I am an Indian passport holder. I am planning to apply for a Belgium visa for a conference. I am also planning to visit Spain after this conference.  In the online application form, I need to fill up a box called:  "Member State(s) of destination". But in the answer box, they have provided provision to enter only one EU country name. When I enter 'Belgium', then I cannot enter 'Spain' without cancelling 'Belgium' first.  When I click further information it says: "Please indicate which Schengen Member state you are visiting."  Which country should I enter then?  Any help will be greatly appreciated.

I am traveling to Paris staying there for 5 days then flying to Spain and staying there for 10 days.  My understanding is that since Spain is where I am spending most of the time then I should apply for the visa in the spanish embassy.  But how about these fields in my case, How should I fill them? "Member states of destination" & "Member state of first entry"... Should they be "Spain" and "France" respectively?


The end goal is reduce the footprint that apps and their dependencies use. To that end, we need to know the sizes of packages and their dependencies.   Unfortunately as any experienced Linux user will tell you, there is no safe way to automatically remove dependencies i.e., through a script. Inevitably if you do this you will break something. So you have to go about it manually.   Hence the user needs some way to find out what is taking up disk space because mere package size is insufficient. I have scoured the web looking for a command to provide this information but did not find one, so I constructed my own.

I am running out of disk space on my root partition, and I'm attempting to remove some packages and not others.


i'm currently trying to store data via localstorage on my website, and if for example I do so :   localStorage.setItem("vue",10206726906969851)   When I want to get the value back I get this result :   localStorage.getItem("vue") -> "10206726906969852"   So why does the value changes ? Thank you in advance for your help

Is this defined by the language? Is there a defined maximum? Is it different in different browsers?


I couldn't find an answer on the internet but my script fails solving this. I have to know this because this is required to prove something else (it has to do with random numbers and their period).  I cannot say if they are coprime because I don't know if they are coprime because of the fact that division by $0$ doesn't work.  On the other hand I say they are not coprime because we don't get to $\text{gcd}(0,13)=1$.  But this is very confusing for me, please help!

I have tried $\gcd(0,8)$ in a lot of online  gcd (or hcf) calculators, but some say $\gcd(0,8)=0$, some other gives $\gcd(0,8)=8$ and some others give $\gcd(0,8)=1$. So really which one of these is correct and why there are different conventions?


Swordsages are not proficient in medium armor.  Mithral breastplate is medium armor, but treated as light armor.   Are swordsages proficient in medium armor?  If a swordsage wears mithral breastplate, do they still receive the AC bonus from Wisdom?

counts as one armor weight category less (heavy, medium, light) for "purposes of movement and other limitations... which are left unspecified.   An example of where this might come up: Armor Crystals; which can only be put on certain weight categories of armors.   What other circumstances will cause this problem, and which way does this interaction fall?


So I'm making a small game on Blender Game Engine and its racing. What i want is so that when a player presses w the car starts moving and slowly gains velocity. I know about the controller's that make an object move but i want to know how to make it BUILD speed as it progresses.(the reason i tagged this as python is because i am assuming this will take some python. Do i use Python for this)?

In the attached , I have a representation of a airplane/jet fighter (cube scaled at one end to indicate direction of flight). I am using torque to steer, and adding Linear Velocity along a local axis for thrust/brakes. What I want to know is how to clamp the velocity along the plane's local axis so when the plane steers, it does not simply keep flying in the direction that is was before it turned. I would prefer a solution with logic bricks, but if that is not possible, python would be acceptable. (it just needs to keep a speed relative to how long the thrust/breaks have been held no mater which direction it is pointing.)


Hello I have downloaded youtube-dl through the terminal but I can not use it. I can't even find the icon for it on my screen. Help, please.

I have installed youtube-dl(program for downloading videos from youtube) successfully but I am not able to see it either in dash or among application folder. It is listed in software centre and synaptic packet manager. somebody suggest a way out..thanks in advance


I want to record my screen, audio and webcam in Ubuntu. Any suggestion for good software to do this?

How can I record my screen on Ubuntu?   The app I'm looking for has ideally all of these features:   Can record in a format that can be played back easily on any platform and/or accepted by YouTube or another popular video site Can record just a window (instead of the whole screen), possibly selecting it with a mouse click Can start recording after a configurable delay (e.g., I launch the app and have time to do arrangements to my desktop/window before actual recording starts)


In SharePoint on premises, we have correlation ID and ULS logs, we also have developer Dashboard. But how do we troubleshoot issues in SharePoint online.

I want to read ULS logs for my sharepoint online server.   Is there any standard way of doing it ?


Am I able to add more disk space to the OS?  I did the default during the install, and wondering in case I ever needed to allocate more.

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


I have used the /testfor command a lot but I ran into a problem I thought you could help with.  This is my command:  /testfor @p[r=3] {Inventory:[{id:"minecraft:log",Count:64b}]}   In this command I want it to test for log number 2, which is birch wood, but the thing is I don't know how to insert that.  I want it so it detects if the player has a 64 stack of birch wood.

Let's say I want to track a group of players to see which one of them (if any) have a specific block type in their inventory that's of a specific datavalue; for instance Red Wool (minecraft:wool with a data value of 14).  I already know how to detect if a player has any wool in their inventory: /testfor @a {Inventory:[{id:"minecraft:wool"}]}. However, this doesn't discriminate between the various colours.  It'll find anyone with any colour wool, whereas I want to find only players with red wool.  I've tried modifying the data tag to also include a data value, such as /testfor @a {Inventory:[{id:"minecraft:wool",data:14}]} but this results in unmatched NBT tags and the  error message <Player> did not match the required data structure.  Obviously it's because data (or Data, damage, dataID, etc.) isn't the name of the NBT tag, or that the structure is wrong.  I realize I can accomplish this using the /clear command, but that's a bit clunky when running on a 20Hz /fill clock.  How can I filter out specific data values when using the /testfor or /scoreboard players commands?


I made a conveyer belt and then I tried putting a cube on top of it. The belt carries the cube like you would expect, but about half way through, the cube falls through the belt.

I've created conveyor belt and and two objects with rigid body physics. But the first object won't fall and second object falls backwards.  How can I fix it?


I have a simple problem basically I am unable to understand the meaning of some questions involving or/not, and using comma with and. I have the following questions:-  1.Whats the meaning of, say , X does not play football or cricket.  What we can infer from this. Can we say X does not play both of them? or one of them?  2.How the previous line is different from X does not play either football or cricket.  next is  3.If x does not play both of them, why in books such kind of statements are there instead of neither/nor.  and  4.whats the meaning of M and N, who reads newspaper, are not sitting together.  Here,  Do M and N, both reads newspaper? Please clarify these things to me. I am not a native Englishman so I found it very difficult to understand and as in logical reasoning questions these statements are common to see I face lot of problems. Please also tell me about such more things that can be confusing, may be, provide a link.

In mathematics, "A or B" includes "A and B". Does "either" mean "A or B but not (A and B)" or does it include the possibility of "A and B"? The context might be mathematics, formal logic or ordinary language.


How can I generate a CSR for attaching SSL certificate to the site? In various articles about installing SSL certificates are described different ways of generating private key and CSR. That's like two different versions: (a) openssl req -nodes -newkey rsa: 2048 -keyout myserver.key -out server.csr and (b) openssl genrsa -des3 -out www.mydomain.com.key 2048.  So -   How to generate a CSR and private key? What is the difference between the teams generate CSR and key (a) and (b)? Do I need to set a password when generating the CSR and key? Reduces whether a site is vulnerable to attack as the password for the private key?

I'm running CentOS 6.2 LAMP and I've just purchased an SSL certificate via Namecheap that I'm trying to install on my server.  is the certificate I purchased.  How do I complete this process without the use of a web host?  So far, I have installed SSL using yum install mod_ssl openssl and I am now being asked for a CSR via NameCheap and to choose my Server type.  Are mod_ssl and openssl both in there for Apache2?    What is a CSR and how do I generate one?  The tutorials I've found online are all using self signed certificates, which is not what I want.


I am trying to create a simple file indexing utility in Python 3.4. The goal is to enable quick searching for a filename using an index.  To do this I have used the os.walk function, but I get a UnicodeEncodeError when trying to print the name of a directory. I looked at other questions such as  and  but they don't seem to describe the same error (UnicodeEncodeError).  My code is:  def index_files(path_to_index):     indexed_files = []      for dirname, dirnames, filenames in os.walk(path_to_index):         # print path to all subdirectories first.         for subdirname in dirnames:             print(os.path.join(dirname, subdirname))          # print path to all filenames.         for filename in filenames:             full_path = os.path.join(dirname, filename)             print("Found " + full_path)             indexed_files.append(full_path)   The output I'm getting is:  Traceback (most recent call last):   File "[OMITTED LOCAL PATH]indexer.py", line 40, in <module>     main()   File "[OMITTED LOCAL PATH]indexer.py", line 37, in main     indexed_files = index_files(path_to_index)   File "[OMITTED LOCAL PATH]indexer.py", line 16, in index_files     print(os.path.join(dirname, subdirname))   File "C:\Python34\lib\encodings\cp850.py", line 19, in encode     return codecs.charmap_encode(input,self.errors,encoding_map)[0] UnicodeEncodeError: 'charmap' codec can't encode characters in position 31-34: character maps to <undefined>   What is the proper way to do this?

When I try to print a Unicode string in a Windows console, I get an error . UnicodeEncodeError: 'charmap' codec can't encode character .... I assume this is because the Windows console does not accept Unicode-only characters. What's the best way around this? Is there any way I can make Python automatically print a ? instead of failing in this situation? Edit:  I'm using Python 2.5.  Note: @LasseV.Karlsen answer with the checkmark is sort of outdated (from 2008). Please use the solutions/answers/suggestions below with care!!  is more relevant as of today (6 Jan 2016).


