i got a raspberry 4B 8GB. and in the Raspbian OS Blender 2.79 works super fine. But the OS performance its terrible. So i installed Ubuntu 20.10 and came with Blender 2.83 but DOESN'T RUN, so i want to install the 2.79 version but doesn't exist in the Ubuntu Repository. So. How i can install Blender 2.79 without call Blender 2.83 instead? Thanks a lot


TP-Link AC1300 T6E PCI-E Wifi card not working

I am running the latest version of ubuntu (18.04.1) and the TP link T6E PCI-E wifi card is not working. I do not have the ability to run a wired connection to my computer. I have no idea where to even start I am just starting to learn linux.


I've heard a famous result that $26$ is the only integer, such that $26-1=25$ is a square number and $26+1=27$ is a cubic number.In other words, $(x,y)=(5,3)$ is the only solution for $x^2+2=y^3$.  How if we make it like this $x^3+2=y^2$? Are there any integral solutions? If so, finite or infinite many?  I've checked first $100$ naturals and no solutions satisfy the equation. However, I have no ideas how to start the proof.


Problems while updating nested list stored in instance variable

I'm currently trying to store results from a calculation in a four dimensional list. This list is an instance variable of my class. def __init__(self):         self.data = {}         # Create 5 x 8 x 2 x 4 matrix         self.data_list = [[[[0.0] * 4] * 2] * 8] * 5  I'm trying to update this list in a nested for loop    def calculate_kpis(self, counter):         # Loop over all velocity ranges         for distance in range(0, 5):             # Loop over all distances             for velocity in range(0, 8):                 # Loop over all relevances                 for ego_relevance in range (0, 2):                     if ego_relevance == 0:                         # ======================                         # Overall                         # ======================                                                 # Extract KPIs from JSON                         KPIs = [                             self.data['Velocity ranges'][velocity]['Tables'][distance]['Overall']['FN']['Hit']['value'],                             self.data['Velocity ranges'][velocity]['Tables'][distance]['Overall']['TP']['Hit']['value'],                             self.data['Velocity ranges'][velocity]['Tables'][0]['Overall']['FP']['Hit']['value']                             ]                                                 # Calculate KPIs                         KPIs = self.get_KPIs(KPIs)                         # Average the KPI results                         if counter != 0:                             for index in range(len(self.data_list[distance][velocity][ego_relevance])):                                 KPIs[index] = round(((self.data_list[distance][velocity][ego_relevance][index] + KPIs[index]) / 2.0), 2)                         # Store KPIs in matrix                         for index in range(0, 4):                             self.data_list[distance][velocity][ego_relevance][index] = KPIs[index]  Anyways, I'm having trouble to update only one specific element in the list. Trying to update a single element by the following statement leads to an update of every list element: self.data_list[distance][velocity][ego_relevance][index] = KPIs[index]  Would could be the reason for this?


2019 Novel Coronavirus (nCoV) lifetime outside an organism

How long will it remain potent outside an organism?  I'm thinking in the context of if it can survive a couple of weeks or a month in the mail for the recipient to get infected.  Edit:  I tried looking at the WHO's page dedicated to the virus, have not found anything pertaining to my question in the PDFs there (maybe I overlooked something, I guess I'm just lacking the proper keyword to use for the search)  I tried looking at the coronavirus Wikipedia page and have not found anything there.  I did find somewhere that a flu virus would typically not remain potent for more than 14 days outside of an organism, but I'm not sure if this applies to all viruses.


Load Graphics as Empty Boxes for Positioning and Quick Compiling

Is there a package that loads all images (tikz, pgfplots, images, etc.) only as empty boxes? This would greatly speed up compilation of documents when making edits to the content and layout when the positioning of positioning is needed, but the adjusting of the actual graphical content is not.


Is the MakeFeatureLayer temporary location the same as "in_memory"?

From the :     The layer that is created by the tool is temporary and will not   persist after the session ends unless the layer is saved to disk or   the map document is saved.   However, it does not state where this temporary location is.   Is it the same as the  that Esri suggests using while geoprocessing?


I like dog or I like dogs which is correct and why?

Why do we say 'I like dogs'? Why can't we say 'I like dog' if we are referring to a particular dog? Most people use 'I like dogs'. Which is correct and why?


What does it mean when a %CPU exceeds (# of cores) x 100%?

Several responses to a question  suggested I try Opera kiosk mode, so I decided to download it and give it a try. Once the download had completed and the disk image was being verified, Safari hung for over a minute and there were periods where Safari used a very high %CPU:    In Mac OS X 10.5, I was accustomed to seeing Safari freeze, but it never used up more than 200% CPU (2 cores x 100%). Is this a bug in Activity Monitor? Or does this mean that %CPU is now more akin to ?


Where can I find "Enable access log" option in ststistics module?

In drupal 7 statistics configuration page, there is all option are available for module, like as shown in following image.  D7,        While in case of drupal 8 statistics configuration page there is only one option,  D8,        Where can I find that configuration setting? I did check,  page on drupal.org, but it is to be updated and not mentioning about drupal 8. Thanks


Linked List Exception in thread "main" java.lang.NullPointerException at asasasa.main(asasasa.java:10)

class LNode { LNode next; int value; } public class asasasa {     public static void main(String ar[]) {          LNode list = new LNode(), list2=list;          list.value = 9;          list = list.next;          list.value = 6;          list.next = null;         while (list2.next != null) {              System.out.println(list2.value);              list2 = list2.next;         }    }   }  * Exception in thread "main" java.lang.NullPointerException   at asasasa.main(asasasa.java:10)* Kindly help with the concept and give a simpler code for such linked list


PyMongo returns float instead of integer

I have a collection in Mongo in which I store URLs, for that I use the following fields:    protocol (type: string) - e.g.: https host (type: string) - e.g.: google.com port (type: integer) - e.g.: 80   In mongo client I execute   db.myCollection.find()   and it returns  {"protocol" : "https", "host" : "google.com", "port" : 80}   In Python with PyMongo I execute   for service in myCollection.find():   print service['port']   and it returns  80.0   Is my number stored as integer?   Using PyMongo, how can I return it as integer and not float?


Teenagers who can use a device to turn into monsters?

I watched this cartoon around 2010. It was about some teenagers who can use a device to turn into monsters. There were, I think, four teams which fought over some magical stones. The hero team consisted of two boys and a girl. I remember that the girl was the daughter of the main villain and had some markings on her face (like her father).   There was some tournament that took place. The main character's main monster was something like "The Platinum Giant" or something like that. The other teams (or the evil teams) were all under the command of the main villain. They competed with each other so they can earn new monsters (but I am not very sure if they earned monsters).   There where these old guys (I think they were senseis), which the teacher of the main characters was one of. The main villain was also one of them, but he got kicked out and started the evil teams. The main character used his father's monsters. His father disappeared and left him his monsters.  It is not "Monster Rancher" or "Chaotic".


How has Voyager not run out of shuttlecraft?

I’ve been re-watching Star Trek: Voyager, lately. Over the first three seasons, Voyager loses multiple shuttlecraft. How many shuttlecraft does Voyager have?  Does the ship have some sort of large replication technology to instantly build new shuttlecraft as they are lost? A ship as small as an Intrepid class couldn’t have that many shuttlecraft in her shuttlebay(s).


Is there any impact of reaping zombie processes?

I will execute following command for reaping zombie   /usr/bin/preap $(ps -ef | grep defunct | grep -v grep | awk '{ print $2 }' | xargs)   Is there any service impact of this approach ?


I want to know a book on Probability theory (Measure-theoretic) for self-study, like at the level of Terence Tao's analysis and measure theory book (he does not have any prob. th. book I guess).  I found P. Billingsley matching this criteria to some extent, but any book other than this.   Thanks


Switched from Legacy to UEFI and then back, and now Windows does not start?

I changed the boot mode from Legacy to UEFI and now my Windows 7 won't start, even after switching it back to Legacy. I switched to UEFI to see if I can boot from a SD card.   Instead it starts the Windows Boot Repair tool.


Render output corrupted on Google Chrome

Any ideas why this is happening with Google Chrome?


My computer "saves" some status it had in a precise moment time ago. And by that I mean that everytime I turn it on, it opens the terminal windows that were open, even with the path it was, and the applications that were running. I recall installing an application that allowed me to run Thunderbird at startup, but it didn't work, and I believe this problem started since then. Sadly I don't remember the name of this application. Anyone know how to avoid this problem? It slows down the startup.  EDIT: I use xubuntu


Will Ubuntu work on this laptop - Dell E7270?


I'm starting a new campaign and my players want to play a "journey". They want to explore a continent, walking to the objective, like a LOTR-styled thing. They literally want to walk through the forests and the mountains. How do I make such a thing? Is it possibile or is it too hard?


Logistic Regression with dummy variables?

I am working on a problem where response variable is binary and my features are dummy variables. I observed when I include intercept to model all the dummy variables' p-values are equal to 1. When I remove constant p-values seems ok. My question is should not we include intercept when we have dummy variables as our only features? If it is so, what is the reason for that? Another follow up question is about perfect multi-colinearity, I remember from linear regression, if we do not drop one of our dummy variables we cannot invert the matrix due to multi-colinearity thus we cannot get our coefficients. I know logistic regression coef. found through MLE but I wonder if multi-colinearity still causes different issues in this case?


word to describe a complex/multi-dimensional question which can't be pithily answered

I am looking for the word to use in the following situation - suppose one is asked a grand question that could form the basis for a mini research project in a way that almost suggests it has a simple, one-word, one-number sort of answer. The response from the one being asked would be "that's a very [insert word here] question" - unfortunately the only thing which comes to mind is "loaded" but that is not correct, and has its own meaning.


Prove the following Combinatorial identity

For any m $\ge$ 1. Prove that $$\sum_{j=0}^m\frac{1}{j+1}{m \choose j} = \frac{1}{m+1}(2^{m+1} -1 )$$  Attempt: I tried using subsets after rearranging the equation. Then even though the R.H.S gives the no of substes of n+1 excluding empty. I am unable to get a interpretation for L.H.S


Is there such a concept as „encrypted operations“ on cyphertext?

Homomorphic encryption allows computation of (arithmetic or boolean) operations on ciphertext with the result being another ciphertext.  In that case...   client A encrypts p_in  A sends encrypted data c_in to the computer C C performs a set of known (from perspective of C) operations f_p(c_in) = c_out A is able to decrypt c_out to p_out  due to the homomorphic property f_p(c_in) = c_out => f_p(p_in) = p_out   Is there a concept that would allow computation of "encrypted" operations on ciphertext?   client A encrypts p_in to c_in and f_p to f_c A sends encrypted data c_in and encrypted operations f_c to the computer C C performs a set of (semantically) unknown (from perspective of C) operations f_c(c_in) now from here there are two options:   f_c(c_in) = c_out: the result is a ciphertext as well f_c(c_in) = p_out: the result is a plaintext    While 1. is a strict "enhancement" to homomorphic encryption, 2. has different implications and limitations.    the encrypted operations ENC_f(f_p, s) = f_c should not be (too) dependent on p_in or c_in   instead ENC_f(f_p, s) = f_c and ENC_p(p_in, s) = c_in should (somehow) have a shared secret s the whole concept becomes less useful the more conditions for p_in / c_in are in f_c  the plaintext result of f_c(c_in)is known to C so f_c should not reveal too much about its input, e.g.    if f_c would be a SUM or AVG function it could be abused by C to find out more about other c* =/= c_in on the other hand if f_c is something like f_c(c_in) = p_in < 1300 since the only output is either true or false and neither (semantics of the) operation nor (semantics of the) input is known to C there seems to be no issue with C obtaining more information that they should    Is there any concept known with any type of operations (logic gates...) that would allow for such an application (either 1. or 2.)? Or is it maybe proven that such a concept can or cannot exist?


