I have come to the conclusion that Stack Exchange websites are for really highly trained professionals dealing with really high tech questions and most of the time, I have the feeling, that simple and primitive questions for new learners are not welcome. Now I have asked this question:    And since no answer is given, I think I better remove and come back when I have higher knowledge of neural networks. How can I do that?

What circumstances can cause a question or answer to be deleted, and what does that actually mean?    How can a post be deleted? When can't I delete my own post? Can I still see my post even after it's deleted? Can I see a list of my deleted posts? How can I undelete one of my posts? What does deletion mean for a post? How do votes to delete work? What are the criteria for deletion? What else should I know about deleted posts? If I flag my question with a request to delete it, what will happen?       For more information, see the articles about  and  in the .


They've mentioned this before but I'm confused now because Marley says that they need to be more advanced than the other nations. So are there other countries out there with like modern tech? And would those be countries in our world?

In the Attack on Titan wikia they often mention other nations aside Eldia and Marley which supposedly have more advanced technology than this 2 nations. Which other known nations are there in Attack on Titan world aside Eldia and Marley and why are they more advanced than Marley when only Eldia is supposed to be isolated from the world?


When talking about months should I use the preposition "on" or "in"?   For instance,      I am going to be there on/in April.

I have found the following usage of "on", "at" and "in" on the internet. Is there any other exception and/or rule for that?  Prepositions of Time Use in for  Months: in April / in September / in that month Seasons: in (the) summer / in (the) winter Years: in 1332 / in 1984 / in that year / in the next year Long Period(s) of Time: in former century / in 90's / in the Ice Age / in the past / in the future  Exceptions: in the morning / in the evening Use at for  Time: at 8 o'clock / at 9:30 / at bedtime / at sunset / at dinnertime / at 5:33:10 AM  Exceptions: at Christmas (= during the Christmas holidays but not necessarily on December 25th) / at Easter  / at noon / at night / at the weekend / at the present time / at the moment Use on for  Days: on Monday / on Friday / on Christmas Day (= on December 25th) / on Easter Sunday / on Independence Day Dates: on February 18th / on her birthday / on 21 March 2015 / on  Notice:  We have in the morning and on Monday but we say on Monday morning, not in Monday morning, and so on. When we say last, next, every, this we do not also use at, in, on: She runs next Tuesday. (not on next Tuesday) / He leaves us every Easter. (not at every Easter) / I See you this evening. (not in this evening) Look at these examples for the combination of times in a sentence: We will meet next week at six o’clock on Monday. / I heard a funny noise at about eleven o’clock last night. / It happened last week at seven o’clock on Monday night.   Look at  as well which says:  This all hints at a coherent metaphor: hours and other short periods of time are places; days are surfaces; months and longer time periods are containers.


How can I get the following behavior?   I make a linked duplicate of an object (in my case an object with a rigid body physics) I change the Mass value of the rigid body property from the original object, so 1 kg becomes 2 kg When I now select the linked duplicate the mass is still 1 kg. This is also the case when I change the mass value of the original object in object mode.   Is that even possible with Blender? I don't want to update each time all duplicates whenever i changed the properties of the original object.

Using the cell fracture addon, I created many objects from my mesh. I want to have a rigid body physics on all of them. How would I copy one of the fractured pieces physics to all the pieces? I tired ctrl L and the copy attributes addon, but none of them have the option. Any help is great.


I am a math major in my early years of undergrad, and I'm wondering if math majors can or should consider pursuing graduate school in (theoretical) physics. I don't think there's a barrier in terms of logistics, since there's quite a bit of overlap between pure math and theoretical physics — but I'm not sure if math majors fulfill the prerequisites (if any) to pursuing graduate school in physics. Would a typical math major be required to take some more physics classes than usual, or have some research experience in theoretical physics before trying for grad school in related areas? Or are schools (and advisors) happy to accept pure math majors with minimal physics background whatsoever (maybe to start certain things from scratch in grad school)? My question is specific to PhD programs right after undergrad, and schools in the U.S. or U.K.

I am a mathematics major without any undergraduate level courses in physics. I am lately interested in physics. Is there any chance for me to go into good theoretical physics graduate program without any background in physics?   I am not sure if this kind of question is acceptable here, though.  ADDED My concern is do Universities even accept students with math majors into physics department without physics courses?


I will be traveling to Ghana, but I will have a layover in the Netherlands. As the holder of a Canada travel document, do I need a transit visa? I already have a Ghanaian visa.      I do have a Canadian permanent resident permit. My flight route: Vancouver transit Schipol-Accra. Returning: Accra-transit in Paris-Vancouver. I have a Ghanaian visa in my travel document because Ghana is my destination

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


How can I remove all the emoji icons from a SQL Server table?  I want to remove all 😋 😋 icons and keep only Hebrew and English Spaces.. letters  In the end I want to keep only Basic Latin (0020—007F) and Hebrew (0590—05FF).

I'm trying to write a query which replaces the special characters with space. Below code helps to identify the rows. (alpha-numeric characters, comma and space is valid):  SELECT columnA FROM tableA WHERE columnA like '%[^a-Z0-9, ]%'   How can I integrate the replace function into the select statement so that all characters other than alphanumeric, comma and space in the result set are  replaced by ' ' (space). This one won't work:  SELECT replace(columnA,'%[^a-Z0-9, ]%',' ') FROM tableA WHERE columnA like '%[^a-Z0-9, ]%'


phone_missing=false echo "missing $phone_missing"  if [ ! $phone_missing ] then         echo "Lost phone at $readabletime"         $phone_missing=true fi   I just can't understand this.  The line   echo "missing $phone_missing"   echos missing false, I would expect the statement   if [ ! $phone_missing ]   to be true and enter the if clause, but it doesn't? What am I missing here!?

I want to try simple script  flag=false while !$flag do    read x    if [ "$x" -eq "true" ]    then      flag=true    fi    echo "${x} : ${flag}" done   But when I run it, if I type true, I will see that x="true" and flag="true", but the cycle doesn't end. What is wrong with the script? How can I properly invert a boolean variable?


I'm trying to use command blocks to spawn a Grinder mob once at a certain spot whenever the player's "Grinders" score is equal to the set ammount. Eg. 1. I'm using this command (With differences for each amount and position):   execute @p[score_Grinders=20] ~ ~ ~ setblock 17 5 22 redstone_block   The setblock sets a block of redstone above a set of command blocks that spawn the Grinder, and those work. However, even when the Grinders score is not met, it places the block, and I can't delete it without first disabling the command block. When inspecting the command block it says it can't execute the command as the player. Please help!

What if I want to make a command like this:  execute @e[score_A=10] ~ ~ ~ summon Creeper   So that the entity must have a score of 10 (not less, not more)?  Does it even exist that or a [score_A_max=] argument?  I know about scoreboard players test, but i guess it is not the case to use it.


So, I'm finding that when I break Redstone blocks while mining I am getting nothing in return. I've read this happens on PE but I'm using the PC version(Windows 7), which I downloaded yesterday. I am in survival mode. Has anyone experienced this? I've mined about 10 of these and have gotten nothing. From what I've read every one of those blocks should have given me something, it doesn't appear to be a rare drop. Thanks!

Normal blocks I can mine fine, but when it comes to diamond and gold ores, the block just gets "destroyed" (as in you can't pick it up). I'm playing on multiplayer with no spawning monsters.


I am trying to install i-nex.  sudo add-apt-repository ppa:gambas-team/gambas3  : The repository 'http://ppa.launchpad.net/i-nex-development-team/daily/ubuntu bionic Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.

Can anybody offer a working solution on how to install iNEX monitoring tool system/hardware information application on my Ubuntu 18.04? I have tried several different things from different websites. I keep getting errors. Why is this so hard? Why do I have to enter my password after every command? Can't there be an easier way? Windows does it, why can't Ubuntu and Linux do it?  I'm partially blind, and all I want to do is load a simple app to get some simple answers. I could have taken my machine apart and put it back together in the time that I've spent researching this topic and entering several lines of text for every suggestion.


I am currently living in the US on a 24-month STEM OPT. I am travelling to India for visa renewal.   My itinerary is Dallas/Fort Worth-Washington/Dulles-Newark-Bombay. Do I need a valid US visa or a transit visa for this itinerary?

I am an international student and authorized to stay in US for 2 years on my I-20 form. My visa expired on June this year and I need to fly to some states outside Georgia to visit colleges. Can I fly within the US?  If I can, what kind of document will the airport check when I depart? Will they notice my expired visa and turn me in to Homeland Security? In other words, will I get into trouble?


I have faced the following sentence:  "The work leverages features unique to a particular platform."  As far as I know an adjective is used before a noun but how can we say "features unique"?  I think "unique features" is correct. But this sentence is written in a valid text and the probability of making a mistake by authors is very low!!!