I'm having trouble increasing the size of my bar chart. I am using a template and can't figure out how to increase the size. Currently my bars and labels are overlapping as shown.  Any ideas on how to fix? Template Code: import matplotlib.pyplot as plt import numpy as np   labels = ['G1', 'G2', 'G3', 'G4', 'G5'] men_means = [20, 34, 30, 35, 27] women_means = [25, 32, 34, 20, 25]  x = np.arange(len(labels))  # the label locations width = 0.35  # the width of the bars  fig, ax = plt.subplots() rects1 = ax.bar(x - width/2, men_means, width, label='Men') rects2 = ax.bar(x + width/2, women_means, width, label='Women')  # Add some text for labels, title and custom x-axis tick labels, etc. ax.set_ylabel('Scores') ax.set_title('Scores by group and gender') ax.set_xticks(x) ax.set_xticklabels(labels) ax.legend()  ax.bar_label(rects1, padding=3) ax.bar_label(rects2, padding=3)  fig.tight_layout()  plt.show()

How do you change the size of figure drawn with Matplotlib?


for ( var i = 0; i < 5; i++ ) {     setTimeout(function() {         alert( i );     }, i * 100 );  }   I took the above example from the internet to understand closures. But I could not understand why it alerts value 5 for 5 times. Instead of alerting 1,2 3,4 ,5. But the following way can be done. Can someone explain why. I am new to JavaScript so please provide some elaborate answers.  var createFunction = function( i ) {     return function() {         alert( i );     }; };  for ( var i = 0; i < 5; i++ ) {     setTimeout( createFunction( i ), i * 100 ); }

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


So, I have been reading about connection of particle physics and thermodynamics of early universe. Like after big bang, and quark - gluon plasma etc..  Anyway, after 1 second after big bang, the ratio of proton and neutron was around 7; which means there were a lot of more protons, rather then neutrons.  And this is also a reason which helped later nucleosynthesis. So, my question is what are the reasons here why there was a bigger number of protons, from neutrons.  Should I watch it here from the perspective are protons and neutrons stable? Is the same like radioactive decays?

In the book of The First Three Minutes by Weinberg, on pages 106-107, it is stated that  SECOND FRAME. The temperature of the universe is 30,000 million degrees Kelvin [...] The nuclear particle balance has conse- quently shifted to 38 per cent neutrons and 62 per cent protons. [...] THIRD FRAME. The temperature of the universe is 10,000 million degrees Kelvin. [...] The decreasing temperature has now allowed the proton-neutron balance to shift to 24 per cent neutrons and 76 per cent protons.  What is the reason for this balance shift between neutrons and protons? And what determines the rate of change of the neutron/proton ratio?


We noticed the server crashes with below errors. Not sure it is related to any defected piece of the hardware or totally not related to   Server detail:Red Hat Enterprise Linux ES release 4 (Nahant Update 6) [root@athena log]# uname -a Linux athena.nsdecatur.local 2.6.9-67.0.7.ELsmp #1 SMP Wed Feb 27 04:47:23 EST 2008 x86_64 x86_64 x86_64 GNU/Linux  messages  Sep 17 15:08:16 athena kernel: EDAC k8 MC0: general bus error: participating processor(local node response), time-out(no timeout) memory transaction type(generic read), mem or i/o(mem access), cache level(generic) Sep 17 15:08:16 athena kernel: MC0: CE page 0x2c2766, offset 0xb10, grain 8, syndrome 0xac08, row 1, channel 0, label "": k8_edac Sep 17 15:08:16 athena kernel: MC0: CE - no information available: k8_edac Error Overflow set Sep 17 15:08:16 athena kernel: EDAC k8 MC0: extended error code: ECC chipkill x4 error Sep 17 15:08:17 athena su(pam_unix)[19579]: session opened for user oracle by (uid=0) Sep 17 15:08:17 athena su(pam_unix)[19579]: session closed for user oracle Sep 17 15:08:17 athena su(pam_unix)[19634]: session opened for user oracle by (uid=0) Sep 17 15:08:17 athena su(pam_unix)[19634]: session closed for user oracle Sep 17 15:08:18 athena kernel: EDAC k8 MC0: general bus error: participating processor(local node origin), time-out(no timeout) memory transaction type(generic read), mem or i/o(mem access), cache level(generic) Sep 17 15:08:18 athena kernel: MC0: CE page 0x39c857, offset 0xd50, grain 8, syndrome 0x1cc8, row 1, channel 0, label "": k8_edac Sep 17 15:08:18 athena kernel: MC0: CE - no information available: k8_edac Error Overflow set Sep 17 15:08:18 athena kernel: EDAC k8 MC0: extended error code: ECC chipkill x4 error Sep 17 15:08:18 athena su(pam_unix)[19715]: session opened for user oracle by (uid=0) Sep 17 15:08:18 athena su(pam_unix)[19715]: session closed for user oracle Sep 17 15:08:18 athena su(pam_unix)[19758]: session opened for user oracle by (uid=0) Sep 17 15:08:19 athena su(pam_unix)[19758]: session closed for user oracle Sep 17 15:08:20 athena su(pam_unix)[19807]: session opened for user oracle by (uid=0) Sep 17 15:08:20 athena su(pam_unix)[19807]: session closed for user oracle Sep 17 15:08:20 athena su(pam_unix)[19850]: session opened for user oracle by (uid=0) Sep 17 15:08:20 athena su(pam_unix)[19850]: session closed for user oracle Sep 17 15:08:20 athena kernel: EDAC k8 MC0: general bus error: participating processor(local node origin), time-out(no timeout) memory transaction type(generic read), mem or i/o(mem access), cache level(generic) Sep 17 15:08:20 athena kernel: MC0: CE page 0x39c857, offset 0xd50, grain 8, syndrome 0x1cc8, row 1, channel 0, label "": k8_edac Sep 17 15:08:20 athena kernel: EDAC k8 MC0: extended error code: ECC chipkill x4 error Sep 17 15:08:21 athena su(pam_unix)[19899]: session opened for user oracle by (uid=0) Sep 17 15:08:21 athena kernel: EDAC k8 MC0: general bus error: participating processor(local node origin), time-out(no timeout) memory transaction type(generic read), mem or i/o(mem access), cache level(generic) Sep 17 15:23:54 athena syslogd 1.4.1: restart. Sep 17 15:23:54 athena syslog: syslogd startup succeeded Sep 17 15:23:54 athena kernel: klogd 1.4.1, log source = /proc/kmsg started.

kernel: EDAC MC0: UE page 0x0, offset 0x0, grain 0, row 7, labels ":": i3200 UE  All of a sudden today, our CentOS release 6.4 (Final) system started throwing EDAC errors. I rebooted, and the errors stopped.  I have been searching for answers, but they fall into two camps, memory or a chipset. I would like some advice on where to search further to narrow this down to chipset or memory.


What all options are available for filling missing data ?  One obvious choice is the mean, but if the percentage of missing data is large, it will decrease the accuracy.  So how do we deal with missing values if they are in great number ?

I have a very large dataset and about 5% random values are missing. These variables are correlated with each other. The following example R dataset is just a toy example with dummy correlated data.  set.seed(123)  # matrix of X variable  xmat <- matrix(sample(-1:1, 2000000, replace = TRUE), ncol = 10000) colnames(xmat) <- paste ("M", 1:10000, sep ="") rownames(xmat) <- paste("sample", 1:200, sep = "") #M variables are correlated   N <- 2000000*0.05 # 5% random missing values  inds <- round ( runif(N, 1, length(xmat)) ) xmat[inds] <- NA  > xmat[1:10,1:10]          M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 sample1  -1 -1  1 NA  0 -1  1 -1  0  -1 sample2   1  1 -1  1  0  0  1 -1 -1   1 sample3   0  0  1 -1 -1 -1  0 -1 -1  -1 sample4   1  0  0 -1 -1  1  1  0  1   1 sample5  NA  0  0 -1 -1  1  0 NA  1  NA sample6  -1  1  0  1  1  0  1  1 -1  -1 sample7  NA  0  1 -1  0  1 -1  0  1  NA sample8   1 -1 -1  1  0 -1 -1  1 -1   0 sample9   0 -1  0 -1  1 -1  1 NA  0   1 sample10  0 -1  1  0  1  0  0  1 NA   0   Is there a (best) way to impute missing values in this situation? Is the Random Forest algorithm helpful? Any working solution in R would be much appreciated.  Edits:  (1) Missing values are randomly distributed among the variables and samples.As number of variables is very large (here in the example - 10000), while the number of samples is small here in the above dummy example it is about 200. So when we look at any sample over all the variables (10000), there is high chances that there will be missing value at some variable - due to large number of variables. So just deleting the sample is not option.   (2) The variable can be treated both as quantitative or qualitative (binary) in the process of imputing. The only judgement is how well we can predict it (accuracy). So predictions like 0.98 instead of 1 might be acceptable rather 0 vs 1 or -1 vs 1. I might need to tradeoff between computing time and accuracy.   (3)  The issue I have thinking how overfitting can affect the results as the number of variables are large compared to number of samples.   (4) As the total quantity of missing values is about 5% and is random (not concentrated in any variables or samples as precaution was taken to remove the variables or samples that have very high missing values)   (5) Making data complete for analysis is first objective and accuracy is secondary. So not too sensitive to accuracy.


In unanswered questions across the StackExchange network, there is an ability to share the question via numerous social media outlets. The banner that says this is missing a few things. Here is a picture:  Obviously, it is missing about 3 ways to share the question. At least we can email. I do remember it being there in full some time ago. I just now noticed it on ,  and . I was going to post this in History but decided to check other sites to see if they have the issue too. When I found out they did, I came here to report it.

The list has several empty strings in it for me right now:


My lock screen option from settings is gone, and neither Windows+L nor Ctrl+Alt+L are locking the screen - they are simply turning it off. When I move the mouse, no password is prompted for before resuming operation.  How can I restore the missing locking functionality?  Using Ubuntu 17.10.

The screen lock is not working, it does not lock the screen (no password required).  I would like it to prompt for a password every time the screen locks (clock screen).  All instructions tells me to enable this in privacy but I can not enable or disable as it's grey (gray).  Ubuntu 17.10 upgraded from Ubuntu 17.04, upgraded from Ubuntu 16.10.    Any help or advise would be great as I already tried many setting and installs and removes suggested on online.


