How can I expand the Boot partition on Ubuntu 14.04.2 as it keeps telling me I have very little space left on that partition and I don't want to uninstall any files as I don't know what is necessary and what isn't?

My /boot partition is nearly full and I get a warning every time I reboot my system. I already deleted old kernel packages (linux-headers...), actually I did that to install a newer kernel version that came with the automatic updates.  After installing that new version, the partition is nearly full again. So what else can I delete? Are there some other files associated to the old kernel images?  Here is a list of files that are on my /boot partition:  :~$ ls /boot/ abi-2.6.31-21-generic         lost+found abi-2.6.32-25-generic         memtest86+.bin abi-2.6.38-10-generic         memtest86+_multiboot.bin abi-2.6.38-11-generic         System.map-2.6.31-21-generic abi-2.6.38-12-generic         System.map-2.6.32-25-generic abi-2.6.38-8-generic          System.map-2.6.38-10-generic abi-3.0.0-12-generic          System.map-2.6.38-11-generic abi-3.0.0-13-generic          System.map-2.6.38-12-generic abi-3.0.0-14-generic          System.map-2.6.38-8-generic boot                          System.map-3.0.0-12-generic config-2.6.31-21-generic      System.map-3.0.0-13-generic config-2.6.32-25-generic      System.map-3.0.0-14-generic config-2.6.38-10-generic      vmcoreinfo-2.6.31-21-generic config-2.6.38-11-generic      vmcoreinfo-2.6.32-25-generic config-2.6.38-12-generic      vmcoreinfo-2.6.38-10-generic config-2.6.38-8-generic       vmcoreinfo-2.6.38-11-generic config-3.0.0-12-generic       vmcoreinfo-2.6.38-12-generic config-3.0.0-13-generic       vmcoreinfo-2.6.38-8-generic config-3.0.0-14-generic       vmcoreinfo-3.0.0-12-generic extlinux                      vmcoreinfo-3.0.0-13-generic grub                          vmcoreinfo-3.0.0-14-generic initrd.img-2.6.31-21-generic  vmlinuz-2.6.31-21-generic initrd.img-2.6.32-25-generic  vmlinuz-2.6.32-25-generic initrd.img-2.6.38-10-generic  vmlinuz-2.6.38-10-generic initrd.img-2.6.38-11-generic  vmlinuz-2.6.38-11-generic initrd.img-2.6.38-12-generic  vmlinuz-2.6.38-12-generic initrd.img-2.6.38-8-generic   vmlinuz-2.6.38-8-generic initrd.img-3.0.0-12-generic   vmlinuz-3.0.0-12-generic initrd.img-3.0.0-13-generic   vmlinuz-3.0.0-13-generic initrd.img-3.0.0-14-generic   vmlinuz-3.0.0-14-generic   Currently, I'm using the 3.0.0-14-generic kernel.


I dual booted ubuntu 12.04 LTS with Windows 8, but I wanted to get rid of ubuntu. So I got EasyBCD (on windows 8) and removed Ubuntu following a tutorial on youtube, then I got rid of the Ubuntu partitions. After restarting my Sony Vaio, it went to grub rescue and I'm not sure what to do. Help please! Much appreciated!!  I installed ubuntu using a USB.

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


How to clean up network namespace, CentOS 6.5 does not have ip netns pids option, so can't use ip netns pids ns-2001 | xargs kill  ip netns list | grep ns-2001 ns-2001  ip netns pids ns-2001 | xargs kill Command "pids" is unknown, try "ip netns help". usage: kill [ -s signal | -p ] [ -a ] pid ... kill -l [ signal ]  sudo ip netns delete ns-2001 Cannot remove /var/run/netns/ns-2001: Device or resource busy  ip netns help Usage: ip netns list        ip netns add NAME        ip netns delete NAME        ip netns exec NAME cmd ...        ip netns monitor

I am on Ubuntu 12.04, and the ip utility does not have ip netns identify <pid> option, I tried installing new iproute, but still, the option identify doesn't  seem to be working!.  If I were to write a script (or code) to list all processes in a network-namespace, or given a PID, show which network-namespace it belongs to, how should I proceed ? (I need info on a handful of processes, to check if they are in the right netns)


I came across this statement in the book "Quantum Field theory and the Standard Model".     "A particle can be defined as a set of states that mix only among themselves under Poincare transformations."    What does this statement mean?

Only because   Rep is unitary, so saves positive-definite norm (for possibility density), Casimir operators of the group have eigenvalues $m^{2}$ and $m^2s(s + 1)$, so characterizes mass and spin, and It is the representation of the global group of relativistic symmetry,    yes?


Who/whom question: "I have no idea whom he was speaking about." The subject of the phrase, "was speaking about" is, he, hence "whom" is correct (flip it around, "about whom he was speaking'). But it doesn't sound correct.

Like many others, I commonly find myself ending a sentence with a preposition.  Yes, it makes me cringe.  I usually rewrite the sentence, but sometimes (in emails) I just live with it.  To, with... you know who you are.  Should I keep fighting myself on this one, or is it okay in some circumstances?


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


I'm new to git and when I try to merge one branch into another, I'm getting a bunch of errors, like this:  CONFLICT (modify/delete): src/controller/app.js deleted in feat_branch and modified in HEAD. Version HEAD of src/controller/app.js left in tree. CONFLICT (modify/delete): src/controller/service.js deleted in feat_branch and modified in HEAD. Version HEAD of src/controller/service.js left in tree. ...   Im trying to merge using this command git merge feat_branch --no-ff  What am I doing wrong or why this is generating these errors?

I want to resolve merge conflicts in my Git repository. How to do that ?


I am an American with a US passport.I have a 15 hour layover in Paris. Can I leave the aiport to tour the city? Do I need a visa?

I am a US citizen.  I have a transit in Frankfurt for 12 and half hours. I will fly from Detroit to Frankfurt then to Amman, Jordan.  I was planning to stay at the airport hotel, but I was wondering whether I need a visa to leave the airport?


An exercise at the end of a chapter on primitive roots asked me to compute $1^k + 2^k + \ldots + (p-1)^k \pmod{p}$ for any positive integer $k$ and any prime $p$. Clearly, if $k$ is odd, the expression is congruent to $0$ modulo $p$. But how can I even approach this problem if $k$ is even? And how do primitive roots apply? Hints would be greatly appreciated.

I've been working through a bit of Ireland and Rosen's Number Theory for fun. Problem 4.11 of Ireland and Rosen asks     Prove that $1^k+2^k+\cdots+(p-1)^k\equiv 0\pmod{p}$ if $p-1\nmid k$, and $-1\pmod{p}$ if $p-1\mid k$.    My work is leading where I didn't expect to go. Here I assume $p$ id odd. First, if $p-1\mid k$, then we can wrike $k=(p-1)j$ for some $j$. But then $$ 1^k+\cdots+(p-1)^k\equiv 1^{(p-1)j}+\cdots+(p-1)^{(p-1)j}\equiv \underbrace{1+\cdots+1}_{p-1\text{ times}}=\frac{(p-1)p}{2}\equiv 0\pmod{p} $$ since $p-1$ is even.   Secondly, I suppose $p-1\nmid k$. WLOG, I can assume $0<k<p-1$, Since if $k=(p-1)j+r$ with $0<r<p-1$, then  $$ a^k\equiv a^{(p-1)j+r}\equiv a^r\pmod{p}. $$  Then if $g$ is a primitive root, $$ 1^k+\cdots+(p-1)^k=\sum_{i=1}^{p-1}(g^k)^i=\frac{g^k(1-g^{k(p-1)})}{1-g^k}. $$ Since $g$ is primitive, $p\nmid 1-g^k$, but $p\mid 1-g^{k(p-1)}$, so the above sum is again congruent to $0\pmod{p}$.  So in all cases, I get the sum is congruent to $0$ regardless. Have I messed up, or is there a typo? Thanks.


I have an app who has to download some generated images (PNG).   I tried the standard approach ImageDownloader extends AsyncTask, doInBackground() retrieves the image and the onPostExecute() will try to save it to internal image.   (Part of the) code is below:   public class HandleImages extends AppCompatActivity { String filename = "";  public boolean saveImageToInternalStorage(Bitmap image) {     try {         FileOutputStream fos = openFileOutput(filename, Context.MODE_PRIVATE);          image.compress(Bitmap.CompressFormat.PNG, 100, fos);         fos.close();          return true;     } catch (Exception e) {         e.printStackTrace();         return false;     } }  public Bitmap retrieveImage(String url){     ImageDownloader task = new ImageDownloader();     Bitmap image =  Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888);      try {         image = task.execute(url).get();     } catch (InterruptedException e) {         MainActivity.debb("InterruptedException - " + e.getMessage() + " in " + new Object(){}.getClass().getEnclosingMethod().getName());         e.printStackTrace();     } catch (ExecutionException e) {         MainActivity.debb("ExecutionException - " + e.getMessage() + " in " + new Object(){}.getClass().getEnclosingMethod().getName());         e.printStackTrace();     }     return image; }   public class ImageDownloader extends AsyncTask<String, Void, Bitmap> {     @Override     protected Bitmap doInBackground(String... urls) {         try {             String[] filenames = urls[0].split("/");             filename = filenames[filenames.length-1] + ".jpg";              URL url = new URL(urls[0]);             HttpURLConnection connection = (HttpURLConnection) url.openConnection();              connection.connect();             InputStream inputStream = connection.getInputStream();              return BitmapFactory.decodeStream(inputStream);          } catch (Exception e) {             e.printStackTrace();         }         return null;     }      @Override     protected void onPostExecute(Bitmap bitmap) {         super.onPostExecute(bitmap);         if (bitmap != null)             saveImageToInternalStorage(bitmap);     } } }   and the error that I get is: java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.FileOutputStream android.content.Context.openFileOutput(java.lang.String, int)' on a null object reference.   It seems that the FileOutputStream fos = openFileOutput(..) fails, but have no idea why.   Also tried to prepend a path (sdCard.getPath() + "/" +) to the filename. As expected it did not make any difference.   Images are ok, I can see them in the browser. Also tried with uploaded images - instead of the generated ones, same result.   This is pretty odd, does anyone have any idea?   Thanks!

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


I have 1gbit Powerline network. If I plug in 200mbit PL adapter, will it degrade speed between devices connected to my old 1Gbit adapters?

