation for the Weyl quantization.


If $ \alpha_1,\alpha_n, ....\alpha_n $ be the roots of the equation $x^n+1=0$, then  $(1-\alpha_1)(1-\alpha_2)...(1-\alpha_n)$ is equal to  a) 1.  b) 0 c)n d)2  when I put n=3,and directly evalutae the value of $(1-\alpha_1)(1-\alpha_2)...(1-\alpha_n)$ I find no option matching to my answer.    I know the answer is 2. i've seen the solution here .   but, if we put n=3 , $x^3+1$ has roots -1 , and $\frac{1}{2} \pm \frac{3i}{2}$ then if we put that in the expression $(1-\alpha_1)(1-\alpha_2)...(1-\alpha_n)$  , it doesn't give  2. what mistake am i doing ?

then $(1-\alpha_1)(1-\alpha_2)\ldots(1-\alpha_n)$ equals to ? I think here we need the info of whether $n$ is even or odd else how will we say whether by vieta's formula what is the value of $1+(-1)^n$ ?


As of last night my Ubuntu 19.04 laptop won’t boot into its latest kernel. In the hours beforehand I had completed an apt-get upgrade and autoremove. The system continued along perfectly fine. After a reboot however, I reach an (intramfs) shell prompt.  Typing exit at this prompt I am then given the alert message:  ALERT! /dev/mapper/ubuntu--vg-root does not exist. Dropping to a shell!  I have discovered that I can successfully boot into an older kernel through the grub menu.  Latest installed kernel: 5.0.0-25-generic (not working  Backup kernel: 5.0.0-21-generic (working)  My system runs an LVM partitioned drive.  I found an old thread with the same symptoms that advised running ls /dev/mapper at the intramfs shell. All that returns is /dev/mapper/control  Any help would be greatly appreciated. Also, if there’s more info required please just let me know.  TIA

today I installed Ubuntu 64-bit on a netbook. When the netbook boots this, error report appeared. I think there is a problem with the partitions.  Gave up waiting for root device. Common problems:   — Boot args (cat /proc/cmdline)     — Check rootdelay= (did the system wait long enough?)     — Check root= (did the system wait for the right device?)   — Missing modules (cat /proc/modules; ls /dev) ALERT! /dev/mapper/ubuntu--vg-root does not exist. Dropping to a shell!   BusyBox v.1.21.1 (Ubuntu 1:1.21.1-1ubuntu1) built-in shell (ash)    Enter 'help' for list of built-in commands.    (initramfs)   Output of lsblk as requested:  $ lsblk NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT sda      8:0    0 232.9G  0 disk  ├─sda1   8:1    0   231G  0 part  ├─sda2   8:2    0     1K  0 part  └─sda5   8:5    0     2G  0 part [SWAP] sr0     11:0    1   1.2G  0 rom  /cdrom loop0    7:0    0   1.1G  1 loop /rofs


I'm just beginning to study cakephp to build web applications and I have very limited knowledge at now.  I am following an example of a book, consisting of a login page to connect. I build models, controller and MySQL connection already, and now i'm with the view 'login.ctp'  This is mi code for login.ctp is just this:
Login de Usuario
 <?php echo $form->create(array('action' => 'login')); ?> <?php echo $form->input('usuario'); ?> <?php echo $form->password('pass'); ?> <?php echo $form->submit(); ?> </form>   (Also in UsuariosController I have function login())   class UsuariosController extends AppController {     var $name = "Usuarios";     var $scaffold;     var $helpers = array ('Form');     function login(){...}  }   but, when I go to localhost/cakephp/usuarios/login, show this error:  Error: Call to a member function create() on a non-object    File: C:\xampp\htdocs\cakephp\app\View\Usuarios\login.ctp    Line: 2   I don't understand this, have I to declare $form  in another side? (doesnt work either with '$this->$form->create...') I do not know what to do :/  Thank you in advance for your time.  EDIT:  from what I've read, the variable $ form can be used directly to create forms, so I say I do not understand and if I have to declare somewhere  for example () :  <?php echo $form->create(); ?>      <?php     echo $form->input('username');   //text     echo $form->input('password');   //password     echo $form->input('approved');   //day, month, year, hour, minute, meridian     echo $form->input('quote');      //textarea ?>   <?php echo $form->end('Add'); ?>

So I'm refactoring my code to implement more OOP.  I set up a class to hold page attributes.  class PageAtrributes  {   private $db_connection;   private $page_title;      public function __construct($db_connection)      {         $this->db_connection = $db_connection;         $this->page_title = '';     }      public function get_page_title()     {         return $this->page_title;     }      public function set_page_title($page_title)     {         $this->page_title = $page_title;     } }   Later on I call the set_page_title() function like so  function page_properties($objPortal) {         $objPage->set_page_title($myrow['title']); }   When I do I receive the error message:     Call to a member function set_page_title() on a non-object   So what am I missing?


I see a list here with a section titled M-theory -   In there these two look promising,  and   I would like to know if people have opinions of good starting points towards understanding M-branes and how they are used for constructing exact examples of AdS/CFT. [...I guess all exact AdS/CFT scenarios are M-theory constructions..]

seems like a really hot topic and I'd like to start reading about. I am looking for the best introduction at my level, i.e. I have a background in QFT, CFT and general relativity at the level of a master student in theoretical physics. What would you recommend me to start tackling the subject? I have been looking for resources and so far I have noticed:  -this synthetic introductory lectures by Horatiu Nastase:   -the videos of lectures done by P. Vieira at Perimeter for Perimeter Scholar International students:   -the subject starts entering the most recent textbooks on string theory. We have the Schwartz and Becker (  ) and also the Kiritsis (  )  I probably missed a lot of resources, as the literature on the subject is already quite huge. I would really appreciate some advice on that, as I already had the frustration of losing my time on not-so-good books when started to learn something new, so if I could (to the best) avoid that this time...