I want to find the total amount of payment, but when I compile and run the code, I get this error  Exception in thread "main" java.lang.NullPointerException.   payment class  package tutorial3;     public class Payment {         private double amount;         public Payment()         {          this(0.0);         }         public Payment(double amount)         {          setAmount(amount);         }         public void setAmount(double amount)         {             this.amount = amount;         }          public double getAmount()         {             return amount;         }          public String toString()         {             return "amount paid is " + getAmount();         }     }     main class:   public class main {         public static void main(String[] args){                Payment [] p = new Payment[2];             Scanner sales = new Scanner (System.in);             double total = 0;             for(int i=0; i<3; i++)             {              System.out.print("Sales amount? ");              double amt = sales.nextInt();              Payment cash = new Payment(amt);             }                     for( Payment pv : p  ){                 total += pv.getAmount();             }         }           }

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 run a blog on wordpress. Recently I received a abuse complaints from the server which when verified returned this:  ============================================================  Received: from [192.241.188.154] by usfamily.net  (USFamily MTA v5/:PG5vcm1hX2NoYW1iZXJzQG1yaW5hbHB1cm9oaXQuY29tPjxkamtpbm5leUB1c2ZhbWlseS5uZXQ_) with SMTP id <20140301115044001084500013> for <djkinney@usfamily.net>;  Sat, 01 Mar 2014 11:50:44 -0600 (CST)  (envelope-from norma_chambers@myblog.com, notifiable emailnetwork 192.241.188.)  Received: by myprimarydomain.com (Postfix, from userid 498)  id 1C5EE1305AE; Sat, 1 Mar 2014 17:12:39 +0000 (UTC)  To: djkinney@usfamily.net  Subject: FW: Good day  X-PHP-Originating-Script: 498:sslnEn.php  From: "Norma Chambers" <norma_chambers@myblog.com>  Reply-To: "Norma Chambers" <norma_chambers@myblog.com>  X-Priority: 3 (Normal)  MIME-Version: 1.0  Content-Type: text/html; charset="iso-8859-1"  Message-Id: <20140301171239.1C5EE1305AE@myblog.com>  Date: Sat, 1 Mar 2014 17:12:39 +0000 (UTC)  Content-Transfer-Encoding: quoted-printable

  Top Meds Website good deal http://dumantarim.com/modules/mod_araticlhess/rlf.h=  tml

  ============================================================   Now I assumed that it meant this: Several unsolicited emails were sent from the id norma_chambers@myblog.com. If my assumption is correct, this email id should have existed on the VPS AND user had access to the email account to send mails. Does it really means that my server (VPS) was hacked? I am not actually using any contact form on my blog as such but this may be caused by any plugin etc.??? Not sure :(  Am I on the correct path to trace this problem? Please shed some light.

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 have Micromax a87 android phone,in my phone doesn't support the Tamil font in browsers and Facebook,YouTube. I searched for solution but shows that its possible only by rooting the mobile.I don't want to root my phone. Is it possible to display the Tamil font in Facebook and browsers without rooting the phone?

Please excuse the length of this question. I need to explain all this to help others and to avoid helpful contributors to provide answer without asking clarifications.  My requirement in one line: "to enable an Android phone to display Tamil characters properly".  Elaboration: Tamil, like any other Indian language has complex character rendering system. Unlike English or other Latin based script, it has glyph (what you see in screen) composed of more than one character.  Android does not have ability to render such complex scripts (with exceptions). My aim is to know how I can provide such an ability to an Android phone or tablet.  Little background that I gathered so far: To display a glyph in screen, Android first needs a suitable font file.  Android device has a folder /system/fonts which has few of them.  The most interesting file in that folder is the DroidSansFallback.ttf.  As the name suggests, when Android's system fails to find a character in system fonts (that could be DroidSans.ttf or DroidSans-Bold.ttf etc) it falls back to search it in DroidSansFallback.ttf.  By replacing a suitable font file from PC (Latha.ttf or Lohit-Tamil.ttf - these are fonts for Tamil) and DroidSansFallback.ttf will enable to display Tamil characters in the device. It is not so easy to replace and it involves rooting the device and mounting the system as writable.   In spite of those troubles, even if the DroidSansFallback.ttf is replaced, the Tamil characters that are displayed are not rendered properly.  The Tamil character "தி" is a conjunct of two characters and instead of getting displayed as "தி", it will be displayed as "த ி" without space in between. Though this is enough to read short messages, it cannot be used to read books etc.  From Android 4.0 on wards, Tamil and other few languages are supported through browser as said in Android 4.x API overview as seen below.  Support for Indic fonts (Devanagari, Bengali, and Tamil, including the complex character support needed for combining glyphs) in WebView and the built-in Browser   The words to notice is "in WebView and the built-in Browser", which means that Tamil characters will be rendered perfectly if it is rendered as HTML content and will not be rendered otherwise.  Opera and other few browsers did this even before Android 4.0 by substituting image instead of character.  I noticed that in few devices that target Indian market (ex: LG Optimus One, most of Samsung phones and tablets) are able to display Tamil properly both in browser and even in places out of browser like in contacts, text messages, file names etc.  To my surprise they do this even in Android 2.3 onwards.  I also noticed that the same model targeting non-Indian country running same version of Android does not support Tamil character display.  This made me to investigate further and reached a conclusion that Android (as other Linux based OS) depends on a font rendering engine to display such complex characters.  The two engines that I came across are Skia and Harfbuzz. I noticed LG uses skia and Samsung uses Harfbuzz libraries in their devices to bring this ability.  I came across many websites suggesting to replaces these libraries and fonts. It did not work and results in freezing.  Fortunately I backed up using clockworkmod and hence I restored my phone.  Though I had explained this with Tamil, this is applicable for most of the Indian languages.  Here comes my question (if you are still reading;) ) Now, far sure it is clear that a TTF file should be present to provide characters and an appropriate libraries (libskia.so or libharfbuzz.so) are required to render them correctly.  Does any one know how these manufacturers are able to provide the ability? I am even ready to build my own ROM from AOSP (Android Open Source Project).


I just happened to see it in the freezer and it looks really good hasn't been opened or thawed but everywhere I look I seem to get a different answer on weather it would be okay to eat or not. Hopefully I can get an answer here before its thawed out lol :) Thanks yall

How do I know if a given food or ingredient I have is still good, or if I should discard it?  How can I best preserve a food or ingredient?     This broad question is intended as a "general reference" question to quickly answer many how long will food keep for? questions. Please feel free to edit this question to expand and clarify as needed.


How to dynamic down casting in C#? I have these classes as follows: public class Base { }  public class A : Base {     public string name; }  public class B : Base {     public string name; }  public class C : Base {     public string name; }  I also have a Go method. I want to make it dynamic child class type(A, B, C), not "Base" type. So that any child class can work. How do I make testA have a datatype dynamically? public class Main {     private void Go()     {         Test(new A{ name = "My Name is A"});     }      private void Test(Base base)     {         var baseType = base.GetType();            // Class A (or Class B, Class C)         var baseTypeName = base.GetType().Name;   // "A" (or "B", "C")          // I want to make it dynamic child class type(A, B, C), not "Base" type.         // So that any child class can work         // How?          // This code is fixed for A.         var testA = new A();         testA.name = "Sucess";          // I want testA dynamic Data Type.         var testA = ?;         testA.name = "Sucess";     } }

One may not always know the Type of an object at compile-time, but may need to create an instance of the Type.    How do you get a new object instance from a Type?


I was trying to post an answer to a question on Stack Overflow but for some reason the frontend (yes, frontend lol) had disabled the button. The button was disabled, so for posting it I had to go to inspect mode and enable the button. I did post the answer haha.

Question:   Answer:   The question was closed at 11:57:57 (according to the hover-over-"x-mins-ago" bar) and the answer was posted at 12:16:35. It's a fairly lengthy answer, so it's possible that it was started to be written before it was closed but I swear I've started to answer a question then I got a banner along the top saying "this question has been closed" and the answer was no longer post-able.


I know that the local database stores the information about the installed packages，but I do not know what the sync database is. So what is that ? Why i need it ?

man pactree says:     -s, --sync      Read package data from sync databases instead of local database.   What is the difference between the two, and when would I prefer to use one over the other?  man pacman also mentions:   package database files database   How do these fit into the picture?


All similar questions I've looked though here, mentions multiple interface inheritance. However, I am not sure how MII could be a workaround to the problem.  Lets say, I have two library class (My_Class_1 and My_Class_2) of different methods. Then I want to create a new class, that can use both of these classes' methods natively, like:  public class My_Application : My_Class_1, My_Class_2 {       public My_Application(){          method_from_Class1();          smth_property_declared_in_My_Class_2 = "hello";      }  }   However, that is not possible with C#. What are flexible workarounds, to extend/enrich class with other classes? In PHP, that is unbelievably simple, just in the top of the class we can:  use example_trait_1; use example_trait_2;   I would rather not use interfaces; in my view, they have no relation to solving this problem.  p.s. I don't want to create initialize objects for those classes. I want them to be native part of the application class.

Since multiple inheritance is bad (it makes the source more complicated) C# does not provide such a pattern directly. But sometimes it would be helpful to have this ability. For instance I'm able to implement the missing multiple inheritance pattern using interfaces and three classes like that: public interface IFirst { void FirstMethod(); } public interface ISecond { void SecondMethod(); }  public class First:IFirst  {      public void FirstMethod() { Console.WriteLine("First"); }  }  public class Second:ISecond  {      public void SecondMethod() { Console.WriteLine("Second"); }  }  public class FirstAndSecond: IFirst, ISecond {     First first = new First();     Second second = new Second();     public void FirstMethod() { first.FirstMethod(); }     public void SecondMethod() { second.SecondMethod(); } }  Every time I add a method to one of the interfaces I need to change the class FirstAndSecond as well. Is there a way to inject multiple existing classes into one new class like it is possible in C++? Maybe there is a solution using some kind of code generation? Or it may look like this (imaginary c# syntax): public class FirstAndSecond: IFirst from First, ISecond from Second { }  So that there won't be a need to update the class FirstAndSecond when I modify one of the interfaces.  EDIT Maybe it would be better to consider a practical example: You have an existing class (e.g. a text based TCP client based on ITextTcpClient) which you do already use at different locations inside your project.  Now you feel the need to create a component of your class to be easy accessible for windows forms developers. As far as I know you currently have two ways to do this:  Write a new class that is inherited from components and implements the interface of the TextTcpClient class using an instance of the class itself as shown with FirstAndSecond.  Write a new class that inherits from TextTcpClient and somehow implements IComponent (haven't actually tried this yet).   In both cases you need to do work per method and not per class. Since you know that we will need all the methods of TextTcpClient and Component it would be the easiest solution to just combine those two into one class. To avoid conflicts this may be done by code generation where the result could be altered afterwards but typing this by hand is a pure pain in the ass.