I would like to understand the correct grammatical order in the sentence,     In your essay, you must use grammatically correct sentences with accurate spelling and punctuation in a style appropriate for the situation.   I hold the view that “style appropriate” is written bad because the grammatical order indicates that an adjective needs to be before the noun.  Is it grammatically correct?: NOUN + ADJECTIVE X  So,     In your essay, you must use grammatically correct sentences with accurate spelling and punctuation in an appropriate style for the situation .   It is true that it works like this  ADJECTIVE + NOUN   Resource: Cambridge English Objective First Book, Fourth Edition


I am trying to use my pc wireless card as an AP, while being connected to my wifi network thru the very same card, but I have a problem. What I am trying to achieve is the equivalent of Windows' Virtual Wi-fi technology. In line of principle, it's very simple:  service network-manager stop iw dev wlan0 del iw phy phy0 interface add new0 type station service network-manager start iw phy phy0 interface add new1 type __ap hostapd -B /etc/hostapd.conf   with a suitable configuration for hostapd:  cat /etc/hostapd/hostapd.conf  interface=new1 driver=nl80211 logger_syslog=-1 logger_syslog_level=2 logger_stdout=-1 logger_stdout_level=2 ssid=XXXX country_code=us hw_mode=g channel=1 macaddr_acl=0 auth_algs=3 ignore_broadcast_ssid=0 eap_server=0 wpa=2 wpa_passphrase=XXXX wpa_pairwise=TKIP CCMP rsn_pairwise=TKIP CCMP   However, the driver nl80211 refuses to put the virtual IF new1 into AP mode. Here comes the interesting bit: the output of iw list contains  Supported interface modes:          * IBSS          * managed          * AP          * AP/VLAN          * monitor software interface modes (can always be added):          * AP/VLAN          * monitor valid interface combinations:          * #{ managed } <= 1, #{ AP } <= 1,            total <= 2, #channels <= 1, STA/AP BI must match          * #{ managed } <= 2,            total <= 2, #channels <= 1   It is obvious my wifi card (an Intel Centrino Advanced-N 6235 [8086:088e] under iwlwifi) supports AP mode (I have tested it), and I had interpreted the "valid interface combinations" to mean that I could have at most 1 managed and 1 AP vifs on this card at the same time. But then I noticed the mysterious-looking constraint, STA/AP BI must match.  Does anyone know what this means, and whether this is what is thwarting my attempts at using two vifs on my card, one in station the other in AP mode? Cheers

I am trying to create a WiFi hotspot or an access point on my Linux laptop. I am using Opensuse Kde 12.3.  I found out a software called hostapd which lets you create hotspot but it requires two interfaces. One connected to the internet and the other on which you want to create the access point () . The problem I have is that I don't have Ethernet connection. The wlan interface is being used to connect to the internet.   Is there any way to create the hotspot on the same interface that is connected to the Internet (like the software connectify does on Windows)? I was thinking of creating a virtual interface (like the one airmon-ng creates to monitor wifi) and use it as the second interface. Is this possible?  UPDATE  Here's what i have been able to do up till now :  1) Create 2 interfaces ( one as station and the other as an access point )    iw phy phy0 interface add mySta type station   iw phy phy0 interface add myAcc type __ap   2) Give them seperate Mac ID   ifconfig myAcc hw ether A4:17:FE:6E:00:53 ifconfig myAcc 192.168.27.1 up   3) start hostapd on the myAcc interface  4) start dnsmasq to provide ip address to the connecting devices  All of this works. Devices are able to connect to this network and obtain Ip Address.  The next step is to provide ip masquerading   iptables --table nat --append POSTROUTING --out-interface mySta -j MASQUERADE iptables --append FORWARD --in-interface myAcc -j ACCEPT   But the mySta interface now fails to connect to the internet. It is able to obtain the Essid but it cannot obtain the ip address.  The command dhclient mySta doesn't show any message and after some time gives the error :  ls: cannot access /var/run/netconfig//mySta/: No such file or directory   Can someone figure out how to obtain the ip address ?


my ssh is asking for my keys everytime I try to log onto my servers, this is happening after I upgraded my ubuntu from 13.04 to 13.10, before that it unlocked my keys at my session login, but now it's not working.  How can I reset the mechanism that takes care of my keys?  Thanks!  UPDATE: Solved with this two commands  gnome-keyring-daemon -s ssh-add -D

Before upgrade When I was running git clone git@... (using ssh) once per computer restart a window dialog appeared containing a textbox for inserting my SSH passphrase and confirmed with OK. Then the passphrase was no longer required until the next start of my system. After upgrading to 13.10 After upgrading to Ubuntu 13.10 that window doesn't appear anymore but a message in terminal appears: Enter passphrase for key '/home/username/.ssh/id_rsa':   ...every time when cloning a git repository this appears. How can I fix this? I want to enter my passphrase only once.


I have purchased a laptop that has Windows 7 Home Premium OEM.  I have also purchased a Windows 7 Professional Installation CD.  Can I just put this CD into the drive and load Professional over the Home Premium that is currently on the laptop?

I purchased a retail version of Windows 7 Professional and installed it on a computer.  That machine has died, and I replaced it with a new computer which came with Windows 7 Home Premium already installed.    I'd like to have Professional, not Home Premium, on the new machine, and I don't want to pay for an "Anytime Upgrade" because I already have a valid Windows 7 Professional license (for the dead computer).  Is there a way to legally upgrade using my Professional license key?  I've already installed programs, data, etc on the new machine, so I don't want to reformat and start from scratch.


I had a table named uniq_select_records with the following columns:  sno number,  item_name varchar2(50), start_date date,  end_date date,  action_flag char(1), last_modified_date date,  creation_date date   sno is a column which I used to identify a row for a item_name and it is not unique or primary key but it was not null. sno will be present for each item. no of items is equal to no of sno. sample  sno item_name start_date  end_date Action_flag last_modified creation_date --- --------- ----------  -------- ----------- ------------- ------------- 1   sample1   02-MAY-15  27-MAY-14    A        07-MAY-15        02-MAY-15 1   sample1   02-MAY-15  27-MAY-14    D        07-MAY-15        02-MAY-15 1   sample1   27-APR-15  06-JUN-14    C        07-MAY-15        02-MAY-15 1   sample1   27-APR-15  06-JUN-14    C        07-MAY-15        03-MAY-15 2   sample2   07-MAY-15  11-FEB-15    C        07-MAY-15        22-JAN-15 2   sample2   07-MAY-15  11-FEB-15    A        07-MAY-15        22-JAN-15 2   sample2   07-MAY-15  01-FEB-15    C        12-MAY-15        12-MAY-15   Action flag values C=change, D='Deleted and A=insert sample data is shown above. like this we have millions of records. now we have to select the to record which had the latest change for each item. each item may have its own start_date and end_date.All the items weren't modified on the same date.  Can anyone suggest idea how to fetch the records for each item which are latest change for an item.  thanks in advance.

Table:   UserId, Value, Date.   I want to get the UserId, Value for the max(Date) for each UserId. That is, the Value for each UserId that has the latest date. Is there a way to do this simply in SQL? (Preferably Oracle)  Update: Apologies for any ambiguity: I need to get ALL the UserIds. But for each UserId, only that row where that user has the latest date.


Is it against SE rules or suggested good practice to have a different profiles for every SE site rather than a single  profile?

Take this example: .  I can imagine of any human reasons to create a new user account at SO, e.g. willing to restart with a clean (reputation) history. But particular this one is extreme. The user known as "icepax" currently already has 10 accounts, each involved in only one question/answer.  How and why would one do that? There is certainly more at matter here. Shouldn't it be our task to merge the accounts and inform the user in question about how to use SO and the OpenID properly?


I know about nonlocal keyword and how to fix this error but I am getting a behaviour that I am not understanding in the code below. If you run this, there is no problem  def test( root):         x=2         def f2(r):             print("***")             x=r #Adding this line is ok             print("----",x)         f2(root)         return x test(4)   Now try changing x=r  to be be the last line in f2 does not work as below  def test( root):         x=2         def f2(r):             print("***")             print("----",x)             x=r #Gives an error "local variable 'x' referenced before assignment"         f2(root)         return x test(4)   Thanks

What exactly are the Python scoping rules?  If I have some code:  code1 class Foo:    code2    def spam.....       code3       for code4..:        code5        x()   Where is x found?  Some possible choices include the list below:   In the enclosing source file In the class namespace In the function definition In the for loop index variable Inside the for loop   Also there is the context during execution, when the function spam is passed somewhere else. And maybe  pass a bit differently?  There must be a simple reference or algorithm somewhere.  It's a confusing world for intermediate Python programmers.


So I am delt with a very bad hand. As Windows user for nearly 10 years  I have an assignment which says  Create 7 users - 2 admin, 2 teachers and 3 students [DONE]  Create folder in Home - Admin Files,Teacher Files,Student Files [Done]  Now I have to be able to do this using terminal   Allow students read-only access to the files in the Student Files folder, and no access to the other folders. Allow teachers full access to all  files except the Admin Files folder, to which they have no access. Allow administrators full access to all files.   How do I change the file permission for the scenario above?  Thanks in Advance

Can you explain briefly the main concepts and command line tools used to manage file permissions?


I've a MacBook w/ the following specs:    Very annoyingly, CommandControlQ locks the screen. I can't even remap it to anything else; trying to do so in Keyboard locks the screen instead of registering the key combination.  Is there a way to get rid of this shortcut?

I would like to disable  Shift+Command+Q keyboard shortcut for Log Out.   I am using Karabiner at the moment, but I only managed to disable it completely using the following xml:  <?xml version="1.0"?> <root>     <item>         <name>Disable COMMAND SHIFT Q for Logout</name>         <identifier>disable_CMD_SHIFT_Q_private</identifier>         <autogen>__KeyToKey__ KeyCode::Q, VK_SHIFT | VK_COMMAND | ModifierFlag::NONE, KeyCode::VK_NONE</autogen>     </item> </root>   but I would like to have the keyboard combination available in emacs (in ESS for debugging).  Is there some way that I can effectively unmap the keyboard combination?


Is it right to use the word "Collapse" to describe what this button do or "Minimize" is more correct?    What the difference in meanings of words "collapse" and "minimize" in context of computer program interfaces?


For Python 2.7 I have a little utility for debugging:  def printvar(label, var):     print "%s:\n%s" % (label, pformat(var))   Often I call it like printvar("foo", foo).  Is it possible to simplify that a tiny bit and only pass in the variable, like printvar(foo), but still have it print the name of the variable? Using introspection or something?

I have enum and use the variables like myEnum.SomeNameA, myEnum.SomeNameB, etc.  When I return one of these variables from a function, can I print their names (such as myEnum.SomeNameA) instead of the value they returned?