I want to display running clock inside terminal.  I have already gone through  answer but this method only works in zsh terminal. But I want to display in bash.  Is there any other way to display it in bash terminal?

I prefer to use terminal and spend most of the time using it. I am searching a way to see time in terminal while I use it parallel. The time would change automatically when it passes. It would be awesome if it would display left to my command prompt.  If this is my command prompt in terminal:  saurav@saurav-P4I45Gx-PE:~$   Then I would like to see clock(time) as:  saurav@saurav-P4I45Gx-PE[06:27:01]:~$   or  saurav@(06:27:01):~$   or any other format. where 06:27:01 is the time. What I want is just to show the time which changes when seconds pass.  So is there any way to achieve this?


public class HelloWorld{   class Student { int marks;  }   public static void main(String []args){  Student studentArray[] = new Student[2]; studentArray[0].marks = 100; studentArray[1].marks = 75;  int m=0; m = studentArray[0].marks;  System.out.println(m);       } }   This compiles with no problem but when I execute it, I am getting null pointer exception error as following:      Exception in thread "main" .lang.NullPointerException at   HelloWorld.main(HelloWorld.java:13)   can somebody help me to locate where the cause is?

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


I have records as follow in a tables on sql server 2005  fname  lname  address  zip  xxx    yyy     UK      001  zzz    yyy     UK      001  aaa    yyy     UK      002   ddd    jjj     US      003  eee    jjj     US      003    I need to get the result in the following format    fname    lname  address  zip xxx,zzz   yyy    UK      001 ddd,eee   jjj    US      003   Basically every records which have a count address and zip 2 times will have their first name grouped and separated by comma.   Ok Here is my approach: but not working and stuck right now  select fname, lname, address, zip from table people  where address is not null and zip is not null group by address,zip  having count(address)=2 and count (zip)=2  order by address   -- Now to coalesce the records I am using   SELECT fname = COALESCE(fname + ', ', '') + ISNULL(fname, 'N/A'), fname, lname,streetname, housenumber FROM people  WHERE address is not null and zip is not null   group by address,zip  having count(address)=2 and count (zip)=2  order by address

I'm trying to migrate a MySQL-based app over to Microsoft SQL Server 2005 (not by choice, but that's life).  In the original app, we used almost entirely ANSI-SQL compliant statements, with one significant exception -- we used MySQL's group_concat function fairly frequently.  group_concat, by the way, does this: given a table of, say, employee names and projects...  SELECT empName, projID FROM project_members;   returns:  ANDY   |  A100 ANDY   |  B391 ANDY   |  X010 TOM    |  A100 TOM    |  A510   ... and here's what you get with group_concat:  SELECT      empName, group_concat(projID SEPARATOR ' / ')  FROM      project_members  GROUP BY      empName;   returns:  ANDY   |  A100 / B391 / X010 TOM    |  A100 / A510   So what I'd like to know is: Is it possible to write, say, a user-defined function in SQL Server which emulates the functionality of group_concat?   I have almost no experience using UDFs, stored procedures, or anything like that, just straight-up SQL, so please err on the side of too much explanation :)


I could not detexify this:    How can you get it in LaTeX?

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?


What if a certain question is asked on a specific SE community, but has a duplicate on a different SE community. Should it be possible for those questions to be linked to each other? Or how should they be dealt with? I think this happens specifically with the meta parts on SE, where people usually visit the meta page of the community they frequent most, instead of going to the general meta SE.  For example, I personally frequent the Anime & Manga SE and I just noticed , which is an obvious duplicate of .  How should this situation be dealt with best?

What's the right course of action for cross-site duplicates?  There are two flavors:   A question is posted which belongs on another site and ends up already having been asked there. I can't find an example right now, but it's bound to happen soon if it hasn't already. The same question is posted in two places at the same time. Take  for example, which is a duplicate of , posted within a half hour of each other by the same user.   Possible actions:   Move it to the proper site and close it once it gets there as a duplicate. Provide a way to close it right away as a cross-site duplicate, without moving it first. Flag it and let a moderator merge them. Close it as "no longer relevant" or something else.   Additionally, flavor 2 is a bit of a special case; perhaps the question really spans both sites in terms of content and intended audience. Should multiple-postings in this case be allowed? If so, should they somehow be linked to each other? If not, how do we avoid a migration war?


So i am running this piece of code here: username='john' print('Weclome ',(username),'!')  but it keeps putting a space between the username and the exclamation mark. How do I remove it so it just outputs 'Welcome John!'

I'd like to do it in Python. What I'd like to do in this example in C: #include <stdio.h>  int main() {     int i;     for (i=0; i<10; i++) printf(".");     return 0; }  Output: ..........  In Python: >>> for i in range(10): print('.') . . . . . . . . . . >>> print('.', '.', '.', '.', '.', '.', '.', '.', '.', '.') . . . . . . . . . .  In Python print will add a \n or space, how can I avoid that? Now, it's just an example, don't tell me I can first build a string then print it. I'd like to know how to "append" strings to stdout.


In      lsession    SESSION   displays login session identifier of a process.   What does the "login session" of a process mean?   ps has other fields cgname and cgroup for the cgroup of a process. So the login session of a process can't refer to the cgroup of the process.  Thanks.  $ ps  -o lsession,pid,cmd SESSION       PID CMD c2          22135 bash c2          27852 ps -o lsession,pid,cmd

I read , but I wonder what  a "systemd login session" is? Is it  called more frequently as a "systemd logind session"?  Is it some process? (like a lxsession process?) What is its process name or command name?   Is it itself a process session or process group? Is it related to the process session lead by thelogin  process?   Thanks.