I had kind of an "illumination" by watching a TV serie, and got the urge desire to make it in a game the way I want it. I of course don't intend to make money out of it. So I was curious to know, would I be in a trouble if I made a game, mostly a demo about the first two episodes of the TV serie, on it without asking for any money. Won't the original developper (if by chance hear about it), get me in a court or something ? (of course in the credits or something i would say that the original serie came from them) PS : if they don't, then my second question is : Am i allowed to ask for donation, help or something to continue making a sequel, or a full game from that demo ?

I have been wanting to create a mobile game based on some of my favorite anime.  I want to know if using character images and names from those anime (even after giving full copyright credits and disclaimer) infringes any copyrights?  Would this come under "fair use" in the DMCA (I mean there are already so many not-so-legal sites using this "fair use" to continue running).  What are the possible things I can do for making this game? I have seen many online browser games based on anime which use images and elements from that anime, while I have also seen many games advertise themselves based on a anime but just use diffrent names for characters of that anime (sometimes modifying the character images, too).


Suppose that the functions $\ f_1, f_2, g_1, g_2: \mathbb{N}\to\mathbb{R}$ (set of real numbers greater or equal to 0) are such that $\ f_1 \in \Theta \ (g_1)$ and $\ f_2 \in \Theta \ (g_2)$.  Prove that $ \ f_1 + f_2 \in \Theta (\max\{\ g_1, g_2\})$  I have no idea how to go about this proof. Could someone please explain?  Thank you!

I need to prove that     $f_1 \in \Theta(g_1) \land f_2 \in \Theta(g_2) \implies f_1 + f_2 \in \Theta(\max\{g_1, g_2\})$    is relevant, but I have a slightly different case, so I don't know how to translate it into this one, because I need to turn the $f$'s into $g$'s.  Am I allowed to say $\max\{f_1, f_2\} \in \Theta(\max\{g_1, g_2\})$?  Or even $\Theta(\max\{f_1, f_2\}) = \Theta(\max\{g_1, g_2\})$?


The words listen, shout, etc. are intransitive verbs, but why are they used in passive sentences with preposition to, at, etc.?  e.g:     she was never listened to.   I don’t like to be shouted at.                                                  When intransitive verbs are used with preposition, are they considered as transitive verbs?

Milton slept in this room.    According to   , sleep is an intransitive verb (A1). So we shouldn't be able to rewrite the sentence in the English  passive voice.   But I want the most important part of the sentence to be the room and not Milton, so I wrote     This room was slept in by Milton.    First, is this grammatical?   Second, I thought the passive voice in English can only use transitive verbs??   I researched about the English Passive Voice on  and Purdue University's  .   This answer has been marked as a possible duplicate of . But the most upvoted answer there does not address the property of intransitive as assigned by the dictionary, which is an integral part of this question. In addition the same answer there is confusing  because it says both that transitivity is not a property of verbs and yet ends up talking about transitive verbs. In addition, the same answer does not explicitly deal with verbs other than "sense verbs". So I'm not sure if that answer applies to to sleep.


So, I am a medical physics student with a long term goal of learning QFT. Unfortunately, I do not have the time to take courses that would build up to QFT. I have taken the time to search for many textbooks on QFT, all of which require much more mathematical and physical knowledge than I have at the moment. My background is: Calc 1-3 and DiffEQ, Linear Algebra, Freshman Physics, Electromagnetism (ala Griffiths) and Quantum Mechanics (also ala Griffiths).  I am planning on reading Merzbacher and Sakurai MQM, and then Sakurai AQM. Will this be enough to prepare me for Peskin? I have taken the time to read through many different questions on the subject, and I have come to the conclusion that none of them address my needs. I suspect there are many people who will also be interested in such a self-contained study "path" to QFT, instead of merely asking for one textbook to rule them all. And many of these people are at the point I am now, having just finished regular QM ala Griffiths. I am hoping for the smoothest path to QFT. Each textbook should not assume more knowledge than contained in the last ones.

I found Sean Carroll's "A No Nonsense Introduction to General Relativity" (about page .  pdf ), a 24-page overview of the topic, very helpful for beginning study.  It all got me over the hump of learning the meaning of various terms associated with GR, most of which I had heard before without understanding.  It also outlined the most important examples.  Is there a similar document for quantum field theory, which presents the main equations, briefly describes the main ideas, and summarizes the most important applications and results so that the reader can feel the lay of the land before studying in depth?


Is it true that $\sqrt{2\sqrt{3\sqrt{4\sqrt{\ldots\sqrt{n}}}}}<3$ for any positive integer $n$?  We cannot prove the statement using induction as it is, because the left-hand side is increasing while the right-hand side stays constant. So we need to modify the right-hand side to something like $3-\dfrac{1}{n}$. But it is hard to quantify how much the left-hand side increases when we go from $n$ to $n+1$.

An old challenge problem I saw asked to prove that  $\sqrt{2 \sqrt{3 \sqrt{4 \ldots}}} < 3$. A simple calculation shows the actual value seems to be around $2.8$, which is pretty close to $3$ but leaves a gap. Can someone find $C < 3$ and prove $\sqrt{2 \sqrt{3 \sqrt{4 \ldots}}} < C$?


I tried changing the gtk-3 files, but the color remains the same.

I'm searching how to customize the desktop icons font size on Ubuntu 19.10 GNOME (standard) edition. For example, i Want 8px.  With 18.04, it was as simple as   gsettings set org.gnome.nautilus.desktop font 'Ubuntu 8'   On 19.10, there is no org.gnome.nautilus.desktop schemadir. I searched inside all  parameters gsettings list-recursively and dconf dump /, cannot find any related to desktop icons font.


I am a beginner in java I am trying to make a communication with serialPort, however at the time of executing the method that receives data it throws me the error.     Exception in thread "Thread-2" java.lang.NullPointerException at   Controlador.ControladorMain$4.run(ControladorMain.java:354) at   java.lang.Thread.run(Thread.java:748)   I do not understand that it is failing, I have tried the code on another computer and there it does not throw the error I am confused, someone can help me.  public void receiveFile() {     final InputStream in=serialPort.getInputStream();     Thread t;     t = new Thread(new Runnable() {         @Override         public void run() {             System.out.println("listening...: ");              while (true) {                 FileOutputStream file = null;                 ObjectInputStream out = null;                  try {                                             out = new ObjectInputStream(in);                      if (view.jCheckBoxArchiboR.isSelected())                          file = new FileOutputStream("File.txt");                     else                          file = new FileOutputStream("content.txt");                       byte[] buf = new byte[1024];                      while (true) {                         if (!view.jCheckBoxArchiboR.isSelected())                            view.jTextAreaBinRecibido.setText(textoABinario(fileRead("content.txt")));                          int len = out.read(buf);                          if (len == -1)                              break;                          file.write(buf, 0, len);                     }                     if(out.available()<1)                         sendFile("ack.txt");                   } catch (IOException ex) {                     ex.printStackTrace();                     System.out.println("An error occurred while receiving the file");                  } finally {                     try {                     out.close();                     } catch (IOException ex) {                         ex.printStackTrace();                     }                 }             }         }     }     );     t.start(); }   line 354 where the error appears is this.   out.close();

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 a macro lens for the camera on my phone. I want to calculate the magnification of the lens because the one i purchased does not state it.  I've found this guide which states the mathematical relationships -   The only thing that i don't understand is the difference between the focal length and the distance between the object and the lens? I thought the focal length was the distance between object and lens.  Thanks Bobby

I was under the impression that the “focal length” of a lens is the distance at which stuff appears in-focus. (E.g., perhaps I set the camera so that objects 3 meters away appear sharp, and anything nearer or further than that is blurry.) But everything I've read seems to suggest that focal length is actually a slightly odd way of describing the field of view of the lens, and actually nothing to do with focus at all. (?)  So what's the correct term for “stuff at this distance will be in focus” then? (I.e., the thing you change with the focus ring.) If I want stuff 3 meters away to appear sharp, what parameter have I set to 3 meters?


I want the user to enter a lower case b and the program recognizes that the b is lower case, and switch it to an upper case B. Since you cannot edit Strings during run time, how can I use a separate method from the main method in order to assign "name" to "name2". Once I try to print out "name2" after the method changes it, the compiler claims name2 hasn't been initialized even though it has been in a separate class.     I've tried initializing name2 as name2=""; so the compiler doesn't say "name2 hasn't been initialized once I try to print name2 to console, however, you cannot redefine a String during run time.    import java.util.Scanner;  public class Runner {      public static void main(String[] args)     {         Scanner input = new Scanner(System.in);          String name;         String name2;           TextArguments test1 = new TextArguments();          System.out.println("Please enter a lower case b");         name = input.nextLine();           test1.test(name,name2);             System.out.println(name2);     } }       public class TextArguments {     public String test(String name, String name2)     {                                        if(name == "b")          {            name2 = "B";         }         else         name2 = name;          return name2;     } }   Expected results:   Enter a lowercase b. b B  Actual Results:  test1.test(name,name2); ("name2 might have no been initalized")

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 saw these in a lot of WordPress themes, what are they used for and how can I create my own? I mean for example the "twentythirteen" tag at the end, what contains the actual theme's name.  get_comments_number(), 'comments title', 'twentythirteen' edit_post_link( __( 'Edit', 'twentythirteen' )

I'm using twentytwelve theme with 1.0 version. I saw many codes like following,  'name' = __('page','twentytwelve');   If I give,  'name' = 'page';   It's also working fine. Then why using __()? What is use of that?