Is it right to downvote answers to questions which show little to no effort?

Is it justified to downvote a complete answer to a question which does not show much effort on the asker's part toward solving the question? I believe this is a question applicable to most problem-solving-based communities on SE, but if it's needed, I'm writing with specific reference to questions on Math Stack Exchange.


Test for file existence only work for exactly 1 file, how to have it work for 2 files?

If I have any a single xyz.PDF file this works:  [ -e *.PDF* ] && echo 'yes'   However if I have two files, e.g.  xyz.PDF abc.PDF   I get   $ [ -e *.PDF* ] && echo 'yes' -bash: [: sometstgg.PDF: binary operator expected   How to get around this and allow for either 1 or many files?


Understanding a particular evaluation of $\prod\limits_{n=2}^{\infty}\left(1-\frac{1}{n^3}\right)$

I'm having a hard time understanding the following evaluation of the infinite product  $$ \prod_{n=2}^{\infty}\left(1-\frac{1}{n^3}\right).$$ In particular, I don't understand how you go from line 2 to line 3. Here $\omega = -\frac{1}{2}+ i \frac{\sqrt{3}}{2}$, which is a primitive third root of unity.  $$\begin{align}\prod_{n=2}^{\infty}\left(1-\frac{1}{n^3}\right)  &=\prod_{n=2}^{\infty}\frac{(n-1)(n^2+n+1)}{n^3} \\  &=\lim_{m\to\infty}\frac{1}{m}\prod_{n=2}^m\frac{(n-\omega)(n-\omega^2)}{n^2} \\  &=\lim_{m\to\infty}\frac{\Gamma(m+1-\omega)\Gamma(m+1-\omega^2)}{m(m!)^2\Gamma(-\omega)\Gamma(-\omega^2)(1-\omega)(1-\omega^2)(-\omega)(-\omega^2)} \\  &=\frac{1}{3\Gamma(-\omega)\Gamma(-\omega^2)} \\ &=\frac{\sin{\pi(-\omega)}}{3\pi} \\  &=\frac{\cosh (\frac{\sqrt{3}\pi}{2})}{3\pi } \end{align}$$ EDIT: I think I'm starting to make sense out of this by writing out the terms. $$ \begin{align} \prod_{n=2}^{m} \frac{(n- \omega)(n-\omega^{2})}{n^{2}} &= \frac{(2-\omega)(3-\omega) \cdots (m- \omega)(2-\omega^{2})(3-\omega^{2})\cdots (m- \omega^{2})}{2^{2} \cdot 3^{2} \cdot \cdots  \cdot m^{2}}  \\ &= \frac{1}{(m!)^{2}} \frac{\Gamma(m+1-\omega)}{(1-\omega)(-\omega)\Gamma(-\omega)} \frac{\Gamma(m+1-\omega^{2})}{(1-\omega^{2})(-\omega^{2})\Gamma(-\omega^{2})} \end{align}$$ Now I have to figure out how to take the limit as $m \to \infty$.


Let's say I have two variables: height and weight. I want to produce 4 groups: high height/high weight, high height/low weight, low height/ high weight and low height/low weight. I also want to see that these four groups are significantly different from one another in terms of hight and weight. Do you suggest me to use cluster analysis (e.g., k-means) or do you know any other simpler method?


Variable Selection using Principal Component Analysis

I am trying to model credit risk for retail loans, with my dependent variable being a default flag. I have 15 independent factors, which I need to cut down, using principal component analysis. While I have conducted PCA, I am not really sure as to how do I identify the final variables based on the principal factors generated. The PCA output results in generation of 7 principal factors, as also component matrix containing the Coefficient of Principal Component Score of Variables. Can I group the variables having high correlation for each of the principal factors and use these for regression (say log regression)? If the preceding statement is correct, how do I identify the most relevant variable within each group that I can further shortlist for regression.    Edit: Thanks for the prompt revert guys, really appreciate it. Let me state some more details I am actually working with a very large number of variables (92 to be precise) and hence using a correlation matrix may be very tedious. I essentially what to find out which variables have similar corelation to default and hence select one of these, from various groups of related variables. And in turn, use the most suitable set of original variables (not factors of variables) for log regression. Is there an alternative approach to achieve the same, if not PCA.  @amoeba: I not trying to use the original variables here, while the similar thread you shared does not really answer what I am asking.


Convolution operator in CNN and how it differs from feed forward NN operation?

I understand that the architecture of Convolutional Neural Networks (CNN) and Feed forward (FNN) are quite different. And that CNNs use pooling and filters of shared weights over a patch of the image. I am not so clear on the core convolution operator (1):   If anyone could link me to an explanation, I have looked at the Colah blog and Nielsen's online book, and I understand what it is doing but don't understand the convolution operator.  Also, it looks quite similar to the the core FNN function is there and difference? (2).  (1) convolution operator is $a^1 = \sigma(b + w*a^0)$ which is equivalent to:  $a^1 = \sigma(b + \sum^4_{l=0}\sum^4_{l=0}w_{l,m}a_{j+l,k+m})$  (2) feed forward operation:  $a^1_i = \sigma(\sum^n_{j=1}w_{ij}x_j +b_i)$  Many thanks  Sources: functions taken from:


disable "Software Updater" automatic check and automatic download

I thought I'd disabled software updater's automatic check/download features in the settings so I can just manually do it when I want to, and this works most of the time - but, every once in awhile it'll go off on its own right after I boot up, check for and download the updates without me telling it to, then ask me to install - why does this happen and can I get it to stop? Just want to do updating all myself before I shutdown and no longer need to use the machine.  REASON: very low-end laptop gets locked-up after I boot up when this happens as all its meager resources are maxed out (temps spike) and I can't do anything until it finishes - and you can't tell it's off doing it except for things begin to get choppy, hang, freeze for a bit, etc. and then you'e just stuck :-\  I know - get a better computer, heh, heh...


:  Why wasn't this link in the chat made clickable?


Using the Answer form of Answers module?

I am building a Drupal 7 site using: page manager, Panels, Views and the  module.  In the  and on the  there is an option to put the Answer form in the same page with the question.   How can I do that on my site? I can find how to define that.. In addition, how can I do put the answer form on a Panel Page?    Please Note: This Question is different because it dealing with the specific version (7.x-4.0-alpha1) of the answer module. in this version the Answer form can be displayed in the question page.  The other question I have asked has no relation to the answer module specifically, although I am trying over few days to achieve the same goal. I already wrote that the answer I got is problematic, and did not solve the problem.  I will be very happy to get any help or suggestions, since I am dealing with this issue for few days without a solution!


How to view the folder size in Google Drive?

In Google Drive, you can use Sort split-button and choose Quota Used to show the size of each file there.   However, folder sizes are not shown.   I guess it's really a basic requirement in order to manage folders in Google Drive. I have a folder full of subfolders and files, and I can't go summing up the size of each file recursively.   I need to decide whether deleting this folder or not. But I need to know it's size beforehand.  Is there any way to see how much volume a folder has taken?


Efficient sprite animation display methods?

I'm making a game sprite, with animations for transitioning to different states, such as idle, sleeping, etc. I'm wondering what the most efficient way to play the animations is. As of now, I have a couple of ideas:  store all frames as separate PNG images, and display only the frames for the current state (e.g. play frames 1-5 for idle, 5-10 for transitioning, 10-15 for sleeping) make the animations into GIFs and play the one corresponding to the current state. merge them all into a spritesheet.  Please let me know which would be the best approach, or if there's a better way to do things. I'm new to handling images and animation with code, so I'm not sure what the advantages and disadvantages are. Thanks! In case the information helps anyone, I'm planning to use Python for this (although I could also do Java or C++, if there are good solutions in those languages), and the sprite image size isn't large, it's pixel art.


Failed to fetch ppa - cannot update anymore

I can't update my machine anymore.   To me it seems I have the problem that my machine doesn't accept the package signatures. However I have no idea how to solve it, any help would be appreciated.  Software Updater complains with:  Failed to download repository information - Check your Internet connection. -> While I have internet.  sudo apt-get update:  ... Ign:15 http://ppa.launchpad.net/chris-lea/node.js/ubuntu xenial/main  amd6 DEP-11 Metadata Ign:16 http://ppa.launchpad.net/chris-lea/node.js/ubuntu xenial/main DEP-11 64x64 Icons Fetched 45.2 kB in 19s (2,289 B/s) Reading package lists... Done W: GPG error: http://packages.microsoft.com/repos/vscode stable  InRelease: The following signatures couldn't be verified because the  public key is not available: NO_PUBKEY EB3E94ADBE1229CF W: The repository 'http://packages.microsoft.com/repos/vscode stable  InRelease' is not signed. N: Data from such a repository can't be authenticated and is therefore  potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user  configuration details. W: GPG error: http://ppa.launchpad.net/font-manager/staging/ubuntu  xenial InRelease: The following signatures couldn't be verified  because the public key is not available: NO_PUBKEY F738B17DF9E284B7 W: The repository 'http://ppa.launchpad.net/font-  manager/staging/ubuntu xenial InRelease' is not signed. N: Data from such a repository can't be authenticated and is therefore  potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user  configuration details. W: An error occurred during the signature verification. The repository  is not updated and the previous index files will be used. GPG error:  http://ppa.launchpad.net/budgie-remix/ppa/ubuntu xenial InRelease: The  following signatures couldn't be verified because the public key is  not available: NO_PUBKEY 3B139A1EF422D205 W: The repository 'http://ppa.launchpad.net/chris-lea/node.js/ubuntu  xenial Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore  potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user  configuration details. W: Failed to fetch http://ppa.launchpad.net/budgie-  remix/ppa/ubuntu/dists/xenial/InRelease  The following signatures  couldn't be verified because the public key is not available:  NO_PUBKEY 3B139A1EF422D205 E: Failed to fetch http://ppa.launchpad.net/chris-  lea/node.js/ubuntu/dists/xenial/main/binary-amd64/Packages  404  Not  Found W: Some index files failed to download. They have been ignored, or old  ones used instead.   As suggested by comment I followed the URL:    - not signed (I downloaded it together with anaconda) -> url doesn't exist  xenial There seems to be a 0.7.3~201712020419~ubuntu16.04.1 version  - there is ./dists/xenial/Release (I'm not sure if this is what you are looking for)  - I couldn't find the xenial/Release file   I'm sorry but I'm still a bit unsure what I'm exactly looking for as my experience with the package manager is quite limited. As it is right now I can't update any package (for example the ones in canonical).