My computer loads up then gets to black screen and reads....  Intel UNDI, PXE-2.1 (build 082) Copyright (C) 1997-2000 Intel Corporation For Atheros PCIE Ethernet Controller v2.0.0.4(03/03/09) CLIENT MAC ADDR: 00 13 74 0 00 00 GUID: FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF PXE-E51: No DHCP or proxyDHCP offers were recieved. PXE-M0F: Exiting Intel PXE ROM Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key  What is happening?

My computer no longer boots Windows or the installed operating system. Instead, I may get this error:  PXE-E61: Media test failure, check cable -or- Check cable connection!  PXE-M0F: Exiting PXE ROM.   and/or one of the following messages or similar:  Operating System not found  No boot device available- No bootable devices--strike F1 to retry boot, F2 for setup utility  No bootable device -- insert boot disk and press any key  No Boot Device Found. Press any key to reboot the machine  Default Boot Device Missing or Boot Failed  Reboot and Select proper Boot device or Insert Boot Media in selected Boot device   What does this mean and what can I do?     This question comes up often and the answers are usually the same. This post is meant to provide a definitive, canonical answer for this problem. Feel free to edit the answer to add additional details.


I have a question, if there anyone which wirelles card rt3290 working? I have information that this card is blacklisted and does not work for anyone.  I tried probably everything available on the internet and it still does not work. The laptop service has not dealt with it either

I just installed Ubuntu 12.10 on an ASUS X401U, and after installation there is no list of wireless connections. I didn't have that problem with an installation on HP. What I can do to enable Wifi?  07:00.0 Network controller [0280]: Ralink corp. Device [1814:3290]


I would like to use a long squiggly arrow in beamer. I already found a similar question here: , but it doesn't seem to work in my case.

Is it possible to get a path in tikz that looks like \rightsquigarrow?


I'm a student originally from the West Coast but currently studying in New England. I came across an interesting question concerning dialectology and the use of Patio vs. Porch. I have observed other words like Deck, Veranda, Lanai... etc. Where can I find evidence to show that this is a regional difference or just preference? Thanks!

In AE, a porch is apparently just about the same structure as a veranda, i.e. an open or enclosed gallery or room attached to the outside of a building.     Besides, a porch (or veranda) can apparently also be designated in some parts of the U.S. alternately as a "(sun) deck", a "gallery", "a "lanai", a "terrace", and a "piazza". Are any of these regional usages widespread enough to have gotten to flood into mainstream AE? Also -- in dialectal AE -- can a large outback or outfront balcony, i.e. a platform that projects from the wall of a building and is surrounded by a railing, a balustrade, or a parapet (like of those found attached to hotel suites, or serving as restaurant dining area) be referred to alternately as a "terrace", a "gallery", and a "patio"?


As far as I know, it would be better to follow these two rules when writing an academic paper:   Avoid using passive voice. Keep the object of interest in the subject position.   But often I encountered the situations where those two rules contradict each other. For example, in my research field, the typical first sentence of 'evaluation' section (same as the 'experiment' section in other fields) starts with 'We evaluated the system X..', but some people prefer to write it like 'The system X is evaluated..'. To follow rule 1, one should put 'we' in the subject position, but it contradicts rule 2 as the object of interest is 'the system X' rather than 'we'. In such kind of cases, which rule should come first?

My question is when passive voice is preferred over active voices and vice versa?   I remember that I was taught that in scientific writings, passive voice was preferred over active voice. Is it correct? If I want to describe several actions of mine, for example:     I did thing A. I did thing B. I did thing C. I did thing D. ...   If I keep using the active voice, will that make the description boring? That is why I thought juxtaposition of passive and active voice would make the description better:     I did thing A. Thing B was done by me. I did thing C. Thing D was done by me. ...   But  led me wonder whether juxtaposition of passive and active voice is good, or when it is good and when it isn't?


I have read on other fora that 'nearby' is always one word, yet Bill Bryson, the famous travel writer, exclusively writes 'near by'.

The cops traced residential address of his relatives who lived close   by.   Close up/down, close off, close in are terms well understood, I have not seen such usage of close + by.  Would it be better to write:      The cops traced residential address of his relatives who lived nearby.


I think I barely understand how k-fold CV is working and I have a question about it.  For example, when I run 5-fold cross-validation (in SAS), I use 5 subsets of the training data, and end up with 5 different models. But I have only one output for it.  I understand the error rate is the average of those 5-folds' errors. But my model creating with which data set? When effective variables are being determinated, will SAS average the coefficients? If it's not like this, which fold will be chosen for creating my model?

I am wondering how to choose a predictive model after doing K-fold cross-validation.   This may be awkwardly phrased, so let me explain in more detail: whenever I run K-fold cross-validation, I use K subsets of the training data, and end up with K different models.   I would like to know how to pick one of the K models, so that I can present it to someone and say "this is the best model that we can produce."   Is it OK to pick any one of the K models? Or is there some kind of best practice that is involved, such as picking the model that achieves the median test error?


for my lectures I am preparing beamer presentations.   I would like to include sections (possibly more than one in a single beamer presentation) and to be able to have continuing numbering of definitions, theorems etc in the next beamer presentations.  I know how to number them in a single presentation but then in the next one the numbering begins from 1 again and I can't refer to a theorem from a previous beamer presentation.  Is there any way of doing this? Help is much appreciated

I have two files, say file1.tex and file2.tex. file1.tex is the first of a series of files, and it begins with counters (say chapter 1 for instance, although my counters are not used for chapters). Then at the end of file1, the counter for chapters is at say 7 ; I want to carry the value of the counter to file2.tex so that I can use a counter which will have the value 7 in file2.tex. In this way I could possibly carry on the counter in file2.tex to a counter in some file3.tex and so on.   I assume I would need to compile file1.tex first, and then file2.tex, and then file3.tex... of course.  Is that possible? And if so, how? I couldn't think of anything.