I am trying to render a scene in blender, but whenever I click, "render image" the final render is just white.  I made sure everything was within the view layer.  I'm not sure what else could be causing this.  If you have any ideas, please share them!

A scene I made is not rendering, at all. This grey screen stays the same and nothing changes.  Here are my settings:  [


I'll keep it short:  I have a list of binary strings that, after being multiplied, show strange behaviour.  Here it goes.  binary_strings = [[0, 1, 1, 0], [1, 0, 1, 1]] * 4 for index, string in enumerate(binary_strings):     if index == 0:         string += [0]   expected result:  [[0, 1, 1, 0, 0],  [1, 0, 1, 1],  [0, 1, 1, 0],  [1, 0, 1, 1],  [0, 1, 1, 0],  [1, 0, 1, 1]]   result achieved:  [[0, 1, 1, 0, 0],  [1, 0, 1, 1],  [0, 1, 1, 0, 0],  [1, 0, 1, 1],  [0, 1, 1, 0, 0],  [1, 0, 1, 1]]   If binary_strings is not multiplied, then it works as expected. If insted of += operator I use string = string + [0], result is also 'correct'.  This is a problem that I have a solution to, but would really like to understand what is going on as it migth prevent future problems. It seems to be something related to the way python relates objects in memory. Other than that, I have no further understanting of might be going on.  Thanks!  edit: another issue here is that changing the operator changes the outcome to the corrected one, which is not something I have seen discussed. If it has, please link me that discussion. Thanks!

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I am getting a NullPointerException int the following code.For the complete program refer .  Logcat  FATAL EXCEPTION: main                                                                             Process: com.example.android.googleplaces, PID: 2813                                                                             java.lang.NullPointerException                                                                                at com.example.android.googleplaces.MainActivity$ParserTask.onPostExecute(MainActivity.java:200)                                                                                at com.example.android.googleplaces.MainActivity$ParserTask.onPostExecute(MainActivity.java:169)   and code:  class ParserTask extends AsyncTask<String, Integer, List<HashMap<String,String>>>{  JSONObject jObject;  // Invoked by execute() method of this object @Override protected List<HashMap<String,String>> doInBackground(String... jsonData) {  List<HashMap<String, String>> places = null; PlaceJSONParser placeJsonParser = new PlaceJSONParser();  try{ jObject = new JSONObject(jsonData[0]);  /** Getting the parsed data as a List construct */ places = placeJsonParser.parse(jObject);  }catch(Exception e){ Log.d("Exception",e.toString()); } return places; }  // Executed after the complete execution of doInBackground() method @Override protected void onPostExecute(List<HashMap<String,String>> list){  // Clears all the existing markers if(mGoogleMap!=null) mGoogleMap.clear();  for(int i=0;i<list.size();i++){  // Creating a marker MarkerOptions markerOptions = new MarkerOptions();  // Getting a place from the places list HashMap<String, String> hmPlace = list.get(i);  // Getting latitude of the place double lat = Double.parseDouble(hmPlace.get("lat"));  // Getting longitude of the place double lng = Double.parseDouble(hmPlace.get("lng"));  // Getting name String name = hmPlace.get("place_name");  // Getting vicinity String vicinity = hmPlace.get("vicinity");  LatLng latLng = new LatLng(lat, lng);  // Setting the position for the marker markerOptions.position(latLng);  // Setting the title for the marker. //This will be displayed on taping the marker markerOptions.title(name + " : " + vicinity);  // Placing a marker on the touched position if(mGoogleMap!=null) mGoogleMap.addMarker(markerOptions); } } }


We are using SharePoint Enterprise 2013 On-Premises  I have a procedures library and I would like to have a column called 'Code' so when a document is uploaded a value is added to the column for example  P100-1  Then when a another document is uploaded it will get   P100-2  I am trying to replace the system we have that is currently in a file share

Within our SharePoint Enterprise 2013 On-Premise environment we have documents that need to be tagged with codes for example:   Procedure Document: P100-001 Forms: F100-001   So when a procedure document is upload I would like it to get assigned the next available code, e.g. P100-002.  What is the best approach for this?  EDIT: So it looks like the best solution is to use a workflow, I have created the workflow but unsure of what I need to type    Basically I want a string of text P100- and the add the item ID


I keep getting this error:  NullReferenceException: Object reference not set to an instance of an object moveBlock.Update () (at Assets/Scripts/moveBlock.cs:27)  whenever I press Play in Game or when I press Space while in play. I looked at other questions posted but it is not clear to me what the solution is. I think I am missing a GetComponent line, but I'm not sure. using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UIElements;  public class moveBlock : MonoBehaviour {      public float speed = 10;     public GameObject[] blocks;     private GameObject b;      void Update()     {         Vector3 input = new Vector3(Input.GetAxisRaw("Horizontal"), 0, Input.GetAxisRaw("Vertical"));         Vector3 direction = input.normalized;         Vector3 velocity = direction * speed;         Vector3 moveAmount = velocity * Time.deltaTime;                  if (Input.GetKeyDown(KeyCode.Space))         {             b = (GameObject)Instantiate(blocks[Random.Range(0, 7)], new Vector3(0, 6, 0), Quaternion.Euler(Vector3.right));             //b.AddComponent<Rigidbody>().isKinematic = false;         }         b.transform.Translate(moveAmount); // <-- Line 27 throws the exception.     } }

Since many users are facing the NullReferenceException: Object reference not set to an instance of an object error in Unity, I thought that it would be a good idea to gather from multiple source some explanation and ways to fix this error.  Symptoms I am getting the error below appearing in my console, what does it mean and how do I fix it?  NullReferenceException: Object reference not set to an instance of an object


This is the current version of the problem I have tried but there was no solution to the problem, please let me know how I can initialize JtextFields in this situation  public class Teacher_Profile extends JFrame {  private JTextField textField_5; private JTextField textField_6; private JTextField textField_7; private JTextField textField_8;  private JTextArea textArea;  private JComboBox comboBox; private JComboBox comboBox_1;  private LoginDAO a; private Teacher_Profile g = new Teacher_Profile(this); private Teacher hi = new Teacher();      public Teacher_Profile() {     super(); }  public Teacher_Profile(Teacher_Profile aq) {     super();     this.g = aq; }  public Teacher_Profile(Teacher v) {      a = new LoginDAO();     textField_5 = new JTextField();     textField_6 = new JTextField();     textField_7 = new JTextField(); textField_8 = new JTextField();      JButton btnClear = new JButton("Get");     btnClear.addActionListener(new ActionListener() {         public void actionPerformed(ActionEvent e) {             if(e.getActionCommand().equals("Get"))             {                 Marks_Details ss = a.fetchMarksData(comboBox_1.getSelectedItem().toString(),textField_7.getText());                  //JOptionPane.showMessageDialog(null, "Type: " + ss.getType() + "\nMax_Marks: " + Integer.toString(ss.getMax_Marks()) + "\nWeightage: " + Float.toString(ss.getWeightage()) + "\n Course_Code: " + ss.getCourse_Code());                  g.textField_5.setText(ss.getType().toString());                 g.textField_6.setText(Integer.toString(ss.getMax_Marks()));                 g.textField_7.setText(Float.toString(ss.getWeightage()));                 g.comboBox.setSelectedItem(ss.getCourse_Code());             }         }     });     btnClear.setBounds(236, 269, 89, 23);     panel_1.add(btnClear);   This is what I have tried but getting stack overflowerror      Exception in thread "AWT-EventQueue-0" java.lang.StackOverflowError     at private Teacher_Profile g = new Teacher_Profile(this);


Suppose I have what I think is a great idea for a new Settlers expansion. (Like 5,000 other people, no doubt!) What would be the most effective way to realize this possibility? Write to the makers and outline the idea? Pitch it like a novel manuscript? Or do such things not get publicly sourced? If I want to play it, is my best bet just to make my own set for use by friends and family? This question doesn't have to be about Settlers; it can be read as being about any game in the market. There are so many editions & flavours of all the most popular games, and I guess the core question is: Are they all generated internally or could a community member propose one?

I made a Yu-Gi-Oh card but it is not broken like current broken Yu-Gi-Oh cards and here it is to see but please before you make your decision about it take another look on ''dragun of red eyes''.


I got Total Commander on my Android phone.  I need to check the directory size for a folder and the solution is:  ..  I understand that but my question is how to add a new button to the button bar?


In $101$ random integer numbers $a[i],i=0, \cdots,100$, prove that we can always find $10$ non-increasing or non-decreasing sequence.   A sequence is a sequence of numbers is an array of numbers picking up from the original array with increasing index.

Anyone have any ideas on this question? I think you have to use the pigeon hole principle..but I am not sure about that?     The numbers $1,2,3,\ldots,101$ are written down in a row in some order. Is it always possible to cross out $90$ numbers in a way such that all $11$ numbers left will stay either in increasing or decreasing order?


I am really confused when efficient and effective appear  in a sentence.   I get quite confused about the whole meaning of the sense it pulls of.

I feel that there is a subtle difference in meaning between 'efficacy' and 'efficiency', but I couldn't find any authoritative sources that could help me confirm or refute this. Is there any difference between the two words, especially in scientific context?