Copying the current directory's path to the clipboard

What's a quick way of copying the path to the directory that's currently open in Finder?   Copying that path is very easy in Linux and Windows file managers - you just need to copy it from the address bar. I don't see a corresponding option in Finder.


My dual boot Ubuntu system has its Ubuntu OS corrupted.  Efforts to fix it via changing source.list and other means proved in vain.  Now I want to re-install Ubuntu on that partition with a USB stick.  Will my files on that partition and other partitions be left intact?  I just wanna fix the OS.  Wanna confirm this as I am using the computer for many things and cant afford to have it screwed up.  Thanks.


there is a whole bunch of files all of them who have the pattern  joob_1_1 joob_1_2 joob_2_1 joob_2_5   so it is joob then underscore numeric underscore numeric - these are also the only files in the folder if that makes it easier. I want to rename them into  job_1_1 job_1_2 job_2_1 ....   there has to be some way to do that automated ? It is just getting rid of that single letter


What forces are at work causing sand to migrate to the centre of a spinning bucket of water?

A bucket is filled with water and a handful of sand. The water is then spun. Why and what forces are in play which cause the sand particles to congregate in the centre of the bucket?


Is a star rating more user-friendly and valuable than a simple up/down vote model?

Which rating mechanism do users find more valuable in a scenario where the user is looking for an article in a Knowledge-Base where there are multiple articles that cover a single topic?   Is a 5-star rating more user-friendly and valuable than a simple up/down vote model?


Let $f:\mathbb{R}^n \to\mathbb{R}^n$ be a self-adjoint linear map.  Is it true that $\ker (f) \perp f(\mathbb{R}^n)$?   I see a similar result for compact operators (Fredholm's alternative theorem), but I can't prove it for $f: \mathbb{R}^n \to \mathbb{R}^n$ using just my knowledge on linear algebra.  Could you give me a hint?  Many thanks!


Cannot install NVIDIA drivers due to unmet dependencies

I'm trying to install CUDA and NVIDIA drivers to use a GeForce 1080 and a Titan XP GPU on my workstation.  However, running:  sudo apt-get install nvidia-driver-440   I got the following error, which I don't know how to solve:   Reading package lists...  Done   Building dependency tree          Reading state information... Done    Some packages could not be installed. This may mean that you have   requested an impossible  situation or if you are using the unstable  distribution that some  required packages have not yet been created or been moved out of  Incoming.  The following information may help to resolve the  situation:   The following packages have unmet dependencies:     nvidia-driver-440 : Depends: libnvidia-gl-440 (=  440.59-0ubuntu0.18.04.1) but  440.64.00-0ubuntu1 is to be installed                       Depends: libnvidia-compute-440 (= 440.59-0ubuntu0.18.04.1) but 440.64.00-0ubuntu1 is to be installed                       Depends: libnvidia-decode-440 (= 440.59-0ubuntu0.18.04.1) but it is not going to be installed                       Depends: libnvidia-encode-440 (= 440.59-0ubuntu0.18.04.1) but it is not going to be installed                       Depends: libnvidia-fbc1-440 (= 440.59-0ubuntu0.18.04.1) but 440.82-0ubuntu0~0.18.04.2 is to be installed                       Recommends: nvidia-settings but it is not going to be installed                       Recommends: nvidia-prime (= 0.8) but it is not going to be installed                       Recommends: libnvidia-compute-440:i386 (= 440.59-0ubuntu0.18.04.1) but it is not installable                       Recommends: libnvidia-decode-440:i386 (= 440.59-0ubuntu0.18.04.1) but it is not installable                       Recommends: libnvidia-encode-440:i386 (= 440.59-0ubuntu0.18.04.1) but it is not installable                       Recommends: libnvidia-ifr1-440:i386 (= 440.59-0ubuntu0.18.04.1) but it is not installable                       Recommends: libnvidia-fbc1-440:i386 (= 440.59-0ubuntu0.18.04.1) but it is not installable                       Recommends: libnvidia-gl-440:i386 (= 440.59-0ubuntu0.18.04.1) but it is not installable   E: Unable to correct problems, you have held broken packages.   Info on my OS (output of lsb_release -a):  No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 18.04.4 LTS Release:    18.04 Codename:   bionic   Any help? :)


Cartesian product of arbitrary number of lists - Java

I am trying to implement a cartesian product of an arbitrary number of lists. I have been thinking about this for hours, and I can't figure it out.  For example, if I have:  list letter = [1, 2, 3] list num = [a, b, c]  then we will print cartesian product of:   letter x letter letter x num num x num  num x letter   However, if i had a fixed number of lists, it would be easy. But I don't know how to do an arbitrary number of lists.


Recuva is a Windows application used to undelete files .  It has a nice GUI and is very dependable.  Is there anything similar for Ubuntu?


Minimum queens to reach $8 \times 8$ squares as a graph problem

A homework problem asks     What is the minimum number of queens to reach all squares on a $8 \times 8$ chess board?   We are expected to solve this by somehow casting the problem as a graph problem (e.g. Minimum Spanning Tree, Vertex Cover, Independent Set, ...)  How would you reduce this problem to a graph problem, and which graph problem is the most straightforward to reduce this to?  (My first try at this problem was to reason that the number of different squares that a queen can reach is at most $\small 8 + (8-1) + (8-1) + (7-1) = 28$. This is from assuming $8 \times 8$ squares and choosing to place the queen at one of the $4$ center squares. I don't know if this approach can lead to a solution.)


Does anyone know how to bold calligraphic \mathscr fonts in a math environment? I can get a fancy calligraphic font if I use \mathscr, but \boldsymbol does not work, nor does \mathbf. There is a hack which uses poor man's bold, but I was wondering if there is an alternate way to do this "cleanly". I've also seen \bm used for \mathcal font, but that's not what I'm looking for unfortunately.  I'm using calligraphic fonts with the following packages:  \usepackage{amsmath} \usepackage{amsfonts} \usepackage{mathrsfs}


Children's SF book about moon folk going to live on another planet

I remember reading a book, probably aimed at about a fourth grade level, in which there were aliens native to the moon. They decided to leave because more and more astronauts from earth were turning up. They headed off to live on another planet. Various semi-comedic adventures ensue. I honestly don't remember any details beyond that, though.


I'm wondering whether there is a difference between these two expressions. I never know which one to use. Google seems to return the same amount of results for both, so I suppose there might be a difference.        What are the alternatives for this project?     What are the alternatives to this project?


How does using a teleconverter affect the aperture of a lens?

I have hear that a teleconverter affects the apperture of a lens.  But I don´t know how to calculate it.  Is there a formula to calculate how much will a 1.5X or 2X teleconverter affect apperture?


The ring of polynomials in $X, Y$ all of whose partial derivatives with respect to $X$ vanish for $Y=0$ is Noetherian?

The ring of polynomials in $X,Y$ all of whose partial derivatives with respect to $X$ vanish for $Y=0$ is Noetherian ?


Shouldn't there be a way to prevent automatic awarding of a bounty? For example, if someone provides an answer that sounds good but is totally wrong, it may happen that it gets a score of +2, but doesn't deserve the bounty. If no one else answers, half the bounty will automatically go to this person. Automatic awarding is good if an inactive user offers a bounty, but I think there should be a button that basically means "I know the bounty should now be awarded, but I have read the answers and none of them deserve the bounty".  The button should obviously not refund the bounty, just let it go to /dev/null instead of awarding it to someone who doesn't deserve it.


Why do polarized sunglasses remove (most) reflections on car windows?  I know that both lenses of polarized sunglasses are polarized in the same direction and I can see that reflections in my own windshield and the windows of other cars appear, disappear, or change depending on how I tilt my head, but why?  Why is the light in those reflections polarized?  edit: And why is most of the light in the various reflections on the interior of my own windshield and various windows/windshields at what seem like a variety of angles all polarized in a sufficiently narrow set of ways as to make polarized sunglasses work?


I know that a rectifier converts AC voltage into pulsating DC voltage.  However, when would you use a half wave rectifier as opposed to a full wave rectifier ?   Can you give an example of some appliances that use half wave and full wave rectification.


Why is the direction of net force on an object and the direction of acceleration of that object is different in this situation?

A $ 2.0 kg $ block is being pulled across a frictionless table by a rope with negligible mass at an angle $ \theta=60° $ (from positive direction of $ x $ axis, we have taken horizontal surface of table as $ x $ axis) The tension in the rope is $ 12N $ and causes the box to slide across the table to the right with an acceleration of $ 3.0 m/s² $ But the direction of net force is along the rope. The direction of acceleration isn't. Why is that? There is a net vertical force and that force is vertical component of tension force. The gravitational force is balanced by the normal force (the magnitude of normal force and gravitational force are always same). Why is the acceleration only along horizontal component of tension force. It should be along the the net tension force (along the rope)


as vs like (both mean looking like here)

Consider:  They were all dressed as clowns. The bomb was disguised as a package.  If I replaced "as" with "like", what would it bring any difference in meaning? Would it be acceptable in conversation? Both would act as subject complement here. I couldn't give any other complicated examples than this, which might make it more tricky to answer, but I guess there must be some.


Can I bypass the Google Verification on my Huawei Mate 8?

I just bought a Huawei Mate 8 and I can't set it up due to the Google account verification in the setup process. I've messaged the seller asking for the account details but he doesn't know. I don't have an OTG cable or USB and I need a way to get past this so I can do a full reset of the phone. Please help! (This is different to the other questions as the factory reset option still leaves me with the same problem with FRP and I can't use ADB because I can't enable USB debugging)


The twisted cubic curve in $\mathbb P^3$

I am trying to solve exercise 2.9 b from section 1.2 of Hartshorne algebraic geometry. It asks to find out the generator of $I(\bar Y)$ where $\bar Y$ is the projective closure of the twisted cubic curve in $\mathbb P^3$ given by $\{(t,t^2,t^3)| t\in k\}\subset \mathbb A^3$.  My claim is that $I(\bar Y)= \langle x_1^2-x_0x_2, x_2^2-x_1x_3,x_1x_2-x_0x_3\rangle$. Let’s call the right hand side ideal as $\alpha$.  I have shown using the first part of the exercise which says $I(\bar Y)=\langle \beta I(Y)\rangle$ where $\beta $ is homogenisation map, that, $\alpha \subset I(\bar Y)$.  For the reverse inclusion, I am trying to show $\alpha $ is a homogeneous radical prime ideal.  I defined the map, $\theta :k[x_0,x_1,x_2,x_3] \rightarrow k[u,v], \theta$ sends, $x_0$ to $u^3$, $x_1$ to $u^2v$, $x_2$ to $uv^2$ and $x_3$ to $v^3$.  My claim is that $\alpha = \ker \theta$. $\alpha \subset \ker\theta$ is clear. I am stuck with the second part.   If I’m done with this part I can prove $Z(\alpha) \cap U_0 \subset \phi_0^{-1} (Y) $ where $U_0 = \mathbb P^3- Z(x_0)$ and $\phi_0$ is the homeomorphism from $U_0$ to $\mathbb A^3$. Then using irreducibility of $Z(\alpha)$ and taking closures both the sides I can say that $Z(\alpha) \subset \bar Y$. Which, by homogeneity and radical condition will tell us $I(\bar Y) \subset \alpha$. Also it would tell us that the 3-IPLs embedding of $\mathbb P^1 $ into $\mathbb P^3$ is the twisted cubic curve in $\mathbb P^3$.  I need help in completing the proof of the claim regarding the kernel of $\theta$.