I am using firebase database for my app and I saved my users in it. This is my UserInformation class:  public class UserInformation {   private String email1; private String Password1; public HashMap<String, Boolean> SayingsLevels=new HashMap<>(); public HashMap<String, Boolean> songs=new HashMap<>();  public UserInformation (String email, String Password){     this.email1=email;     this.Password1=Password;     SayingsLevels.put("1", false);     SayingsLevels.put("2", false);     SayingsLevels.put("3", false);     songs.put("1", false);     songs.put("2", false);     songs.put("3", false);  }   And I saved it with this code on my main activity:  firebaseUser=FirebaseAuth.getInstance().getCurrentUser();                 UserInformation user=new UserInformation(email1,password1);                 String id=firebaseUser.getUid();                 mDatabaseReference.child("user").child(id).setValue(user);   Now, I want the get the hashmap data that was stored in my database. I used the following code:  mDatabase.addValueEventListener(new ValueEventListener() {          @Override         public void onDataChange(DataSnapshot dataSnapshot) {              mDatabase = FirebaseDatabase.getInstance().getReference();             firebaseuser=FirebaseAuth.getInstance().getCurrentUser();             id=firebaseuser.getUid();             for(DataSnapshot dataSnapshot1: dataSnapshot.getChildren() ){                UserInformation user= dataSnapshot1.child("user").child(id).getValue(UserInformation.class);              }   but on variable user I'm getting all the time null, what I did wrong? Thanks for help!

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'm running Windows 10 version 1607 (OS Build 14393.693)  Recently after restarting my computer, all icons have either gone missing or not getting displayed properly. Have a look at the following screenshots:      I have tried rebuilding the Icon cache. I have also started the PC in safe mode and rebuild icon cache. But it's all same for me.   Any help would be highly appreciated. Thanks

I opened the PC in the morning, and this is what I got:      As is visible the icons of the UWA apps were no affected and the start menu also is unaffected.    When Control Panel is in category view the entire page is empty and in large/small icons the name is visible, no icons.  I deleted the iconcache.db in %USERPROFILE%\AppData\Local folder. Following the instructions here: . But to no avail and now windows is not rebuilding the cache.   I also ran sfc /scannow but no changes took place.  What should I do?  (01/01/2016 8:00PM GMT +5:30) Edit: I tried opening the system properties and I got 0x8000ffff error and this:        Then I closed the popup and pressed the OK button on the System Properties Windows and I got 0x8007057A error:      Opening the Image Backup Control Panel page I again got an 0x8007000E error:        I tried using system restore via advanced startup but once again I got 0x800FFFF error.  P.S.: I did try restarting, didn't work.


When I validate a change set with RunLocalTests in production (as well as using the CLI with that flag for CI/CD and packaging integration) there was a class that was erroring out as a dependency. I've deleted the class from production since it was no longer needed. Using workbench was easy to delete the class. Now I'm still getting the same error with RunLocalTests  Dependent class is invalid and needs recompilation  I think the solution is to use Compile all classes in production but I'm afraid of causing working classes to fail. Would you please let me know what are potential issues if use this method of recompiling all classes in prod?

Running into an issue with a deployment, getting a ton of errors of the following flavor: line -1, column -1: Dependent class is invalid and needs recompilation: Class MeansRegisterCustomerTest : Constructor not defined: [LightningLoginFormController.VerifyResponse].<Constructor>() Stack Trace: null Seems like the 'Compile all classes' option in Apex settings has worked for people with similar issues. Is there any risk in recompiling all Apex classes? I don't see how this could break something that was not already broken, but would like to hear people's thoughts on this before potentially breaking a bunch of code.


My system is currently running Ubuntu 18.04. Ubuntu 20.04.1 has been out one week ago, yet it is not proposed as an upgrade by the software manager:  A call to sudo do-release-upgrade -c returns Checking for a new Ubuntu release There is no development version of an LTS available. To upgrade to the latest non-LTS develoment release  set Prompt=normal in /etc/update-manager/release-upgrades.  Am I being impatient, or is something wrong here? (In case that is relevant, I was actually running 16.04, and wanted to switch to 20.04 once the first point release is out. Hopping to 18.04 is a necessary step in the process -- this one happened flawlessly).

I understand that the first point release of Ubuntu 18.04, namely 18.04.1 is now available and that my system should now offer it as an update.  My current OS version is 16.04.5 LTS. In System Settings/Software and Updates I have set 'Notify me of a new Ubuntu version' to 'For long term support versions'. I have tried both the main server and the server for United Kingdom, neither offers an update when Software Updater is clicked or via the Ubuntu Software icon.  Can anyone please tell me why I don't get the option of updating to 18.04?  Edit:  I don't remember the details exactly, but I think that my last LTS point release update was offered automatically a lot sooner after the published release date than where we are now with 18.04.1.  Edit 10th August  It appears that there has been some problem with the update process and that it should be fixed next week, see:    Edit 14th August 18.04.1 LTS now available from UK server,


I want to tranform multiples text cells (with numbers in it), to numeric type of cells. To finally manipulate the numbers

I have a user with a query from an SQL Database that returns a series of string in this form:  000123123.23000 000123123.23000 000123123.23000 000123123.23000 000123123.23000   These are really numbers, however they cannot be summed.  The correct way to fix this might be to cast the data in the SQL query, but then the Excel query viewer can't display it. As a workaround I do    = <CELL> +1 -1.   Is there a more elegant solution?


I am running a logistic regression against the "Default" dataset of . I am using the  package in R (available on CRAN) to test the goodness of my model. MWE: rm(list=ls()) indf <- read.csv("https://pastebin.com/raw/suXpddVR") indf$default <- as.factor(indf$default) indf$student <- as.factor(indf$student) mod <- glm(default ~ student+balance+income,            data=indf,            family="binomial") print(summary(mod))  library(performance) performance::check_model(mod)  Diagnostic plot is as follows:  As you can see from the plot in the upper right the residuals don't follow a normal distribution. How can I cure that? I have tried putting the squares of the variables in the model, but they are non-significant and the problem remains.

First I'm a little bit confused with the assumptions of a model with binomial response and logit link function. Since it is basically a logistic regression. Today one of my professors told me that I had to prove normality of my residuals, but of what I know the assumptions are:  First, binary logistic regression requires the dependent variable to be binary and ordinal logistic regression requires the dependent variable to be ordinal.  Second, logistic regression requires the observations to be independent of each other.  In other words, the observations should not come from repeated measurements or matched data.  Third, logistic regression requires there to be little or no multicollinearity among the independent variables.  This means that the independent variables should not be too highly correlated with each other.  Also these are the plots I have:     So basically my question is: what assumptions can I prove/not prove with these plots?


I am reading the following code segment, this function was once invoked as generator = image_gen.get_image_gen_rgb(nx, ny, cnt=20).  I am not very clear about the usage of **kwargs in the function of get_image_gen_rgb. Does cnt=20 was used to setup the parameter of n_image in create_batch  def get_image_gen_rgb(nx, ny, **kwargs):     def create_batch(n_image):         print("n_image: ",n_image)         X = np.zeros((n_image, nx, ny, 3))         Y = np.zeros((n_image, nx, ny,2))          for i in range(n_image):             x, Y[i,:,:,1] = create_image_and_label(nx,ny, **kwargs)             X[i] = to_rgb(x)             Y[i,:,:,0] = 1-Y[i,:,:,1]          return X, Y   create_batch.channels = 3   create_batch.n_class = 2   return create_batch

In the following method definitions, what does the * and ** do for param2?  def foo(param1, *param2): def bar(param1, **param2):


I want to create a controller that passed a parameter search as an input to findDuelIdOrEmail method: @RequestMapping(value = "/app/friend_search", method = RequestMethod.GET) public ResponseEntity<List<FriendResponse>> getAll(         @RequestHeader("Authorization") String authToken,         @RequestParam(value = "search", required = false) Object search) throws Exception {      TokenPayload tokenPayload = tokenProvider.verifyAndDecode(authToken);       List<FriendResponse> friendResponseList = new ArrayList<>();     boolean isNull = search == null;     boolean isEmpty = search != null && search.toString().equals("");      if (isNull || isEmpty) return ResponseEntity.ok(friendResponseList);      friendResponseList.add(this.friendService.findByDuelIdOrEmail(search));     return ResponseEntity.ok(friendResponseList); }  I have a findDuelIdOrEmail method which contains a variable profile that initialized with null value. The code is shown below: public FriendResponse findByDuelIdOrEmail(Object duelIdOrEmail) throws Exception {     Profile profile = null;     final String duelIdOrEmailString = duelIdOrEmail.toString();     final User userEmail = this.userRepository.findByEmail(duelIdOrEmailString);       if (userEmail == null) {         final int userId = this.generateUserId(new Long(duelIdOrEmailString));         profile = this.profileRepository.findByUserId(userId);     } else {         profile = this.profileRepository.findByUserId(userEmail.getId());     }      if (profile == null) {         throw new ResourceNotFoundException();     } else {         FriendResponse response = this.generateFriendResponse(profile, 1, null);         checkResponse(response);          return response;     }  My guess is the profile variable caused NPE. I tried to handle the null value by validating it with if(profile == null). But, I still got the NullPointerException. What is the best practice to handle this problem? Any tips will be appreciated.


I have a link that redirects to  "/Certification/abc123.asp". Now what I want is page should redirect to some another page that is "details.aspx?URL=/Certification/abc123.asp" but URL in address bar should appear  "/Certification/abc123.asp". I have created Url rewriting rule in web.config.  Below is my code: in web.config   <rule name="Redirects to Certifications" stopProcessing="true">       <match url="(.*certifications*)"/>       <conditions>         <add input="{HTTPS}" pattern="^OFF$"/>       </conditions>       <action type="Redirect" url="http://{HTTP_HOST}/ERRoot/details.aspx?url={REQUEST_URI}"  appendQueryString="true"/>     </rule>   By this I match my URL, if it contains "certifications" then it redirects to "details.aspx" page with Querystring key "url" that contains original URL. But my URL displays the page i have redirected to.  I want "/Certification/abc123.asp" to display in my address bar.  Note: There is no page like /Certification/abc123.asp. It is just a URL  Please help. Thanks in advance !!!

What is difference between Server.Transfer and Response.Redirect?   What are advantages and disadvantages of each? When is one appropriate over the other? When is one not appropriate?


I am confused if I should use persons or people. Persons sounds weird to me.

I had a little fight about persons vs. people.  Could you advise if both of the following are correct, if possible with reference to a dictionary?        A table for two people please.   A table for two persons please.      Besides that, how would you ask for a table in a restaurant?  I read  and , but they didn't really solve the question if both are correct.  I also found the last paragraph of , which suggests that (1) is "more correct", but doesn't say (2) is wrong.