So I see there are lots of issues on this.  I've read through all the posts,  but cant seem to find a permanent solution on this.  I have Ubuntu 17.10 and everytime my computer reboots,  I have to reset the dns servers.  The only solution that seems to work for me is to:   Add google's DNS servers to my /etc/resolv.conf file.  Verify they are listed in my network manager gui Restart network manager.  (sudo systemctl restart NetworkManager)   Im not sure why adding the dns servers to resolv.conf works, only to have it overwritten,  but I'f I dont.  My DNS doesn't work.   I know this is not the proper way,  but every other method I've tried seems to fail.  The other issue I have is, I have several other computers on the local network (raspberry pi's)  I can't ssh into them using their names.  I can with their IP address.  Here's my current resolv.conf  # Generated by NetworkManager nameserver 127.0.1.1   Here's my /etc/hosts  127.0.0.1   localhost 127.0.1.1   Bootes64 192.168.1.101   homeassistant 192.168.1.102   media 192.168.1.103   wdnas 192.168.1.120   security  # The following lines are desirable for IPv6 capable hosts ::1     ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters   Is there a permanent solution to this?  EDIT   This has been marked as a duplicate of a similar issue,  However That is one of the first questions I ran across with google.  NONE of the suggestions there work.  and Seeing as the last update was in 2014,  I have some serious misgivings that it will work on a 17.10 machine.

I suspect that the name server provided by my ADSL modem/router is buggy. Whenever I browse to a website for the first time in ubuntu, resolving the domain name takes at least 15 seconds.  To work around that problem, I changed the nameserver configuration in /etc/resolv.conf from 192.168.1.1 (my ADSL modem) to 8.8.8.8 (google's primary DNS). This seems to fix the problem, but unfortunately my changes to /etc/resolv.conf are overwritten by "NetworkManager" at each startup.  What is the proper way to configure the name server IP in ubuntu 10.4?


How can the equality below hold? If I have a maximally entangled qudit state $\lvert \Phi\rangle_{AB}$ and any $d\times d$ matrix $M$, then it is claimed that  $$ (M_A\otimes I_B)\lvert \Phi\rangle_{AB} = (I_A\otimes M_B^T)\lvert\Phi\rangle_{AB}$$  I can see that this works for qubits and using the Pauli spin operators, but I am not seeing it in the general case.

Apparently the (d-dimensional) maximally entangled state, $|E \rangle = \sum_{i} |ii\rangle /\sqrt{d}$ is invariant under operations of the form $U \otimes U^\dagger$. I want to prove this result, which amounts to showing that  $$\left(\sum_i U | i \rangle \otimes V |i \rangle = \sum_i | ii \rangle \right)\Rightarrow (V = U^\dagger )$$  I have no idea how to even start. I suppose it's some simple linear algebra result, but I don't see it. A hint would be appreciated.


I have a point inside a polygon. I want to copy the attributes from the point to the polygon. Is there a way to do it in QGIS?

I have two shapefiles....   points containing a number field 'response_time' a polygon grid of square polygons containing fields including 'PNTCNT' with the number of points per polygon, calculated already using the tool 'points in polygon'   There are between 0 and 600 points within the bounds of each polygon in the grid.  I want to add fields to the polygon grid for the mean, min and max response times within each polygon, in addition to the PNTCNT field already there.  I have tried the 'Join attributes by location' tool, making the polygon layer the target and the points the join layer, and vice versa. I've selected 'take summary of interesting features'.  But I can't get the result I want. All I end up with is the polygon grid again but with an extra field 'COUNT' which replicates (or duplicates) the 'PNTCNT' field. No min, max and mean of values from the points layer.  What am I doing wrong? Is there a better way to do this? I have tried this using QGIS 1.7 and 1.8.


so I'm making a car in blender when I noticed a weird opacity on my mesh while in X-ray mode, why is it there? can I get rid of it? and how can I prevent it from happening?

What's happening is that I have tried to flip the normals, inside and out, but there are always faces which have to be flipped!  Normals recalculated   Inside View    If I flip them again, all faces get flipped and end up horrible and, not working at all. So how can I make all of the faces flip to the right direction?


On old Dell Dimension 2400, with 40 Gb hard drive and 1 Gb RAM, had installed via USB drive--Lubuntu 14.04 (NO dual boot). Previously had Windows XP, Service Pack 3 on this hard disk. Obviously, I am not very thorough and did not check to see where Lubuntu had downloaded onto hard disk. Had already downloaded several Lubuntu apps updates in the past, but when trying to set up download for current apps updates, get error message saying disk is almost full. The lightbulb went on and I went to look at disk data.     It appears all of Lubuntu is in boot disk.    How do I fix this? Why would Lubuntu have installed to boot disk and not into boot AND  extended partitions? (I don't remember the specifics of my install as it was some time ago).