This is my third day with 2 pregnant dwellers. I have everything for them to be born nothing has been moved around in my vault, I have space so there should be no problem for them to be born! Not sure if they will ever give birth and I wish I could kill them but they are too scared and run all over the place. Anyone have any ideas?


Equivalence between definitions of simple connectedness.

Wikipedia gives two definitions of simple connectedness:   A topological space $X$ is simply connected iff it is path-connected and any loop in $X$ can be contracted to a point. A topological space $X$ is simply connected iff it is path-connected and any two paths with the same start-point and end-point are homotopic.   I do not see how these are equivalent. What is the connection between loops being contractable and and paths being homotopic? I am mostly looking for intuition here, as opposed to a formal proof.  By the way, I am aware of another definition: A topological space $X$ is simply connected iff its fundamental group is trivial. I would like to avoid that characterization here.


Difficulty of breaking RSA for a given key size

Is it true that breaking a 1024-bit RSA key is as difficult as breaking a 128 bit symmetric key (e.g. AES)? I know that breaking a RSA key is equivalent to factoring the modulus $N$. To factor it, you  have to see if any number between $2$ and $N/2$ divides $N$, right? But that would still be much greater than $2^{128}$ trials (which is the worst-case scenario for cracking a 128 bit AES key). Then, how is breaking a 128-bit AES key the same as a 1024-bit RSA key?


Can anybody show me how to do the boxes in the image attached in latex.   Thanks ahead


We know that all series of the following form diverge: \begin{equation}  S_k = \sum_{n=\left\lceil \mathrm{e}^k \right\rceil}^\infty \frac{1}{n (\ln n) (\ln \ln n)\dots(\ln^k n)} \end{equation} where the notation $\ln^k$ is function composition. Additionally, this series is interesting because for large $k$, it diverges very slowly.  Then does the following series converge? \begin{equation}  S = \sum_{n=1}^\infty \frac{1}{f(n)} \end{equation} where $f(n)$ is defined recursively by the monotonic function \begin{equation} f(n) = \begin{cases}  n & \text{if }n \le \mathrm{e} \\  n \cdot f{\left(\ln n\right)} & \text{otherwise} \end{cases} \end{equation}  The first few terms of this series are \begin{equation} 1 + \frac{1}{2} + \frac{1}{3 \ln 3} + \frac{1}{4 \ln 4} + \dots + \frac{1}{16 (\ln 16) (\ln \ln 16)} + \dots \end{equation}  and the maximum power of $\ln$ in the denominator gradually increases.  This series should eventually grow slower than all $S_k$ (it is in some kind of sense a limit) because the terms will eventually drop below those of $S_k$ for any particular $k$. But at the same time it seems to grow faster than all series of the form \begin{equation}  T_k = \sum_{n=\left\lceil \mathrm{e}^k \right\rceil}^\infty \frac{1}{n (\ln n) (\ln \ln n)\dots(\ln^{k-1} n){(\ln^k n)}^2} \end{equation} which are known to converge, albeit also very slowly.


How do I link my old clash of clans village to my new account

My clash of clans account is linked to my dads Game Center acount and I want to link it to my account. How?


Abstract Algebra topic: Equivalence relations

If R1 is reflective and not transitive, R2 is transitive but not symmetric and R3 is symmetric but not reflexive. We need to find an example of a set S and the three relations R1 R2 R3.


How do I check whether a package from multiverse is installed?

I am on an Ubuntu system that has the multiverse repository enabled, and I'd like to see whether I can disable it.  How can I check whether any package from multiverse is installed on the system?


Asus Rampage IV Black edition wireless driver not working

I'm new to Ubuntu I have installed Ubuntu on my computer everything seems to work fine but Wi-Fi. I was wondering if anyone know how can I install Wi-Fi drivers for Asus Rampage IV Black edition?  I ran this command in terminal lspci -vvnn | grep 14e4, it gave me the chipset of my wifi:      Broadcom Corporation BCM4352 802.11ac wireless network Adapter [14e4:43b1] (rev 03).    Any idea how can I get the driver from here? Thanks


In the Dragonball series, Goku's power increases as he fights with his enemies. He becomes Super Saiyan, then Super Saiyan level 1 to Super Saiyan level 100. Is the power of Goku unlimited?  And was Gohan superior to Goku in the context of power?


I am using ubuntu 16.04 in dual boot with windows 10.     This is how my disk profile in Gparted looks like, how should I use those unallocated 300 GB (or some of it) to extend my ubuntu ext4 partition, what procedure should I follow?


Using more than 4 GB ram in Ubuntu 32 bit

I have 6GB ram and my system is Ubuntu 14 & 32 bit. How can I use the ram more than 4GB? please help me.


Why does Windows need to restart every time it updates while Linux doesn't?

Even the smallest update of one package or security patch makes Windows need to restart. Why? If an anti-virus application doesn't need it after patch update, why Windows need it after updating Security Essentials' virus-signature files? On the other hand, Linux mostly doesn't need it except when it upgrades its kernel. Note: I am talking especially about Windows 7. I don't know much about Windows 8, or the Server editions.


I want to upgrade from ubuntu 12.10 to 13.10 but i had question when upgrading does the data get removed or should we make backup of it or can we install just like that


Do the glowing pillars in The Storm Halls do anything?

I've noticed that occasionally if I shoot at (or near) the glowing red pillars they will kind of explode a bit for a second and then reform. Does this affect my attacks in any way? What about nearby enemies? Is this purely cosmetic (like pillars in other dungeons crashing down)?


What are the benefits for claiming authorship on the arXiv?

When you post an article on the arXiv, it gives the poster a link for co-authors to claim authorship of the paper. I have claimed authorship for most of my articles but some in the beginning of my career were posted by senior collaborators and I have not yet claimed authorship. My name is on the paper, but not in the electronic sense in arXiv's servers. There is also a solo-author paper that arXiv that I submitted but arXiv does not have me registered as the author.  Are there any reasons to try to fix this? What are the benefits to having a complete authorship record on arXiv's servers?


Android app crashes on entering text in search field with onTextChanged

I am trying to add search functionality to a custom adapter that calls a list from a web service. However when I try and enter anything into the search text field the app crashes. I am getting a      "java.lang.NullPointerException: Attempt to invoke virtual method   'android.widget.Filter android.widget.ArrayAdapter.getFilter()' on a   null object reference" error.   I understand what this means but I am not sure what to replace the code with.  Thanks  public class CallSoapGetTicketHoldersForEvent extends AsyncTask<GetTicketHolderForEventParams, Void, String> {      private Exception exception;      @Override     protected String doInBackground(GetTicketHolderForEventParams... params) {         return params[0].foo.GetTicketHoldersForEvent(params[0].eventname,params[0].username,params[0].password);     }      protected void onPostExecute(String result) {          // Calling Application class (see application tag in AndroidManifest.xml)         Local.Set(getApplicationContext(), "TicketHolders", result);           //sets list view for ticket holder information         String[] RowData = result.toString().split(";");         List<String> TicketholdersArray = new ArrayList<>();         for(int x=0;x<RowData.length;x++)         {             TicketholdersArray.add(RowData[x].toString());         }          ListView listView1 = (ListView) findViewById(R.id.your_list_view_id);         ArrayAdapter<String> adapter = new ArrayAdapter<String>(GuestlistActivity.this,R.layout.liststyle, TicketholdersArray);         adapter.setDropDownViewResource(R.layout.spinnerstyledrop);         listView1.setAdapter(adapter);          edtSearch = (EditText) findViewById(R.id.edtsearch);          lstSearch = (ListView)findViewById(R.id.LstSearch);          lstSearch.setAdapter(adapter);          edtSearch.addTextChangedListener(new TextWatcher() {             @Override             public void beforeTextChanged(CharSequence charSequence, int start, int count, int after) {}              @Override             public void onTextChanged(CharSequence charSequence, int start, int before, int count) {                 GuestlistActivity.this.adapter.getFilter().filter(charSequence);             }              @Override             public void afterTextChanged(Editable s) {}         });     } }


Tex4ht error with tikz in TL2015: Undefined control sequence \pgfsys@svg@newline

I just installed new TL 2015, on brand new Linux mint 17.2. Installation went OK. When I try to compile any file now with tikz code in it, I get this error:  (/usr/local/texlive/2015/texmf-dist/tex/latex/pgf/compatibility/pgfcomp-version -0-65.sty ! Undefined control sequence. \pgfsys@svg@newline ->\Hnewline   l.190   \pgfusepathqfill}   All of these files compiled ok in TL 2014.  Here is a MWE  \documentclass[12pt]{article}     \ifdefined\HCode \def\pgfsysdriver{pgfsys-tex4ht.def} \fi  \usepackage{tikz}   \begin{document}   \begin{tikzpicture} \draw (0,0) -- (1,0); \end{tikzpicture}     \end{document}   and now doing htlatex foo.tex gives the error. It does not matter if I comment off the \def\pgfsysdriver{pgfsys-tex4ht.def}, still give same error:  \documentclass[12pt]{article} \usepackage{tikz} \begin{document} \begin{tikzpicture} \draw (0,0) -- (1,0); \end{tikzpicture} \end{document}   It compiles ok with lualatex and pdflatex.  Here is the file list:  *File List*  article.cls    2014/09/29 v1.4h Standard LaTeX document class   size12.clo    2014/09/29 v1.4h Standard LaTeX file (size option)     tikz.sty    2013/12/13 v3.0.0 (rcs-revision 1.142)      pgf.sty    2013/12/18 v3.0.0 (rcs-revision 1.14)   pgfrcs.sty    2013/12/20 v3.0.0 (rcs-revision 1.28) everyshi.sty    2001/05/15 v3.00 EveryShipout Package (MS)   pgfrcs.code.tex  pgfcore.sty    2010/04/11 v3.0.0 (rcs-revision 1.7) graphicx.sty    2014/10/28 v1.0g Enhanced LaTeX Graphics (DPC,SPQR)   keyval.sty    2014/10/28 v1.15 key=value parser (DPC) graphics.sty    2014/10/28 v1.0p Standard LaTeX Graphics (DPC,SPQR)     trig.sty    1999/03/16 v1.09 sin cos tan (DPC) graphics.cfg    2010/04/23 v1.9 graphics configuration of TeX Live   pdftex.def    2011/05/27 v0.06d Graphics/color for pdfTeX infwarerr.sty    2010/04/08 v1.3 Providing info/warning/error messages (HO)  ltxcmds.sty    2011/11/09 v1.22 LaTeX kernel commands for general use (HO)   pgfsys.sty    2013/11/30 v3.0.0 (rcs-revision 1.47)   pgfsys.code.tex pgfsyssoftpath.code.tex    2013/09/09  (rcs-revision 1.9) pgfsysprotocol.code.tex    2006/10/16  (rcs-revision 1.4)   xcolor.sty    2007/01/21 v2.11 LaTeX color extensions (UK)    color.cfg    2007/01/18 v1.5 color configuration of teTeX/TeXLive  pgfcore.code.tex pgfcomp-version-0-65.sty    2007/07/03 v3.0.0 (rcs-revision 1.7) pgfcomp-version-1-18.sty    2007/07/23 v3.0.0 (rcs-revision 1.1)   pgffor.sty    2013/12/13 v3.0.0 (rcs-revision 1.25)  pgfkeys.sty      pgfkeys.code.tex  pgfmath.sty      pgfmath.code.tex   pgffor.code.tex     tikz.code.tex supp-pdf.mkii pdftexcmds.sty    2011/11/29 v0.20 Utility functions of pdfTeX for LuaTeX (HO) ifluatex.sty    2010/03/01 v1.3 Provides the ifluatex switch (HO)    ifpdf.sty    2011/01/30 v2.3 Provides the ifpdf switch (HO) luatex-loader.sty    2010/03/09 v0.4 Lua module loader (HO) epstopdf-base.sty    2010/02/09 v2.5 Base part for package epstopdf   grfext.sty    2010/08/19 v1.1 Manage graphics extensions (HO) kvdefinekeys.sty    2011/04/07 v1.3 Define keys (HO) kvoptions.sty    2011/06/30 v3.11 Key value format for package options (HO) kvsetkeys.sty    2012/04/25 v1.16 Key value parser (HO) etexcmds.sty    2011/02/16 v1.5 Avoid name clashes with e-TeX commands (HO) epstopdf-sys.cfg    2010/07/13 v1.3 Configuration of (r)epstopdf for TeX Live  ***********   It looks like something wrong with tex4ht and tikz in TL 2015.  which htlatex /usr/local/texlive/2015/bin/i386-linux/htlatex


