Handling a conditional statement in a single line
How does the ternary operator work?
Check a string to see if all characters are hexadecimal values How does Cypher exit/enter the Matrix without an operator? In The Matrix, Cypher enters the Matrix to speak with the Agents, then leaves again. We never see if he has an operator, and as he kills Tank and Dozer you might assume he doesn't have one.  If he didn't have an operator how does he jack in/out of the Matrix? Schengen Visa for both business and tourism How does one obtain a Witcher 3 Troll Mutagen from a non-quest specific troll, at least one of which you never exchange dialogue with? I have played the Witcher 3, exchanged dialogue with 5 trolls already, and decided not to kill them. All 5 trolls were involved in specific quests. I have killed two trolls of which I did not exchange dialogue. I have yet to receive a Troll Mutagen.  How does one obtain a Witcher 3 Troll Mutagen from a non-quest specific troll, at least one of which you never exchange dialogue with? What metadata does a LibreOffice file contain and how to remove it? Evaluating the integral $\int_0^{\frac{\pi}{2}}\log\left(\frac{1+a\cos(x)}{1-a\cos(x)}\right)\frac{1}{\cos(x)}dx$ Solve $x^2$ $mod$ $23 = 7^2$ What is the procedure to solving $x^2$ $mod$ $23 = 7^2$? According to WolframAlpha, there is no integer solution but I am completely confused as to what steps was taken to determine that.  Before asking the question, I did try to solve this using brute force by plugging in some arbitrary numbers to see whether the square of that number mod $23$ gave me a remainder of $49$ but the procedure was quite tedious. Hence the reason I turned to WolframAlpha.   Going back to the question, I want to know how WoflramAlpha determined that there was no integer solution to solving for $x$. Show that $\mathbb{Q}\times \mathbb{Q}$ is denumerable I am new to functions and relations, and with some concepts I am not so familiar. I have a question in an homework:     Show that $\mathbb{Q} \times\mathbb{Q}$ is denumerable.   From what I understood, denumerable means that it is infinitively countable. There are some  on the web about this topic, but I am still not understanding their explanation, maybe because they are not explained so easily (for me).  From what I understood, a set is denumerable if there's a relation with the natural numbers (but I am still not understanding what is this relation).  I have heard also about equinumerous sets (contain a bijective function = onto + one-to-one function), but I cannot relate this information with the problem to try to solve it. How many non congruent trapeziums are possible with the side lengths from {1,3,4,5,6} I need to find number of mutually non  congruent trapeziums with side lengths from {1,3,4,5,6}.   I know for a trapezium with a,c as non parallel sides the condition for my question is that  $$|a-c|&lt;b+d&lt;a+c$$  But i cant apply it to count the cases. Can someone help in how to get the number of cases? Recursive cast from SimpleXMLObject to Array How was Will aware of the lights? In  (2016) Will Byers gets taken to the "Upside Down". But he manages to communicate with his mother, e.g through the christmas lights.  &nbsp;   When Joyce is in the cupboard and says "Once for YES, twice for NO.", how would Will make that happen? He can't see his mother, but does he see the lights she is holding?  &nbsp;   Does the alphabet Joyce draws just appear on the wall in the Upside Down, together with the lights?  In the last episode Joyce and Hopper enter the house in the Upside Down, and when they go through the hallway the kids on the other side see the lights go on (suggesting that just standing close to those lights is enough to make them turn on).    But those lights don't seem to be there in the Upside Down.    My Question:   Is there a reasonable explanation on how Will managed to communicate with his mother through the christmas lights? How to prove that the center of the dihedral group $D_{2n}$ is $\{1,r^{n}\}$ and the center of $D_{2n-1}$ is $\{1\}$?  I don't know how to prove it in this general case. Do cards with abilities that target trigger heroic? Editing question title creates whole new question and other question list problems How do you force Chrome pages/tabs to crash using JavaScript? Java Access Denied How to filter by messages, not by conversation? I have been emailing my Gmail account error messages from a project I am working on.   I am trying to use Gmail filters/labels to sort out the class of errors.  But because the subject line is basically always the same even if I have a specific filter for 3 known error cases, the label is applied to the conversation, instead of the specific message.  Therefore, all the errors get all the filters.  I do not yet want to delete the errors, but would rather file them separately.   I have not yet used the NOT contains string yet, but that looks to be non-scalable as I get to the fourth or fifth error case I am done with handling.  Is there any option other than turning off Conversations for all my email?  (I guess I could use one of my spare accounts to turn off conversations and do the work there but would be nice to have such an option). Is there a possibility to make reference to the line in the lstlisting environment? I was wondering if it is possible to refer to the lines of the code enclosed in lstlisting environment rather than just manually write a number of the line I want to describe. I have never met with this feature, is this available? Solve recurrence relation $ a_{n+1} = (n+1)a_n + 1 $ $a_0 = 1 \\ a_{n+1} = (n+1)a_n + 1 $  Could you help me solve this? And maybe someone know good source explaining how to solve recurrence relations? Limit of $n$th root of $n$! I am asked to determine if a series converges or not:  $$\displaystyle\sum\limits_{n=1}^{\infty} \frac{(2^n)n!}{(n^n)}$$  So I'm using the $n$th root test and came up with $\lim_{n \to {\infty}}\frac{2}{n}\times(\sqrt[n]{n!})$ I know that the limit of $\frac{2}{n}$ goes to $0$ when $n$ goes to infinity but what about the $(\sqrt[n]{n!})$?