Our application is made from asp.net webforms using framework 4.5. And since migrating to Amazon AWS from an inhouse server. We've been flooded by this error through out our system.  On the software side, I've already increased the command timeouts to 180 seconds (error happens even on simple split second queries), but still no avail. I've also made sure all connections are Disposed after usage.  On the network side, our application has two web servers + a database server. Traffic is controlled by a load balancer. We've already tried turning off one web server just to see if it happens when the user's session jumps from one server to the other, but still no success, error still occurs.  Hope someone has encountered and resolved this issue.       Level 1  Exception Type: SqlException  ClientConnectionId = 91d69d77-d17e-46c0-b643-7187a194c5ee  Class = 20  LineNumber = 0  Number = 64  Server =   [IPADDRESS]  State = 0  Source = .Net SqlClient Data Provider  ErrorCode = -2146232060  Message = A transport-level error has occurred when receiving   results from the server. (provider: TCP Provider, error: 0 - The specified network name is no longer available.)  StackTrace =    at   System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)     at   System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)     at   System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)     at       System.Data.SqlClient.TdsParserStateObject.ReadSniError(TdsParserStateObject stateObj, UInt32 error)     at   System.Data.SqlClient.TdsParserStateObject.ReadSniSyncOverAsync()     at System.Data.SqlClient.TdsParserStateObject.TryReadNetworkPacket()     at   System.Data.SqlClient.TdsParserStateObject.TryPrepareBuffer()     at System.Data.SqlClient.TdsParserStateObject.TryReadByteArray(Byte[] buff, Int32   offset, Int32 len, Int32& totalRead)     at System.Data.SqlClient.TdsParserStateObject.TryReadString(Int32 length, String& value)     at   System.Data.SqlClient.TdsParser.TryReadSqlStringValue(SqlBuffer value, Byte type, Int32 length, Encoding encoding, Boolean isPlp, TdsParserStateObject   stateObj)     at System.Data.SqlClient.TdsParser.TryReadSqlValue(SqlBuffer value, SqlMetaDataPriv md, Int32 length, TdsParserStateObject stateObj,   SqlCommandColumnEncryptionSetting columnEncryptionOverride, String columnName)     at System.Data.SqlClient.SqlDataReader.TryReadColumnInternal(Int32 i,   Boolean readHeaderOnly)     at System.Data.SqlClient.SqlDataReader.TryReadColumn(Int32 i, Boolean setTimeout, Boolean allowPartiallyReadColumn)     at   System.Data.SqlClient.SqlDataReader.GetValues(Object[] values)     at   System.Data.ProviderBase.DataReaderContainer.CommonLanguageSubsetDataReader.GetValues(Object[] values)     at   System.Data.ProviderBase.SchemaMapping.LoadDataRow()     at System.Data.Common.DataAdapter.FillLoadDataRow(SchemaMapping mapping)     at   System.Data.Common.DataAdapter.FillFromReader(DataSet dataset, DataTable datatable, String srcTable, DataReaderContainer dataReader, Int32 startRecord,   Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue)     at System.Data.Common.DataAdapter.Fill(DataSet dataSet, String srcTable,   IDataReader dataReader, Int32 startRecord, Int32 maxRecords)     at System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables,   Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior)     at System.Data.Common.DbDataAdapter.Fill(DataSet   dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior)     at   System.Data.Common.DbDataAdapter.Fill(DataSet dataSet)

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


I am slightly confused. Some say that the initial state of the universe was a singularity, and some say that before the Big Bang; there was a singularity. Can anybody elucidate?

Is the  defined as before or after ? Seems like a simple enough question to answer right? And if just yesterday I were to encounter this, I'd have given a definite answer. But I've been doing some reading while writing up my thesis and I'm finding conflicting definitions of the Big Bang.  Everyone agrees that in standard Big Bang cosmology, the Big Bang is defined as the singularity; the moment in time when the scale factor goes to zero. Okay, but when you include the theory of inflation, it gets a bit murky.  So here's what I mean by conflicting definitions. As an example, in The Primordial Density Perturbation by Lythe and Liddle, they define the Big Bang as the beginning of the era of attractive gravity after inflation. However, Modern Cosmology by Dodelson defines the Big Bang as coming before inflation; it effectively uses the old definition that the Big Bang is the moment when the scale factor approaches zero.  This contradiction is evident in multiple places. When doing a google search for it, one can find many persuasive explanations for both definitions. All definitions agree that we cannot any longer define it as the singularity where $a=0$. But every one makes sense in its own way and so, I become more and more confused about which is right the more of them I read.  The argument for the Big Bang coming after is that inflationary theory diverges from the standard Big Bang cosmology around $10^{-30}s$ before we'd expect to run into the singularity, when inflation ended, and that we have no evidence to anything coming before that, thus the big bang is now defined as the initial conditions for the hot, expanding universe that are set up by and at the end of inflation.  The argument for the Big Bang coming before seems to be that inflation is still a period where the scale factor grows and as such, the Big Bang can be defined as the closest value to zero (which is before inflation), or rather, the earliest time as the scale factor approaches zero. This essentially seems to be based on saying "well, we defined it as the moment when the scale factor was smallest before inflation was added. Why would we not continue to have that as the definition after inflation is added?"  The former argument has merit because it defines the start of the epoch where the universe is describable (practically) by the standard Big Bang cosmology. But the latter argument has merit because of its simplicity and that it uses the spirit of the original definition; the smallest scale factor and the moment when the expansion of the universe seems to begin.  Thus, my root question: Which definition is correct? Do we say the Big Bang came before or after inflation?  P.S. I realize that asking this here only serves to add one or more additional persuasive arguments to an already crowded debate. However, this is Physics.SE, so I figure whatever we decide here can be definitive. Even if we can't find a truly correct answer, this can set the record straight, or at least, firmly crooked.


Is it necessary to submit a bank statement which does not have enough funds,though I'm being supported by a friend in Germany when applying for a schengen visa to Germany from Zimbabwe?

I want to know that will it still be necessary for me to sent my bank statement to the Germany embassy for schengen visa , whilst i received a invatation from the one inviting me from Germany ?


I've found using the 'find' command to search for individual files that some inconsistencies occur. Eg, I wanted to search for a particular file with the word paper in its name. If I type sudo find /mnt  -iname *paper* the output is:-   /mnt/data/MyPhotos/Wallpapers   which is fair enough, except it wasn't what I was looking for. But if I type  sudo find /mnt  -iname "*paper*" the output becomes:-   /mnt/data/MyMusic/FLV-Music/Joe_Jackson_Sunday_Papers_small.mp4 /mnt/data/MyMusic/FLV-Music/Status_Quo_Paper_Plane_medium.mp4 /mnt/data/MyPhotos/Wallpapers   Now I see the file I was searching for (the 2nd one). So why in the first case is only the last file shown as output, whereas in the second case all files including the string paper in their names are output. Why should the quotes make a difference here.

I can't for the life of me figure out how find with the test -name works.  I run find / -name *in and returns a bunch of results:  /sbin /sbin/sulogin /dev/stdin   to name a few.  It's as if it performed filename expansion, but that happens before the shell runs the command, so that can't be it. Also because I don't have any files in the current directory that match *in. Plus, single quoting *in yields the same results, which further supports that this can't be filename expansion.  The documentation leads me to believe that find with -name uses regular expressions, but the regex pattern *in doesn't match the results I showed above.  Can someone enlighten me?


I'm wondering what is the purpose of "Harpulia" and "Javanese" processes (see screenshot below)  Hi !  They're high in CPU usage (and make my macbook pro fans to be running loud) and they do not seem to be essential as I can cut it so the fans are slowing down.  Oftentime these processes appear when I watch a video on chrome but it is not the only time they appear. On the other hand, they do not seem to be related to any chrome processes.  Thanks in advance for the help.  PS : on the screenshot these processes does not use much CPU compared to most of the time (it can be more than 100% per process).

Anyone knows why this happens and how to resolve it? they show up out of nowhere and stay until I kill each manually. some of these names change to something new too. I thought this might be because I left the root access open so I closed it later..


In Google Optimize I have multiple experiments running on a single website.  I want to create a segment for a specific experiment and a specific variation. Like this:    Does it include only the sessions for that specific experiment and the variant 1 from that specific experiment? E.g how does it make sure that the users from this experiment (some other variant) and another experiment's variant 1 are not included?  EXP1 - VAR1 & EXP2 - VAR2 = MATCH EXP1 - VAR2 & EXP2 - VAR1 = ?     PS! This is not the same question as this one:   That other one is about browsers, and clearly, you can't use multiple browsers at once BUT you can be part of multiple experiments at the same time!

Using Google Analytics, I'm trying to create a "supported browsers" segment using the Conditions section, but the boolean order of operations isn't occurring as expected. A simple example is below.    AND usually takes precendence over OR, so I'd expect my segment above to be interpreted as (Safari AND v10) OR (Chrome AND v57), which would allow me to include a number of Browser/Version combinations.  However, it seems like that's not the case, here. I believe this because:   My results zero out with the segment configured as pictured, but if I remove either the first or fourth clause, I'll get results. This is consistent with my filters being interpreted as Safari AND (v10 OR Chrome) AND v57, such that Safari AND (v10 OR Chrome) and (v10 OR Chrome) AND v57 both return results. The horizontal line by each AND operator seems to divide the clauses as described above.   OR-precedence doesn't make any sense to me, since the "Add Filter" button already allows the user to add additional clauses which would be equivalent to an AND, allowing the user to choose OR-precedence if they needed to. As it is, there seems to be no way to construct an AND-precedent segment.


What is the proper spelling rule that applies to "zeros", "heroes" and the like?

The following words and their plurals seem to be somewhat inconsistent:   combo / combos concerto / concertos grotto / grottos / grottoes (?) hero / heros (?) / heroes potato / potatos (?) / potatoes tornado / tornados / tornadoes tomato / tomatos / tomatoes volcano / volcanos / volcanoes   Is there a common source for -s versus -es? With regards to words such as "heros", is it likely to see more words start dropping -es in favor of -s?  (If you have any other good examples of strange plurals from words ending in "o" feel free to edit them into the question.)


If this is my file.tex:  Ras is capable of binding tightly to downstream effector molecules and  thereby propagate specific signaling pathways \cite{12581669}   and this my biblio.bib:  @article{12581669,   author = {Herrmann, C.},   title = {Ras-effector interactions: after one decade},   year = 2003,   journal = {Current opinion in structural biology},   volume = 13,   number = 1,   pages = {122--9},   pmid = 12581669,   keywords = {} }   I get:   citation '12581669' on page 1 undefined.    and the numbering is "?"**  Some idea of what should I do?