I have a 50GB server SSD and 40G ram, running Ubuntu, my tmpfs is taking 2 partitions of 15GB of my SSD?

How do I get some space back? I have no space.  Edit: Clarification, I did run at least a few different Conda environments, could then be the source of this tmpfs files ?  Filesystem      Size  Used Avail Use% Mounted on udev             15G     0   15G   0% /dev tmpfs           3.0G  920K  3.0G   1% /run /dev/sda1        49G   47G  2.0G  96% / tmpfs            15G     0   15G   0% /dev/shm tmpfs           5.0M     0  5.0M   0% /run/lock tmpfs            15G     0   15G   0% /sys/fs/cgroup /dev/loop0       98M   98M     0 100% /snap/google-cloud-sdk/126 /dev/loop1       55M   55M     0 100% /snap/core18/1705 /dev/loop2       94M   94M     0 100% /snap/core/8935 /dev/loop3       99M   99M     0 100% /snap/google-cloud-sdk/127 /dev/sda15      105M  3.6M  101M   4% /boot/efi


Show that if $n$ is composite then there exists a prime $p \leq n^\frac{1}{2}$ such that $p\mid n$.  I would like to use contradiction to prove this claim but I'm not sure about how I should contradict this statement.


I am using ubuntu 17.10 and many types of files as .png .pdf .mp3 and more shows the unspecified Icon in nautilus. How can I fix that?

Even after downloading and installing icon packages this problem still remains as you can see in the picture


From where does the "s/he" practice originate?

Is s/he eating enough through the day?  I see this all the time these days. Why do they do this? This means:  Is s or he eating enough through the day?  which makes no sense. Clearly, they meant to type:  Is (s)he eating enough through the day?  Or:  Is he/she eating enough through the day?  Or:  Is [s]he eating enough through the day?  Why do they not realize that "/" means "or"? They must have read this somewhere prominent as it has spread a lot. Even though I can "interpret" it, it's very annoying to see this and know that other eyeballs are registering it and their brains make "mental notes" for future times when they are themselves in need to express the same thing, and then they use the same practice.


How to lock a file in linux/unix by a java program?

I need to lock a file in unix/linux OS. I have googled and read about java.nio.channels Filelock and Reentrant File Lock . But both works in Windows but not in unix. Is there any other way of implementing a lock on file in unix? Any sample code would be highly appreciated.  Thanks, Vignesh


How does GUI in Unix/Linux actually work?

I need some clear explanations on the following questions.   What is Desktop Environment?  What is Desktop Manager? What is Display Manager? What is X window system, server, X11 and Xorg? What is the relation between the above, which runs/depends on which? How can I check what Desktop Manager and Display Manager I am using in Raspbian?    Thank you in advance!


I changed /etc/sudoers, and now I can't run as sudo

I messed around with the sudoers file without really knowing what I was doing using   Assume I did everything that was in the top answer along with editing it with vim and not visudo. How do I fix this?  I'm running Xubuntu 12.04, and I didn't set a root password.


Why is the square of a negative number positive?

Everyone knows that whenever we square a negative number it becomes positive but everyone just accepts this as a universal truth. I want to know why this happens? I also want to know as to why do two negatives make a positive? And moreover is (-2)^2=4=(2)^2 then how will be justify that this does not make -2=2 ?


We let {$a_n$}$_{n\in N}$ be $a_n$=$\frac{f^{n}(0)}{n!}$. I have to show that if $f$ is an even function so is $a_{2n-1}$$=0$ for all n$\in$N. How can I show it? By induction maybe? Can anyone give a hint? If we try induction:  Induction start: n=1: $$f(x)=f(-x)$$ $$f'(x)=-f'(x)$$ $$x=0 ->2f'(0)=0->f'(0)=0$$  Induction assumption is then: $$f^{2n-1}(0)=0$$  But now I can't move on my own. What to do then?


I have a problem creating the table. It says unexpected parenthesis at line 3  CREATE DATABASE scl_teachers;  USE scl_teachers;  CREATE TABLE clteacher (     'id' INT (10) PRIMARY KEY auto_increment,     'f_name' VARCHAR(255) NOT NULL,     'mid_initials' (255) IS NULL,     'l_name' VARCHAR(255) NOT NULL,     'saturation' VARCHAR(2) );


How does color (or reflection in general) work?

I'm confused, does the absorption and emission determine the color of something? Or does that only happen when something is emitting energy?  When light hits an object, the photons get absorbed, then emitted with a different wavelength right?


Just curious, I am new and getting used to some of the features of SE. I went to my profile and it said I was in the top 2%. So, I clicked on the link and started navigating through the list of users until I got to the bottom. I was listed only once initially. Then I clicked to page #2 and then pressed the show 50 and I noticed I came up twice. I may have missed something but why would I be listed twice? I am number 1 and 2. I can't be the first AND second most gainful user for the week. Is this a bug?


how we can check if all the div are displayed none

I want to show message like NO result found if all div are set display none element.each(function(i, el) {     if (all element set display:none) {         no result found     } }


Apache 2.4: Differences between prefork, event and worker modes

Apache 2.4.x :    prefork event worker     What are the conceptual differences between these three? What are the types of applications or each or situations in which each MPM is useful?


Inconsistent copy and paste behaviour. Is there a fix?

I've encountered what I can best describe as "unpredictable" behaviour of the "clipboard". But in its own way, it actually is "predictable"", as it is not an X bug, as such.  It largely results from different X applications using different X features in different ways...     But it doesn't really help to know that it isn't "actually" a bug. because it feels like a bug!    There is a list (below) of what I've found / tested.    Is there some way (a daemon?), which irons out all these wrinkles? I'd prefer something that doesn't sit in the panel.  The X / Ubuntu clipboard is potentially awesome, because of its 2/3 levels ability, but is a bit annoying because of the inconsistent implementations...     I've been trying to understand why the copy/paste thing didn't always do what I expected... It's amazing what you can learn when you read the info docs :) ... But a question can hit the target faster.    The main issue seems to come about when the source application is shut down, and you try to access "clipboard" data which came from that application.  X GUI applications have two major copy/paste methods (modes).      Mode NAME    Text Copy method         Text Paste  method ----------   ---------------------    ------------------- PRIMARY      currently selected       mouse middle-click CLIPBOARD    Control+C selection      Control+V   I've tested the behaviour of the selection modes for a few different X applications: gvim, gedit, firefox, and gnome-terminal.  NB:   * All pasting was done into gedit  * The gedit source was from another (root) instance)  * I've tried a couple of "managers", parcelite and pastie, but I can't see any point in comparing them, because neither address the problem. That is, normally expected copy / paste keyboard actions are "inconsistent"  + --------------------------------------------- + ------------------------------------------- + ------------ | Modes used in the source Application          | Availability upon CLOSING the Applicaton    | Application + --------------------------------------------- + ------------------------------------------- + ------------ | --- No manager ---  | PRIMARY only, no CLIPBOARD Copy/Cut used:     | PRIMARY Empty!   (previous)CLIPBOARD ok     | (all tested) |                                               | --                                          |       | CLIPBOARD as last action (implicit PRIMARY):  | PRIMARY Empty!             CLIPBOARD Empty! | gvim |                                               | PRIMARY Empty!             CLIPBOARD ok     | gedit, gnome-terminal |                                               | PRIMARY Empty!             CLIPBOARD Empty! | firefox |                                               | --                                          | | PRIMARY as last action, preceded by CLIPBOARD | PRIMARY ok                 CLIPBOARD Empty! | gvim |                                               | PRIMARY Empty!             CLIPBOARD ok     | gedit, gnome-terminal |                                               | PRIMARY Empty!             CLIPBOARD Empty! | firefox | --- Manager: parcelite ---  | PRIMARY only, no CLIPBOARD Copy/Cut used:     | PRIMARY ok       (previous)CLIPBOARD ok     | (all tested) |                                               | --                                          |       | CLIPBOARD as last action (implicit PRIMARY):  | PRIMARY ok                 CLIPBOARD Empty! | gvim, firefox |                                               | PRIMARY ok                 CLIPBOARD ok     | gedit, gnome-terminal |                                               | --                                          |       | PRIMARY as last action, preceded by CLIPBOARD | PRIMARY ok                 CLIPBOARD Empty! | gvim, firefox |                                               | PRIMARY ok                 CLIPBOARD ok     | gedit, gnome-terminal |  + --------------------------------------------- + ------------------------------------------- + ------------


Raster generalization - buffers in rasters, expand pixels?

Is it possible to create buffers for pixels of raster files? Actually I need to expand the pixels classified as 1 (in white in the figure) with a spatial range of 1 or 2 pixels, in order to perform some generalization.  I'm using QGIS, is this possible with gdal or something?


How do I save after editing a file in terminal using Vi in Edubuntu?

In page it says in order to solve a problem in Apache 2.4, we have to create a configuration file inside the conf-available directory. For example servername.conf.  sudo vi /etc/apache2/conf-available/servername.conf   And inside this we just need to add one line  ServerName localhost  I can do that but how do I save it ?


I was asked to build a java system that will have the ability to load new code (expansions) while running.  How do I re-load a jar file while my code is running? or how do I load a new jar?  Obviously, since constant up-time is important, I'd like to add the ability to re-load existing classes while at it (if it does not complicate things too much).  What are the things I should look out for? (think of it as two different questions - one regarding reloading classes at runtime, the other regarding adding new classes).


How to properly write thai/malaysia language characters in xml using php?