My first issue was when I tried to apt-get update or apt-get upgrade. On upgrade I get the following error:  You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies: linux-image-server : Depends: linux-image-3.2.0-27-generic but it is not installed E: Unmet dependencies. Try using -f.   I tried running apt-get install -f and this was the output(after saying yes on prompt)  (Reading database ... 186183 files and directories currently installed.) Unpacking linux-image-3.2.0-27-generic (from .../linux-image-3.2.0-27-generic_3.2.0-27.43_amd64.deb) ... Done. dpkg: error processing /var/cache/apt/archives/linux-image-3.2.0-27-generic_3.2.0-27.43_amd64.deb (--unpack):  failed in write on buffer copy for backend dpkg-deb during `./boot/System.map-3.2.0-27-generic': No space left on device  No apport report written because the error message indicates a disk full error                                                                           dpkg-deb:    error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.2.0-27-generic   /boot/vmlinuz-3.2.0-27-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.2.0-27-generic /boot/vmlinuz-3.2.0-27-generic Errors were encountered while processing: /var/cache/apt/archives/linux-image-3.2.0-27-generic_3.2.0-27.43_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   I tried running apt-get autoremove and it gives me the same error as apt-get upgrade.  When I run df, I get this for /boot:  /dev/sda1                    233191     230297         0 100% /boot   So, I read elsewhere that I should try to purge old kernels. I checked for what kernels I had with:  $ dpkg -l linux-image-\* | grep ^ii ii  linux-image-2.6.38-13-server  2.6.38-13.52  Linux kernel image for version 2.6.38 on x86_64 ii  linux-image-3.0.0-13-server   3.0.0-13.22   Linux kernel image for version 3.0.0  on x86_64 ii  linux-image-3.0.0-14-server   3.0.0-14.23   Linux kernel image for version 3.0.0  on x86_64 ii  linux-image-3.0.0-15-server   3.0.0-15.26   Linux kernel image for version 3.0.0  on x86_64 ii  linux-image-3.0.0-16-server   3.0.0-16.29   Linux kernel image for version 3.0.0  on x86_64 ii  linux-image-3.0.0-17-server   3.0.0-17.30   Linux kernel image for version 3.0.0  on x86_64 ii  linux-image-3.2.0-24-generic  3.2.0-24.39   Linux kernel image for version 3.2.0  on 64 bit x86 SMP ii  linux-image-3.2.0-25-generic  3.2.0-25.40   Linux kernel image for version 3.2.0  on 64 bit x86 SMP ii  linux-image-3.2.0-26-generic  3.2.0-26.41   Linux kernel image for version 3.2.0  on 64 bit x86 SMP   When I try to remove the oldest with this:  $ sudo apt-get purge linux-image-2.6.38-13-server Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies: linux-image-server : Depends: linux-image-3.2.0-27-generic but it is not going to be     installed E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).   How can I free up or extend boot without messing up my installation?


Let $f, \ u, \ v: \mathbb{R} \to \mathbb{R}$ with $f$ continuous, $u$ and $v$ differentiable.  (1) Let $F(x) = \int_{0}^{v(x)} f(t)dt$, prove that $F$ is differentiable and calculate $F'(x)$.  (2) Now let $F(x) = \int_{u(x)}^{v(x)} f(t)dt$ and prove again that $F$ is differentiable and calculate $F'(x)$.  I tried to prove it using the fundamental theorem of calculus. In this way, i got:  As f is continuous, so F is derivable and its derivative is $F'(x) = f(v(x))$. This way i didn't use that u is differentiable (a bit weird i guess). Am i right? I either tried to use this method in second item, but again it falls into the same problem.

Given $$f(x) = \int_{0}^{\phi (x)} g(t) dt$$ How could we find $f'(x)$? Please explain your answer.


I want to return by reference to a variable that's inside a switch, like for example: sometype & getbar();  void foo() {         switch ( {statement} ) {         case {statement}:             sometype & handle = getbar();         ...  But I'm getting compiler errors:  initialization of 'identifier' is skipped by 'case' label initialization of 'identifier' is skipped by 'default' label  And it looks like it's not possible to do this: void foo() {         sometype & handle;         switch ( {statement} ) {         case {statement}:             handle = getbar();         ...  Because a reference variable requires initialization. Is there a way to do this with keeping the switch statement?

I've always wondered this - why can't you declare variables after a case label in a switch statement?  In C++ you can declare variables pretty much anywhere (and declaring them close to first use is obviously a good thing) but the following still won't work:  switch (val)   {   case VAL:     // This won't work   int newVal = 42;     break; case ANOTHER_VAL:     ...   break; }     The above gives me the following error (MSC):     initialization of 'newVal' is skipped by 'case' label   This seems to be a limitation in other languages too.  Why is this such a problem?


I am new to programming.  I want to set java environment, but it is not working even I set the path.  This is the directory, I put the first one on path C:\Program Files\Java\jre1.8.0_181\bin:   here is my path for java in system variable:   I tried to restart cmd and even my laptop, but it is still not working  Thank you for you help!

java program is not running on my windows 10 pc.  C:\Users\Antony>set path=C:\Program Files (x86)\Java\jre1.8.0_171\bin  C:\Users\Antony>cd Desktop  C:\Users\Antony\Desktop>javac helloworld.java 'javac' is not recognized as an internal or external command, operable program or batch file.  C:\Users\Antony\Desktop>  environment path =C:\Program Files (x86)\Java\jre1.8.0_171\bin   C:\Users\  java -version java version "1.8.0_171" Java(TM) SE Runtime Environment (build 1.8.0_171-b11) Java HotSpot(TM) Client VM (build 25.171-b11, mixed mode, sharing)   still showing same error


I used to have an iPhone, but I changed to an android (shock, horror!). Unfortunately Apple refuses to let me go and whenever friends message me the messages get sent as iMessages (unless they remember to specifically chnge the format). I never get these messages. They never get resent as SMSs automatically as is supposed to happen. How can I get my phone number deleted from the iMessage list. I've turned off iMessage on the old iPhone.

How can I disable iMessage for a phone number if the iPhone it's attached to has been destroyed? My sister dropped her iPhone in the bath, so she is now using an older non-Apple phone. Whenever I send her a message, it gets sent as an iMessage (and even says "Delivered"), but her device never receives the message.  The only information I could find was  which states the following:     If you plan on transferring your SIM card or phone number from an iPhone to a device that does not support iMessage, turn off iMessage in Settings > Messages first. If you do not, other iOS devices may continue to try to send a message using iMessage first, instead only using SMS or MMS.   However, since this iPhone was destroyed, we can't get into the settings to unregister her phone number.