I've browsed the forums and found a number of posts that have addressed this issue, but none of the solutions seem to work for me. I have the following script that I just copied from the bibtex home page to get familiar with it. Instead of the citation number I get a question mark. I compile using Latex+Bibtex+Latex+Latex+PDFLatex+ViewPDF just as has been previously suggested and the problem persists.   \documentclass[11pt]{article} \usepackage{cite}  \begin{document}  \title{My Article} \author{Nobody Jr.} \date{Today} \maketitle  Blablabla said Nobody ~\cite{Nobody06}.  \bibliography{mybib} \bibliographystyle{plain} \end{document}   My bibliography (Bib.bbl)  @misc{ Nobody06, author = "Nobody Jr", title = "My Article", year = "2006" }    Looking at previous posts one thing that is concerning is that my .bbl looks empty as shown below. Further, I don't have a .blg  \begin{thebibliography}{}  \end{thebibliography}


I remember reading a series of fantasy novels around early 2000. I think the name was the Cartographers Map, the other title was Hunters Moon (Something Moon?) but I've searched of these titles and not found any suitable results.    I remember there was a warrior elf with magic tattoos that glowed blue. I also remember the main villain was an ice queen from the north lands named Chytrine(?).  There were dinosaur-like birds on the evil army's side. There were many different states / countries around a vast lake. There were many different armies and magical groups. It was a very violent series.

So, I began reading this series years ago and put it down, and now I've been thinking about it and want to see how it ended.   It was a basic Epic. Group needed to destroy evil somewhere off in the world. Must have read it in the early 2000s. The most I remember is based off of the characters.   There was a species of elven hybrids; they were winged, the product of a forced union by an evil magical entity. The elves hated them. Another species (I think they were terromancers), created a mountain kingdom/realm to protect them.  One of the main characters was a wizard prodigy; he'd been babied his entire life and while magically advanced, had a lot of growing up to do.   There was a general who, in order to gain advantage on the battlefield, bonded to (I think) an earth god through a shamanistic pain ceremony.   Another was an unlanded (I think) elf (his kingdom had been destroyed) he was a mercenary.  They were all fighting to get the wizard/child to the north to kill/defeat this great evil who lived in a stronghold on the other side of the world.  Thanks all! And sorry it's so vague. I've been searching the internet for most of the day. Nothing's turned up.


Suppose $f\in C^\infty(\mathbb{R})$ and for any $x\in\mathbb{R}$, there exists $N\in\mathbb{N}$ such that $f^{(N)}(x)=0$. Show that $f$ is a polynomial.   This is from one of the Analysis qualifying exam problems. I can show there exists an interval $(a,b)$ on which $f$ is a polynomial by using Baire category theorem, but I can't extend it to the real line. Any suggestion?  I think I get some new ideas about this problem. First I can find an interval $I=(a,b)$ by using Baire theorem (same idea from the question that Clement C. added.) where $f$ coincides with a polynomial $g$ on $I$. Then we consider $f^{(i)}(a), i\leq N_g$ where $N_g$ is the degree of $g$. We must have $f^{(N_g)}(a)=0$ because $f^{(i)}(a^+)=f^{(i)}(a)=g^{(i)}(a), i\in\mathbb{N}$. So if we apply the Taylor's theorem at $x=a$, we can extend $I=(a,b)$ to $I_\epsilon=(a-\epsilon,b)$ such that $f=g$ on $I_\epsilon$. Following the same idea, we can show that $$\inf\{a:f=g \text{  on  } (a,b) \}=-\infty$$ Similarly we can show $f=g$ on $\mathbb{R}$.  Update: I just found that the idea above might not work after I was trying to write down a rigorous proof. The main problem is $C^\infty$ function is not neccesarily analytic. (For example, let $f(x)=0$ on $(-\infty,0]$ and $f(x)=e^{-1/x}$ on $(0,\infty)$). So I can only extend $(a,b)$ to some larger (or equal) interval $(c,d)$ if I only use the $C^\infty$ property. So the claim above $$\inf\{a:f=g \text{  on  } (a,b) \}=-\infty$$ might not be true.  I really have no idea how to extend this interval to the real line now.

Let $f\colon\mathbb{R}\to\mathbb{R}$ be an infinitely differentiable function, and suppose that for each $x\in\mathbb{R},$ $\exists\  n=n(x)\in\mathbb{N}$ such that $f^{(n)}(x)=0$. For each fixed $n\in\mathbb{N}$, consider the sets $F_n=\{x\in\mathbb{R} : f^{(n)}(x)=0\}$ and let $I=[a,b]$ a finite closed interval.  Show that $$I=\bigcup_{n=0}^\infty(I\cap F_n).$$ Show that there is a non empty open set $A\subset I$ where $f$ is a polynomial.   My attempt:  If $x\in I$ then by hypotesis there is $n$ such that $f^{(n)}(x)=0$ then $x\in F_n$ so then $\bigcup F_n\supset I$ then $$I=I\cap\bigcup_{n=0}^\infty F_n=\bigcup_{n=0}^\infty(I\cap F_n).$$  Let $$B_k=\bigcap_{n=k}^\infty F_n.$$ I want to show that $I\cap B_k$ has non-empty interior for some $k\in\mathbb{N}$. Then there is $A\subset B_k$ and by Taylor's Theorem $f$ will be a polynomial. But I didn't know how to prove this. I tried using the following bigger set: $$B=I\cap\bigcup_{k=0}^\infty B_k=I\cap\bigcup_{k=0}^\infty \bigcap_{n=k}^\infty F_n.$$ I think that it suffices to show that $B^o\neq\emptyset$ maybe using the Baire's Theorem proving that $B$ is a not meagre set.   More general Problem  Let $f$ be an infinitely differentiable function on $[0,1]$ and suppose that for each $x \in [0,1]$ there is an integer $n \in \mathbb{N}$ such that $f^{(n)}(x)=0$. Then does $f$ coincide on $[0,1]$ with some polynomial? If yes then how. I thought of using Weierstrass approximation theorem, but couldn't succeed. Answer: The proof is by contradiction. Assume $f$ is not a polynomial. Consider the following closed sets: $$ S_n = \{x: f^{(n)}(x) = 0\} $$ and $$ X = \{x: \forall (a,b)\ni x: f\restriction_{(a,b)}\text{ is not a polynomial} \}. $$ It is clear that $X$ is a non-empty closed set without isolated points. Applying Baire category theorem to the covering $\{X\cap S_n\}$ of $X$ we get that there exists an interval $(a,b)$ such that $(a,b)\cap X$ is non-empty and $$ (a,b)\cap X\subset S_n $$ for some $n$. Since every $x\in (a,b)\cap X$ is an accumulation point we also have that $x\in S_m$ for all $m\ge n$ and $x\in (a,b)\cap X$. Now consider any maximal interval $(c,e)\subset ((a,b)-X)$. Recall that $f$ is a polynomial of some degree $d$ on $(c,e)$. Therefore $f^{(d)}=\mathrm{const}\neq 0$ on $[c,e]$. Hence $d< n$. (Since either $c$ or $e$ is in $X$.) So we get that $f^{(n)}=0$ on $(a,b)$ which is in contradiction with $(a,b)\cap X$ being non-empty.


In general, physics seems to consider elementary particles such as electrons to be point-like. On the other hand, naked singularities seem to cause all sorts of trouble, including closed time-like curves, and are generally considered to be non-physical.   What is the exact difference between a point-like particle (eg electron as we know it) and a naked singularity (eg black hole electron), and why exactly considering a particle point-like is ok, while considering it to be superextremal black hole is not?

Theoretically, What is the difference between a black hole and a point particle of certain nonzero mass. Of-course the former exists while its not clear whether the later exists or not, but both have infinite density.


Edit: by now I've figured out i<=>ii! Just not iii<=>i  For an assignment I need to prove the following: i<=>ii<=>iii. My approach was to prove i<=>ii and i<=>ii. I'm mainly getting stuck on the 'iii<=>i' parts here.  (i) f is injective  (ii) For all A, B ⊆ X:  f ( A ∩ B ) = f ( A ) ∩ f ( B ).  (iii) For all A, B ⊆ X: f ( A \ B ) = f ( A ) \ f ( B ).  I saw a proof like this before, but I did not really understand all of the answers, and as the question was posted years ago, I thought it'd be better to post my own question.

Let $A$ and $B$ be sets, where $f : A \rightarrow B$ is a function. Show that the following properties are valid equivalent*:  $f$ is injective. For all $X, Y \subset A$ is valid: $f(X \cap Y)=f(X)\cap f(Y)$ For all $X \subset Y \subset A$ is valid: $f(X \setminus Y)=f(X) \setminus f(Y)$.   I do know what injective is, but I thought number (2.) and (3.) were valid for any kind of function. Just to see if I understood this right: $f(X\cap Y)$ means, first, make the intersection from $X$ and $Y$ and then map it to $B$ via $f$. $f(X)\cap f(Y)$ actually means, map all $f(X)$ and $f(Y)$ and intersect both. Aren't those both properties valid for all functions? I can't think of a counter example. Thanks in advance guys! *edited by SN.


In , it has been explained why maximizing the ELBO minimizes KL divergence, but then this: $$ELBO_\lambda = E_q[\log \space p(x,z)] - E_q[\log \space q_\lambda(z|x)]$$ became this: $$ELBO_\lambda = E_{q_\lambda(z|x)}[\log \space p(x|z)] - KL(q_\lambda(z|x)||p(z))$$ and I don't understand how. What I also noticed, that while in the first equation, there are expected values with respect to $q$, in the lower index, but in the second, it is not in the lower index, so I don't know what $E_{q_\lambda(z|x)}[]$ is supposed to mean.

I don't completely understand KL divergence yet, and how the breakdowns are completely different for similar looking distributions. In  it says: $$KL(q_\lambda(z|x) || p(z|x)) = E_q[log \space q_\lambda(z|x)] - E_q[log \space p(x,z)] + log \space p(x)$$ The two distributions in the comparison look similar, both stating the probability distribution of $z$ given $x$, but in the first case it's the cross entropy ($q$ relative to $q$?), in the second case we're subtracting the cross entropy of $p(x,z)$ relative to $q$ plus $log \space p(x)$. Could someone explain why this problem should be solved like this?