I tried approach by line, parabola, polar coordinates, double limit. I do not know any other way to determine whether this limit exists or not.

Compute $$\lim_{(x,y) \to (0,0)} \frac{\sqrt{xy + 1} -1}{x + y}$$  If you look at the graph of the function, it suggests that the limit does not exist. In fact, the limit DOES NOT exist. But how do I prove that?  When I approach the function from either $x$ or $y$-axis, the limit is equal to $0$. It is also equal to $0$ for every line (except for $x=-y$) passing through the origin.  I tried to approach $0$ on a parabola $y=x^2-x$ but the limit was again $0$.  Any thoughts would be appreciated.  Edit:  I did a mistake when calculating the limit as I approached $0$ on the parabola $y=x^2-x$ the result should be $1$ for that limit proving that the limit does not exist.


I have searched for this and there are a number of previous answers but all seem overly complex.   I'm new to C# and Windows development in general (previous Mac developer).   I have written a simple console application in C# using Visual Studio Community edition. My application uses two third party libraries (CommandLineParser and json.NET) added to my project with NuGet from within VS.   All I want to do is build my project as a standalone .exe file that can be simply run from a command prompt without having to worry about the end user having to install lots of DLLs (something that I'm not used to dealing with as a new Windows user).  I understand that the end user would need to have the .NET framework installed. Is there an idiot-proof guide to building a single .exe file in my use case?  I can't help but think that this must be a very common problem.   Thanks.

Is it possible to embed a pre-existing DLL into a compiled C# executable (so that you only have one file to distribute)? If it is possible, how would one go about doing it?  Normally, I'm cool with just leaving the DLLs outside and having the setup program handle everything, but there have been a couple of people at work who have asked me this and I honestly don't know.


I'm using Linux Mint, with the TeX Live distro and Texmaker as my editor. Basically, I would like to be able to use llncs.cls as a document class without having to always put that file in with the document I'm trying to compile. Under MikTeX (which I used back when I used Windows), there was a way to resolve it by giving it a place to search for packages etc. if it couldn't find them normally. However, I have no idea how to do this in Linux. Could someone help me out?

I know how to define a package or a class, but how do I make it available (to myself) at all times?  Say I have the package file commonstuff.sty (or myprettyclass.cls), that I want to be able to include in any .tex file I create on my computer. Where do I put it? Do I need to run some installer on it, or is it enough to keep it in a certain folder?  Note: I know I can just place it in the same folder as the .tex file, but that's not what I'm after here. I'm looking for a way to "install" the package centrally on my computer.


I didn't see this listed on the books page so here it is. I'm currently in an introductory Solid State course, and we are using Kittel's book. I have been having a rough time with this book although I am starting to get used to it as we get farther in. What are good introductory solid state books?

What are some good condensed matter physics books that can fill the gap between Ashcroft & Mermin and research papers? Suggestions for any specialized topics (such as superconductivity, CFT, topological insulators) are welcomed.


I'm looking for something along the lines of "tough decision" but want a phrase which emphasizes on the degree of severity of the toughness of the decision.

This has cropped up several times in the past couple of months, and I've been struggling to find  a fitting word to describe this phenomenon. I'll describe it:  You have two choices(no, it's not Hobson's choice). Both of them are desirable, yet both of them each have a tiny part which is most undesirable, such as a tough condition, or a demanding clause. You have difficulty deciding which one to pick.  Whenever something like that comes up, I think of the expression "Can't burn a candle at both ends", but I'm not looking for that.  I'm looking for an expression that describes a difficult choice. Any suggestions?  EDIT: It's idiomatic. I'm quite sure it is. It's an expression of some sort. And no, it isn't "dilemma"


I have a simple shoe size converter app and I want it to be so that if the answer requires no decimal places, there are none, just whole numbers. If the answer was 2, I don't want it to say 2.000000, it should say 2. If it requires one decimal place, it should show to one decimal place for example 12.8 instead of 12.80. How would I do this?   ViewController.m file  - (void)viewDidLoad         {             [super viewDidLoad];             _countryNames = @[@"Europe", @"United Kingdom", @"Japan"];              _sizeRates = @[ @11.5f, @.875f, @7.0f];         }  -(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component                  NSString *resultString = [[NSString alloc] initWithFormat: @"%3f USS = %3f %@", size, result, _countryNames[row]];                 _resultLabel.text = resultString;             }

I have the value 25.00 in a float, but when I print it on screen it is 25.0000000. How can I display the value with only two decimal places?


spark version 2.1.1     /Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/bin/java     Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/spark/sql/SparkSession$         at org.example.sparktest$.main(sparktest.scala:7)         at org.example.sparktest.main(sparktest.scala)     Caused by: java.lang.ClassNotFoundException: org.apache.spark.sql.SparkSession$         at java.net.URLClassLoader.findClass(URLClassLoader.java:382)         at java.lang.ClassLoader.loadClass(ClassLoader.java:418)         at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355)         at java.lang.ClassLoader.loadClass(ClassLoader.java:351)         ... 2 more

I am getting a NoClassDefFoundError when I run my Java application.  What is typically the cause of this?


I need to extract everything between the SQL keywords FROM and WHERE from a file. There can be multiple combination of FROM and WHERE. Also this has to be case insensitive match. The SQL file is as below:      SELECT col1 as column1,     Col2 as column2,     Col3 as column3,       (SELECT t1.col4       from table_1 t1, table_3 t3       WHERE t1.col5 = t2.col6       AND t1.col2 = t3.col11       ) as column4     FROM     table_2 t2,     table_4 t4     where t2.col7 ='Active'     AND t2.col12 = t4.col13     AND t2.col8 IN ('abc','def','ghi')     AND t2.col8||''||t2.col9 <> 'jkl'     AND t2.col10 IS NULL;   Output desired should be  table_1 t1 table_3 t3 table_2 t2 table_4 t4   I have tried the following which almost solves the problem, except that if the table name is present in the next line where "FROM" is, this breaks and doesn't prints as output.  #!/bin/sh     awk '     BEGIN {IGNORECASE=1} { found = 0; }     /FROM/ {         if (!found) {             found = 1;             $0 = substr($0, index($0, "FROM") + 4);         }     }     /WHERE/ {         if (found) {             found = 2;             $0 = substr($0, 0, index($0, "WHERE") - 1);         }     }            { if (found) {             print;             if (found == 2)                 found = 0;         }     }     '

My data is like:   First_file.txt  Start abcd efgh hijk lmn  Second_File.txt  opq rst uvw xyz END      I want to grep all the line between patterns START & END even END pattern in next file  Output should be like:  abcd efgh hijk lmn opq rst uvw xyz


I was wondering if the Stack Overflow developers had created a bookmark page where all of my favourited questions will be displayed.  This page should also have a quick way to search its contents. I think that would be helpful to everyone.

What does bookmarking a question mean? How do you bookmark a question? Do users get updates on their bookmarked questions? Are my bookmarks publicly visible? How do you see your own bookmarks? How do you see other users' bookmarks? How do you see which users have bookmarked a particular question? What impact does the bookmark system have on the voting system? Can I "un-bookmark" a question? Can I search within my bookmarks?


I'm sorry if this question seems extremly dumb or/and pathetic. I'm quite new to electronics. For one of my electronics projects, I want to buy a power supply like , but it says Output: 12V 2A and I know that 2 amps is dangerous for the human body. So what does it mean? Will I hurt myself if I touch the two cables or is it fine? I don't really understand this. I'm sure you all know the answer and if so, please explain why. Thank you!  EDIT: My question has been marked as a duplicate but it's different. The other question is about what voltages / currents are dangerous but I do now that. However, I'm asking if the 2A power supply always outputs 2 amps or if it is the maximum current it CAN output.

By safe I mean safe for us when we touch a wire that is not insulated. I have heard that human body resistance is normally 50k Ohm when dry and 20K Ohm when wet. Therefore, these voltages or currents should be safe for a person who is wet. It should be considered when no insulator is present to protect the body.


So I didn't save it, as I didn't know you had to but in this screenshot is what I have. You can see in the UV selector menu thing it shows my texture, highlighted in red.  Now how do I restore it?

I was following a  on how to use the Texture Paint feature on blender so I could paint on a terrain I am modeling. I was successful to paint the whole terrain with beautiful, exuberant vegetation, and crystalline water running through the valley.  So I saved my file, and I went to sleep. But now I've reopened the file and everything seems like I left it yesterday, except that I can see no texture in the terrain... The weird thing is that the textures i used are still there... I don't understand, I barely understand the interface, please help. I'm not even sure if the texture is there or if it was never "saved" or something...     I am now going through the second part of the tutorial for possible answers but I (and hopefully many more) will be grateful for your help.


I am new to apex help me for this, what is the changes i need to do  public class MyCustomController{ Public Account acc; public MyCustomController(){ List<Account> lstAccount  = [select id,Name,Phone,Industry,Website,Active__c,Rating,BillingCity,Description,Fax, ShippingCity,AnnualRevenue,BillingCountry,ShippingCountry from Account where id=:ApexPages.currentPage().getParameters().get('Id')];  } public Account getAccount() { return acc; } public Pagereference saveMethod() { update acc; Pagereference pageRef = new ApexPages.StandardController(acc).view(); return pageRef; } }


I'm trying to write a bash script which, among several other things, will "log in" as a user (preferably with su if possible) without needing to interact with the password prompt, i.e., will automatically input the password.  I only need it to perform one command and then the session can end.  This is for an "automatic checker" for an introductory Linux class I'm teaching.  The students have an exercise where they create usernames with specific passwords on their Raspberry Pis (running Raspbian), and I want this script to automatically verify the passwords are correct.  The students run the "automatic checker" on their Pis and I verify the output, so they have a chance to fix any errors before turning in.  Since this is for a classroom exercise with dummy passwords, the security of these passwords is completely irrelevant.  I know there are already a few questions about automatic logins, but none of them work for me.  The closest I've come to a solution is getting the su command to say a terminal is required.  Using "expect" will not work because it will require installing packages on the students' Pis.  If there are other ways to verify the passwords are correct then I'm open to those.  I don't think I can do a hashed password comparison due to the salt.

