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I upvoted an answer, and remained on the page and read a few more answers, while noticing that the user that I originally upvoted made several edits. I later noticed something from one of the edits that made me want to remove my upvote, but I got the message: "You last voted on this message 6 minutes ago. Your vote is now locked unless the answer is edited." I noticed that no edits were indicated, so they must have taken place during the grace period. This was not a case of me rushing or misreading, the answer originally posted was fine. An edit was made during the grace period. I went back 6 minutes after I upvoted, saw something that I didn't approve of appended to the original answer and wanted to change my vote, but couldn't. To clarify, I understand that this is ; I am NOT trying to report a bug. I am requesting that a feature be implemented such that this situation can be resolved without having to resort to making a fake-edit and a following rollback. Potential Solution: Perhaps votes that occur during the grace period should simply not be locked-in. | Please do not close this as a duplicate unless you can remove the “status-completed” tag from the (because it’s obviously not been completed). Steps to reproduce: Have someone post an answer. Downvote the answer. Have the someone edit the answer within the initial 5 minutes of the answer’s existence. Try to undo the downvote more than 10 minutes later. You cannot undo the downvote. |
Any good places to start getting into Bayesian statistics? I'm a graduate student in social sciences, with a decent amount of stats classes under my belt, but I'm far from fluent. Any references would be much appreciated. Thanks! | Which is the best introductory textbook for Bayesian statistics? One book per answer, please. |
In 2268, Spock's brain has been stolen by hostile aliens and later re-transplanted by Dr. Leonard McCoy. But 10 years earlier, Spock talks to his self from 2387 about future things and how to tackle them. In these discussions, did Spock learn about his brain being at risk or did he not? At least, one would expect the older Spock would warn his younger alter ego to avoid removal of his brain, since Dr. Leonard McCoy ran into severe complications while finishing the surgery, so probably the whole procedure caused secondary damages to his nervous system. Still, to my knowledge there are no historical records about such a dialog, so did Spock in fact conceal this information to his younger ego and, if so, why? | Did Spock Classic (in the new timeline universe) warn NuSpock of upcoming natural disasters? i.e. V'ger, the whale probe, Praxis and explosion, the Borg, violent first contacts, the wave from Generations, etc? |
I'd like to be able to typeset as simply as possible a table with cells joigned by arrows with TikZ (because I want to use it in conjunction with Beamer and PDFLaTeX). Here is the code I'm comfortable with, involving PSTricks macros: \documentclass{beamer} \usepackage{etex} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[francais]{babel} \usepackage{pst-node,auto-pst-pdf,tabularx} \begin{document} \begin{frame} \footnotesize \renewcommand{\arraystretch}{3} \begin{tabular}{|l|*{8}{>{$}c<{$}|}} \hline Valeur $x_i$ (par ordre croissant) & 1 & 3 & 4 & ... & 20 & 23 & ... & 67\\ \hline Effectif $n_i$ & \rnode{A}{2} & 4 & \rnode{D}{2} & ... & 3 & \rnode{G}{6} & ... & 145 \\ \hline Effectifs cumulés & \rnode{B}{2} & \rnode{C}{6} & \rnode{E}{\,8\,} & ... & \rnode{F}{64} & \rnode{H}{70} & ... & \ovalnode{I}{2453} \\ \hline \end{tabular} \hfill\rnode{J}{Effectif total} \ncline[nodesep=2pt]{->}{A}{B} \ncline[nodesep=2pt]{->}{C}{D} \ncput*{+} \ncline[nodesep=2pt]{->}{D}{E} \ncput*{=} \ncline[nodesep=2pt]{->}{F}{G} \ncput*{+} \ncline[nodesep=2pt]{->}{G}{H} \ncput*{=} \ncangle[nodesep=2pt,angleA=0,angleB=0]{->}{J}{I} \end{frame} \end{document} I've searched a little, before posting, and I only found some solutions which seems quite complicated to me (eg or ). I cannot afford at present the time investment needed to become skilled enough in TikZ (which I only master for simple drawings). I also heard about the matrix command of TikZ, but it doesn't work with beamer on 2 different TeXlive installation at home (packages from standard Ubuntu 15.04 repositories on one, « vanilla » TeXlive installed from TUG on the other). Here is the code I tested ( as a working example) : the working code : \documentclass[a4paper]{article} \usepackage{etex} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[francais]{babel} \usepackage{tikz} \usetikzlibrary{matrix} \begin{document} \begin{tikzpicture} \matrix(dict)[matrix of nodes,%below=of game, nodes={align=center,text width=1cm}, row 1/.style={anchor=south}, column 1/.style={nodes={text width=2cm,align=right}} ]{ meaning & $b_1$ & $b_2$ & $b_3$ & $b_1b_2$ & $b_1b_3$ & $b_2b_3$ & $b_1b_2b_3$\\ common list \\ private list\\ }; \draw(dict-1-1.south west)--(dict-1-8.south east); \draw(dict-1-1.north east)--(dict-3-1.south east); \end{tikzpicture} \end{document} the not working code: \documentclass{beamer} \usepackage{etex} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[francais]{babel} \usepackage{tikz} \usetikzlibrary{matrix} \begin{document} \begin{frame} \begin{tikzpicture} \matrix(dict)[matrix of nodes,%below=of game, nodes={align=center,text width=1cm}, row 1/.style={anchor=south}, column 1/.style={nodes={text width=2cm,align=right}} ]{ meaning & $b_1$ & $b_2$ & $b_3$ & $b_1b_2$ & $b_1b_3$ & $b_2b_3$ & $b_1b_2b_3$\\ common list \\ private list\\ }; \draw(dict-1-1.south west)--(dict-1-8.south east); \draw(dict-1-1.north east)--(dict-3-1.south east); \end{tikzpicture} \end{frame} \end{document} The error at compilation time is : ! Undefined control sequence. <argument> \pgf@matrix@last@nextcell@options egreg pointed out that my question may be duplicate with . But the error is different - anyway, adding the fragile option to the frame solve this peculiar problem. Moreover, the point is not necessarily to use TikZ's matrix environment. I'd like to have a simple yet fancy and PDFLaTeX compatible way for joining nodes, whether they are in tables or not. I can do this easily with PSTricks, but it's hard to have PSTricks working with Beamer and PDFLaTeX. Hoping someone will have an idea, preferably a simple and efficient one... natsirt | I am having trouble getting a basic example of a matrix of notes to show up in my beamer presentation. I am using the code copied from the pgf manual. Here is a complete working example. The error I get upon compilation is: "Package pgfbasematrix Error: Single ampersand used with wrong catcode." \documentclass{beamer} \usepackage{tikz} \usetikzlibrary{arrows,decorations.pathmorphing,backgrounds,fit,petri,positioning,matrix} \begin{document} \begin{frame} \begin{tikzpicture} \matrix (magic) [matrix of nodes] { 8 & 1 & 6 \\ 3 & 5 & 7 \\ 4 & 9 & 2 \\ }; \draw[thick,red,->] (magic-1-1) |- (magic-2-3); \end{tikzpicture} \end{frame} \end{document} |
How do you solve this? $$2^{5^{2017}} \bmod 11$$ I tried my own method, and I got that: $$2^{5^{2017}} \equiv 10\pmod{11}$$ But I'm not sure it's the correct answer. Thanks! | I've read about Fermat's little theorem and generally how congruence works. But I can't figure out how to work out these two: $13^{100} \bmod 7$ $7^{100} \bmod 13$ I've also heard of this formula: $$a \equiv b\pmod n \Rightarrow a^k \equiv b^k \pmod n $$ But I don't see how exactly to use that here, because from $13^1 \bmod 7$ I get 6, and $13^2 \bmod 7$ is 1. I'm unclear as to which one to raise to the kth power here (I'm assuming k = 100?) Any hints or pointers in the right direction would be great. |
I follow that time dilates / distance contracts as you move faster, but sees anomalies in what happens when you slow down again. The time changes are supposedly permanent, with an identical twin ageing a lot more than the twin brother in a rocket accelerating to relativistic speeds... The problem is: Suppose we send the one twin (call him the astronaut-brother) up in a rocket, circling the earth for a day, going close enough to light-speed so that supposedly fifty years pass for the ground-logged twin. Now the rocket slows down and lands. The astronaut brother supposedly finds his brother fifty years older than himself! BUT we know during this process only one day passed for the observer (ground-logged brother). I don't see how the astronaut-brother can possibly find his twin, tens of years older in this scenario, once they're reconciled back in the same time frame? | With today's ultracentrifuge technology, they can spin so fast that the sample can be subjected to accelerations of up to 2 millions Gs. That is equivalent to two solar masses. Has someone tried to measure the time dilation in a radioactive sample? How calculate that time dilation respect to the time outside the ultracentrifuge, for example one week. I think that that time dilation will be significant enough to be measured. |