I have two  ethernet adapters that give me near ideal internet access on my media computer (FIOS 25/25mpbs tests out at 8ms 25.4/24.7) and perhaps 100-140mbps to my router, printer, drive, etc.  I now want to add a few wifi points and instead of having the mess of a powerline adapter + a wifi router I think it will be neater to have an all in one solution.  Most of  are 200mbps, however.  I know that 500 is backwards compatible, but will a mixed solution slow everything down like it can for a mixed wireless g/n network?


Shouldn't the second 'test' line also get replaced? How would I have to write the command to replace all 'test'? $ sed 's/test/toast/' texttest.txt  toast file test file hahahaha 1 toast file test file hahahaha 2

I know this question has probably been answered before.  I have seen many threads about this in various places, but the answers are usually hard to extract for me.  I am looking for help with an example usage of the 'sed' command.  Say I wanted to act upon the file "hello.txt" (in same directory as prompt).  Anywhere it contained the phrase "few", it should be changed to "asd".  What would the command look like?


I just noticed all questions I have voted to reopen on are marked as deleted on my profile (https://stackoverflow.com/users/508666/peehaa?tab=votes&sort=reopen):    But they really aren't deleted.  Example question:

In the "Votes Cast" section of my profile, my vote to close  is annotated with "(deleted)":    However, the close vote does not appear to have been deleted: it successfully closed the question:    Why was this vote marked as "(deleted)"?    If the vote was deleted my some internal process after the question was closed and the closers were recorded, I call that a . Regardless of what happens internally, it's irrelevant to users if close votes are deleted after they have taken effect.


How does one abbreviate "Mr Adams PhD, Mr Benson PhD, Mr Charles PhD" to use just one salutation and one title.

I'm writing a letter to several recipients in the same document and want to address them correctly at the start.  Is the following correct (I suspect not) and if not, what should it be:     Dear Mr's Jones, Smith, Bloggs and Flintstone


I am trying to created virtual machine which in bridged mode. I already asked  but it only assure me that problem is with my host machine. I also tired to install VmWare instead of VirtualBox and problem is exactly same.  So my question is: how can I diagnose what is blocking bridged mode on my Windows 7?  I already:   Disable Windows Firewall I do not have any antyvirus software running

I have virtual box with RHEL installed. My virtual box is running on windows 7 64 -bit. I configured bridged connection, but when I am restarting network interfaces, I receive following error:  Determining IP information for eth1... failed   On Windows XP it works without problems. I disabled Windows Firewall and installed latest Virtual Box, still without success.   NAT is working without any problems. What did I missed?  UPDATE  Ouput of ifconfig -a is:  eth0      Link encap:Ethernet  HWaddr 08:00:27:B6:FC:69           inet addr:10.0.2.15  Bcast:10.0.2.255  Mask:255.255.255.0           inet6 addr: fe80::a00:27ff:feb6:fc69/64 Scope:Link           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           RX packets:430 errors:0 dropped:0 overruns:0 frame:0           TX packets:346 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000           RX bytes:36520 (35.6 KiB)  TX bytes:31455 (30.7 KiB)  eth1      Link encap:Ethernet  HWaddr 08:00:27:C3:84:4A           inet6 addr: fe80::a00:27ff:fec3:844a/64 Scope:Link           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           RX packets:1464 errors:0 dropped:0 overruns:0 frame:0           TX packets:17 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000           RX bytes:135419 (132.2 KiB)  TX bytes:4230 (4.1 KiB)  lo        Link encap:Local Loopback           inet addr:127.0.0.1  Mask:255.0.0.0           inet6 addr: ::1/128 Scope:Host           UP LOOPBACK RUNNING  MTU:16436  Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)   Output of route -n  Kernel IP routing table Destination     Gateway         Genmask         Flags Metric Ref    Use Iface 10.0.2.0        0.0.0.0         255.255.255.0   U     0      0        0 eth0 169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0 0.0.0.0         10.0.2.2        0.0.0.0         UG    0      0        0 eth0   Output of dhclient -v eth1 is:  Listening on LPF/eth1/08:00:27:c3:84:4a Sending on   LPF/eth1/08:00:27:c3:84:4a Sending on   Socket/fallback DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 6 (xid=0x6afb6c4c) DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 9 (xid=0x6afb6c4c) DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 15 (xid=0x6afb6c4c) DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 18 (xid=0x6afb6c4c) DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 13 (xid=0x6afb6c4c) No DHCPOFFERS received. No working leases in persistent database - sleeping.   Moreover the same machine with the same configuration works well on Windows XP. The problem is only on Windows 7.


I am new to apex, and I dont know how to correctly write a Testclass for my trigger.     Trigger has to update field Time_Zone__c of object Task according to Time_Zone__c of object Contact, which is associated with object Task with WhoId  field   Here is the code:  trigger TaskTimeZoneUpdate on Task(before insert, before update){   set<id>setwhoIds = new set<id>();    for (Task objTask : trigger.new) {     if (objTask.WhoId != null) setWhoIds.add(objTask.WhoId);   }    map<id, Contact> mapContact = new map<id, Contact> ([Select    c.Time_Zone__c, c.Id From Contact c where id in :setWhoIds]);      for (Task objTask : trigger.new){        if (objTask.WhoId != null && mapContact.get(objTask.WhoId)!=null)          objTask.Time_Zone__c = mapContact.get(objTask.WhoId).Time_Zone__c;     }  }   Looking forward your response, Thank you

This is a canonical question and answer developed by the community to help address common questions. If you've been directed here, or your question has been closed as a duplicate, please look through the resources here and use them to shape more specific questions. To browse all canonical questions and answers, including more unit test resources, navigate to the  tag.  This canonical question is intended to address several classes of common questions by providing a quick summary and links to comprehensive resources:   How do I start writing my first unit test?  How do I unit test this code?  I need help writing this unit test.   Salesforce Stack Exchange looks for detailed, specific questions that the community can help you with, and can't write tests on your behalf. We feel that working with the resources below can help you get started, and we encourage you to make an attempt to write your test and return to SFSE with your specific questions when you encounter challenges you can't resolve.


Sometimes (Don't know when and why), Stack Overflow website opens in plain HTML format. As it is show in below picture.        This happening only  and not with other Stack Exchange website. I am using Google Chrome.

Stack Overflow seems to be having some CSS issues right now. At first, it presented as CSS disappearing when refreshing in Firefox (though hitting Enter from the address bar seemed to restore it - I'm thinking that's a cache issue though). I loaded my blank Firefox profile and discovered CSS wasn't rendering on Stack Overflow at all (Meta seems fine; haven't checked other SE sites).  I've since checked the site in Chrome and Opera, and can repro in both.


Would it be possible to add another "Add to answer" button directly after the question on the mobile app? After browsing the , I had to scroll past 51 one answers so I could add my bug finding.  I guess it makes sense to force people to scroll through answers so they could see them and avoid duplicates, but it seems counterintuitive when there are questions like these.

When there's one answer, it's no big deal. But when there's dozens and you have to scroll past every single other answer to add a new one, loading them in batches on a sketchy network, that takes a lot longer than it should.  When already on the Answers tab, display a + button to add an answer.


I was in doubt, so I went to . There it says "the photon has zero rest mass", but on the side description it says the mass is $<1.10^{-18} \:\mathrm{eV}/c^2$. So is the mass of the photon really zero or do we just consider it to be zero because it's negligible? More generally, are there massless particles at all?

I was under the impression that gluons had no mass. Then Wikipedia throws this curveball:  Mass: 0 (theoretical value) < 0.0002 eV/c2 (experimental limit)  Which one should a poor soul go by? If the theoretical value just the one that people "thought" was right, until they found out the truth, or is the experimental limit(?) an impossibility that still has not been explained? Or something third?


So my idea was to build a bathroom that is lit only by its window, so I put it together and tried it out, but it didn't come out as I was expecting to, of course I'm a newbie at blender so I thought I ask for some help with it. The result was a too dark scene, besides some light leaking from the walls but that may be simpler to solve, my biggest problem is the very dark room.  I tried increasing the emission strength of the Sun Light I put outside, tried 1, then 14, then 50 just to see how it would be, the render image bellow is with the strength set to 50.  I tried turning off the visibility of the window's glass, it did improve a tiny little bit, but almost not noticeable.  I'm using cycles, the images bellow show the result I got, the solid mode view, outside the bathroom, the node scheme of the sun light I'm using and the node scheme of the glass texture it is used in the window glass.

Here's a sample scene:  A room with a window, a point light to project light into the room, an HDR environment outside the room and a nice Image by Rembrandt that should be somewhat reflected on the glass:    Using a standard glass shader on the window, the direct light from the lamp does not shine into the room, regardless of how bright that light is. So I can't recreate the impression of hard day light, with clearly defined areas of light and shadow.    Adding a transparent shader to the glass shader I get a very pleasing result. The light from the lamp illuminates into the room creating defined shadows, transparency seems unaffected, to see the HDR in the background, the refection seem correct to me (I also like how I get double reflections from the thick glass).    Even though I am quite happy with this solution, I've gotten a few comments on making a setup with light path nodes controlling the mix of transparent and glass. The biggest issue is that the reflections on the glass are brighter than what they should be.  So the question is: By using this approach am I messing up any of the qualities of glass? And if so, what would make a proper glass shader that is realistic, in terms of letting direct light through, while keeping reflections, refraction and transparency?  A file to play with:    The HDR image used was created by


I have 3 separate tables which located in 3 separate servers(SQL Server Management Studio). Each table has a unique ID(int) column but for my next project I have to connect all those 3 tables into one. Before that I would like to know are there any overlapping ID's in any of those tables. Ex : Server1 => DB1 => Table1 => IDs might be 1,2,3,4,5,6....      Server2 => DB2 => Table2 => IDs might be 50,51,52,6,54....      Server3 => DB3 => Table3 => IDs might be 89,90,2,92,93....  As in the example '6' is repeating in Server1 and Server2. Also '2' is repeating in Server1 and Server3. So my goal is to identify those ID's since each table has 50,000+ records it's harder to do manually. I tried couple of methods as in below snippets by looking at some similar issues but none of them worked for me and ended up having "Invalid object name 'DB2.dbo.Table2'." error code Method 1 select ID from [DB1].[dbo].[Table1] intersect select ID from [DB2].[dbo].[Table2] intersect select ID from [DB3].[dbo].[Table3]  Method 2 SELECT *  FROM [DB1].[dbo].[Table1] tab1  INNER JOIN [DB2].[dbo].[Table2] tab2  ON tab1.ID = tab2.ID

I need to do a join across two different database servers (IPs 10.0.0.50 and 10.0.0.51). What's the best way?