Currently I'm debating about whether I want to use a spare workstation running Windows 10 and turn that into the enclosure for a 4x6TB RAID 10 array since it has decent hardware specs or wait until there's room in the budget to purchase a dedicated NAS enclosure from Synology or some other vendor if what I want isn't possible as I would have to reformat/re-array for the enclosure. I know there is some difficulty with software <-> hardware driven array migrations according to this Q&A from '09:    However given 7 years have passed and the rise of NAS storage for small business I was wondering if things have changed and if it's possible to have the RAID 10 initially set up in a spare workstation to use now and then migrate the RAID array and it's data w/o issue to a dedicated NAS enclosure from Synology et al when there's more money so that I can then free up the workstation again.

I'm not too familiar with RAID arrays, but I plan on making a RAID 5 array for a fileserver. However, once I get the RAID running for a while, I have plans to move it to another machine (with completely different hardware). Is it possible to move an array from machine to machine without having to break the array and place the data on it again?


I have used the causality function to test a VAR(3)-model for Granger causality. For one variable the following results were computed: The test found that H0 could not be rejected for the Granger causality test, but for the instant causality test with H0 = No instantaneous causality But how can I interpret this result now? What does instantaneous causality mean?

What is the difference in terms of inference? Does Instantaneous captures the short term cause and effects?


Device: MacBook Pro 8,2 (Late 2011)  Operating System: macOS High Sierra  Security Update: 2020-002  Boot Camp: Version 6.1.0 (6067.60.1)    Context:  A couple of weeks ago I decided it was time to do a clean install - from scratch - of my macOS High Sierra and Windows 7 operating systems installed on my MacBook, after a year of use. I used this  as a guide to install macOS High Sierra:  The installation was correct and without errors, after that I installed the updates from the App Store following the steps of the support website for the installation of Windows 7 from macOS High Sierra with Boot Camp:   .  Issue:  Following the process above, Boot Camp created the installation drive, the disk was partitioned during the process and when the computer restarted, this error appeared:     No bootable device -- insert boot disk and press any key     I have been searching for ways to install Windows 7, without success. Among them:   Try 5 different USB 2.0 drives (HP, Sandisk, Kingston): Since in a video they think that the problem with this black screen warning is due to USB. Install Windows 7 creating the boot from Windows on a PC with the Rufus application and start from the Mac boot screen (without using Boot Camp). It did not work, although if it recognized the usb with Windows 7 it was frozen when clicked, however with the ISO of Windows 10 following the same procedure if it installed correctly, but the version of my MacBook does not have the complete drivers for Windows 10 in addition to which in my opinion is quite slow compared to Windows 7.     I have done the same installation process with BCA to install Windows 8, 8.1 and 10 and have got the same result.     No bootable device -- insert boot disk and press any key

I've been tearing my hair out the last couple days trying to get Windows installed.  I have a MacBook Pro Retina 15 inch mid 2014. Yosemite version 10.10.1. Win 7 64 bit iso (sha1 - 0bcfc54019ea175b1ee51f6d2b207a3d14dd2b58).  I have tried two usb 2.0 flash drives with 'Create a Windows 7 or later install disk' option in BCA. This proceeds smoothly and so does creating the partition using Install Windows 7 option.  However, when it restarts, it says something along the lines of 'no bootable device'  If I hold down 'alt', the only options are to boot back into OS X & the recovery disk.  I realise this question has been asked countless times - I have read a lot of them but few seem applicable to my situation and those that are have not helped yet. I have not tried another USB yet since I am bandwidth limited (both in download speed and data limit) and BCA wants to redownload Windows support files every time and at this point it feels like a shot in the dark.  Any help with this will be greatly appreciated.  Some further questions:   Is there a way to determine whether the usb drives are at fault? Does BCA create the bootable drive in any special way? I.e. is it possible to create it by another method that will still play well with the bootcamp process?


I am trying to use dynamic_cast - with no success.  I have a BASE class, and a class A derived from BASE.  I want to have a pointer to a BASE class object which I later want to cast to class A.  I clearly am not doing this correctly.  The following code compiles:  #include <cstdio>  class BASE { private:      int i;  public:       BASE(void) {i = 1; }      virtual ~BASE(){}       virtual void id() { printf("CLASS BASE\n"); }  };  class A : public BASE { public:     A(void): BASE() {}     A(const BASE & base) : BASE(base) {}     A& operator = (const BASE & base) { static_cast<BASE&>(*this) = base; return *this; }      void id() override { printf("CLASS A\n"); }; };   int main() {      BASE* base = new BASE();      base->id();      A* a = new A(*base);      a->id();      A* anotherA = dynamic_cast<A*>(base);      if(!anotherA)          printf("anotherA is NULL\n");     else             anotherA->id(); }   but running it gives:  CLASS BASE CLASS A anotherA is NULL   I am sure I'm missing something very basic, but I keep staring at the code and can't see what I'm doing wrong.  Any help would be very much appreciated.  I have looked at    but don't understand why dynamic_cast doesn't work - isn't this just a simple downcast?

What are the proper uses of:   static_cast dynamic_cast const_cast reinterpret_cast C-style cast (type)value Function-style cast type(value)   How does one decide which to use in which specific cases?


How exactly does Java prevent itself from buffer overflow ? Is it just by throwing the "ArrayIndexOutofBounds" ? How is it different from C++ ? Why does C++ have bufferoverflow and not Java ?

Does Java have buffer overflows? If yes can you give me scenarios?


I'm working with some PhotoRec output files, and I'm only interested in files that are larger than a certain size threshold let's say 10M. I've found ways to sort recursively in other posts () but I couldn't quite figure out let's say move all of these files to a different location. Right now the structure of the folders looks something like this:  parent folder  re1 re2 re...

I tried this:  find . -type f -size 128 -exec mv {} new_dir/  \;   Which didn't work, and it didn't give me an error. Here is an example of what the file looks like, when using stat -x  $ stat -x ./testfile | grep Size    Size: 128          FileType: Regular File


I'm looking for a Soundcloud desktop client. I found this post quite relevant, and somebody has suggeted Tomahawk, but the post is pretty old:   Is there any great desktop client to browse your sets, listen to your tracks, search for and listen to new tracks, create sets, upload your tracks, and follow people all from inside the client?

Does anyone know a good desktop client for Soundcloud (are there any)? If not complete feature support then at least a player which can integrate and play Soundcloud account songs.  I found , but it runs using Adobe AIR and Adobe AIR is no longer supported for Linux, furthermore if possible I want to avoid using Wine to run Adobe AIR.


Let $R$ be a commutative ring with identity. Suppose $(a)=(b)$ with $a,b$ in $R$. Then $a=bu$, with $u$ a unit in $R$. Is this true?

Recall the following relevant definitions. We say that   $b$ is divisible by $a$ in $R$, or $a\mid b$ in $R$, if $b = r a$ for some $r\in R$. $a$ and $b$ are associates  in $R$ if $a\mid b$ and $b\mid a$, (or, equivalently, if $aR = bR$). $u\in R$ is a unit if it has a multiplicative inverse (a $v\in R$ such that $uv=vu=1$). $a$ and $b$ are unit multiples in $R$  if $a = ub$ for some unit $u\in R$.   Given these definitions, my question is,     If $R$ is a commutative ring with unity and $a,b\in R$ are associates in $R$, are $a$ and $b$ unit multiples in $R$?   I was told that this not always true. But I encountered some difficulties in finding a counterexample.


We have some guide text on our website that reads:     This email will send daily to members whose vouchers are expiring in 10 days time   However a colleague is insisting that the time period is possessive so the sentence should read:     This email will send daily to members whose vouchers are expiring in 10 days' time   Which sentence is grammatically correct?

Which is correct?     1 Three day's work      2 Three days' work      3 Three days work   I would probably guess (2) is right, since the work belongs to the three days ("three days of work"). But I'm not sure. Would it be different if it was only one day?


Please add the ability to add comments to the Android app. Currently I cannot flag comments as being obsolete, too chatty, etc, as I run into them.  This isn't a feature in the mobile site view either, but you have the capacity to add it on the app at least, I hope!

I had come across a rude comment while perusing the feed. "How wude!" I thought to myself, and tapped the comment to flag it.  To my surprise, my only options were to either visit the user's profile or vote up the comment.  While I understand that comments are not as important as questions and answers, I'd argue that it's still worth it to flag particularly bad comments. The app is great to use when following a question in live-time (beats hitting F5), so if some moderation can be taken care of quicker, I'm for it.    Versions:   Stack Exchange: 1.0.6 Android: 4.3 Phone: HTC One


As far as I understand  are a representation of the Dirac algebra and there is a representation of the Lorentz group that can be expressed as  $$S^{\mu \nu} = \frac{1}{4} \left[ \gamma^\mu, \gamma^\nu \right]$$  Usually the representations used for them are the , the  or the .  All of these are 4x4 matrices. I would like to know what the physical reason is that we always use 4x4, since surely higher dimensional representations exist.  My guess is that these are the smallest possible representation and give spin half fermions as the physical particles, which are common in nature. Would higher dimensional representations give higher spin particles?

While studying the Dirac equation, I came across this enigmatic passage on p. 551 in From Classical to Quantum Mechanics by G. Esposito, G. Marmo, G. Sudarshan regarding the $\gamma$ matrices:     $$\tag{16.1.2} (\gamma^0)^2 = I , (\gamma^j)^2 = -I \ (j=1,2,3) $$    $$\tag{16.1.3}  \gamma^0\gamma^j + \gamma^j \gamma^0 = 0 $$   $$\tag{16.1.4}  \gamma^j \gamma^k + \gamma^k \gamma^j = 0, \ j\neq k$$    In looking for solutions of these equations in terms of matrices, one finds that they must have as order a multiple of 4, and that there exists a solution of order 4.   Obviously the word order here means dimension. In my QM classes the lecturer referenced chapter 5 from Advanced Quantum Mechanics by F. Schwabl, especially as regards the dimension of Dirac $\gamma$ matrices. However there it is stated only that, since the number of positive and negative eigenvalues of $\alpha$ and $\beta^k$ must be equal, $n$ is even. Moreover, $n=2$ is not sufficient, so $n=4$ is the smallest possible dimension in which it is possible to realize the desired algebraic structure.  While I got that the smallest dimension is 4, I fail to find any argument to reject the possibility that $n=6$ could be a solution. I also checked  Phys.SE post, but I didn't find it helpful at all.  Can anyone help me?