I have a question about a data analysis that I am running. I am analyzing the results of a survey in which (expectedly) there exists far fewer people in one group than in another. This survey is an Honours project about enhancement drug use, and I have ~40 users and ~590 non-users. Obviously there is a huge difference between the sizes of these groups! I am interested in differences in means on a particular study processes scale. I have the following questions: Is it a problem to use an ANOVA in this case (where the groups are so different in sample size)? I know that the Levene's test is sensitive to differences in sample size (such that it is far more likely to be significant); and this is the case in my data, p < .05. Regardless, Welch and Brown-Forsythe tests still reveal a statistically significant differences in mean scores on this scale. Given that the Welch and Brown-Forsythe tests still reveal significant differences between groups, would I be wrong in concluding that these do in fact exist (despite violating the initial Levene's assumption)? Is there are more robust way to investigate this research question, taking into account the disparity in group sizes? | I have data for three unequal groups: $N = 44$, $N = 354$ and $N = 347$. Is it possible to compare all three groups running a one-way ANOVA or is the first group too small? |
The following two lines give me different results with respect to spacing: \noindent\makebox[\parindent]{?} Blabla \noindent\makebox[\parindent]{?}Blabla The second case is what I want: no space is added between the end of the box and the next letter. However, this piece of code is part of a customized command of mine (to give a simplified example: \newcommand{\myBox}{\noindent\makebox[\parindent]{?}}) and I cannot seem to avoid this extra space after using my customized command. Does anyone have a solution to this problem? Thanks in advance! | I see that the code in many packages and examples contains percent signs % at the end of (many) lines. What are they used for? Do they affect the parsing of those lines? |
Things I remember about this book (and it's not much): Dystopian or Utopian future (I believe it was Dystopian) Children where either born in a lab or brought to a lab and trained for specific functions in life (Scientist, Janitor, Teachers, Etc.). I do remember that there were a few scenes that specific children were trained for specific phobias. Example: The children were in a room and when the color yellow was displayed, a piercing noise blasted them which eventually invoked fear of that color. I read the book either early 90's or late 80's. I have a feeling it was early 90's. I know it's not much to go on, and I'm digging deep in my sponge to remember more. Unfortunately I don't remember the main plot of the story. The scene of the children in the lab is what I remember from long ago. | The world is a world where children are born into a class, and they cannot change it. For example, some children are radiated in the womb, so that they do not want to move to a cold climate, so that they can be permanently employed as cotton pickers. Then there are toddlers who are electrocuted (or physically punished) when they crawl to books, so that they associate books with pain, keeping them uneducated. I believe the main character is a guy who wants to run away with a girl, looking for simpler life, as they are born in the high class. |
APOD_DIR=/home/apod/ if [[ "{$filename}" == *"${date}"* ]] then echo "file exist" # Do not update the wallpaper else # wallpaper does not exist. Fetch it and set as wallpaper file="${APOD_DIR}${date}.jpg" wget -O $file $url gsettings set org.gnome.desktop.background picture-uri file:///$file fi This is a block of the script that i intend to use to fetch the image from url and set it as the desktop background. It works fine while executed from the terminal but while testing it as a cron job, the program is able to fetch the image just fine but the command with gsetting tool does not seem to be effective in changing the desktop background. Cron 50 12 * * * /home/shellScripts/background.sh | I must have a blind spot, but I cannot find what it is. I made a small python script that removes VLC from the sound menu. It runs perfectly in any way I run it from the terminal or from a launcher or whatever you can think of. What the script actually does is nothing more than get the get the current settings: gsettings get com.canonical.indicator.sound interested-media-players edit the list, and set the changed list by: gsettings set com.canonical.indicator.sound interested-media-players "['newlist']" These