Set<Long> set = new HashSet(); set.add(123455678l); set.add(124561233l);   How to convert the above Set into List of type String ? Without Iteration

I have a list of integers, List<Integer> and I'd like to convert all the integer objects into Strings, thus finishing up with a new List<String>.  Naturally, I could create a new List<String> and loop through the list calling String.valueOf() for each integer, but I was wondering if there was a better (read: more automatic) way of doing it?


I want to determine all entire functions $f$ such that $|f(z)| \leq |\sin(z)|$. I searched around on MathSEx and I found the following question from which I tried to get inspired but I think it differs substantially from my question:    Here's what I tried. It is not complete I am missing some cases. First if $|f(z)| = |\sin(z)|$ then let $h(z)= \frac{f(z)}{\sin(z)}$. Then $h$ is analytic on $\mathbb{C}\setminus \left\{n \pi,n\in\mathbb Z\right\}$, and we also have that $|h|=1$ on the unit disc $D$. So $\exists c$ such that $h(z)=c$ with $|c|=1$. $h$ is continuous at all $n \pi$, so $h(n\pi)=c.\sin(n\pi)$; so we have that $\exists c$ such that $|c|=1$ and $f(z)=c.\sin(z)$.  Now I need to take care of the case $|f(z)| < |\sin(z)|$ and I don't know what to do. Should I try to apply the Schwarz lemma to this case since we would get $|h|<1$?  Any help or solution is welcomed.

Suppose $f$ and $g$ are entire functions with $|f(z)|\leq|g(z)|$ for all $z$.  How can we show that $f=cg$ for some complex constant $c$?  Thanks for any help :)


We've just started studying the decidability notion in our Algorithms class. So far we've only defined it and went through some examples of problems that fit different cases : decidable, semi-decidable, undecidable. But that's it. On our test today, this question popped up:    Consider the predicates $P_1,P_2,Q_1,Q_2 : R$ $\rightarrow \{0,1\}$ such that $P_1 \vee P_2 $ , $Q_1 \vee Q_2 $ are semi-decidable and $P_2 = \overline{Q_2}$. What can be said about $P_1 \vee Q_1 $?    I looked on the web before coming here, but I don't really understand how to approach this kind of problems. Can anyone help?

I have the following problem:  Let the following predicates be: $P1, P2, Q1, Q1 : R \to \{0,1\} $ .  It is given that $P1 \lor P2$ and $Q1 \lor Q2$ are semidecidable and $P2 = \lnot Q2$  What can it be said about $P1 \lor Q1$?  I have searched all over the internet and I simply cannot understand the concept of decidability of a predicate, let alone a logic operation with predicates.


On the Ubuntu website it mentioned system requirements of 2ghz dual core system. Might it still run on my 1.7GHz processor?

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


I have been trying to find a short story I read many years ago. I think it was a 60s/70s story. Something happens on Earth, and whenever people touch they become stuck together. These blobs of people exist and create nest for themselves.   There are still some individual people but they live in fear, I think, of being joined with the rest.  Any ideas?

I'm trying to identify a short story I read many years ago (early/mid 80s maybe?) where humans who congregated together somehow joined and 'evolved' into new blob multi-creatures - I don't think it was a choice, rather it just started to happen to them. These new blob creatures wandered around trying to learn how to control themselves, and I think they maybe fought each other.  I can't remember much more than that, tbh. I don't think there was much plot or reason for this 'evolution' given. The story was told from the point of view of one person, who was watching and documenting the metamorphosis. At the end I think he realised he had no choice but to join with them.  Any help would be greatly appreciated.  (It's not "Four in One", btw)


I am using the amsmath package in latex to align three equations.   \begin{align*}  &x_{1} - 3x_{2} + 4x_{3} = -4 \\ 3&x_{1} - 7x_{2} + 7x_{3} = -8 \\ -4&x_{1} + 6x_{2} - x_{3} = 7  \\ \end{align*}     how do i get the output shown above to align each of the numbers in columns. I need all of the operands in the same spot and in my output the equal sign is way off.  thanks

I am trying to write a few systems of equations, and I want the terms to be nicely spaced as below  2x  +   y  +  3z  =  10   \\   x  +   y  +   z  =   6   \\  x  +  3y  +  2z  =  13    Now, using some very ugly code, I was able to produce the results above.  \documentclass[10pt,a4paper]{article} \usepackage{mathtools} \usepackage{amsmath}  \begin{document}  \begin{align*} \begin{bmatrix} \begin{tabular}{r c r c r c r } $2x$ & $+$ & $ y$ & $+$ & $3z$ & $=$ & $10$ \\ $ x$ & $+$ & $ y$ & $+$ & $ z$ & $=$ & $ 6$ \\ $ x$ & $+$ & $3y$ & $+$ & $2z$ & $=$ & $13$ \end{tabular} \end{bmatrix} \end{align*}  \section{Another system of equations, now without the brackets}  \begin{table}[!htpb] \centering \begin{tabular}{r c r c r c r } $2x$ & $+$ & $ y$ & $+$ & $3z$ & $=$ & $10$ \\ $ x$ & $+$ & $ y$ & $+$ & $ z$ & $=$ & $ 6$ \\ $ x$ & $+$ & $3y$ & $+$ & $2z$ & $=$ & $13$ \end{tabular} \end{table}  \end{document}       I would very much want a more automatic way to do this, and a simple method for controlling the spacing between elements. I have looked at earlier posts like     It seems that I am looking for a simple version of this one. I have no need to use side-by-side equations, nor have numbers in front of them.  Using ideas from the post above, I guess the result is done by redefining commands such as - and + inside of the table? I tried to do something like this, but the code looked rather complex =(  To sum it up: Is there a way to define a simple System of Equations enviroment, with proper alignment and a optional command for defining the spacing?


Hello everyone I'm having problems with missing characters in my code, tried to use some things with utf-8 but didnt worked. the entire site is on php but the rest is working fine just this page that is having this problem.   <?php       $tipo =$_GET["tipo"];        $conexao = mysqli_connect("127.0.0.1","root","","db_tcc") or die ("Não foi possível se conectar com o servidor.");       $varsql = "SELECT * FROM tb_guias WHERE TIPO=$tipo ORDER BY id ASC";       $carregar_guias = mysqli_query($conexao, $varsql);           while ($linha = mysqli_fetch_array($carregar_guias))       {         $titulo = $linha["TITULO"];         $blob1 = $linha["IMG1"];         $blob2 = $linha["IMG2"];         $blob3 = $linha["IMG3"];         $texto = $linha["TEXTO"];          $img1 = imagecreatefromstring($blob1);           ob_start();          imagejpeg($img1, null, 80);         $data1 = ob_get_contents();         ob_end_clean();        $img2 = imagecreatefromstring($blob2);         ob_start();        imagejpeg($img2, null, 80);       $data2 = ob_get_contents();       ob_end_clean();        $img3 = imagecreatefromstring($blob3);         ob_start();        imagejpeg($img3, null, 80);       $data3 = ob_get_contents();       ob_end_clean();           echo "

$titulo

";         echo '';        echo"	";        echo '';        echo"	";        echo '';        echo "

$texto

";         echo "

";        }     ?>

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 24 reputation points, but SO chat is still giving me the message "you must have 20 reputation...." Why can't I join the chat?

Following scenario:   user registers, has 1 point user visits chat, notes he cannot post because of only 1 point and needs 20 user goes back to SO, answers a question. gets enough points to chat user goes back to chat, but his profile still shows 1 point   Now my questions:   How long does it take for the profile on chat to update? Is there a way to force updating?   Update: Logging in and out did not help.


In Thor (2011) after Thor shattered the Rainbow Bridge with Mjolnir both him and Loki were going to fall into space (abyss) before Odin arrived for their help. But in the movie we can see water (Asgardian sea) below the Rainbow Bridge during the combat between Loki and Thor. Once the bridge is shattered water gushes above the bridge and both the brothers were thrown up in air. When they landed down we can see both the brothers were going to fall down into space from the verge of the shattered Rainbow Bridge before Odin came for their rescue. Were they both supposed to fall in water (Asgardian sea)? Because, initially there was water below the bridge prior to its destruction.

I noticed something the other night as my kids were watching Thor. Every time they show the crystal bridge leading to the Bifrost chamber, it's got flowing water underneath it. The water flows right up to the edge of where the chamber is and then falls off into the void of stars beneath Asgard. There is no part of the bridge that ISN'T over water.  At the end of the film, Thor and Loki are fighting on the crystal bridge, and it appears that they're a good distance from the Bifrost chamber - probably 30, 40 feet or more. However, when Thor starts smashing the bridge and Loki falls off one side, he's suddenly hanging above the starry void and NOT flowing water.  Is this a continuity snafu within the film or did I miss something? How did that portion of bridge get the void under it and not water?


I'm currently trying to reinstall ubuntu 16.04 back onto a partition on one of my hard drives, but whenever I select "Try Ubuntu without installing" or "Install Ubuntu" from my usb, it shows a few messages on the screen    then briefly shows the purple ubuntu loading screen (for a fraction of a second) and then my pc cycles off and then on. Anyone have some ideas as to what could be a potential cause?

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


My client has a bunch of duplicate content. The problem is all of them have high amount of traffic. So if I implement canonical tags on them, will it hurt the performance?

This is a general, community wiki question regarding duplicate content.  If your question was closed as a duplicate of this question and you feel that the information provided here does not provide a sufficient answer, please open a discussion on .     What does Google consider to be duplicate content? Will the way I am presenting my content result in a duplicate content penalty? How can I avoid having my site's content treated as duplicate content?


In TF2, I have heard of a term known as "Gib" What exactly does this term mean? There is even a strange part called: "gib kills" What does that mean? Low health kill? Adrenaline kill?   Could I please have some clarification on what both terms mean? Both the term "gib" itself and "gib kills".

Especially while talking about FPS, the term "gib" is quite common. While I get it's related to a sudden and gruesome death, I'd like to know its actual meaning and where it comes from.