I am working on a project where I have to send data to API through xml. Its basically a SOAP based API, its working fine with the English language but when i try to send thai characters it does not work. Thai characters converted to "????...". I am using php for server side scripting. My web page charset is "UTF-8". Can any one help me in fixing this issue.


How to assign keyboard functions for single right handed use?

My keyboard layout is optimized for the left hand in single handed use. For right handed use key functions such as undo, redo, cut, copy and paste are becoming unreachable from home row.  How can I remap these keyboard functions, for example cut:  Ctrl+c -> Ctrl+m  I am using x11 gdm3 Display Manager on Ubuntu 18.04 with standard keyboard layout. I do not want to relocate keys.  In System settings Keyboard Shortcuts can be defined. The desired functions are not listed there. I tried to figure out which keysym is used for cut using dumpkeys -l  xmodmap allows to reposition keys but it will not work for key combinations.


Better to deduplicate inside VHDX on client or outside VHDX on host?

I have a 16TB array that I'm hosting in a virtual environment. It contains video and photos from our marketing department. The data resides on the Hyper-V host itself as a VHDX file on a 8-drive SATA array. Our file server is virtualized and running Server 2012 R2. Would best practices be to deduplicate the data from within the file server client, or would it be better to deduplicate the VHDX file on the host? Both?


Force calling the base method from outside a derived class

I have two classes:  public class MyBase {     public virtual void DoMe()     {      } }  public class MyDerived:MyBase {     public override void DoMe()     {         throw  new NotImplementedException();     } }   And I have the following code to instantiate MyDerived:          MyDerived myDerived=new MyDerived();   The thing is how to call DoMe of the base class? If I use myDerived.DoMe(), then the derived method wil be called, resulting in an exception. I tried to cast myDerived to MyBase, yet it is still the derived version of the method that gets called.   Edit: As mentioned in the below comment, I can't change eitehr MyDerived or MyBase because they are not my code.


Where can I find a database with a list of all magic cards?

I am going to write a program to manage my library of Magic cards and I am looking for a database file or list of all of the cards that have been released.  I know that the Gathering site is useful, but it limits the number of cards I can return in a search.  I would happily accept a spreadsheet file, database file, or even a text file.    The more information contained in the database, the better.  Having associated images would just be fantastic, but at this point I would settle for names and basic stats of the cards.


Trim a string to get only domain name in PHP

I am having a list of array of domains from which I want to get only the name of the domain so the list is something like this :   $domain_name = [             "domain",             "somedomain",             "mydomain",             "yourdomain"         ];   And i will be using $_SERVER['HTTP_REFERER'] to catch a domain name. From which I just want to get the domain base name with any www. or .com/ .in/ .io/ .net / .org e.t.c or any tralling slash in the URL. Just want to know the basic domain name. Is there any way to do that in php?


Start N processes with one systemd service file

I found this systemd service file to start autossh to keep up a ssh tunnel:   [Unit] Description=Keeps a tunnel to 'remote.example.com' open After=network.target  [Service] User=autossh # -p [PORT] # -l [user] # -M 0 --> no monitoring # -N Just open the connection and do nothing (not interactive) # LOCALPORT:IP_ON_EXAMPLE_COM:PORT_ON_EXAMPLE_COM ExecStart=/usr/bin/autossh -M 0 -N -q -o "ServerAliveInterval 60" -o "ServerAliveCountMax 3" -p 22 -l autossh remote.example.com -L 7474:127.0.0.1:7474 -i /home/autossh/.ssh/id_rsa  [Install] WantedBy=multi-user.target   Is there a way to configure systemd to start several tunnels in one service.  I don't want to create N system service files, since I want to avoid copy+paste.   All service files would be identical except "remote.example.com" would be replace with other host names.  1.5 year later ...  I asked this question roughly 1.5 year ago.  My mind has changed. Yes, it's nice, that you can do this with systemd, but I will use configuration-management in the future.  Why should systemd implement a template language and substitute %h? .. I think it makes no sense.  Several months later I think this looping and templating should be solved on a different level. I would use Ansible or TerraForm for this now.


My footer does not stay at the bottom of the page

I am using Wordpress and I can't get my footer to stay at the bottom of the webpage. I have a page.php which means that I use the same interface for all of my pages except the page content which I edit in Wordpress. On some pages it works fine but on the pages where the content is less (less text vertically if that makes sense) it is in the middle of the page and creates a white space at the bottom. This is the CSS I'm using for the footer atm. .footer-nav {     display: block;     width: 100%;     height: 200px;     background-image: url(/pics/bannerbottom.jpg);     background-size: 100% 120%;     padding: 20px;     position: relative;     clear: both;     bottom: 0;     margin-top: 100px;     float: left; }  .foot-container {     bottom: 0; }  and the HTML is just a simple div.


Difference between Hashing a Password and Encrypting it

The current top-voted to  states:     Another one that's not so much a security issue, although it is security-related, is complete and abject failure to grok the difference between hashing a password and encrypting it. Most commonly found in code where the programmer is trying to provide unsafe "Remind me of my password" functionality.   What exactly is this difference? I was always under the impression that hashing was a form of encryption. What is the unsafe functionality the poster is referring to?


After purge mussels 6 time in salt water 20 mins each, why they still exude much grime?

I  buy mussels at Pusateri and Whole Food Market for a year in Toronto. They sell them on ice and dry, not in running water.      , Bart teaches add salt to cold water and  soak for 20 mins. But I repeat 6 times...so 20 mins x 6 times = 120 mins of soaking!!! Mussels exudate less black grime every next time, but even after 6 times, water still has much black grime! See my pic under! Why? This happening for a year!     Part 2,  has GIF that shows you what I mean.


Given:   let rows = [     { Amount: 190615.83 },     { Amount: -175867.95 },     { Amount: -14747.88 }, ] const sum = rows.reduce((runSum, v) => runSum + v.Amount, 0); console.log(sum);    The sum should return 0 but it returns -2.3646862246096134e-11 see:  How can I make this add correctly?


Why can't I send emails from the command line to my gmail account

I'm using the command:  echo "Test if email can be sent from server" | mail -s "Test" myaccount@gmail.com  This is on an Ubuntu Server 12.04 completely up to date.  To catch you up on my troubleshooting:  1) I have installed mailutils with the "Internet Site" option (or whatever that internet option was; I can't remember exactly what it was called off the top of my head).  2) I have added myself to the group 'mail'.  3) I have checked that my ISP does, in fact, block port 25. I followed  using port 587, which is unblocked (I'm not sure that this has an effect on outgoing mail; it looks like a mail server to me)  4) I've also tried echo "Test if email can be sent from server" | sendmail -f myaccount@gmail.com myaccount@gmail.com, but this also appears to do nothing.  5) I am worried that gmail is receiving on port 587, but that it doesn't know what to do with the traffic. Is this an unfounded consideration?  6) My gmail user name contains a '.' before the '@gmail.com'. Is it possible that this is confusing the mail and sendmail commands? (edit: after some more experimenting, this is probably not the problem)


Consider a square of sidelength $n$ and $ (n+1)^{2} $ interior points. Prove that we can choose 3 of these points so that they determine a triangle (eventually degenerated) of area at most 1/2.  I couldn't get started on this. Any ideas?


What's the rules for using figure captions?

For example, I have the following situation:  An/The example of a password is shown in Figure 1.  a picture goes here  Figure 1 - An/The example of a password  What article should I use? Should I say "The example" or "An example"? The question is not about articles, it's more about figure captions and what I should use.  From  article I see that it may be omitted.


Do megapixels matter with modern sensor technology?

Are more megapixels good?  Are more megapixels bad?  Do more megapixels increase detail? Do they make my images sharper? On the other side, is there a point that is too much? Do megapixels cause increased noise and other problems? How does print and viewing size come into it?  Widespread Internet-forum wisdom used to be that 6 megapixels was the sweet spot — below that just wasn't enough, but above that, there wasn't much benefit. File sizes got larger, but detail was lost to noise and other problems. The arguments are that cramming too many pixels into a small sensor makes each pixel too small to provide any real benefit, and that higher-megapixel sensors outresolve cheap lenses anyway. (Substitute something like 12 instead of 6 if we're discussing APS-C DSLRs, or 24 for full-frame.)  By 2011,  was in the range of 12-18 megapixels. In 2016 most were are in the 16-24 megapixel range. Certainly none are at 6 anymore; even smartphones come with 8 megapixel cameras. Does this offer any real improvement over that old "sweet spot"? Has technology improved to the point where the "wisdom" needs to be updated, or are we all suffering for marketing? Or have we gone past the sweet spot in some ways, but it's okay because of previously-un-argued points. (For example: more noise, sure, but more detail as well.)  Within the 16-24 megapixel common-today range, for the same sensor size, is there any actual benefit to the higher end? How do megapixels directly affect image quality with today's technology? What are the benefits and when do they apply? What are the drawbacks, and when do they apply? How should I adjust my technique (and expectations) based on my camera's megapixel count?


Should trample damage get through a creature with protection from the attacker?

I had the below scenario happen while playing MTG Arena. I have a 1/1 soldier token. I have given it protection from Red, by sacrificing an . My opponent has a  equipped with an . My soldier blocks the Rimrock Knight. Damage still gets through. I was under the impression that protection from red would force all damage to be absorbed by the soldier.  That was not the case.  I'm assuming this is a bug in my understanding of the rules, as opposed to a bug in Arena?


Is there any program like Task Manager for Windows which can kill any full screen program (mostly Windows games I play through wine) when it got stuck and it don't want anything to come above it?  I know Htop and system monitor are great in their own way but is there anything can go on top like Windows Task Manager?


How to get better performance from Minecraft on a i7-8750H and RTX 2070

I have been looking around everywhere to find a way so I can improve the performance of Minecraft on my laptop but not sure what to do so far I have been using things like optifine which does help to some extent but I was wondering if I can improve it further with the use of JVM flags in terms of flags, I have found few combinations of them -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn2G  -XX:+UseG1GC -Dsun.rmi.dgc.server.gcInterval=2147483646 -XX:+UnlockExperimentalVMOptions -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M  -XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+UseNUMA -XX:+CMSParallelRemarkEnabled -XX:MaxTenuringThreshold=15 -XX:MaxGCPauseMillis=30 -XX:GCPauseIntervalMillis=150 -XX:+UseAdaptiveGCBoundary -XX:-UseGCOverheadLimit -XX:+UseBiasedLocking -XX:SurvivorRatio=8 -XX:TargetSurvivorRatio=90 -XX:MaxTenuringThreshold=15 -Dfml.ignorePatchDiscrepancies=true -Dfml.ignoreInvalidMinecraftCertificates=true -XX:+UseFastAccessorMethods -XX:+UseCompressedOops -XX:+OptimizeStringConcat -XX:+AggressiveOpts -XX:ReservedCodeCacheSize=2048m -XX:+UseCodeCacheFlushing -XX:SoftRefLRUPolicyMSPerMB=20000 -XX:ParallelGCThreads=10  Not sure which one of these actually would work or if these would work at all. Here are my PC specs Computer:      ASUS Strix GL504GW CPU:           Intel Core i7-8750H (Coffee Lake-H, U0)                2200 MHz (22.00x100.0) @ 3790 MHz (38.00x99.8) Motherboard:   ASUS GL504GW BIOS:          GL504GW.307, 06/18/2020 Chipset:       Intel HM370 (Cannon Lake-H) Memory:        16384 MBytes @ 1330 MHz, 19-19-19-43                - 16384 MB PC21300 DDR4 SDRAM - SK Hynix HMA82GS6CJR8N-VK Graphics:      NVIDIA GeForce RTX 2070, 8192 MB GDDR6 SDRAM (TU106M) OS:            Microsoft Windows 10 Professional (x64) Build 19042.867 (20H2)


Finding the Ideals of a Direct Product of Rings

Let $R_1 = \mathbb{Z}$, and $R_2 = \mathbb{F}_4$. Find all ideals in $R_1\times R_2$. Which of them are principal ideals? Which are prime? Which are maximal?   I know the ideals in $\mathbb{Z}$ and $\mathbb{F}_4$, but I am having trouble finding the ideals in the cartesian product of both of these rings.  If someone could help me out it would be appreciated.