I want to check, from the linux command line, if a given cleartext password is the same of a crypted password on a /etc/shadow  (I need this to authenticate web users. I'm running an embedded linux.)  I have access to the /etc/shadow file itself.


Which of these is the correct one, or are both correct?   I moved slowly, to not wake my parents. - Intended meaning I moved slowly, not to wake

"Name three things that, if you were told were part of the job, would cause you to not take the position. "   I've just come across this sentence while reading the news.   Question is: Why to not is used instead of not to? This usage in this way imposes different meaning?


I have an american friend who tells me that this sentence:  [...] Since their absence results in a relevant market which is defined too broad, the two-sided critical loss analysis cannot be recommended ultimately for actual merger cases.   sounds more natural than this one:  [...] Since their absence results in a relevant market which is defined too broad, the two-sided critical loss analysis ultimately cannot be recommended for actual merger cases.   I'm no native English speaker, but the first one sounds weird to me. I would be very glad if I could have some more opinions on this - thanks!  Edit: I'm aware that there are (a lot) of other questions concerning the positioning of adverbs. However, since this is the last sentence in my abstract, I want the sentence to be perfect and not choose the "ultimately" at a random position. Maybe someone could explain which position would make the most sense / sounds the most natural.

For example:     Ever wish you could share information broadly   Could it be rewritten to:     Ever wish you could broadly share information   Are there any rules for the position of the adverbs.


Let's say I run a lot of univariate OLS regression models, say 200,000, with 50 data points, then cherry pick the best one (highest r-square). If my $p$-value for this model is way less than 1/200,000, do my results still have any explanatory power?  The probability of getting this result when there is no relationship between the variables was extremely low, even running 200,000 instances of it, correct?  I'm generally interested in rules on how/when cherry-picking can still make sense.

Lets assume you are a social science researcher/econometrician trying to find relevant predictors of demand for a service. You have 2 outcome/dependent variables describing the demand (using the service yes/no, and the number of occasions). You have 10 predictor/independent variables that could theoretically explain the demand (e.g., age, sex, income, price, race, etc). Running two separate  multiple regressions will yield 20 coefficients estimations and their p-values. With enough independent variables in your regressions you would sooner or later find at least one variable with a statistically significant correlation between the dependent and independent variables.   My question: is it a good idea to correct the p-values for multiple tests if I want to include all independent variables in the regression? Any references to prior work are much appreciated.


Let $X,Y$ be independent standard normally distributed random variables and $X,Y\neq 0$. Find the density of $\frac{X^2}{Y^2+X^2}$  I was given the tip of first calculating the density of $(X^2,Y^2)$ and then calculate the density of $(\frac{X^2}{Y^2+X^2},Y^2+X^2)$  When I follow the tips: I know that $X^2\sim\Gamma(\frac{1}{2},\frac{1}{2})$ and $Y$ too. Furthermore, $X^2$ and $Y^2$ are still independent. Therefore the density $f_{(X^2,Y^2)}(x,y)$ can be written as $f_{X^2}(x)f_{Y^2}(y)$ where $f_{X^2}$ and $f_{Y^2}$ are the density functions of $X^2$ and $Y^2$  My next idea, with the tip above in mind is to consider a map $\varphi: (x,y) \mapsto (\frac{x}{x+y},x+y)$  It then follows that $(\frac{X^2}{Y^2+X^2},Y^2+X^2)=\varphi(X^2,Y^2)$ and $f_{\frac{X^2}{Y^2+X^2},Y^2+X^2}(a,b) = f_{\varphi(X^2,Y^2)}(a,b) $  Note that $\varphi^{-1}: (a,b)\mapsto (ba,b-ba)$ and thus $\det D \varphi^{-1}(a,b)=\det\begin{pmatrix} b & a \\ -b & 1-a \end{pmatrix}=b(1-a)+ab\implies \det D \varphi^{-1}(\frac{X^2}{Y^2+X^2},Y^2+X^2)=(Y^2+X^2)(1-\frac{X^2}{Y^2+X^2})+(\frac{X^2}{Y^2+X^2})(Y^2+X^2)=Y^2+X^2$  And hence $P_{(\frac{X^2}{Y^2+X^2},Y^2+X^2)}(A)=\int_A f_{(\frac{X^2}{Y^2+X^2},Y^2+X^2)}(x,y)\,dx\,dy = \int_{\varphi^{-1}(A)}f_{(X,Y)}(x,y)\times (X^2+Y^2)\,dx\,dy = \int_{\varphi^{-1}(A)} f_X(x)\times f_Y(y)\times (X^2+Y^2)\,dx\,dy$  Where do I go from here?

I was reading  and I find the following problem: Let $X$ and $Y$ be independent $\chi ^2 $ with $m$ and $n$ degrees of freedom then $\dfrac{X}{X+Y} = \beta(m/2, n/2)$. Where $\chi^2(k)$ has density function $$f_{\chi^2(k)}(x)=\begin{cases}\displaystyle \frac{1}{2^{k/2}\Gamma(k/2)}\,x^{(k/2) - 1} e^{-x/2}&\text{if }x>0,\\ 0&\text{if }x\le0 \end{cases} $$  I proved that $X+Y$ is $\chi ^2$ with $n + m$ degrees of freedom using the moment-generating function. If $Z=X+Y$ and $U=\dfrac{X}{X+Y}=\dfrac{X}{Z}$ using the formula for the density of the ratio of two independent random variables: $$f_U(u)= \int_{-\infty}^{\infty}f_X(uv)f_Z(v)|v|dv $$  then  $$\dfrac{u^{m/2-1}}{2^{(m+n/2)} \Gamma(m/2) \Gamma((m+n)/2)} \int_0^{\infty} v^{m+\dfrac{n}{2}-1} e^{-(v/2)(u+1)}dv $$  and using some algebra:  $$f_U(u)=\dfrac{u^{m/2-1} \Gamma(m+n/2)}{\Gamma(m+n/2) \Gamma(m/2) (u+1)^{m+n/2}}$$  and this is not $\beta(m/2, n/2)$, it looks more like $\beta(m/2, m/2+n/2)$ but $(u+1)^{m+n/2}$ is causing troubles.  I need help if something is false or any hint.


I need to add proper index to my tables and need some help.  I'm confused and need to clarify a few points:   Should I use index for non-int columns? Why/why not I've read a lot about clustered and non-clustered index yet I still can't decide when to use one over the other. A good example would help me and a lot of other developers.    I know that I shouldn't use indexes for columns or tables that are often updated. What else should I be careful about and how can I know that it is all good before going to test phase?

What are the differences between a clustered and a non-clustered index?


I am brand new to Blender an was following Blender Guru's 2.8 Donut tutorial. He said that one way to get a material to look like glass is to turn transmission up to 1.00. This worked for the most part, but the glass on the main frame of the cup has this weird texture to it in some places. When I move the camera around, the place where the glass is clear shifts so that it is always on the other end of the glass, which leads me to believe that because the light is going through two pieces of glass, it gets distorted. Any way I can fix this?

I was messing with UV unwrapping, and this is what happened:    I reset the UV map, but to no result. For reference, I have older render of the same glass (the version which was unfortunately overwritten):    How to make it smooth again?  It looks like there are two faces in the same place oriented other ways.  That's how face orientation view looks like: How to rotate these faces?


Could someone please help me understand the concept of performing a t-test while controlling/adjusting for one or more variables?  E.g.: Say I have a hypothetical data set, with the following variables sex, age, smoker, weight, height, bmi, smoking_duration, max_oxygen_uptake. Let us say I want to test if smokers have a higher max_oxygen_uptake, than non-smokers?  Then in R I would write: t.test(subset(myData,myData$smoker==0)$max_oxygen_uptake,subset(myData,myData$smoker==1)$max_oxygen_uptake)  But max_oxygen_uptake will likely also depend on e.g. age, bmi and smoking_duration. Maybe also sex. Therefore I am looking for something along the lines of: t.test(var_a,var_b,adjust=c(var_c,var_d,var_e)).  Questions:   How do I perform a t-test, while controlling/adjusting for other variables? How do I decide which variables should be controlled/adjusted for?   I know it has something to do with lm(), but I am having conceptual problems in connecting the t-test to creating a linear model?

Here is the article that motivated this question:   I liked this article, and it nicely demonstrates the concept of “controlling for other variables” (IQ, career, income, age, etc) in order to best isolate the true relationship between just the 2 variables in question.    Can you explain to me how you actually control for variables on a typical data set?      E.g., if you have 2 people with the same impatience level and BMI, but different incomes, how do you treat these data?  Do you categorize them into different subgroups that do have similar income, patience, and BMI?  But, eventually there are dozens of variables to control for (IQ, career, income, age, etc)  How do you then aggregate these (potentially) 100’s of subgroups?  In fact, I have a feeling this approach is barking up the wrong tree, now that I’ve verbalized it.  Thanks for shedding any light on something I've meant to get to the bottom of for a few years now...!


Everything is slowed WAY down - 5 to 10 seconds just to open something from the task bar. Then it slowly fades in. Totally destroyed my confidence in Ubuntu as a viable alternative to WinXp. This has been an ongoing thing with Linux actually being a operating system for normal people and not just for geeks. Until A normal non geek can actually just install a working version without having to resort to the command line to actually get stuff to work. It will not be used by anyone other than the geeks that like to play around with the OS. I wanted to give this system to a NORMAL person ( non geek) but now - I will just have spend another couple of hours trying to reinstall the older v12 or to go back to Windows because they don't have the technical know how to jump through the hoops to get Ubuntu to actually work. They don't want to 'play' with the OS, they just want to run fairly standard programs.

I'm thinking about installing Ubuntu Desktop, but I don't know what flavor is the best for my system. What are the minimum and recommended hardware requirements? What kind of CPU? How much memory? Should I have Hardware Acceleration? What flavor should I use?  This is an attempt of a canonical answer. My answers have the "official  requirements", the recommended are a mix of official sources and opinion based (along with the answer it's told the source). You can comment or edit if you feel that the information is obsolete or incomplete. It is a good rule of thumb that any system capable of running Windows Vista, 7, 8, x86 (Intel) OS X will almost always be a lot faster with any Ubuntu flavor even if they are lower-spec than described below.