I'm looking for all Internet about how sending a custom object using an Intent inside of an setOnItemClickListener. I want to send this Person Object to another Activity, but it's always sending null. I need to put it in 6 EditText different. Can someone help me?  listEndereco.setOnItemClickListener(new AdapterView.OnItemClickListener() {         @Override         public void onItemClick(AdapterView<?> parent, View view, int position, long id) {             Intent intent = new Intent(AdrressApp.this, EditorPerson.class);             Person pessoa = listEndereco.getItemAtPosition(position);             intent.putExtra("pessoa", pessoa);             startActivity(intent);         }     });   Here is the another activity:  Intent i = getIntent(); Person idPessoa = (Person) i.getSerializableExtra("pessoa");   When I run the app I get this error:   Attempt to invoke virtual method 'void android.widget.EditText.setText(java.lang.CharSequence)' on a null object reference

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?


The answer to this question should really focus on the either proving or disproving the points below and stating a summary or conclusion to your answer which states how you think the evidence more strongly aligns.  The first point would have to be whether it would work at all.  How would you cast a spell from two wands? Would you use them in separate hands or together? You do not need to answer these smaller points in your answer they are just my own thoughts.  The second point would have to be whether it would actually affect the power of the spell  As we all know (or at least I hope you do) the wand is used to focus magical energy so really would we not end up with a larger and less focussed point for magical energy?  Would you actually be able to cast one spell that went to two separate targets?  This would only be apt for using two wands in separate hands but the coordination required for this would be incredible and possibly take years to learn to do effectively at least.  End of points. Now for some discussion.  Clearly you would need two wands that would be aligned to you, thus the elder wand rears it's ugly head again! As Dumbledore would have had 2 wands at one point, Harry also did after repairing his own with the elder wand but that wasn't his style. Dumbledore out of all wizards could have learnt to use two wands although knowledge and skill was more to his liking that pure power.(The hallows excluded) I am going to imagine that I will gain an answer that will just state no wizard in the books was seen to do this so it isn't something that will happen.     How would using two wands work?

Can a wizard use more than one wand at the same time?   Kind of like 2-gun shooting gunfighters in the Old West?


Lets say you have those methods : public static void listAdd(List<Integer> list){     list.add(123);     list.add(123);     list.add(234);       } static void compute(String s){     switch(s){     case "1" : s ="other";     break;     case "test" : s ="2222";     break;     default : s ="none";          }     System.out.println("my value inside is none:" + s);  }  Then inside my main i will call both of them:     listAdd(list);     System.out.println(list.size());     String var = "helloworld";     compute(var);     System.out.println(var);  Why does size return 3 [inserted 3 elements changed the list] but my string doesnt change? 3 (outside static) none (system out inside static) helloworld (outside static)

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


I wanted to develop an app similar to  on my own which is based on image classification using neural nets. While in early phases of my research I came across through terms Deep Neural Nets and Convolutional Neural Nets.   What is the difference between two and which will be the best bet for me to work on for this project?  Edit1:- I looked on kaggle's digit recogniser for my initial research

I want to use deep learning in my project. I went through a couple of papers and a question occurred to me: is there any difference between convolution neural network and deep learning? Are these things the same or do they have any major differences, and which is better?


I have a dataset with numerical and categorical features. I am trying to run a k-means algorithm to find clusters of data.  What is the best way to encode categorical features?  I have been doing one hot encoding but I guess that it can be easily improved.

My data set contains a number of numeric attributes and one categorical. Say, NumericAttr1, NumericAttr2, ..., NumericAttrN, CategoricalAttr, where CategoricalAttr takes one of three possible values: CategoricalAttrValue1, CategoricalAttrValue2 or CategoricalAttrValue3. I'm using default . It works with numeric data only. So my question: is it correct to split the categorical attribute CategoricalAttr into three numeric (binary) variables, like IsCategoricalAttrValue1, IsCategoricalAttrValue2, IsCategoricalAttrValue3 ?


There's a not-so-recent video by a user named quirkology , where he shows bets that usually work. From , he puts a wine bottle cap at the center of a glass filled halfway with water, and this cap eventually moves to the sides.   $\qquad\qquad$   And the trick he shows to make the cap rest at the center without touching it is to add water until the glass if entirely filled, then the cap rests in the center.   $\qquad\qquad$   Does anyone have an explanation of that phenomenon?

Why does a cork ball float to the side of a glass as illustrated in the following GIF? What is the physical phenomenon behind this observation and why does it happen?


I'm trying to solve a problem in which this notation occurs. On the one hand, I have the question of what it means that a function f is an element of {0,1} ^ N and what {0,1} ^ N means. Thank you in advance!

Let $ D = 2^\mathbb{N} $, i.e., D is the set of all sets of natural numbers.   What's the meaning of this definition? Intuitively, I would suggest that $ D = \{1,2,4,...\} $ but the explanation "set of all sets" leads me to the guess that this is wrong.


My ubuntu used to play music or vids by pushing the space bar while the cursor is over the file. How can I get this back on 14.10?

Just upgraded from 11.04 to 11.10 and Nautilus no longer previews MP3 files when I hover over them.   Another PC that's been running 11.10 for a while also experienced this after the latest update  Nautilus preferences no longer show options for media / mp3 files, so how can I get this functionality back?


What is the best way to quickly reach on google  iam trying many submission but it not working

What are the best ways to improve a site's position in the Google search results?


I want to show $2^{ℵ_0}=\mathfrak c$.  I already showed $\mathfrak c \leq 2^{ℵ_0}$ as follows:  Each real number is constructed from an integer part and a decimal fraction. The decimal fraction is countable and has $ℵ_0$ digits. So we have  $\mathfrak c \leq ℵ_0 * 10^{ℵ_0} \leq 2^{ℵ_0} * (2^4)^{ℵ_0} = 2^{ℵ_0}$ since $ℵ_0 + 4ℵ_0=ℵ_0$  But how can I prove the other way $2^{ℵ_0} \leq \mathfrak c$?