I am new to blender.   I have a 3D object that are made from an SVG file.  I want to know how to apply an image to said object. To act like a skin for said 3D object. This is the same as creating a clipping mask in Adobe Photoshop.  How do I apply said image to an object to make it act as a skin for the 3D object?

I am trying to create a low poly face with a face from a .png file. The issue is I already have material placed for hair and skin, as shown in the picture below.   I have created a .png file with a face which I would like to overlay over the skin material on the front of the head.    All examples I searched so far assume I also want the color of the material from the .png texture.  Update:  I added UVMapping, changed view to texture, made sure one face is on the eye but nothing is displayed..... see image... I don't know what is going on.


So I have used the boolean operation to create a spherical hole inside a cube and was wondering how I could correct the topology. The result of this was:  So I was wondering how I can edit the topology so I can use subsurface modifier or if it is better if I Use a different method to create the hole. If I should recreate it a different way than what would be a good way keeping in mind that this is from a cube. Thanks!

If I wanted to add a hole into an object e.g. Create a tube  Is there an easy way to do that?  I haven't seen anything regarding negative space so far in Blender, and it would be really helpful for my project  Thanks in advance!


Given 2 independent $exp(1)$ random variables $X$ and $Y$, how would one calculate the joint density function $f$$A,B$$(a,b)$ of the 2 random variables $A$ and $B$, where $$A = X+Y$$ $$B = \frac{X}{X+Y}$$ I attempted to first find the c.d.f $F$$A,B$$(a,b) = P(A<a, B<b)$ but I am stuck trying to convert that into an integral. Thanks in advance.

Been crushing my head with this exercise. I know how to get the distribution of a ratio of exponential variables and of the sum of them, but i can't piece everything together.  The exercise goes as this:  If X,Y are independent exponentially distributed with beta = 1 (parameter of the exponential distribution = 1) then what is the distribution of X/(X+Y)  Any ideas?  Thanks a lot.


Is it possible to store variables into arrays? What is the correct way of doing it? I can't seem to be able to store it in this way.   var fxVal = '<?php echo $fxVal;?>'; var equitiesVal = '<?php echo $equitiesVal;?>'; var boVal = '<?php echo $boVal;?>'; var balance = '<?php echo $account_balance;?>';  var myData = [fxVal,equitiesVal,boVal,balance];

How do I append an object (such as a string or number) to an array in JavaScript?


Question:     If $f(x)$ is such a function so that $f(f(x)) = x$ and $f(0) = 1$ then find the value of:   $$ \int_0^1(x+f(x))^{2016}dx$$   I have no clue where to start this question. A small hint would be appreciated.

This question was asked in an entrance test for an undergraduate mathematics program today, held all over India.   Question: $f$ is a differentiable function in $[0,1]$ such that $f(f(x))=x$ and $f(0)=1$.  Find the value of $\int_{0}^{1} (x-f(x))^{2016} dx$.  I tried to solve it by substituting $f(f(x))$ in place of $x$, but could not proceed much further. Any hints or solutions will be appreciated.


file contents:  # cat file.txt  ----- MATCH ----- MATCH ----- MATCH -----  # cat text.txt  add this text file before first match   sed commands:  # sed '0,/MATCH/r text.txt' file.txt ----- add this text file before first match MATCH add this text file before first match ----- MATCH ----- MATCH -----  # sed '0,/MATCH/i prependme once' file.txt prependme once ----- prependme once MATCH ----- MATCH ----- MATCH -----   I'm trying to merge these commands somehow to get the following output:  ----- add this text file before first match MATCH ----- MATCH ----- MATCH -----

File1 contents:  line1-file1      "1"  line2-file1      "2" line3-file1      "3"  line4-file1      "4"    File2 contents:  line1-file2     "25"   line2-file2     "24"   Pointer-file2   "23"   line4-file2     "22"  line5-file2     "21"   After the execution of perl/shell script, File2 content should become:  line1-file2     "25"   line2-file2     "24"  line1-file1      "1"  line2-file1      "2" line3-file1      "3"  line4-file1      "4"  Pointer-file2   "23"  line4-file2     "22"  line5-file2     "21"   i.e  paste the contents of File1 in File2 before the line that contains "Pointer".


I have these 2 tasks in Windows scheduler - GoogleUpdateTaskMachineUA and GoogleUpdateTaskMachineCore. I only have Chrome on my machine (which I use sparely). I am ok with Chrome to be updated automatically. I feel that only one job is responsible for updating Chrome. Is that a correct assumption and which one if yes? And generally speaking - whats the difference between these two jobs (GoogleUpdateTaskMachineUA, GoogleUpdateTaskMachineCore)?

My machine has 5 Google updaters running:   Service: Google Update Service (gupdate)     Keeps your Google software up to date. If this service is disabled or stopped, your Google software will not be kept up to date, meaning security vulnerabilities that may arise cannot be fixed and features may not work. This service uninstalls itself when there is no Google software using it.   C:\Program Files (x86)\Google\Update\GoogleUpdate.exe /svc  Service: Google Update Service (gupdatem)     Keeps your Google software up to date. If this service is disabled or stopped, your Google software will not be kept up to date, meaning security vulnerabilities that may arise cannot be fixed and features may not work. This service uninstalls itself when there is no Google software using it.   C:\Program Files (x86)\Google\Update\GoogleUpdate.exe /medsvc  Service: Google Updater Service  C:\Program Files (x86)\Google\Common\Google Updater\GoogleUpdaterService.exe  Scheduled Task: GoogleUpdateTaskMachineCore     Keeps your Google software up to date. If this task is disabled or stopped, your Google software will not be kept up to date, meaning security vulnerabilities that may arise cannot be fixed and features may not work. This task uninstalls itself when there is no Google software using it.    Runs at logon of any user Runs daily at 10:08 AM    C:\Program Files (x86)\Google\Update\GoogleUpdate.exe /C   Scheduled Task: GoogleUpdateTaskMachineUA  Keeps your Google software up to date. If this task is disabled or stopped, your Google software will not be kept up to date, meaning security vulnerabilities that may arise cannot be fixed and features may not work. This task uninstalls itself when there is no Google software using it.   Runs every hour  C:\Program Files (x86)\Google\Update\GoogleUpdate.exe /ua /installsource scheduler     Now obviously Google doesn't need all these items running at the same time; some are going to be legacy duplicates.  Which one is the current, true, preferred, Google updater?  Would the real Google updater please stand up, please stand up,  please stand up.    My setup:   Windows 7 Professional 64-bit Chrome one interactive user account


When executing the following command, I get the error "Data tag parsing failed: unbalanced quotation"  /give @p leather_helmet 1 0 {display:{Name:"Nightslash Helm",Lore:["Legendary helmet found only in a secret hideout."]},ench:[{id:0,lvl:9999},{id:1,lvl:99999},{id:2,lvl:99999},{id:3,lvl:999999},{id:4,lvl:999999},{id:5,lvl:99999},{id:6,lvl:999},{id:7,lvl:99}],Unbreakable:1}   I don't see why the command would be wrong. What should I change for this error to go away?

I'm trying to make a command that creates a book that has many items with enchantments at level 1,000. However, I don't know why it keeps saying:     Data tag parsing failed: Unbalanced quotation:   {ench:[{id:0,lvl:1000}],Unbreakable:1,display:{Name:"Prot   It's supposed to say "Protection Armor", but it only shows "Prot" for some reason. This is the same with all of my other items. Here is the one part of the command that I've showed you:  {ench:[{id:0,lvl:1000}],Unbreakable:1,display:{Name:"Protection Armor"}}


This illustrates what I am trying to accomplish:  public class GridModel : PropertyChangedBase {     public List<string> LeftValue { get; set; }     public List<string> LeftValue = new List<string> { "Alpha", "Beta", "Gamma" };     [...] }   but I am getting an obvious "identifier repeated" error.  Is there a syntax for that? Perhaps with a constant or fixed List?

I'm used to writing classes like this:  public class foo {   private string mBar = "bar";   public string Bar {     get { return mBar; }     set { mBar = value; }   }   //... other methods, no constructor ... }   Converting Bar to an auto-property seems convenient and concise, but how can I retain the initialization without adding a constructor and putting the initialization in there?  public class foo2theRevengeOfFoo {   //private string mBar = "bar";   public string Bar { get; set; }   //... other methods, no constructor ...   //behavior has changed. }   You could see that adding a constructor isn't inline with the effort savings I'm supposed to be getting from auto-properties.  Something like this would make more sense to me:  public string Bar { get; set; } = "bar";


I ran lsmod command on an emulator for a board, and the output is Not tainted . What does that mean ?

Under certain conditions, the Linux kernel may become tainted. For example, loading a proprietary video driver into the kernel taints the kernel. This condition may be visible in system logs, kernel error messages (oops and panics), and through tools such as lsmod, and remains until the system is rebooted.  What does this mean? Does it affect my ability to use the system, and how might it affect my support options?


I am trying to find $$\lim_{n\rightarrow \infty}\prod_{k=2}^{n}\frac{k^3-1}{k^3+1}.$$I have no idea how I can start. Please help me.  Thanks!


So I installed Ubuntu 18.04 app using  website, and this . All seems cool. But after installation and assigning username and password, I try to use this code as described:  sudo apt update && sudo apt upgrade   and then I am getting this error:   Previously, I tried to do sudo apt autoremove but nothing happened. Please, someone, help me with it.  P.S. Sorry for my kind of poor description. I am a newbie to ubuntu.

After installing Ubuntu 18.04 from the Windows store I open Bash and want to run sudo apt-get update, but this returns the following errors:  Err:1 http://security.ubuntu.com/ubuntu bionic-security InRelease   Connection failed [IP: 91.189.91.26 80] Err:2 http://archive.ubuntu.com/ubuntu bionic InRelease   Connection failed [IP: 91.189.88.162 80] Err:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease   Connection failed [IP: 91.189.88.161 80] Err:4 http://archive.ubuntu.com/ubuntu bionic-backports InRelease   Connection failed [IP: 91.189.88.162 80] Reading package lists... Done W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/bionic/InRelease  Connection failed [IP: 91.189.88.162 80] W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/bionic-updates/InRelease  Connection failed [IP: 91.189.88.161 80] W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/bionic-backports/InRelease  Connection failed [IP: 91.189.88.162 80] W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/bionic-security/InRelease  Connection failed [IP: 91.189.91.26 80] W: Some index files failed to download. They have been ignored, or old ones used instead.   When I open 91.189.91.26 in a browser, it shows the site without a problem.  Previously this worked without any problem, but I did a clean reinstall of Windows and now it doesn't work anymore. It seems some firewall or proxy issue, but I tried with the firewall disabled and I got the same result.  Any idea why this is happening? Maybe it is a 18.04 issue? If so, is it possible to return to 16.04 on Windows 10? Becasue I don't see a uninstall option.