I can insert the special characters fine when using PHPmyAdmin, but it just doesn't work when inserting them via PHP. Could it be that PHP is changing the special characters into something else? If so, is there a way to make them insert properly?  $name = mysqli_real_escape_string($name); this is not work...

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


I have this main class:  public class Main {      public static void main(String[] args) {         Server server = new Server(8192);          InetAddress address = null;         try {             address = InetAddress.getByName("192.168.178.249");         } catch (UnknownHostException e) {             e.printStackTrace();         }         int port = 8192;         String s = "het werkt";         byte[] sdata = s.getBytes();          server.send(sdata, address, port);     } }   And this server class:   public class Server {      private int port;     private Thread listenThread;     private boolean listening = false;     private DatagramSocket socket;     private final int MAX_PACKET_SIZE = 1024;     private final byte[] receivedDataBuffer = new byte[MAX_PACKET_SIZE * 10];      public Server(int port){         this.port = port;     }      public int getPort() {         return port;     }     public void start(){         try {             socket = new DatagramSocket(port);         } catch (SocketException e) {             e.printStackTrace();         }          listening = true;          listenThread = new Thread(new Runnable(){             @Override             public void run() {                 listen();             }         });         listenThread.start();     }      private void listen() {         while(listening) {              DatagramPacket packet = new DatagramPacket(receivedDataBuffer, MAX_PACKET_SIZE);              try {                 socket.receive(packet);             } catch (IOException e) {                 e.printStackTrace();             }             process(packet);          }     }      private void process(DatagramPacket packet){         byte[] data = packet.getData();         System.out.println(new String(data));     }      public void send(byte[] data, InetAddress address, int port){         assert(socket.isConnected());         DatagramPacket packet = new DatagramPacket(data, data.length, address, port);          try {             socket.send(packet);         } catch (IOException e) {             e.printStackTrace();         }     } }   It returns this error:   Exception in thread "main" java.lang.NullPointerException   at com.jakibah.javahacker.Server.send(Server.java:74)   at com.jakibah.javahacker.Main.main(Main.java:22)`   Line 74 is this: } catch (IOException e) { And Line 22 is this: server.send(sdata, address, port);  Why is it returning this error and how can I fix it? Is it because of the way I send my string?

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?


For e.g- in $U(10)=\{1,3,7,9\}$ are elements and $3$ & $7$ are generators but for a big group like $U(50)$ do we have to check each and every element to be generator or is there any other method to find the generators?

A cyclic group is a group that is generated by a single element.  That means that there exists an element $g$, say, such that every other element of the group can be written as a power of $g$.  This element $g$ is the generator of the group.  Is that a correct explanation for what a cyclic group and a generator are? How can we find the generator of a cyclic group and how can we say how many generators should there be?


I am recently doing my IB Maths HL internal assessment and my topic is how to calculate the surface area of an egg. I want to apply calculus knowledge into this question but my knowledge about this area is limited. I only know the basic information about calculus, for example, using integration to calculate the volume of an object. I have already searched for relevant information online for many days but I still have no idea. I need to finish my internal assessment in 2 weeks! Could anyone please help me with it?! Thank you!  Well, I know there has already been a same question but i don't really understand the answer for that question. I know it is related to integral but i have no idea how to do that. I hope someone can explain it in details. If it is just an idea of how to do it, I can search for ideas everywhere by using Google and have no need to ask for help here. I really need help like step by step maybe. Thanks.  [I have worked out the formula A=∫_(x_2)^(x_1)▒〖2πf(x)·√(1+f^' (x)^2 )·dx〗, however, f'(x) involves a constant C which is unknown. I am confused how can I solve the equation when I have no idea what C is.

This morning, I had eggs for breakfast, and I was looking at the pieces of broken shells and thought "What is the surface area of this egg?" The problem is that I have no real idea about how to find the surface area.    I have learned formulas for circles, and I know the equation for an ellipse; however, I don't know how to apply that.   The only idea I can think of is to put an egg on a sheet of paper and trace it, and then measure the outline drawn, and then try to find an equation for that ellipse and rotate that about the $x$-axis.  Now, my problem is how I can find the equation of the ellipse from the graph, and will my tracing method really be the edge of the egg?  Also, can I use the ? Will I have to use some techniques to solve the integral that are not covered in the ?  There has to be a better method for finding the surface area. Please, help me understand how to find the surface area of an egg; i.e., how to use my mathematical knowledge for something other than passing exams.


$ ls -l total 28 drwxrwxrwx 1 t t 4096 May  8  2018  dir1 drwxrwxrwx 1 t t    0 Mar 12  2015  dir2 drwxrwxrwx 1 t t 4096 Jan 17  2014  dir3 drwxrwxrwx 1 t t 4096 Jun 12  2017  dir4 drwxrwxrwx 1 t t    0 Aug 24  2012  dir5   Why is the size  of  a directory either 0 or 4096?  Is the size of a directory 0 because the entries in it can fit into its inode?  Is the size of a directory not 0 because the entries in it can't fit into its inode and thus need some data block(s)?  Why is the nonzero size of a directory always 4096?   Thanks.  Note my observation is the same in ext4 filesystem and in NTFS filesystem. Does it mean both filesystem types implement directories in a similar way?

What does size of a directory mean in output of ls -l command?


What it's supposed to designate:  A list of the name of each game.  So there are multiple games and therefore multiple names.  But should either or both take an s at the end in a list of game(s) name(s) ?

I wonder whether there are rules or guidelines regarding plural nouns in nominal compounds. For example a compound university students list. If there are many lists and many universities is it grammatically correct to say universities students lists? Must all elements be in the plural form or can some be left in singular, even though the meaning is plural? I've seen an expression universities student lists; is it correct?


I'm having problems with a Rounding issue in c#. I would like to round the result of a calculation up to 4 decimals (awayfromzero). If I use Math.Round(variable,...) it rounds down, if I enter the result manually, it rounds up.. I have no idea why..  What am I doing wrong? The result of the below code is: Rounded: 591.24575 591.2457 - 591.2458  double number1 = 1136.81; double number2 = 4.00; double number3 = 2182.257; double result = (number1 * number2 - number3) / 4; Console.WriteLine("Rounded: " +result+" " + Math.Round(result, 4, MidpointRounding.AwayFromZero) + " - " + Math.Round(591.24575, 4, MidpointRounding.AwayFromZero)); Console.ReadLine();

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


I downloaded NodeJS from the official website as a tarball and extracted it but I can't install it. The BULDING.md file says I should  ./configure   then  make -j4   However, trying ./configure inside the directory returns this error:  bash: ./configure: No such file or directory   I solved this error (see the comments), but now after running make -j4 I get this error:  node bin/npm-cli.js install marked --no-global --no-timing --no-save node bin/npm-cli.js install marked-man --no-global --no-timing --no-save bash: node: command not found bash: node: command not found Makefile:154: recipe for target 'node_modules/.bin/marked' failed make: *** [node_modules/.bin/marked] Error 127 make: *** Waiting for unfinished jobs.... Makefile:159: recipe for target 'node_modules/.bin/marked-man' failed make: *** [node_modules/.bin/marked-man] Error 127   yet I have all dependencies (git, python, g++ and make). What am I missing here? Note: I know I could install it using apt but I want to use this as part of learning.

How do I install the latest  on Ubuntu? I've been looking around, and I can't find anything. Is there a Ubuntu package for node.js, or do I have to compile it myself?


Yesterday I made a small but important  to this . But when I came back today to check that my edit had been reviewed and accepted, I noticed that my edit had been approved by three reviewers, but then rolled back by the author of the answer.   I tried to find a way to message the answer's author, , directly, but after searching meta I found that unless the author has their contact details on their profile page, there is no way for a new user to contact them (as user's need 50 reputation to comment on an answer).   I then tried to resubmit my edit, but it was rejected for nonsensical reasons by two reviewers, who had clearly not read the link I provided in my edit comment.   I then considered flagging thewaywewere's answer for moderator attention, but after creating an account to do this, I found out that this is also not an option for new users (as user's need 15 reputation to flag an answer).   I didn't want to write this question (as it doesn't have an answer that will be useful to future users of this site), but I was left with no other options (as I don't have time to repeatedly submit the same edit until the author accepts it). And so if someone here with more reputation than me could make the change I was trying to make, I'd appreciate it.   And in case someone were to read through my edit and still think that the answer by  is correct, that is, you think that using --oem 3 (the default OCR engine mode) together with tessedit_char_whitelist=0123456789, still works in tesseract-4.0.0a (which by default uses the LSTM OCR engine), then please read through these three links on the topic.  UPDATE: It seems the answer to my question is "as a new user you can't" and that I should either write my own answer (which would have one variable changed from a 3 to a 0) or 'move on' leaving an incorrect answer as the accepted and top answer to the question.

My edit to an answer was accepted by two of the three reviewers, with the third rejecting with a claim that part of my edit was incorrect.  In fact, my proposed edit was entirely and demonstrably correct, and the reason given for rejecting is invalid.  How can I let that reviewer know about their error, and have them change their review to "Accept" - changing stats for both of us?  Please note:  This is not the same question as asking for an appeal of an edit that was rejected.  It's asking what I can do about one of the three reviewers, a dissenter who voted against my edit based on their incorrect information.


I  can't seem to find a way to integrate this function. It is continous and derivable in the real field.  Is this integral actually impossible to evaluate? I couldn't  found it in any manual.  $\int x^x dx $

I'm trying to find $\int x^x \, dx$, but the only thing I know how to do is this:  Let $u=x^x$.  $$\begin{align} \int x^x \, dx&=\int u \, du\\[6pt] &=\frac{u^2}{2}\\[6pt] &=\dfrac{\left(x^x\right)^2}{2}\\[6pt] &=\frac{x^{2x}}{2} \end{align}$$  But it's certain that this isn't the correct way to evaluate that, and the answer must be wrong.