$\aleph_0$ is the cardinality of the set of natural numbers, $\aleph_0 = |N|$. $c$ is the cardinality of the continuum, i.e. the set of real numbers $c = |R|$.  I know that $|P(A)| = 2^{|A|}$. This means that the cardinality of the power set of a set is 2 raised to the power of the cardinality of that set.  This basically means that to prove  $2^{\aleph_0} = c$, I need to prove $c = |P(N)|$. I've seen the Cantor diagonal argument, although I have no idea on how to use it to prove this.   Could anyone suggest ideas of the simplest way to prove that $2^{\aleph_0} = c$?


I am executing the string that contains the below code  DECLARE @BadgeNo NVARCHAR(MAX); SET @BadgeNo='8107';  SELECT * INTO #Testing     EXEC spNotification 'Param1','Param2','Param3','Param4';  EXEC  spSqlTmpTblToHtmlTbl 'tempdb..#Testing'   I just want the result in html format. So I am executing spnotification to get the results.  The spSqlTmpTblToHtmlTbl converts the temp table to table format. But here is an issue that I can't create a temp table from spNotification result. I know   select * into    command won't work with the exec command. So how can I achieve this?

How do I do a SELECT * INTO [temp table] FROM [stored procedure]? Not FROM [Table] and without defining [temp table]?  Select all data from BusinessLine into tmpBusLine works fine.  select * into tmpBusLine from BusinessLine   I am trying the same, but using a stored procedure that returns data, is not quite the same.  select * into tmpBusLine from exec getBusinessLineHistory '16 Mar 2009'   Output message:     Msg 156, Level 15, State 1, Line 2   Incorrect syntax near the keyword   'exec'.   I have read several examples of creating a temporary table with the same structure as the output stored procedure, which works fine, but it would be nice to not supply any columns.


Put another way, is it possible to reverse the work done by the TeX engine? instead of going from source to file, going from file to source?

I know that hardly any information is passed to the PDF when a .tex file is compiled.  But is there a tool that can convert a PDF document back to (La)TeX?


I am developing an application in Android Studio and want to make a favourites page. To do this, I would like the user to be able to save the activity to the favourites, and when opening the favourites page from the home page, the user can view the button to start this activity.   I have looked up numerous other similar questions but none which suits my specific issue.  I have looked at different possibilities such as SharedPreferences, ToggleButton etc. but none I can get to work.   I would really appreciate your help.  Thank you so much in advance.

I've been working on the Android SDK platform, and it is a little unclear how to save an application's state. So given this minor re-tooling of the 'Hello, Android' example:  package com.android.hello;  import android.app.Activity; import android.os.Bundle; import android.widget.TextView;  public class HelloAndroid extends Activity {    private TextView mTextView = null;    /** Called when the activity is first created. */   @Override   public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);      mTextView = new TextView(this);      if (savedInstanceState == null) {        mTextView.setText("Welcome to HelloAndroid!");     } else {        mTextView.setText("Welcome back.");     }      setContentView(mTextView);   } }   I thought it would be enough for the simplest case, but it always responds with the first message, no matter how I navigate away from the app.  I'm sure the solution is as simple as overriding onPause or something like that, but I've been poking away in the documentation for 30 minutes or so and haven't found anything obvious.


Sorry about this dumb question, but i´ve recently found out that you can declare a String or string variable at C#. I would like to know the difference between them, which one is used at specific situations, etc. Thanks for the help and for your time.

Example (note the case):  string s = "Hello world!"; String s = "Hello world!";   What are the guidelines for the use of each? And what are the differences?


We have a web application that we are about to take live. But I have a fear that the server won't be able to handle all the requests and it won't be as comfortable to the users as a website should be. Currently I'm thinking about using 2 things. One of them is having 2 more additional servers and use them to loadbalance the users between the servers. So it would be 1 Loadbalanced server, 2 webapplication servers and 1 backend (database) server.  The other thing is HTTP cache. Can it be enough if I just get one more server and set it up as a cache server with NginX? Which would you do if you are limited in terms of resources and why? (Maybe how?)

This is a  about  Related:      I have a question regarding capacity planning. Can the Server Fault community please help with the following:   What kind of server do I need to handle some number of users? How many users can a server with some specifications handle? Will some server configuration be fast enough for my use case? I'm building a social networking site: what kind of hardware do I need? How much bandwidth do I need for some project? How much bandwidth will some number of users use in some application?


I am trying to concatenate a directory full of .mp4 files into a single video through the terminal.  I have found plenty of methods that say they can do this but either require FFmpeg (which, to the best of my knowledge, is no longer supported) or they simple do not work.  Is it still possible to do this and if so how might I go about doing it?

What's the best & easiest GUI software that can join a video that I have downloaded in several parts?


I'm trying to understand the upsides/downsides of investing to an index fund vs. investing directly to stocks of some best-known and well-established large-cap companies. Every single article on investment strategies says that for someone, who does not want to become full-time investor, the best thing is to invest in an index fund and wait 10+ years till your money grows. Let's compare some well-established large-cap companies' performance with performance of well-established index funds. For instance, let's take average yearly growth percentage for the last 10 years for some companies:  Apple - 28.09% Amazon - 33.32% Nvidia - 45.27% Microsoft - 26.66% AMD - 27.94% Mastercard - 31.34% Shopify - 44.50% Square - 32.19% MercadoLibre - 36.98% Netflix - 32.81%  Let's compare them to some well-regarded index funds:  Vanguard U.S. Growth Fund (VWUSX) - 18.54% Vanguard Growth Index Fund (VIGAX) - 16.82% Vanguard Total Stock Market Index Fund (VTSAX) - 14.04%  My thoughts:  There is a huge gap between growth of the stocks vs. growth of the index fund Yes, I know that index funds are created by smart people/algorithms to be more reliable than usual stocks of several companies and they follow some particular indices for a reason. Yes, I know they include other stocks apart from the ones I mentioned above to balance the portfolio and defend against drops in price of the main stocks Interestingly, the lion's share of the cost of each of the growth index funds consists exactly of the companies I listed above Yes, I know that I included mostly companies from tech and finance sectors. But those are the ones, which are expected to grow best of all anyway, because the whole economy is driven by them. If the economy would collapse, then those companies would collapse with it and vice versa. I don't see any single chance that any other sector can in the nearest future outperform the tech and finance sectors, or that those sectors may fall much more than the rest of the businesses.  My question is: what would I get investing in much worse growing index fund vs. investing to some chosen well-established large-cap companies?

