JavaFx assign data from serial port
What is a NullPointerException, and how do I fix it?
Local DNS server Frea is trying to kill me I've been trying to play the Dragonborn DLC for Skyrim on the PS3. In order to advance the story, I need to talk to Frea and her dad. But every time I go near the village they try and murder me for slaughtering the village back when I was like level 15 (I'm level 43 now).  I've tried yielding but they won't accept it and I don't know how to make them stop, all I want to do is finish the story. Does anybody know how to fix this issue? Can anyone explain IEnumerable and IEnumerator to me? Can anyone explain IEnumerable and IEnumerator to me? For example, when to use it over foreach? what's the difference between IEnumerable and IEnumerator? Why do we need to use it? How do I check which shell I am using? I read that terminal is nothing but shell, and Unix provides different flavors of shells:   Bourne shell (sh) C shell (csh) TC shell (tcsh) Korn shell (ksh) Bourne Again shell (bash)   Questions:   When I open a terminal window, which shell is opened by default? How do I check how many shells are installed? How do I change the shell used from my account? Backquote in lsblk output What does ` mean in this output from lsblk? What happens when a photon hits a mirror? When a photon of light hits a mirror does the exact same photon of light bounce back or is it absorbed then one with the same properties emitted? If the same one is bounced back does it's velocity take all values on $[-c,c]$ or does it just jump from $c$ to $-c$ when it hits the mirror?  Or, is the phenomenon of a mirror better explained using a wave analogy? If so, what is this explanation? Proof of properties of injective and surjective functions. I'd like to see if these proofs are correct/have them critiqued.     Let $g: A \to B$ and $f: B \to C$ be functions.  Then:   (a) If $g$ and $f$ are one-to-one, then $f \circ g$ is one-to-one.   (b) If $g$ and $f$ are onto, then $f \circ g$ is onto.   (c) If $f \circ g$ is one-to-one, then $f$ is one-to-one?   (d) If $f \circ g$ is one-to-one, then $g$ is one-to-one?   (e) If $f \circ g$ is onto, then $f$ is onto?   (f) If $f \circ g$ is onto, then $g$ is onto?     (a)  Let $a,b \in A$.  If $(f \circ g)(a)=(f \circ g)(b)$, then $f(g(a))=f(g(b))$.  Since $f$ is one-to-one, we know that $g(a)=g(b)$.  And, since $g$ is one-to-one is must be that $a=b$.  Hence $f \circ g$ is one-to-one.    (b) Since $f$ is surjective we know that for all $c \in C$ there is a $b\in B$ such that $f(b)=c$.  Since $g$ is surjective, there is a $a \in A$ such that $g(a)=b$.  Hence, for all $c \in C$ there is an $a \in A$ such that $(f \circ g)(a)=f(g(a))=f(b)=c$.    (c)  This is false.  Let $A=\{1\}$, $B=\{1,2\}$, and $C=\{1\}$. Define $g(1)=1$ and $f(1)=f(2)=1$. Then $f \circ g$ is injective, but $f$ is not injective.    (d)  This is true.  Let $a,b \in A$ where $a \neq b$.  If $(f\circ g)(a)\neq(f\circ g)(b)$, then $f(g(a))\neq f(g(b))$.  Hence $g(a) \neq g(b)$.  (e)  Since $f \circ g$ is surjective, then for every $ c \in C$ there is an $a \in A$ such that $f(g(a))=c$.   Let $b = g(a)$.  Then $b \in B$ and $f(b)=g(f(a))=c$.  Thus $f(b)=c$.  Hence $f$ is surjective.  (f)  Using the same set up as part (c), we have that $g$ is not surjective since there is nothing in $A$ such that $g$ will go to 1. How do I handle the window close event in Tkinter? How do I handle the window close event (user clicking the 'X' button) in a Python Tkinter program? After a botched upgrade from Ubuntu 14.04 to Ubuntu 16.04 I had to wipe my system and start all over. This time I decided to go with a much less CPU intensive desktop environment and installed Lubuntu 16.04-1.  My problem: when I run Steam from the menu shortcut it acts like it is doing nothing. However it does show up in the task manager. If I just type steam in the terminal I get the following.  michael@michael-HP-Pavilion-dm1-Notebook-PC:~$ steam Running Steam on ubuntu 16.04 64-bit STEAM_RUNTIME is enabled automatically grep: symbol lookup error: grep: undefined symbol: pcre_jit_stack_alloc grep: symbol lookup error: grep: undefined symbol: pcre_jit_stack_alloc /bin/bash: /home/michael/.local/share/Steam/ubuntu12_32/steam-runtime/amd64/lib/x86_64-linux-gnu/libtinfo.so.5: no version information available (required by /bin/bash) grep: symbol lookup error: grep: undefined symbol: pcre_jit_stack_alloc awk: /home/michael/.local/share/Steam/ubuntu12_32/steam-runtime/amd64/lib/x86_64-linux-gnu/libtinfo.so.5: no version information available (required by /lib/x86_64-linux-gnu/libreadline.so.6) Installing breakpad exception handler for appid(steam)/version(1468023329) libGL error: unable to load driver: r600_dri.so libGL error: driver pointer missing libGL error: failed to load driver: r600 libGL error: unable to load driver: swrast_dri.so libGL error: failed to load driver: swrast   Then nothing happens including steam doesn't show up in the task manager. Now I did find the command.  