The meaning of real, user, and sys in output of Linux time command

$ time ./Test   real    0m2.906s user    0m2.887s sys     0m0.017s   Here is the program code:  #include <iostream> #include <map>  void func_a() {     std::map<int, int> m;     for (unsigned int i = 0; i < 10000; i++) {         m.insert(std::pair<int, int>(i, i));     } }  void func_b() {     std::map<int, int> m;     for (unsigned int i = 0; i < 1000000; i++) {         m.insert(std::pair<int, int>(i, i));     } }  int main() {     func_a();     func_b();     return 0; }


For every set of $x_i$ there exists a point $x \in \mathbb{R}$ such that: $f(x) = \sqrt[n]{f(x_1) \cdot f(x_2) \cdot f(x_3) \cdot ... \cdot f(x_n)}$

There is a function: $f: \mathbb{R} \to [1 ; + \infty) $ that is continous in $\mathbb{R}$. Prove that for every chosen set of $x_i \in \mathbb{R}$ for $i \in \{1, 2, ..., n \}$ there exists a point $x \in \mathbb{R}$ such that: $$f(x) = \sqrt[n]{f(x_1) \cdot f(x_2) \cdot f(x_3) \cdot ... \cdot f(x_n)}$$  That exercise seams quite basic: if function is continuous in $\mathbb{R}$, then, for every set of values, there exists a value equal to geometric mean of values in the set that is reached by that function. I know that geometric mean is a continous function + that a function $f(x)$ is continous. How do I prove then that a combination of those functions is continous? As I carry on my research, any help would be much appreciated - answers providing materials on similar problems would be great.


Can't indent heredoc to match code block's indentation

If there's a "First World Problems" for scripting, this would be it.   I have the following code in a script I'm updating:  if [ $diffLines -eq 1 ]; then         dateLastChanged=$(stat --format '%y' /.bbdata | awk '{print $1" "$2}' | sed 's/\.[0-9]*//g')          mailx -r "Systems and Operations <sysadmin@[redacted].edu>" -s "Warning Stale BB Data" jadavis6@[redacted].edu <<EOI         Last Change: $dateLastChanged          This is an automated warning of stale data for the UNC-G Blackboard Snapshot process. EOI  else         echo "$diffLines have changed" fi   The script sends email without issues, but the mailx command is nested within an if statement so I appear to be left with two choices:    Put EOI on a new line and break indentation patterns or Keep with indentation but use something like an echo statement to get mailx to suck up my email.   I'm open to alternatives to heredoc, but if there's a way to get around this it's my preferred syntax.


I am studying elementary Algebraic Topology recently. I have seen that a topological space is identified with a group. We are telling the group as Fundamental Group. So every topological space $X$ and for any $x \epsilon X$ there is a fundamental group $\pi_1 (X,x)$. I have a question about the converse. If we consider any arbitrary group $G$, then does there exist a topological space $X$ and an element $x\epsilon X$ such that $\pi_1 (X,x)=G$?


You "show" someone a picture. You "---" someone a song?

In , we have a verb meaning "to show" corresponding to "to see/to look", and we have a different verb corresponding to "to hear/to listen":  inti tara stampa (you look at a picture.) ---- jiena nurilek stampa (I show you a picture) inti tisma' diska (you listen to a song.) ----- jiena nsemmagħlek diska (I 'show' you a song)  In English, do you "show someone a song" (sounds weird to me) or is there a verb that corresponds more directly to the Maltese insemmgħek?


What can trigger the "Getting Windows ready" screen at shutdown?

I have a Windows 10 Enterprise image that I have made sure to disable Windows Update, however I still get complaints from users that they sometimes see that "Getting Windows ready" screen. So aside from Windows Update and turning Windows features on/off, is there anything else that can bring that screen up? EDIT: I'm sure that Windows Update service is in disabled state at any time, so I'm not looking for ways to disable Windows Update again.


Reading about dual nature of light, and atomic transitions, it seems to me, maybe wrongly, that the dual nature depends on the way we look at the phenomena.   Suppose a water wave travels and reach another water source. Why can't we talk about a condition like:  $$\Delta E=h\nu$$  where $\nu$ is the frequency of water molecules impacts? Another point of view should be the interference of waves.  Isn't talking about light dualism quite the same? When a photon interacts with an electron, is must have an exact frequency, but also it might be understood as a wave interference (if I'm not mistaken).


Importing functions from text block in same file

I am trying to use a text block from within the same Blender file, following the (rather old) advice here:   So I have two text blocks. One called Text and one called printy.py which contains the simplest of functions:  def printthing():      print('thing')  In 'Text', all it says is:  import bpy  import printy  printy.printthing()  I've saved and reopened the file. But I get: ModuleNotFoundError: No module named 'printy'  This seems laughably simple and I've seen the approach in a several places, e.g.  but I can't make it work.  What am I missing?


How to remove border from this coffee cup image when Magic Wand in Photoshop can't?

In Photoshop I've taken Magic Wand as far as I can, I think. Now I'm left with this grayish edge around the coffee saucer. How do I remove it? I've tried altering tolerance in Magic Wand but don't seem able to get it. Any suggestions please?


Let $x,y -$ positive integers, such that $xy|(x^2+y^2+1)$. Prove that   $$\frac{x^2+y^2+1}{xy}=3.$$   My work so far:  1) If $x=y=1$ then $\frac{1^2+1^2+1}{1}=3$  2) Let $x=1$ (or $y=1$) $\frac{1^2+y^2+1}{y}=k \Rightarrow y^2-ky+2=0$  $D=k^2-8=m^2 \Rightarrow (k-m)(k+m)=8 \Rightarrow k=\pm3, m=\pm1 $, but $k\in \mathbb N \Rightarrow k=3$  3) $x,y>1$   $xy|(x^2+y^2+1) \Rightarrow x^2+y^2+1=kxy, k \in \mathbb N$  $D=k^2y^2-4y^2-4$  Here I need help...


What does "...you would rather we have the meeting..." mean?

I recently received an email which had a sentence:     "Let us know if you would rather we have the meeting next week with   just Alisa and Bob."   This grammar ("you would rather we have") looks weird to me. I would just say "Let us know if you would rather like us to have a meeting...". Yet the person who wrote is a native speaker and insisted that people actually use it all the time. Can anyone explain how to use it and give more examples?


A wild empty window appeared randomly. Can you help me deal with it?

Today I had this weird empty window pop up and I don't know what it is, where it comes from, what it does nor how to get rid of it. It's just an empty window with only the title bar showing, but an empty title, in the old Windows style.  It looks like this:   Any ideas how I can find out more about this window? Right-clicking on it does nothing. I can move it, it's always on top of all other windows.  I'm using Windows 7 64 Bit.


Bibtex style for "Statistics and Computing"

I would like to create a bibtex style which answers the requirements of Statistics and Computing journal. How could I do that? Here is an example of how the bibliography should look like:  Journal article: Hamburger, C.: Quasimonotonicity, regularity and duality for nonlinear systems of partial differential equations. Ann. Mat. Pura Appl. 169, 321–354 (1995) Book: Geddes, K.O., Czapor, S.R., Labahn, G.: Algorithms for Computer Algebra. Kluwer, Boston (1992) Book chapter: Broy, M.: Software engineering — from auxiliary to key technologies. In: Broy, M., Denert, E. (eds.) Software Pioneers, pp. 10–13. Springer, Heidelberg (2002)  In the text, the references should be as follows:  Negotiation research spans many disciplines (Hamburger 1995).  Thank you for your help!


How can i limit the number of rows a user can update?

One of our Business Research Analysts has a habit of accidentally updating without a where clause.  Preferably the solution is better training and following a procedure like writing a SELECT before UPDATE. Or just security policies...   However, those things aren't going to happen soon. So I would also like to know if there is a way to limit a user to only being able to update X number of rows. i.e if they run an update that will do 10 rows, let it go. If it will be 1 millions rows (happened the other day) prompt them to double check or just stop that query.


What part of speech is “this” in the following sentence

My friends and I are having a stupid argument about this sentence:    Someday this pain will be useful to you.   I claim “this” in this sentence is an adjective modifying pain, but they claim it is a demonstrative pronoun in this instance. Can someone please confirm what part of speech it is? This does not seem hard to me but they seem so confident against it.


Ubuntu install from USB stuck on black screen

I have been trying to install Ubuntu 14.04 alongside windows 8.1 from a bootable USB. I am new to using a Linux OS. I turned off fast boot option, and I left secure boot on (I also tried off, but then it's stuck on a blank screen rather than this). I have a Nvidia 880M if that is affecting anything.  I get stuck on this screen whether I choose "try Ubuntu without installing" or "install Ubuntu". This text is shown when I am stuck on the black screen.


How can I remove bloatware Acer includes in Windows 7?

I bought an Acer laptop with Windows 7  At first I just installed Linux on it, but I need to run some Windows software and test websites in IE.  I could remove all the crap by hand, but is there a good utility that could do this for me?


Searching for title of movie about rapid aging

People are born and grow up and die of old age in a matter of 5 days. The elders (5 days old) train children and send the most promising one on a trek across the dessert to a monolith that is the cause of the rapid aging to hopefully disable it.   I saw it on a reel to reel in the mid 90's. It looks like it was made in the late 70's or 80's. The cast was small. A few men played the elders seated in a row of chairs and the young boy who had to set out to save them who matures into a man and finally an elderly man.  I've been trying to figure out the title for years.


World view does not display face/vert count

I started working on something in a new scene and for some reason the total face/tri/vertex count for everything in the layer i am on is not showing. This never happened before, is there a way to fix it?


Expand draft feature to allow multiple drafts

The draft feature was discussed a lot  and in other posts, but I didn't see much talk about the OP's mention of being able to have multiple.     Optionally, allow multiple draft questions and a page to edit/delete them.    I think the draft feature where it autosaves and stores it server-side is great, but in most things where they have a draft feature (like email clients), they allow you to have multiple drafts (also stored server-side).  The expiration can even work the same as it does for the single draft system right now.  You wouldn't even need full page to store them, I think the user profile page could have a tab for it like it currently has for answers, questions, and everything else.    It could look very similar to how questions look, with it's title and tags listed there.