Whereas companies like Google, Facebook, Netflix, Amazon, Apple have all increased anywhere from 3x-6x in value in the past 5 years. If you just stuck with those companies, you would have easily beaten the S&P 500's 1.5x gains. Then there are some companies like Tesla and Square that have 10x'd in value over the past 5 years. To me it seems that if you just pick a handful of good businesses to invest in, you'll be able to beat the S&P 500. You can even just google the top 10 companies in the S&P 500 and invest in them. The average gains from all of those companies including dividends, have also beaten the S&P 500 in the past 5 years. I am just curious at what I am missing, because every time I research this question common advice seems to be to just stick to an index fund of the S&P 500 as most investors can't beat its returns.


I want to overlay a line image (no background, just the lines) on top of a solid image so that the lines are superimposed over the other, opaque image. I've tried it with the overlay as both a PNG and a GIF, but it keeps displaying as solid, completely covering up the second image. I've even tried playing with the z-index to no avail. Is this not possible? If it is, do you know what I'm doing wrong?         .Overlay {         position: relative;         display: block;         }             .Solid {         position: absolute;         top: 0;         left: 0;         }

I want to overlay one image with another using CSS. An example of this is the first image (the background if you like) will be a thumbnail link of a product, with the link opening a lightbox / popup showing a larger version of the image.   On top of this linked image I would like an image of a magnifying glass, to show people that the image can be clicked to enlarge it (apparently this isn't obvious without the magnifying glass).


What is a function $f(x)$ that is smooth and approximates a staircase function (a function composed of a set of equally spaced jumps of equal length)?  With , I know of $f^n(x)$, where n is an integer and $f(x)=x-\sin(x)$, but it requires quite a large amount of terms to get to a desired sharpness. So, I'm looking for approximations that is not recursive and requires only a finite amount of terms.

I am looking for a smooth staircase equation $f(h,w,x)$ that is a function of the step height $h$, step width $w$ in the range $x$.   I cannot use the unit step or other similar functions since they are just one step. I have been experimenting with various sigmoid curves and while I can get a single smooth step I cannot get to realize the staircase shape. The closest staircase function I have found is given in  in equation (18) and depicted in Fig. 4 and it is a close example of what I want (i.e generate a staircase in the range $x$ for arbitrary step heights and widths) but it is not smooth at all.  Regarding smooth steps, a likely starting point I found is  but it gives a smooth function of just a single step. I have been unable to modify the equation to make it into a staircase. I would like to specify arbitrary step heights and widths and generate a smooth staircase in the range $x$ specified.    Edit (Extra info): The smooth function I mention above has the problem that the upper, horizontal line is not equal in length to the lower, horizontal line which is why I have been unable to adapt it into a staircase function   Edit 2 Including some pictures     Edit 2 Plot of $s$ with a steep slope showing a different width on the first horizontal line


$1 \frac{1}{2} ... \frac{1}{n}$      $\frac{1}{2} \frac{1}{3} ... \frac{1}{n+1}$      $.$      $.$      $.$      $\frac{1}{n} \frac{1}{n+1} ... \frac{1}{2n-1}$      Does the inverse of this matrix have integer entries? Prove your   statement.   I thought of  multiplying every line $i$ by $i!$, but it leads to a very complicated solution (if it leads to a solution at all).  Source: Linear Algebra, Kenneth Hoffman and Ray Kunze. Section 1.6, exercise 12.

Let $A$ be the $n\times n$ matrix given by $$A_{ij}=\frac{1}{i + j - 1}$$ Show that $A$ is invertible and that the inverse has integer entries.  I was able to show that $A$ is invertible. How do I show that $A^{-1}$ has integer entries? This matrix is called the Hilbert matrix. The problem appears as exercise 12 in section 1.6 of Hoffman and Kunze's Linear Algebra (2nd edition).


As is probably a very regular question here, I have a Samsung Galaxy S5 Neo and I'm having problems with the amount of memory being clogged up by what I will assume is garbage. I have installed on my phone ES File Explorer and it helps with cleaning things up, but I'm consistently low on internal storage and as a result my phone is slowed down. I barely have any  documents or downloads on my phone. The largest set of files is pictures which take up 194.38 MB. Here is where the issue is, there is 9.72 GB being categorized as "Other". So the percentages are as follows:   Picture: 194.38 MB Audio 103.99 KB  Video 124.23 MB Document 8.68 MB APPs 6.34 MB Others 9.72 GB   It drives me up a wall because I don't save anything to my internal storage and always use my SD card. So I'm of the feeling that it is my provider and Samsung that have put a bunch of bloatware on my phone. So the question is how to find it and get rid of it all? Suggestions on a set of instructions I could follow? I feel there i no reason my phone should be this restricted for storage considering how I use it.  Thanks in advance.

The internal storage on my phone is almost full. The storage screen tells me    2.77GB / 2.91 GB taken Apps 0.89GB Other 1.89 GB Available 138MB   What is this "other" and how can I clean it up? I already followed the steps of "make more space", it barely makes a difference.   Phone Storage then tells me 43.00MB / 1.09GB is taken.  And on the SD card I have 1.86GB / 14.72GB taken.  I have plenty of storage in various places yet when I try to install apps I'm unable to do so cause of "insufficient storage". How can I fix this?