I need to animate an object's visibility from opaque to fully transparent in a scene, and this object has many materials that are shared by other objects in the scene.  As I understand it, my only option is to create a single user copy of each of the materials for the object I need to 'disappear', then add a transparency shader to each of these materials and then keyframe that shader's strength (for each material) in order to achieve this.  This seems very complex for such a simple objective.  Anyone know of a better way?

I'm kinda new to using Blender Eevee. I used to use Cycles, but that took too long to render. I'm doing a text animation with a video in the background, and I want the text to fade in and fade out. However, I cannot do this because Eevee is different from Cycles. Is there any way I can animate the transparency of an object so I can fade it in and out?


I've some files appearing in Trash folder. How do I check from where they were removed?  I've Tried 'Get Info', but it doesn't tell me from where it was removed. The only option I've is 'Put Back', but again, to where?  How do I check this on OS X 10.9?

Suppose some file "Any File.pdf" is in the Trash (aka ~/.Trash).  How can I determine its original location?  By "original location" I mean the folder where that file would be moved to if one were to apply the "Put Back" command to it (but without actually doing so)?  (See figure below.)  (I had hoped that this information would be available through running "Get Info" on the file, but I did not find it there.)


Used puttygen to make private.ppk for connecting in server with privatepublic.ppk In putty using private.ppk to connect works. How to connect with this key in ubuntu?

I have a production server. To login to the server I must use a .ppk file.  How to login with Ubuntu Terminal and .ppk file?  I tried this :  ssh -i location/file.ppk username@server-ip   but it is showing an error message.


I need to prove the following:  There's no continuous function $f:[a,b]\to \mathbb{R}$ that takes each of its values $f(x)$, $x\in [a,b]$  exactly twice.  First of all, I didn't understand the question. For example $x^2$ takes $1$ twice, in the interval $[-1,1]$. Is it saying that it does not occur for all $x$ in the interval? But what about $f(x) = c$? Is it saying that it does not occur only exactly $2$ times, then? I have no idea about how to prove it. I know that for $f(x)$ such that $f(a)<f(x)<f(b)$, if $f$ is continuous then there is a $c\in [a,b]$ such that $f(c) = f(x)$.  Now, there's the following proof in my book and I really wanted to understand it, instead of just getting a new proof  Since the interval $[a,b]$ has only $2$ extreme points, then the maximum or minimum of $f$ must be in a point $c\in int([a,b])$ and and in another point $d\in [a,b]$. Then, there exists $\delta>0$ such that in the intervals $[c-\delta, c), (c,c+\delta)$ (and if $d$ is not extreme of $[a,b]$, $[d-\delta, d]$) the function takes values that are less than $f(c) = f(d)$. Let $A$ be the greatest of the numbers $f(c-\delta), f(c+\delta), f(d-\delta)$. By the intermediate value theorem, there are $x\in [c-\delta, c), y\in (c, c+\delta]$ and $z\in [d-\delta, d)$ such that $f(x)=f(y)=f(z)=A$. Contradiction.   Well, why the last part? Why is it that I can apply the intermediate value theorem to these values? For example, $<f(c-\delta)<p<f(c)$, then by the theorem I know that there exists $m\in [c-\delta, c)$ such that $f(m) = p$. Same for the other intervals. But what guarantees thhat the greatest of the values between  $x\in [c-\delta, c), y\in (c, c+\delta]$ will be inside the intervals $[c-\delta), c), (c,c+\delta), [d-\delta, d)$?

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.


My Activity class looks like that:  public class FullscreenActivity extends AppCompatActivity {     private Button btnTakePhoto = new Button(this);     private Button btnRecordVideo = new Button(this);      @Override     protected void onCreate(Bundle savedInstanceState) {         requestWindowFeature(Window.FEATURE_NO_TITLE);         this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);          super.onCreate(savedInstanceState);         setContentView(R.layout.activity_fullscreen);          btnTakePhoto = (Button) findViewById(R.id.btnTakePhoto);         btnTakePhoto.setOnClickListener(new View.OnClickListener() {             public void onClick(View v) {                 helloWorldKamera();             }         });     }      public void helloWorldKamera() {         System.out.println("Kamera");     }  }   My activity_fullscreen.xml file looks like that:  <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:background="#ffffff">      <LinearLayout         android:layout_width="match_parent"         android:layout_height="match_parent"         android:orientation="vertical">          <Button             android:text="Foto"             android:layout_width="match_parent"             android:layout_height="match_parent"             android:layout_weight="0.5"             android:id="@+id/btnTakePhoto" />          <Button             android:text="Video"             android:layout_width="match_parent"             android:layout_height="match_parent"             android:layout_weight="0.5"             android:id="@+id/btnRecordVideo"             />     </LinearLayout> </FrameLayout>   Now I get the following error: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference. Do you know how to fix the null pointer exception? I don't know why my button is null. Is it right how I initialize the button or is the error caused by findViewById?

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


I have installed a Puppet Server on Azure and is currently managing a number of Puppet Agents on Azure as well. I am using the internal azure fqdn - this means that all manifests and tasks processes are sent using the internal Azure network.  Now I want to use the same Puppet server to manage nodes outside Azure. However when I use the public DNS of puppet server, the agent is failing due to incorrect CA domain.  Is there a way to specify to CAs in Puppet server? One for Azure hosts, and other for non-Azure hosts?

my puppet.conf on the master  [master] certname = myname.mydomain.com ca_server = myname.mydomain.com certdnsnames = puppet;puppet.local;myname.dyndns.org;hivemind.local;   for my understanding with the certdnsnames defined the following should work:  puppet agent --server myname.dyndns.org --test   but i get the following error:  err: Could not retrieve catalog from remote server: hostname was not match with the server certificate   how to avoid this error? how to correctly define certdnsnames? i have found diffent documentation about this, but no simple example. i i use "," for seperation i cannot sign at all. i also have seen a syntax like  certdnsnames = puppet:puppet.intra.myserver.fr,puppet.myserver.fr:puppet,puppet:puppet,puppet.intra.myserver.fr,puppet.myserver.fr     but for me its not clear when to add a "puppet:" and when not.


I read that density is quite high in the early universe and many speculate that primordial black hole can form and would probably have a mass similar to a human ovum(egg cell). Usually black hole only forms during gravitational collapse of massive star, we know gravitational force is extremely weak and so there should be not enough time for matter or energy to gather into a tiny region of space and produce black hole. So what created these primordial black holes?

In the very early universe, tiny fluctuations created slight over- and under-densities in mass/energy. As far as I understand, if a region becomes sufficiently over-dense, a primordial black hole (PBH) would form. This might be very very unlikely, but it should have some non-zero probability everywhere in space.  So my question is:  A) Do we have any sense of how many of these PBHs to expect?  B) The power spectrum was essentially flat back then, which I believe means that the size of fluctuations were scale-invariant (the average over-densities on one scale are twice as big as those at half the scale). Does this mean that PBHs are equally likely to form of any size ??  C) Does inflation have anything to say about this?


I asked this question on puzzling.se and someone suggested I post it here:  I discovered this by accident, when trying to create a formula that generates prime numbers (an impossible task, I know).  But, I find it very interesting that you take any prime number 5 and greater, then you square it and subtract 1, dividing it by 24 always results in a whole integer.  For example:  5 x 5 = 25 - 1 = 24 / 24 = 1 7 x 7 = 49 - 1 = 48 / 24 = 2 11 x 11 = 121 - 1 = 120 / 24 = 50   The result is always a whole number, regardless of how high the prime number is.  Can someone explain why this is so, mathematically? This does not seem possible (to me). And if this is really true, why can I find nothing written about it?  I have never heard of this theorem before, and nothing is mentioned on Wikipedia or other sources. But perhaps this could be a helpful in reducing $33\%$ of the possibilities when trying to find or prove large prime numbers, computationally.  UPDATE: lab made the observation that all resulting numbers are apparently also divisible by $24$ ..  interesting  UPDATE: following lab's observation , I tried $24 \times 24 = 576 + 1 = 577$  ( a prime number)  .. interesting  and..  $576 \times 576 + 1 = 331,777$ which is also a prime  Further extrapolating in the gap of numbers between $2$ and $50$:  primes:   24 x 3 = 72 + 1 = 73  72 - 1 = 71  72 + 7 = 79 24 x 4 = 96 + 1 = 97   96 + 5 = 101  96 + 7 = 103    24 x 5 = 120 - 7 = 113  120 + 7 = 121 24 x 6 = 144 - 7 = 137  144 + 7 = 151 24 x 7 = 168 - 1 = 167  168 + 5 = 173 24 x 8 = 192 - 1 = 191  192 + 5 = 197 24 x 9 = 216 + 7 = 223   Not a perfect formula for finding primes, but seems to be effective :-)

Let $p>3$ be a prime. Prove that $24 \mid p^2-1$.   I know this is very basic and old hat to many, but I love this question and I am interested in seeing whether there are any proofs beyond the two I already know.


Why would the following code not result in 0? $payments = [439.53, 36.69]; $total = 0;  foreach ($payments as $p) {     $total += $p; }  // float 476.22 var_dump($total);   $invoice = 476.22; // float 476.22 var_dump($invoice);  $balance = $invoice - $total; // float 5.6843418860808E-14 var_dump($balance);  If I round the result it returns 0: // float 0 var_dump(round($balance, 2));

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


Cyanogen said it plans to cease developing its open-source version of Android and will shutter its services by the end of the month. The company's blog mentions,     As part of the ongoing consolidation of Cyanogen, all services and Cyanogen-supported nightly builds will be discontinued no later than [December 31].    Do users get new update as OTA while using CyanogenMod, or do they have to completely erase and flash a new ROM? (That requires flashing new firmware, ROM, recovery etc.) What will happen, if users are continue using CyanogenMod after December 31, 2016?  What about bugs, security, stability?