LD_PRELOAD='/usr/$LIB/libstdc++.so.6' DISPLAY=:0 steam   This does run Steam but it is not a real solution in my eyes. How can I fix it? I have an iOS application - an alarm clock. I released it a little over a month ago. Initially it was paid, but when I saw there were virtually no purchases (from 0 to 4 a day), I changed it to be free for a period of time. When it become free, in less than 10 days it has been downloaded more than 30,000 times, and more importantly (I think) it moved much higher in the search results when the user searches "alarm" - it reached 20th place in the results. During that time I also received very good reviews in the AppStore. But today I changed it back to paid, and now when I search "alarm" my app is shown at the bottom of the 4TH PAGE. Given that one page contains 120 apps, this is very bad for me and I don't understand why this happened. Can anyone tell me how does AppStore ranks search results and is there a way to move my app higher in the rankings, please? :) Huge thanks! How do you prove the second law of thermodynamics from statistical mechanics? How do you prove the  from statistical mechanics? To prove entropy will only increase with time? How to prove? Please guide. Find splitting field of $x^5-4x+2$ over $\mathbb{Q}$ I know how to get the splitting field from the roots but I just can't come up with any factorisation that gives me roots. Any suggestions? apt install "*" method in Ubuntu 20.04 does not work What can you say about $f$ and $g$ in the case that $fg$ is 1) Injective, 2) Surjective - Cohn - Classic Algebra Page 15 phpmyadmin doesn't connection with true data I want to typeset a piece of code containing line breaks.  New lines should indent to a specified point in the previous line.  Here is a monospaced example to illustrate what I mean.  Notice how 'case' and 'of' line up below, as well as 'let' and 'in':  swap : forall a, b. Tuple a b -&gt; Tuple b a swap a b x = case x              of tuple a b y z. let x' = tuple b a z y                                in x'   The code I want to typeset is not monospaced, so I can't just use a verbatim environment to get what I want.  The actual LaTeX of the first line, for instance, is  \mathsf{swap} : \forall\alpha,\beta.\;\mathsf{Tuple}\;\alpha\;\beta\to\mathsf{Tuple}\;\beta\;\alpha   How can I align some text to a specific point in the previous line? how to decode this JSON string? Hide processes from other users based on groups (under Linux)? Is it possible to configure process hiding for certain user groups under a linux system?  For example: Users from group X should not see processes owned by users from group Y in ps/top or under /proc.  Is it possible to configure such a setup with SELinux?  (I vaguely remember a similar feature in the funny grsecurity patch set - but IIRC, it was more generic - and besides, I want to configure a stock linux distro without having to maintain a custom kernel.)  Edit: For better illustration, . The example is not that generic, but one can configure that a user or some users can only see information of their own processes in ps etc. Do sensors wear out? We all know that shutters wear out and they have a limited number of actuation's.  The question I have is, do sensors wear out too? Do they suffer any kind of damage after each shot?  Should I be concerned about this or is the sensor lifespan way longer than the shutter lifespan? Is there a way to include an entire text file as a string in a C program at compile-time?  something like:   file.txt:  This is a little text file  main.c:  #include &lt;stdio.h&gt; int main(void) {    #blackmagicinclude("file.txt", content)    /*    equiv: char[] content = "This is\na little\ntext file";    */    printf("%s", content); }    obtaining a little program that prints on stdout "This is a little text file"  At the moment I used an hackish python script, but it's butt-ugly and limited to only one variable name, can you tell me another way to do it?