My task given by my professor was the following:  $Let \,\, A, \,\, B \in \mathbb{C}^{n\times n}$ be selfadjoint and such that $[A, B] := AB-BA=0.$ Show that $C:= A+iB$ is normal. Show further that there is a unitary $U \in \mathbb{C}^{n\times n} \; \text{such that} \; U^*AU \; \text{and} \; U^*BU$ are both diagonal.   I have proven that $C$ is normal but I'm having problems with proving that the terms are both diagonal matricies.

Let $V$ be a vector space of finite dimension and let $T,S$ linear diagonalizable  transformations from $V$ to itself. I need to prove that if $TS=ST$ every eigenspace $V_\lambda$ of $S$ is $T$-invariant and the restriction of $T$ to $V_\lambda$ ($T:{V_{\lambda }}\rightarrow V_{\lambda }$) is diagonalizable. In addition, I need to show that there's a base $B$ of $V$ such that $[S]_{B}^{B}$, $[T]_{B}^{B}$ are diagonalizable if and only if $TS=ST$.  Ok, so first let $v\in V_\lambda$. From $TS=ST$ we get that $\lambda T(v)= S(T(v))$ so $T(v)$ is eigenvector of $S$ and we get what we want. I want to use that in order to get the following claim, I just don't know how. One direction of the "iff" is obvious, the other one is more tricky to me.


I have a superclass Order which has a subclass OrderBook. The equals(...) method is overridden in the OrderBook. The method implementation is as follows:-  public boolean equals(Order o)     {         if(o==null){             System.out.println("object is null.");             return false;         }         if(o==this){             System.out.println("The object is itself.");             return true;         }         if(o instanceof OrderBook)         {             OrderBook o1 = (OrderBook)o;             if(!(o1.productId.equals(productId))){                 System.out.println("productId mismatch.");                 return false;             }             if(!(o1.customerId.equals(customerId))){                 System.out.println("customerId mismatch.");                 return false;             }             if(o1.book!=book){                 System.out.println("book mismatch.");                 return false;             }         }         return true;     }   I am encountering an unexpected output if I give the following statement:-  Order order1 = new OrderBook("Algorithms","Kunal",false); Order order2 = new OrderBook("Algorithms","Kunal",false); System.out.println(order1.equals(order2));   It should display true but its displaying false. Also, if I change the parameter in the equals(...) to Object o, then the whole program runs without any problem.   My doubt is that why are we using Object when we should be using Order?

I ran into an interesting behavior recently.  It seems that if I override .equals() to take a parameter other than Object, it doesn't get called.  Can anyone explain to me why this is happening?  It seems to violate my understanding of polymorphism in OOP, but maybe I'm missing something.  Here's much simpler code that shows what I'm seeing:  public class MyClass {   private int x;   public MyClass(int n) { x = n; }   public boolean equals(Object o) { return false; }   public boolean equals(MyClass mc) { return x == mc.x; }   public static void main(String[] args) {     List<MyClass> list = new ArrayList<MyClass>();     list.add(new MyClass(3));     System.out.println("Contains 3? " + list.contains(new MyClass(3)));   } }   When this is run, it prints "Contains 3? false".  It looks like the equals(Object) function is called, even though there is another that would work.  By contrast, if I write equals like this the code works as expected:  public boolean equals(Object o) {   if(!(o instanceof MyClass))     return false;   MyClass mc = (MyClass)o;   return x == mc.x; }   Why isn't it figuring out which version of the function to call based on the type of the parameter?


I noticed the 'and' and 'or' logical operators were not defined with a corresponding method in the operator module of the Python standard library. Why can't these operators be overloaded like the others?  Is there official Python documentation that describes this design choice? I could not seem to find any online.

I tried overriding __and__, but that is for the & operator, not and - the one that I want. Can I override and?


I have a usecase that i want to check if the session is going to expire in 30 sec or 60 sec. if so I should be able to extend the session. I am fine with any solutions with session or cookies. How do I acomplish that. Pls eloborate your solution. But I should know before the session expires.

I need to keep a session alive for 30 minutes and then destroy it.


I have Elementary OS installed along with windows 8.1. I want to uninstall Elementary OS and install Ubuntu. How can I do that? I searched Google for any relevant article or link but couldn't help myself. Please guide me through the whole procedure.

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


I am connected to a VPN as a domain user. I would like to run a local application as the domain user from the VPN instead of my local workgroup user.  If I select run as a different user and insert the username; domain\user and the respective password I get:     login failure: unknown user name or bad password   Does Windows know that I am referring to the domain from the VPN? How do I achieve this?

My Windows 7 computer is on LAN in an intranet with a Windows domain, but it is not a member of that domain. However, I need to run some applications under domain accounts while I'm logged on locally as a local admin.  I know you can use the runas utility to start processes under accounts different from the one under which you have logged on. The thing is that Windows needs to know or authenticate the account under which a process is starting.  When I do something like:  runas /user:DOMAIN\USERNAME cmd.exe   (and put in a correct password afterwards) I get this kind of error:  RUNAS ERROR: Unable to run - cmd.exe 1326: Logon failure: unknown user name or bad password.   Does anybody know how to cope with this?


NOT ANSWERED -  I think Zanna gets th gist of it. It seems most miss the point... the system is mine and my responsibility. I simply do not want to be prompted for a pasword as specified below... GETS MORE AND MORE FRUSTRATING. my email if someone wants to answer directly to me is zeteo1052@gmail.com ...................... I have not found the answer to this anywhere on line and I am getting really frustrated. I will pay for support if it will get me the answer I've been looking for. I am 68 years old and a retired computer desktop support technician. I have been using Ubuntu for over 2 years now and will not go back to Windows (the dark side) LOL I want to be able to access files and folder, install packages, burn usb drives or dvd's etc. without always being prompted for a password. I really understand the DANGER of it and always have a backup of my computers if need to restore it. I am not worried about losing anything. This is my computer and supposedly my OS and is my headache no matter what happens. I'm getting old and need to save all the time I can...  LOL Is there any way you can help me? I know all about the visudo and tried all the procedures I could find but I am still being prompted for the password. Thank for your time and consideration.

Inspired by this ....  I am the sole person using my system with 12.04. Every time I issue a sudo command; the system asks for the user password (which is good in its own way).  However I was thinking; without activating the root account; how can I execute the sudo commands which will not ask for user password to authenticate.  NOTE: I want to execute sudo command without authenticating via password; only when they are executed via terminal. I don't want to remove this extra layer of security from other functions such a while using 'Ubuntu software center' or executing a bash script by drag-drop something.sh file to the terminal.


I have some precious photos (family children) and sounds (baby voices) stored on my old Samsung AT&T SGH-a687 phone, not the SD card, that is experiencing a white screen of death after about a week of graphics pixelation and stripes problems due to a bad gpu.  I'm wondering what I can do to get those information I stored on the phone out. I tried connecting the phone to my MacBook Pro (I also have Windows if that's easier), but I can't get anything out. So I'm wondering what I can do to salvage those photos. How do I get these photos out onto my computer?

I would like to get some pictures and audio out of an AT&T SGH-a687 phone onto my Mac computer. I first tried connecting it to a New PC Studio on a PC, but there was a problem after transfer 2 photos, so I tried again. But the PC could no longer detect the phone, even though the "connected to computer" icon appears on the phone. I tried a different cable, different USB ports. No use.  So I downloaded the Samsung Kies on my Mac. Same thing, it tries to search for the phone once I connect the phone, but the computer doesn't detect anything. The phone still shows the "connected to computer" icon.  There is also Bluetooth (no internet on the phone) on the phone, but it failed to send the picture each time I tried.  What can I do at this point? Please also suggest data extraction software for either Mac or PC, if that's the easier route.


Let's call a function $ f: \mathbb{R} \rightarrow \mathbb{R} $ Two to one if for any $y \in Im(f)$ there is exactly two distinct $x_1,x_2 \in \mathbb{R}$ such that $f(x_1)=f(x_2)=y$  Is it true that every Two to one function with domain $\mathbb{R}$ must have infinite number of discontinuity?  P.S: As answered before  it must be discontinous but can it have finite number?

This is from Apostol's Mathematical Analysis.  Let $f$ be a function defined in $[0, 1]$ such that for each real number $y$ either there is no value of $x \in [0, 1]$ such that $f(x) = y$ or there are exactly two such values of $x$. Prove that a) $f$ must be discontinuous on $[0, 1]$. b) $f$ has an infinite number of discontinuities in $[0, 1]$.  Long back I had tried to solve the problem. I reasoned for a) as follows: Suppose that $f$ is continuous and let $m, M$ be its minimum and maximum values on $[0, 1]$. Clearly if $m = M$ then $f$ is constant and clearly for every $x \in [0, 1]$ we have $f(x) = m = M$ which contradicts given property of $f$. So we must have $m < M$. Clearly there are now four distinct points $a, b, c, d$ in $[0, 1]$ such that $f(a) = f(b) = m, f(c) = f(d) = M$. By checking possible linear orderings of $a, b, c, d$ I could find a find a value of $y \in (m, M)$ for which there exist more than 2 values of $x$ such that $f(x) = y$. However this approach looks very clumsy and I suspect much simpler and easier proof is possible. Part b) seemed bit complex and my only guess was that probably $f$ was discontinuous on each subinterval of $[0, 1]$ but I could not prove this claim (may be the claim is wrong!). Perhaps there is a simpler solution to this part of the problem. Apostol's also asks to provide an example of such a function. Any hints on the overall problem will be appreciated.  Update: After looking at Marc's answer, I think I have found a way to show that there are infinitely many discontinuities. Earlier the solution was a part of the question itself but it made the question look quite lengthy hence I moved it to a separate answer.