So Cyanogen Inc (cyngn), known for their support for their support for CyanogenMod and their efforts to integrate Cyanogen OS into devices such as the OnePlus One, Alcatel POP Mirage, and . Cyanogen Inc just recently .  What does this mean for CyanogenMod, Cyanogen OS, and the devices which originally shipped with Cyanogen OS? Will they no longer receive OTA updates?


Most computers now have safety things that turn them off if they get too hot (for example, according to the Intel website, my Intel T4400's T Junction is 105 degrees C).  With most internal safeguards most computers just shut off before they get too hot.   Thus, why is overheating considered to be so bad, when they turn off anyway before any real damage can be done?

Will higher temperatures damage a computer over time, even when not reaching the maximum temperature? For example, if the maximum is 105 degrees celcius, will the computer break faster when continually having it on 80 degrees celsius instead of, for example, 60 degrees celcius.


OK, this is possibly a controversial suggestion, and I'm not entirely convinced by it myself, but I figure I'll put it out there to see what people think. If we take the standard description for what comments are for, :  Comments are temporary "Post-It" notes left on a question or answer. You should not expect them to be around forever: Once a clarification has been made, an edit added to the post to include new information, or the issue in the comment is otherwise resolved, it is subject to deletion. In reality, many obsolete or chatty comments remain untouched due to the high volume of comments posted, but this does not mean that they can't or shouldn't be deleted in the future. When should I comment? You should submit a comment if you want to: Request clarification from the author; Leave constructive criticism that guides the author in improving the post; Add relevant but minor or transient information to a post (e.g. a link to a related question, or an alert to the author that the question has been updated).  None of these reasons really necessitate a comment existing forever. Requesting clarification and leaving constructive criticism are useful to get the OP to improve their post. Which they may or may not do. And the ability to add relevant, but minor info such as links to other posts can be handled by the 'related questions' in the sidebar. People spend a lot of time concerned with comments.     I could go on. So is there really a reason they should stick around? I propose this idea for discussion: A comment will only be visible for 48 hours. After that point it will be deleted from view. That should be enough time for the OP to see it and act upon the suggestions in the comment. Any comedy comments would have been seen and everyone would have enjoyed them at a the time, but 48 hours is a long time in the digital world, and questions that old are basically consigned to the files where they're of most benefit to people searching via site search and Google, and these people don't really care about the comments - they're there to find the answer to the question they were searching for. (And if you think that, just because there are comments there that means people will actually read them then you're mistaken. ) I'm sure some people may say that there are sometimes useful links, comments, info posted in comments. So perhaps as a compromise we can keep comments persistent that recieved >5 votes. I don't know. But basically, binning off all the comments after 2 days would clean up the sites and potentially stop people being so precious about them and reinforce the idea that they are 'temporary Post-It notes'.

Most of the time (but not always) when I post a comment it is only relevant for a short time - a day or two.  For example a comment might say "Please post some code." A reply might be "Thanks, I've added code to the question."  From this point on, both comments are nothing more than a distraction from the question itself, and from any more helpful comments which appear under the question.  If my comment received a few votes, it will appear in the short list of comments and possibly drown more valuable content.  If I'm diligent, I might come back and delete my comment, but then we have a hole in the conversation which can be even more of a distraction. Ultimately eventually the responder should come back and delete their response, but this is unlikely to happen if the responder is a passer-by and has no ongoing interest in the question.  The votes on answers to  indicate that the community preference is to delete your own comments when they become irrelevant, but in practice I don't think this happens often, and when it does, it can break comment continuity.  I'd love to see a mechanism whereby I could post a comment, and it would be deleted after a day or two. Users replying to the comment could use the same mechanism.


I'm looking for alternative software to develop raw files (cr2) on Ubuntu?  I know that I can use wine to run DPP, but I wonder if there is another option worth trying?

I have a DSLR (Canon 550D) and since I'm taking my first steps in the world of RAW photography I don't know which would be a good program to use to edit these files. I've tried  and  but wasn't satisfied. I'm sure there must be better software out there...


Take a look at this:    The "Your flagging history" summary is gone! On a site where I have more flags...    This is fine. It seems that whenever the first section has no data to show, nothing shows.

Today I've helped flag a lot of spam for this: .  When I've visited my profile on WebApps to see my flag history of flag, the information about my flagging history was missing.  Note that these spam flags were my only flags on this site.    Normally, I should have more information like when I'm looking at my Stack Overflow account.    Is this a bug?


Riemann's hypothesis implies that the gap $g_n$ between primes is $$g_n=O(\sqrt{p_n}\log{p_n})$$ And Legendre's conjecture is equivalent to $$g_n=O(\sqrt{p_n})$$  Then, would proving the second conjecture imply the Riemann's Hypothesis to be true?

is that there exists a prime number between $n^2$ and $(n+1)^2$. This has been shown to be very likely using computers, but this is merely a heuristic. I have read that if this conjecture is true, the biggest gap between two consecutive primes is $O(\sqrt{p})$; the Riemann Hypothesis, on the other hand, implies that this gap is $O(\sqrt{p}\log{p})$, which is a wider gap for sufficiently large inputs. This leaves me asking the following question, which I am aware may be a bit naive, but I want to be sure:  Would a proof of Legendre's conjecture also be considered a proof of ?  EDIT: I am aware that the way the asymptotic above were expressed was in terms of prime numbers, and that the Riemann Hypothesis is concerned about everything in between as well; would a proof of this sort need to show this upper bound for all inputs, or would the prime numbers be sufficient?  EDIT 2: It seems to me that, if a proof of Legendre's conjecture could result in a proof of the Riemann hypothesis, that this would come from the $\log{x}$ term of the asymptotic, showing that this term is never smaller than what results from the distance between primes. In other words, this would have to be an inductive proof, showing an initial case and, as a result of that initial case and the fact that the gap is $O(\sqrt{p})$ for that case, all future cases must therefore be $O(\sqrt{p} \log{p})$. I hate to add to my question once again, but please tell me if this is completely off.


Currently, I can save the file in the same directory of the project. I'd like to save some data in a text file and save this file in an SD card if any is inserted to my board (BeagleBone Black). Otherwise, if no card is inserted, the file should be saved to the current location.  I know that the following sequence is required to do this task directly in terminal:  # Check if some card is inserted under the usual name fdisk -l | grep mmcblk0p1 # if something returned, then a card is inserted sudo mkdir /media/sdcard/ sudo mount /dev/mmcblk0p1 /media/sdcard/ cd /media/sdcard/ touch data.txt umount /dev/mmcblk0p1   I thought about calling these commands in my C program using system function. But I don't know how to check if the first command has returned something or NULL.  I have two questions:  1- Is using the above commands is the best way to check if an SD card is inserted?  2- How to check the output of a command run by system?

I've got a utility that outputs a list of files required by a game.  How can I run that utility within a C program and grab its output so I can act on it within the same program? UPDATE: Good call on the lack of information.  The utility spits out a series of strings, and this is supposed to be portable across Mac/Windows/Linux.  Please note, I'm looking for a programmatic way to execute the utility and retain its output (which goes to stdout).


Let $GL_n(\mathbb F_q)$ be the General linear group over a finite field $\mathbb F_q$, where $q$ is any prime power. Then how can I show that for $1 \leq m \leq n$ there is an element of order $q^m-1$ in $GL_n(\mathbb F_q).$  I know that the maximal possible order of an element in $GL_n(\mathbb F_q)$ is $q^n-1,$ which follows from the fact that order of an invertible matrix in $GL_n(\mathbb F_q)$ is same as the order of the minimal polynomial, and order of an irreducible polynomial $f(X) \in \mathbb F_q[X]$ with $f(0) \neq 0$ and $\text {deg}(f)=m$ is same as the order of any (hence all) root of $f$ in $\mathbb F_{q^m}^{\times}.$   In this problem since $\mathbb F_{q^m}$ is not necessarily a subfield of $\mathbb F_{q^n}$ for $1 \leq m \leq n,$ I cannot prove it. I need some help. Thanks.

For fixed prime power $q$ show that the general linear group $GL_n(\mathbb F_q)$ of invertible matrices with entries in the finite field $\mathbb F_q$ has an element of order $q^n-1$.   I tried to show this question with showing diagonal matrix but i can't find element directly  competible with order i think i am on wrong way please give me clue ?


I am using EM algorithm to estimate measured data ($y$) as a sum of two weighted gaussian distributions:  $$model = \sum \limits_{i=1}^{L=2} w_i \phi(\theta_i)$$  Where $\theta$ = ($\mu$, $\sigma$). The problem is that the algorithm does not converge properly if the initialization is quite dissimilar to the real values (I generate the observed data as a sum of two gaussians + noise). So my question is about a good approach to estimate the initial values before running EM.  For the initialization, I tried to use a model (empty at the beginning) and then in a loop I compute this:   Initialization:  $$r = y - model$$ (r=residual)  $$\hat\theta_i = argmax_\theta |r^T\phi(\theta_i)|^2$$ (with newton optimization)  $$\hat w_i = \frac{\phi(\hat\theta_i) r}{\phi(\hat\theta_i)^T\phi(\hat\theta_i)}$$  $$model = model + \hat w_i \phi(\hat\theta_i)$$  But I am not getting good initial values, they are quite dissimilar to the real ones, so my EM algorithm doesn't converge.  Edit 1: If I try to find my initial values as I mentioned before, by computing the residual and the correlation with the gaussian functions to find the estimated values of $\mu$ and $\sigma$ and then the weights, in the first iteration I find a correct value of $\mu$ but the value of $\sigma$ is really small, so the factor $\frac{1}{\sigma \sqrt{2\pi}}$ is huge and so the correlation. That leads to wrong values for the weights and the rest of parameters for the next iterations. This is the point where I am stuck.

As a part of my studies, I’m trying to cluster co-occurrences of URLs and tags in data from Delicious. I found a promising method for this in a paper called “” (pages 6-13). It used a Separable Mixture Model (SMM, described in the paper “” pages 2-4) to model the data and an adapted EM-algorithm to fit the known data to the model.  I coded the algorithm with Java and ran it with a little piece of real data from Delicious. Unfortunately, the results did not seem correct. The results showed that each tag had equal (although varying from tag to tag) possibility to belong to each concept.  Now, while this problem could have came from me simply coding the adapted EM-algorithm wrong, I would also like to rule out the possibility of incorrectly initialized variables. This time, since I didn’t know any better way to do it, I simply initialized all the $R_{r\alpha}$ (variables that denote the possibility of co-occurrence $r$ to have raised from concept $\alpha$) to be equal, $1/K$ ($K$ being the number of concepts).  My question is two-fold. Could the flat results come from the flat variable initialization? How should I initialize the variables from the EM-algorithm in this case?