Tag filter on close vote reviews includes incorrect articles

I have a filter set on my close vote review list of [vb6] [inno-setup] which correctly filters the list of possible posts. Most of the time.  Occasionally however, I will get a post that seems to be incorrectly tagged with one of my filter tags.    When I open , it does not have the tag highlighted, and according to the , never has.  This would seem to be a bug in StackOverflow itself.


What is the difference between $\Lambda$ and $\Sigma$ baryons?

The Lambda (uds) - 1115 MeV The Sigma (uds) - 1192 MeV   Other than the 77 MeV,  why are these 2 different particles?  Is it the spin of 1 quark?  If so, is it possible to determine which one?  If not spin, what could it be?


Octave command window showing unreadable text

When I start Octave, on the command window I see this:    However, after I run some commands, I can see they are in history and they do execute. I can see the text if I copy-paste it somewhere.   How can I make the command window text visible?


Kernel problem; latest version won't load; older version does. What to do?

I have installed Ubuntu on a desktop my parents use. All was fine. However I think they accepted a request to update the system and now when they switch it on (the machine only has Ubuntu) they see a long list of text ending with 'kernel offset: disabled'. The list begins with 'BUG: Unable to handle kernel NULL deference at [a load of numbers].' An image of what's I'm seeing is attached to this message.  I've been able to get back into ubuntu by choosing a previous version. The updated version is 4.4.0-64-generic. The version I can get into is 4.4.0-62-generic.   I don't want my parents to have to hold the shift key every time they switch on and choose this older version [the idea of them using Ubuntu is that it's simpler than Windows, which it is, so long as these things don't happen!].  So, what should I do now? I think I have a few options but I'd really appreciate guidance.   Re-install from USB and start again and choose not to do updates. Find a way to make UBuntu boot into the 62-generic version Undo the update of the kernel [I think this is the cause of the issue, based on my newbie reading of other questions]   Any help much appreciated.    EDIT: In a terminal I typed:   sudo apt-get purge linux-image-4.4.0-64-generic linux-headers-4.4.0-64-generic linux-headers-4.4.0-64  Then I rebooted and all's well. Phew. God bless you askubuntu! Sorry for polluting the site. But maybe it's ok to keep this posted for other newbies like me?


I have 4 servers. prod1.example.com, prod2.example.com, dev1.example.com, and dev2.example.com. They all send their mails to smtp.example.com. This server does the relay. Now I want that dev1 and dev2 send all their e-mails to devbox@example.com except for the e-mails that are sent to admin@example.com. The e-mails from prod1 and prod2 are relayed without any restriction.  I read that in the access file you can define that a server must be handled by a filter instead of a simple RELAY (with FILTER foo:bar). I cannot find how and where I need to define this foo (transport) and bar (destination). Al these different parameters confuse me. Also in what order are the different files handled?  Can anybody help me out?


proof: primitive pythagorean triple, a or b has to be divisible by 3

I'm reading "A friendly introduction to number theory" and I'm stuck in this exercise, I'm mentioning this because what I need is a basic answer, all I know about primitive pythagorean triplets is they satisfy $a^2 + b^2 = c^2$ and a, b and c has no common factors.  Now.. my approach (probably kind of silly) was to "classify" the odd numbers (not divisible by 3) as $6k+1$, $6k+2$ and $6k+5$, and the even numbers with $6k+2$ and $6k+4$, then, trying different combinations of that, I could probe all the cases when I assume c is not 3 divisible, but I still have to probe that c cannot be 3 divisible and I don't know how to do it.  Anyway, probably there is a better simpler solution.  (Sorry, if this is a stupid question, I'm trying to teach myself number theory without much math background)


Is "two-thirds" or "two thirds" correct?

I just recently answered a question related to how much water was filled in a glass. I answered "two thirds" but the answer was wrong because in the key answer book it was "two-thirds". Please tell me if my answer is wrong and why?


I am using MVC3 ASP, and have configured my web.config file to login into the MYSQL DB as root. I have created many stored procedures which i can connect fine with. i now want to change this login user to a public user, called tempuser and NOT root anymore.   However, when i change the login user from "root" to "tempuser", i get the error:  Unable to cast object of type 'System.DBNull' to type 'System.String'   i get the above error at the execution of ExecuteNonQuery().   I have granted access to the functions by:  GRANT EXECUTE ON FUNCTION check_user_exists to tempuser@'%';   I have also granted 'select' and 'update' on this table that im accessing which the function uses. I can login to mysql command line as tempuser and call the function manually with no problems. But when i run ExecuteNonQuery() i get the above error. I am currently using Visual Web Developer 2010, Razor Engine, MVC3.   ANy help, please.   I have been trying for weeks now with no luck.   Here is the code that is being executed. The ExecuteScalar() function is where the error is. The error is the subject of this question: However, if i login as "root" user, i dont get the error.    [HttpPost]     public ActionResult Register(RegisterModel model)     {         if (ModelState.IsValid)         {             // Attempt to register the user              DBController dbcontroller = new DBController();              if (dbcontroller.DBConnection())             {                 MySqlCommand command = new MySqlCommand("check_user_exists_signup", dbcontroller.conn);                 command.CommandType = System.Data.CommandType.StoredProcedure;                  // Add parameters for the check_user_exists_signup STORED FUNCTION                 command.Parameters.Add(new MySqlParameter("@userName", model.UserName));                 command.Parameters["@userName"].Direction = System.Data.ParameterDirection.Input;                  // RETURN parameter for the insert_users STORED FUNCTION                 MySqlParameter cnt_user = command.Parameters.Add("@cnt_user", MySqlDbType.Int32);                 command.Parameters["@cnt_user"].Direction = System.Data.ParameterDirection.ReturnValue;                  try                 {                     command.ExecuteScalar();                     object ret = command.Parameters["@cnt_user"].Value;                                  dbcontroller.conn.Close();   The stored proc is :  CREATE DEFINER=`root`@`localhost` FUNCTION `check_user_exists_signup`(        userName varchar(20)) RETURNS int(11)     DETERMINISTIC BEGIN DECLARE cnt_user int;    select count(*) into cnt_user     from users     where user_name = userName;  RETURN cnt_user;  END


Is there a non-gendered word for fishermen, that doesn't feel as self-conscious as fisherpersons or as folksy as fisherfolk?


Run script in Terminal via context menu (Open with Terminal)?

this question is simple about "Open/Run in Terminal"....  Looks Ubunutu doesn't support bash/shell-scripts the way we know from KDE and any other OS:  I tried the obvious:    Right click in file manager   Open with other Application... Show all applications   but there is no Terminal application listed, only "Find Online Applications". You can't even browse for a new application as you would do in any other OS.   Any ideas? I found only hacks like creating a launcher item but that's far from a solution or ideal.   To make it really clear:   I want to run any bash script accessible with the file manager via right-click, "Open with" -> "Terminal" so i can see the output. Its really like double click on a batch file under Windows and it just runs the bloody script, not closing the terminal except I wrote so in the script. So finally this is NOT about double click to run, its about the running the script through context menu as said in the title already!  thanks!  Ubuntu-x64-14.04/Unity/No Mods or tweaks.


How to use principal components analysis to select variables for regression?

I am currently using principal components analysis to select variables to use in modelling.   At the moment, I make measurements A, B and C in my experiments -- What I really want to know is: Can I make fewer measurements and stop recording C and or B to save time and effort?    I find that all 3 variables load heavily onto my first principal component which accounts for 60% of the variance in my data. The component scores tell me that if I add these variables together in a certain ratio (aA+bB+cC). I can get a score on PC1 for each case in my dataset and could use this score as a variable in modelling, but that doesn't allow me to stop measuring B and C.    If I square the loadings of A and B and C on PC1, I find that variable A accounts for 65% of the variance in PC1 and variable B accounts for 50% of the the variance in PC1 and variable C also 50%, i.e. some of the variance in PC1 accounted for by each variable A, B and C is shared with another variable, but A comes out on top accounting for slightly more.     Is it wrong to think that I could just choose variable A or possibly (aA+bB, if necessary) to use in modelling because this variable describes a large proportion of the variance in PC1 and this in turn describes a large proportion of the variance in the data?   Which approach have you gone for in the past?   Single variable which loads heaviest on PC1 even if there are other heavy loaders?     Component score on PC1 using all variables even if they are all heavy loaders?


I'm new to statistics and reading stats books I found different definitions for Variance.  Definition1: $ s^2 = \frac{1}{n-1} \sum_{i=1}^n (x_i - \bar{x})^2 $  Definition2: $ s^2 = \frac{1}{n} \sum_{i=1}^n (x_i - \bar{x})^2 $  I would like to know why is used different definition for same thing?


Problem 7.33-b) (Daniel.V.Schroeder-An introduction to thermal physics):     When attractive forces of the ions in a crystal are taken into   account, then the allowed energies are grouped into bands, separated   by gaps where there are no allowed energies. In a conductor the Fermi   energy lies within one of the bands; in this section we have treated   the electrons in this band as "free" particles confined to a fixed   volume. In an insulator the Fermi energy lies within a gap, so that at   $T=0$ the band below the gap is completely occupied and the band above   the gap is unoccupied. A semiconductor is an insulator in which the   gap is narrow enough for a few electrons to jump across it at room   temperature. Figure below shows the density of states in the vicinity   of the Fermi energy for an idealized semiconductor, and defines some   terminology and notation to be used in this problem.      b) Normally the width of the gap is much greater than $kT$. Also, let $g(\epsilon)=g_0\sqrt{\epsilon-\epsilon_c},$ where $g_0$ is a constant independent of $\epsilon.$ Working in   this limit, derive an expression for the number of conduction   electrons per unit volume, in terms of temperature and the width of   the gap.     I found a solution online which calculates the number of conduction electrons using  $$N_c=\int_\limits{\epsilon_c}^{\infty}g(\epsilon)\bar{n}_{FD}(\epsilon) \ d\epsilon=g_0\int_\limits{\epsilon_c}^{\infty}\frac{\sqrt{\epsilon-\epsilon_c}}{\exp((\epsilon-\epsilon_F)/kT)+1} \ d\epsilon. \tag1$$  What I don't understand here is that in the same book they state that for $T=0$ we have $\mu=\epsilon_F$ and the formula for the number of electrons is given simply by  $$N=\int_\limits{0}^{\infty}g(\epsilon) \ d\epsilon.\tag2$$  So why doesn't $(2)$ apply to the problem at hand?  The correct answer seems to be  $$\frac{N_c}{V}=\left(\frac{2\pi m k T}{h^2}\right)^{3/2}2e^{-2(\epsilon-\epsilon_F)/kT}.$$  Using the theory about the limit of the Fermi-Dirac distribution in  thread then I should get   $$N_c=\lim_{T\rightarrow 0}g_0\int_\limits{\epsilon_c}^{\infty}\sqrt{\epsilon-\epsilon_c}\cdot\frac{1}{\exp((\epsilon-\epsilon_F)/kT)+1} \ d\epsilon = g_0\int_{\epsilon_c}^{\infty}\sqrt{\epsilon-\epsilon_c} \ d\epsilon = \infty.$$  Thus the theory in that thread does not help here at all?