I am new to python, so this may be a silly question...  Why does the function fetchsamples not see the variable smilies? Strangely, the variable frownyDict and smileyDict are accessible, while smilies is not.  The error I get is:  Traceback (most recent call last):   File "simple.py", line 41, in <module>     fetchsamples()   File "simple.py", line 18, in fetchsamples     print smilies UnboundLocalError: local variable 'smilies' referenced before assignment   Below is the python code:  ##my global vars  frownyDict={} smileyDict={} frownyDict['_counter_']=0 smileyDict['_counter_']=0 frownies = 0 smilies = 0    def fetchsamples():     print frownyDict;     response = [":) happy",":( sad","sad","dunno"]     counter=0     print smilies     for tweet in response:         if (tweet):             tweet=tweet.encode("iso-8859-1", "ignore")             if ":)" in tweet:                 parse(smileyDict,tweet)                 counter+=1                 smilies+=1             if ":(" in tweet:                 parse(frownyDict,tweet)                 counter+=1                 #frownies+=1                 frownyDict['_counter_']+=1;             if ":)" in tweet or ":)" in tweet:                 guess(tweet)                 # let's predict!              if (counter % 50==10):                 print frownyDict;                 print smileyDict   if __name__ == '__main__':   fetchsamples()

The following code works as expected in both Python 2.5 and 3.0:  a, b, c = (1, 2, 3)  print(a, b, c)  def test():     print(a)     print(b)     print(c)    # (A)     #c+=1       # (B) test()   However, when I uncomment line (B), I get an UnboundLocalError: 'c' not assigned at line (A). The values of a and b are printed correctly. This has me completely baffled for two reasons:   Why is there a runtime error thrown at line (A) because of a later statement on line (B)? Why are variables a and b printed as expected, while c raises an error?   The only explanation I can come up with is that a local variable c is created by the assignment c+=1, which takes precedent over the "global" variable c even before the local variable is created. Of course, it doesn't make sense for a variable to "steal" scope before it exists.  Could someone please explain this behavior?


It seems like a lot of trouble to go to for something that we don't really need in Quidditch.

We find out in the Deathly Hallows that a snitch has a "flesh memory" and can recall the first person that touched it.  It is claimed that this is to help settle a "disputed capture".  Does this imply that one doesn't need to "catch" the snitch as much as you just need to be the first to touch the snitch?  I seem to recall that you need to actually catch it though, which raises the question: Does the flesh memory of the snitch really settle anything?


My website has varaible content length, and this sometime means that the footer does not site at the bottom of the page, is there a way to make the footer fill whatever space is left?

In the markup shown below, I'm trying to get the content div to stretch all the way to the bottom of the page but it's only stretching if there's content to display. The reason I want to do this is so the vertical border still appears down the page even if there isn't any content to display. Here is my DEMO:   body {     font-family: Trebuchet MS, Verdana, MS Sans Serif;     font-size:0.9em;     margin:0;     padding:0; } div#header {     width: 100%;     height: 100px; } #header a {     background-position: 100px 30px;     background: transparent url(site-style-images/sitelogo.jpg) no-repeat fixed 100px 30px;     height: 80px;     display: block; } #header, #menuwrapper {     background-repeat: repeat;     background-image: url(site-style-images/darkblue_background_color.jpg); } #menu #menuwrapper {     height:25px; } div#menuwrapper {     width:100% } #menu, #content {     width:1024px;     margin: 0 auto; } div#menu {     height: 25px;     background-color:#50657a; } <form id="form1">

 </form>


/give @p bow 1 0 {ench:[{id:21,lvl:100},{id:48,lvl:2000},{id:49,lvl:2000},{id:50,lvl:2000},{id:51,lvl:2000,{id:34,lvl:2000}],display:{Name:"Dead Man Crack",Lore:["This Bow Is Only Effective When Shot At The Butt"]}}     This is my command and is it's always saying "unbalanced square brackets".  Does anyone have a answer, a clue or even a hint?

Often, when making a command block contraption, you need to set an entity's data tag. These tags can sometimes be very long, with many layers of nested curly and square brackets. For example, this is the command to summon a villager with a single custom trade:  /summon Villager ~ ~ ~ {Profession:3,Career:2,Offers:{Recipes:[{buy:{id:minecraft:diamond,Count:6b}},sell:{id:minecraft:diamond_hoe,tag:{ench:[{id:16s,lvl:10s}]}]}}   The single-line command block interface of Minecraft makes it incredibly difficult to find and fix errors, especially when it comes to mismatched brackets. In fact, for illustration purposes, I put an error in the above command.  What techniques can I use to find and fix unbalanced square or curly brackets when writing long and complicated data tags?


I have a super weird question. Whenever I try to open a file or try to show a file by clicking on the message in Telegram Desktop, this popup shows up:      I always have to click 'Yes', which is super annoying 'cause I open so many files.  By the way, I'm using Ubuntu 16.04 and Telegram Desktop version 1.4.3.  Does anyone know how to resolve that and give permanent permission?

I have installed chromium snap package. Each time I download file and try to open it or download folder I see a GNOME prompt form with question:      Allow opening file?   Allow snap "chromium" to open file "/home/username/Download"?   How can I disable it permanently? Is there an option to grant read/open permission to this folder for particular snap package?    OS: Ubuntu 18.04 LTS X: GNOME snapd version: 2.33


I'm a beginner at java. I want to be able to swap elements using index value while using my own method or without using collections.swap import java.util.LinkedList; import java.util.Scanner;  class Main {     private static LinkedList<Integer> llist;   public static void main(String[] args) {     LinkedList<Integer> languages = new llist<>();     Scanner s = new Scanner(System.in);      // add elements in the linked list     llist.add(5);     llist.add(4);     llist.add(3);     llist.add(2);     System.out.println("LinkedList: " + languages);     exchange(3,2);     System.out.println("LinkedList: " + languages);   }      public static void exchange(int i, int j) {     llist.set(i, llist.set(j, llist.get(i))); }    }  Whenever I build this one there is no error that pops up, but when I run it, it gives me the java.lang.NullPointerException.

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?


Windows 10 default Start Menu looks like this:    Without using third party application Classic Shell, please let me know, how to change it in Windows 7 Style Menu?  Regards  InTech

I've upgraded from Windows 7 to Windows 10 and now I only find this new slower Start menu with all the tiles in it   (picturesource: )  Can I enable the older Windows 7 one again which suites my needs more?


I have:  array(2) {      [0]=> array(23) {          ["data_cerere"]=> string(10) "2014-07-15"          ["nr_cerere_oferta"]=> string(13) "{49291-39958}"          ["clientul"]=> string(13) "Mihaela Curca"          ["client_email"]=> string(24) "aaaa@yahoo.com"       }      [1]=> array(23) {          ["data_cerere"]=> string(10) "2014-07-15"          ["nr_cerere_oferta"]=> string(13) "{76351-31554}"          ["clientul"]=> string(13) "Anca PLAVETIU"          ["client_email"]=>   string(28) "bbbbb@yahoo.com"       }         }   I want to check the array for "nr_cerere_oferta == x" and if found to remove the row.  In this case "nr_cerere_oferta == {76351-31554}" the array will be:  array(2) {      [0]=> array(23) {          ["data_cerere"]=> string(10) "2014-07-15"          ["nr_cerere_oferta"]=> string(13) "{49291-39958}"          ["clientul"]=> string(13) "Mihaela Curca"          ["client_email"]=> string(24) "aaaa@yahoo.com"       }  }

Is there an easy way to delete an element from an array using PHP, such that foreach ($array) no longer includes that element?  I thought that setting it to null would do it, but apparently it does not work.


here is my relatively broad question: how does the temperature and density of a medium effect the speed at which sound travels through it?   Now I shall elaborate:  it is my understanding that there is some sort of ratio between these two factors that determine the speed of sound in the medium.   from this, I assume that sound travels faster in objects that have a higher temperature (due to atoms/molecules having more energy and hence being more inclined to transfer energy more quickly in order to assume its former energy state and become more stable) and a higher density (which I can only assume to be because the particles  are closer together and so somehow travel faster because of this, however, couldn't one also say that the opposite is true because there is less obstruction to block the waves? this is a point of confusion for me, help would be appreciated).  is there some sort of relationship or equation that relates the three factors and are there any other factors that determine the speed of sound in an object (eg. elastic properties of the medium)?  is there a value for this ratio that maximises the speed of sound (ie. some sort of linear constant) and is the relationship between speed and temperature and speed and density linear? if not what is it?  finally, with regard to the equations V=λ/T V=fλ and T=1/f where T=period, is the speed (velocity) of sound also dependent on the frequency and wavelength of the sound waves, or is it the other way round in which the frequency and wavelength are dependant on the velocity of the wave which is in turn dependant on other factors such as temperature and density? of course if the latter is true, what decides how the given product of frequency and wavelength is factored into individual components?

I was reading a textbook. I found that it was mentioned the speed of sound increases with increase in temperature. But sound is a mechanical wave, and it travels faster when molecules are closer.   But an increase in temperature will draw molecules away from each other, and then accordingly the speed of sound should be slower. How is it possible that the speed of sound increases if temperature increases? What is the relation of speed of sound and temperature?


I am a 4th-year undergraduate student and I have fully read R. Shankar's book on Quantum Mechanics and Griffiths book Quantum Mechanics. I have also done a bit of the Application of QM on multielectron systems,molecules, etc.  Not going ahead in the application part, I want to focus on the foundations of QM part which I find really interesting. But I have very limited knowledge of mathematics. I have read Curtis "An introduction to Linear Algebra", Gallian "Group Theory"(1-10 chapters only) and have a little bit of knowledge on differential geometry.  With this as my Mathematical background, which would be the best book (a bit mathematical) for introduction to Quantum Mechanics which includes an introduction to Hilbert Space and functional analysis?  PS: This not the duplicate of referred links as this is particularly for ones who don't have much mathematical background as opposed to other questions which assumes one to know much mathematics.

I am a 4th-year undergraduate student and I have fully read R. Shankar's book on Quantum Mechanics and Griffiths book Quantum Mechanics. I have also done a bit of the Application of QM on multielectron systems,molecules, etc.  Not going ahead in the application part, I want to focus on the foundations of QM part which I find really interesting. But I have very limited knowledge of mathematics. I have read Curtis "An introduction to Linear Algebra", Gallian "Group Theory"(1-10 chapters only) and have a little bit of knowledge on differential geometry.  With this as my Mathematical background, which would be the best book (a bit mathematical) for introduction to Quantum Mechanics which includes an introduction to Hilbert Space and functional analysis?  PS: My question is specifically for the ones who have limited mathematical knowledge in contrast to answers which assumes you have done graduate level mathematics.