I viewed my MSO user profile this morning and noticed that the helpful flags count has dropped from some 30+ (from memory) to just 4:    I've flagged more than 4 for OT posts in the past few weeks alone. What's happened to them? (Triangular freehand shape intentional)

Today I saw a terrible thing in my profile     I'm a Deputy badge holder but my profile is only showing 10 helpful flags.  What is happened to my flags?  The flagging history also looks so confusing, missing many flags.


Please can any one help me with a script to restart apache2 at boot on ubuntu 10.04. I have tried so many tutorials but never worked and I tried crontab -e but is there any other way? because it only restart after boot. thank you.

I need to run a bash script at boot-time as superuser in Xubuntu. I don't know where to start. I have to do something described in a Arch Linux guide. That guide says exactly:     Add following at the end of the file : /etc/rc.sysinit   # Do my action /etc/rc.d/do_my_action  /bin/dmesg >| /var/log/dmesg.log   But I do not have /etc/rc.sysinit and /etc/rc.d/ in Xubuntu. I'm sure there are equivalent ones, right?


When sshing into my machine, I see the following:  Welcome to Ubuntu 18.04.1 LTS (GNU/Linux 4.15.6-sound-29 x86_64)   * Documentation:  https://help.ubuntu.com  * Management:     https://landscape.canonical.com  * Support:        https://ubuntu.com/advantage   * Security certifications for Ubuntu!    We now have FIPS, STIG, CC and a CIS Benchmark.     - http://bit.ly/Security_Certification   * Want to make a highly secure kiosk, smart display or touchscreen?    Here's a step-by-step tutorial for a rainy weekend, or a startup.     - https://bit.ly/secure-kiosk    * Canonical Livepatch is available for installation.    - Reduce system reboots and improve kernel security. Activate at:      https://ubuntu.com/livepatch  0 packages can be updated. 0 updates are security updates.  Last login: Sat Oct 13 18:31:05 2018 from ::1  How to disable these advertisements, without disabling the update and login parts (the Want to make a highly secure kiosk, smart display or touchscreen? ... part)?

I would like to add some fields to the ssh MOTD.  MOTD today:  Linux toker 2.6.31-22-generic-pae #69-Ubuntu SMP Wed Nov 24 09:04:58 UTC 2010 i686  To access official Ubuntu documentation, please visit: http://help.ubuntu.com/    System information as of Tue Jan 25 19:25:53 CET 2011    System load:  0.23                Processes:           139   Usage of /:   76.8% of 911.20GB   Users logged in:     1   Memory usage: 17%                 IP address for eth0: 192.168.1.102   Swap usage:   0%    Graph this data and manage this system at https://landscape.canonical.com/  38 packages can be updated. 38 updates are security updates.  No mail. Last login: Tue Jan 25 19:22:06 2011 from 192.168.1.106   I know that I could change this to a static message by pointing /etc/motd to something else than /var/run/motd but I do not want to loose the generated data that is presented today.  Is it possible to add the disk usage off two additional hard drives to the message that is generated by default? For example:  Linux toker 2.6.31-22-generic-pae #69-Ubuntu SMP Wed Nov 24 09:04:58 UTC 2010 i686  To access official Ubuntu documentation, please visit: http://help.ubuntu.com/    System information as of Tue Jan 25 19:25:53 CET 2011    System load:  0.23               Processes:           139   Memory usage: 17%                Users logged in:     1   Swap usage:   0%                 IP address for eth0: 192.168.1.102    Usage of /:            76.8% of 911.20GB   Usage of /media/hddb/:    8% of 1.8T   Usage of /media/hddc/:   16% of 1.8T    Graph this data and manage this system at https://landscape.canonical.com/  38 packages can be updated. 38 updates are security updates.  No mail. Last login: Tue Jan 25 19:22:06 2011 from 192.168.1.105


I will be travelling with my minor son (17 yrs) from South Africa to Germany later this year. He is South African and German citizen. The passports have different surnames. Firstly, on which name must i book the ticket? Secondly, which passport does he have to use when during his travels?

I am a 17-year-old and am traveling to Germany later this year from South Africa. My German passport and my South African passport have different surnames. Will there be any problems in my travels and, if so, how do I overcome this issue?


This is so weird - I am trying to password protect a folder in nginx, and it's sorta working... here is my config block:          location /private/ {                 auth_basic "Restricted";                 auth_basic_user_file /usr/share/nginx/htpasswd;                 index index.php;         }   ...and when I visit http://example.com/private, I am prompted for an .htaccess password (good), but BEHIND that prompt I see the browser partially loading the page (some broken HTML and images)-- obviously very bad. It seems like the images subfolder is being allowed through, even before the user enters a user/pass.  How can I prevent the /private dir (and EVERYTHING under it) from being served before the user gives the correct user/pass?

So to help prevent brute force attacks against my phpmyadmin install I've configured nginx to require HTTP Basic Auth (extra username and password) and then the requests need to come from a whitelisted IP Address. However the IP Address whitelist works fine if I run  however without adding the extra .php block I could load  without my IP being whitelisted. This issue doesn't affect the HTTP Basic Auth. Is there a reason this happens? Anyway to get around having to add extra .php blocks? A copy of the config area for phpmyadmin is below.  # Setup and secure phpMyAdmin location /phpmyadmin/ {   allow 1.2.3.4;   deny all;   auth_basic "phpMyAdmin - HTTP Basic Login";       auth_basic_user_file /etc/nginx/pma_pass;     location ~ \.php$ {     include snippets/fastcgi-php.conf;             fastcgi_pass unix:/run/php/php7.0-fpm.sock;     allow 1.2.3.4;     deny all;     } }


What is my spell save DC?    I am a level 1 Rogue (going Assassin archetype) and have no spells.    My stats are as follows:   STR: +1   DEX: +3   CON: +2   INT: +1   WIS: +0   CHA: +2

At third level, a Barbarian can take the Path of the Totem Warrior, gaining (among others), the following feature:  Spirit Seeker Yours is a path that seeks attunement with the natural world, giving you a kinship with beasts. At 3rd level when you adopt this path, you gain the ability to cast the Beast Sense and Speak with Animals spells, but only as rituals.  According to , that would make the Totem Warrior a Spellcaster. What is the spellcasting ability of a Totem Warrior? Is there any situation where that is relevant?


i was reading  after hearing about it on the news, while reading i saw the term "floaters" which made me remember of a recent Family Guy Episode in which there is a joke about them in Peter's vision.  I am wondering, what exactly are they? what is their technical term? and is it possible to remove them permanently (apart from the obvious gouging out your eyes).

I have noticed that if you look directly at tubelight (I have only white ones in my home) and close your eyes little, you see little random shaped colourless things sometimes with slow speed and sometimes with falling down.   They are shaped like circles with something in between and in chains of random length.   My father has also seen them. So, I am sure I am not imagining things. What the hell are they?


I purchased my 110 year old colonial house 6 months ago. It has a field stone foundation that looks completely original (with a few small repairs). The house is located in North Eastern Massachusetts and is exposed to the worst of the elements around here. This has lead to the walls of the foundation starting to crumble, the mortar is loose on most of the wall and unstable. I can peel pieces off with my fingers. When I "knock" on the joints it almost sounds hollow. this is widespread throughout the basement. However the walls seem solid enough.  My question... I want to sure up these walls. I want to get a more water/rodent tight perimeter.   What are the steps I need to take?  How much of the old mortar should I remove? if I removed all of the "loose stuff" it seems like this project would take months! years even! What kind of mortar can I use as a replacement? I read online that its bad to use Portland cement? Best to use Type N Lime mortar?  What tools will I need? Is this a do-it-yourself job? or should I hire someone?   thanks for any info... getting really nervous about this project!

What kind of mortar should I use to point a fieldstone foundation?  The old mortar is crumbling, and sandy mortar is falling out onto the basement floor.  I plan to remove the crumbling mortar (see ), then point the foundation with new mortar.  But what kind of mortar should I use?    I have had a hard time finding definite answers about fieldstone foundations on the Internet, but I'll include some of what I've found here.  First,  has this to say about fieldstone foundations:     Most fieldstone foundations have, or had at some time, a thin mortar coating on the face of the stone. The purpose of this coating was to assist in holding the stones in place. This thin mortar coating will inevitably flake off from any moisture migration, revealing the surface of the stones. As this coating continues to erode, the mortar between the stones will begin to crumble and the soft, sandy mortar begins to slowly fall out onto the basement floor. It looks like a small pile of sand at the base of the foundation. When this occurs, tuck pointing is needed to refill the voids where the old mortar has fallen out. It's very important that you scrape away or chip away the crumbling mortar (in between the stones) in order to establish a small cavity or key way which can hold the new mortar that is being applied. Never apply new mortar over any old crumbling mortar, as this is a temporary fix and it will only last a couple years. All crumbling mortar must be removed in order for the newly applied surface to bond properly. While upgrading your field-stone foundation, only work on a section at a time. Do not remove the old mortar throughout the entire basement all at once. Complete all removal, tuck pointing and parging one section at a time.       To avoid annual tuck pointing, you should finish the foundation with a complete top coating of mortar. Be sure it is lime based. This top coat does not have to look like a stone artisan's creation: It merely has to serve the purpose of keeping the newly installed mortar in place. It's sort of like applying a frosting to a cake.    seems to suggest that I should be using not straight type-S hydrated lime, but type-S mortar, which consists of one part Portland cement, ¼ to ½ part lime, and an amount of sand equal to 2¼ to 3 times the total volume of cement and lime.  Do I need to analyze the existing mortar to make sure that the new mortar has the same lime content, as ?  Should I expect the new mortar to start crumbling and releasing dust soon, or should it stay solid and dust-free for many years?


I need to customize the success/error message after submitting details. It needs to cover areas like contact form, forum create etc.,  Especially below message,    Drupal Version : 7.57  Theme : Bootstrap  Also, Is there is any possibility defining a new style for above messages?

When "themeing" modules, especially core modules, as far as I know it is a good idea to take the module specific tpl.php files, duplicate the ones you need, and modify them once they're in the relevant theme directory.  However, what if I want to modify a .inc file? Is it the same process as with tpl.php files, or is there a better workflow? Basically what I would like to do is change some of the user status messages found in user.admin.inc in the core Drupal 7 User module. I'm not sure if editing this file directly is a good idea. Thoughts?


I have a "block--system-menu-block.html.twig" file, which prints the menu content into the menu. {# Menu. #} {% block content %}   {{ content }} {% endblock %}  However, I would like each menu item (the resulting
 elements) to get a unique ID. For example:
abc

abc
  ... The idea is that I can use that in my css to have different colors or hover colors for my menu items. I have already achieved this with JavaScript on the front end, but I would rather have it done in the backend, in the twig files. Is that possible? If so, any ideas?

I want to generate the html elements and their classes to fit my styling of the main menu.    I'm confused by all the near-possibilities offered in the api documentation and by looking at core themes etc. and still can't quite see what I have to do, or where I have to do it. I would be very grateful for clear pointers to:     which php functions I have to write;  which variables I need to add / update;  in which files the functions will go.   Presumably, in MYTHEME.theme I will need a preprocess function of some sort to add to the attributes and item.attributes variables that links.html.twig uses to print the menu ul and the menu item li's.   [Update] So far I have discovered one way to place classes on the Main Menu's ul but ideally I would like to add a class to each submenu's ul indicating the depth of the sub-menu. And I cannot locate any documentation or examples from which I can understand the generation / modifying of the main menu's individual link items.    This function goes into the file  MYTHEME.theme.  function MYTHEME_preprocess_page(&$variables) {    // Pass the main menu and secondary menu to the template as render arrays.   if (!empty($variables['main_menu'])) {     $variables['main_menu']['#attributes']['id'] = 'main-menu-links';     $variables['main_menu']['#attributes']['class'] = array('links', 'clearfix', 'MYNEW_class');   }  }


Looking for a word that describes someone who has a subtle intention to ridicule the other person by questioning everything they say? They act slightly hostile and hypersensitive and make expressions in response to what is being said as if to try and make the other person's question seem silly or invalid.

I was just thinking about someone I went to school with who had a penchant for putting people down, and I was trying to think of a word that describes this, but couldn’t find it. It would be a synonym of caustic, abrasive, discouraging, and undermining, but these all have slightly different connotations (to wear away", cause discouragement or to make fall). I want an adjective that has the connotation of a hammer hitting you on the head. The word does not necessarily need to describe someone who does this on purpose, out of evil intent. Is there such a word?    The word should give you a mental picture of someone barraging you with negative comments, but it not necessarily affecting you. Think of someone who so often has something negative to “contribute” that many can just either ignore it or roll their eyes at it, and that is the extent of its effect. I keep getting the mental picture of the word buffet as in, how waves buffet the shore. A constant hitting, without the hitting necessarily being devastating in its destruction.


I keep on seeing questions either "put on hold" or "closed" by the same thing, like for instance here a question has been "put on hold" for being off-topic:    And here is a question which has been "closed" for being off-topic:    So what is the difference then between a question being "closed" and "put on hold"?

Questions can be closed or marked as duplicates.  What does it mean for a question to be "closed"? What does it mean for a question to be marked as a "duplicate"? Who can close a question? What are the reasons for closing a question ? Is closure the end of the road for a question? When are closed questions eligible for deletion?   Related        For more information, see "" in the .


Sorry if this isn't allowed, let me know and I'll delete, but I'm in first year algebra focused on proofs (congruences, complex numbers, etc.) And I was wondering if anyone had any tips on writing final exams on this topic. One of the things I did a lot on the midterm was finish a proof feeling satisfied but I would do something wrong at the start and lose all the marks because I based my proof off of something false.  Another thing is, if I get a true or false question, for example $\forall x \in (2^k + 1: k \in \Bbb N), \exists l \in \Bbb Z, x = 3l$, what should I do to make sure that this is true or false? Or maybe if it says "prove or disprove this statement"  This example is really specific, but for any question where it says disprove or prove, or true or false, how should I know whether to prove it (or that it's true), or to disprove it (or say false). Should I plug in odd numbers, even numbers, negative numbers, positive numbers, etc.. in all the variables? Just go with my gut? Try to prove or disprove right away and see if I get an answer? Use contradiction, and if it's false I know the statement is true and vice versa?  Thanks! (Any other tips are welcome :))

When writing formal proofs in abstract and linear algebra, what kind of jargon is useful for conveying solutions effectively to others? In general, how should one go about structuring a formal proof so that it is both clear and succinct? What are some strategies for approaching problems that you will need to write formal proofs for?


I have an android application which has more than 20 layouts. In recent days if I make any changes in layout (generally id changing, creating new component or layout) crashes my app or changes some layouts by itself. I have a menu and when I click menu icon it shows my custom actionbar layout instead of custom menu layout. Most of time app crashes.   I have tired clean and rebuild project but it doesnt work. I made some search but there is nothing about it. Please help me.

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 new to MySQL, and I accidentally dropped a table with approx 3gb worth of data. Good news, I think I have a backup file .dump. Now is there an easy way to import this file to my MySQL?

I was given a MySQL database file that I need to restore as a database on my Windows Server 2008 machine.  I tried using MySQL Administrator, but I got the following error:     The selected file was generated by   mysqldump and cannot be restored by   this application.   How do I get this working?


Using MySQL, I can do something like:  SELECT hobbies FROM peoples_hobbies WHERE person_id = 5;   My Output:  shopping fishing coding   but instead I just want 1 row, 1 col:  Expected Output:  shopping, fishing, coding   The reason is that I'm selecting multiple values from multiple tables, and after all the joins I've got a lot more rows than I'd like.  I've looked for a function on  and it doesn't look like the CONCAT or CONCAT_WS functions accept result sets.  So does anyone here know how to do this?


Lets say, to simplify the problem of online games a bit, my goal would be to run a near identical simulation on multiple computers in sync. Would sending commands be a good idea?  Now if only sending commands is not good, should all the physics entities be sent every half second or so?  I'm wondering this because my game will essentially be a Box2D fighting game. Players can also spawn items, which must be added to the Box2D world.  What I'm wondering is how much and what kind of information should I send over the server?  Should I simply send key presses, and every half second snap back dynamic object positions to where the server thinks they should be?  Any helpful tips / articles regarding this would be a great help!  Thanks

I am currently tackling real-time multiplayer physics updates for a game engine I am writing. My question is how best to use Box2D for networked physics. If I run the simulation on the server, should I send position, velocity etc to every client on every tick? Should I send it every few ticks? Maybe there is another way that I am missing?  How has this problem been solved using Box2D before? Anyone with some ideas would be greatly appreciated!


INSERT into L5_DIRECTORS (director_id, first_name, last_name)  Values             (1010, 'Rob', 'Minkoff'),             (1020, 'Bill', 'Condon'),             (1050, 'Josh', 'Cooley'),             (2010, 'brad', 'bird'),             (3020, 'lake', 'bell');  EDIT: I figured it out, I had to write each row individually and run it, I do not why it would not work all together but thanks for the help anyway.


I couldn't install PacketTracer on my Ubuntu 20.04 using sudo dpkg -i PacketTracer_730_amd64.deb command.

I am trying to install Packet Tracer 7.3 (latest version) on Ubuntu 20.04 but do not succeed to so so because of two dependencies which are not installable ("libdouble-conversion1" and "qt-at-spi").  However I successfully installed the previous version (7.2.2) which was available in an Ubuntu installer format (.run file) but I nothing happens when I run it from my gnome desktop.  I am quite a newbie in Linux so I appologies if answers are obvious...  Thanks in advance ;-)  Denis


Let $q = p^{n}$ and let $E$ be an elliptic curve. Hasse's bound from the Weil's conjecture tell us that  $$ |\sharp E(\mathbb{F}_{q}) - q - 1| \leq 2\sqrt{q} $$ for any $q$. Since this is a uniform bound over $E$, there should exists an elliptic curve $E$ that $\sharp E(\mathbb{F}_{q})$ takes a maximum value among all the elliptic curves (over $\mathbb{Q})$.   My question is: is there any algorithm to find such $E$ for any given $q$? It seems that the distribution for fixed $p$ and varying $E$ is something called 'vertical' Sato-Tate conjecture, and the above bound seems to be sharp.

I always thought that Hasse's bound is sharp (at least for elliptic curves). In other words I always thought that given a prime number $p$, I can find two elliptic curves $E_1,E_2$ over $\mathbb F_p$ such that  $\#E_1 = \lceil 1+p-2\sqrt p \rceil$ and $\#E_2 = \lfloor 1+p+2\sqrt p\rfloor$. But is this even true? If so, is there an easy way to construct these curves? I've seen the proof of how to obtain these bounds but I don't think it gives me any information on the sharpness of the bound.


Recently, there was some news that said that the researchers at NASA have come across some impossible kind of space engine which does not require any fuel. I have read at a few places like ,  and . They all say that this engine seems to violate the laws of physics including conservation of momentum.  The original paper is .  Is the statement that it violates conservation of momentum true?

In 2006, New Scientist magazine published an article titled 1 [] about the  [] which stirred up a fair degree of controversy and  that New Scientist was engaging in pseudo-science.   Since the original article the inventor claims that a "Technology Transfer contract with a major US aerospace company was successfully completed", and that papers have been published by Professor Yang Juan of The North Western Polytechnical University, Xi'an, China. 2   Furthermore, it was  that the Chinese were going to attempt to build the device.  Assuming that the inventor is operating in good faith and that the device actually works, is there another explanation of the claimed resulting propulsion?  Notes:  1. Direct links to the article may not work as it seems to have been archived. 2. The abstracts provided on the  website claim that they are Chinese language journals which makes them very difficult to chase down and verify.


If $E=pc$ for massless particles, then it should be $p=0$ as $p=mv$ and $m=0$. Why do we use the equation $E=pc$ for massless particles?

In classical mechanics, massless particles don't exist because for $m=0$, $p=0$.  The relativistic relation between energy, mass and spatial momentum is: $E^2= (pc)^2 + (mc^2)^2$ . So it is said that setting $m=0$ in the first equation you get $E=pc$.  How could setting $m=0$ in that equation give you $E=pc$ whilst $p$ appears in the equation and we know $p=γmu$? If you set $m=0$ you will have indeterminacy due to "$γm$". It seems to me like we are doing a "trick" in order to get the $E=pc$. Perhaps there is another proof for this relation?