commands are executed by a python script,. However, when run from a cronjob (crontab -e) only the gsettings - get - part works, but not the gsettings - set - section. That the get section works fine with cron, I checked by making the script write data (the original as well as the edited) to an external file. Not a python problem To see if the problem is related to python code, I created a bash script that applies a changed sound menu items list. The story is the same: the bash script runs fine from the command line or a launcher, not from cron, while any other command in the same script would run fine. Also, if I add any command at the end of the script below, it works fine and it looks like the script is satisfied with its own work. Why is the gsettings set command not working when initiated from cron? This is the script: #!/usr/bin/python3 import subprocess def read_soundmenu(): # read the current launcher contents get_menuitems = subprocess.Popen([ "gsettings", "get", "com.canonical.indicator.sound", "interested-media-players" ], stdout=subprocess.PIPE) return eval((get_menuitems.communicate()[0].decode("utf-8"))) def set_current_menu(current_list): # this takes no effect from cron # preparing subprocess command string current_list = str(current_list).replace(", ", ",") subprocess.Popen([ "gsettings", "set", "com.canonical.indicator.sound", "interested-media-players", current_list, ]) current_list = read_soundmenu() for item in current_list: if item == "vlc.desktop": current_list.remove(item) set_current_menu(current_list) |
Bonjour, Comment produire un document avec des exercices dont les corrigés apparaissent à la fin du document et quels soient clickable avec latex. J'aimerais avoir quelque chose comme ça: | I would like to create this sheet which was made it by adobe indesign Could someone create it with latex ? Here's my code: \documentclass[12pt,a4paper,twocolumn]{report} \usepackage[margin=0.5in]{geometry} \usepackage[french]{babel} \usepackage{fontspec} \usepackage{graphicx} \usepackage{amsthm,amssymb,amsfonts,mathtools} \usepackage[utf8]{inputenc} \usepackage{multicol} \usepackage{multirow} \usepackage{amssymb} \usepackage{array} \usepackage{graphicx} \setlength{\columnseprule}{0.5pt} \thispagestyle{empty} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \begin{document} %%%%%%%%%%head%%%%%%%%%%%%%%%%%%%%%%% \twocolumn[ \begin{@twocolumnfalse} \begin{center} \fbox{\Large Exercise Sheets} \end{center} \hrulefill \end{@twocolumnfalse} ] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \fbox{ Exercise $1$:}\\ Compute the following limits \begin{multicols}{2} \begin{enumerate} \item $\lim_{x\to 2}\dfrac{4x^{3}-5x-22}{x^{2}-x-2}$ \item $\lim_{x\to 0^{+}}\dfrac{x-\sqrt{x}}{x+\sqrt{x}}$ \item $\lim_{x\to 1}\dfrac{\sqrt{x+3}+\sqrt{x}-3}{x-1}$ \item $\lim_{x\to 2}\dfrac{x^{2}\sqrt{x+2}-8}{4-x^{2}}$ \end{enumerate} \end{multicols} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \fbox{ Exercise $2$:}\\ Let $n\in\mathbb{N}^{*}$ \begin{enumerate} \item calculate : ${\displaystyle \lim_{x\to 0}\dfrac{1-\cos(x)\cos(2x)\ldots+\cos(nx)}{x^2} }$ \item b \item c \item d \item e \item f \end{enumerate} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \end{document} |
When we ride a bicycle, we tend to move our body left if we are taking a right turn and vice versa. Why is it like that? | I think it's clear enough that if you turn your bicycle's steering wheel left, while moving, and you don't lean left, the bike will fall over (to the right) as you turn. I figure this is because the bike's momentum keeps it moving in the direction you were going, and since your wheels have friction against the ground, the top of the bike moves forward relative to the bottom of the wheels. The top of the bike going north while the bottom of the wheels go northwest will understandably cause you to topple. So to counteract this and keep you from falling over, leaning into the turn is necessary. But is there also a direct causal relationship -- that leaning will cause the bike to start to turn? If I start leaning left, I will turn left... but maybe that's because I know that if I don't turn the steering wheel left, the bike will fall over (to the left). I experimented with unruly turns of the steering wheel when I was a kid, and got my scrapes and bruises. Now that I'm a cautious and sedate adult I'm not anxious to experiment that way. :-) (I also want to ask why airplanes bank into a turn... they don't have the same issues as a bike, i.e. the bottom part has no special friction against the ground. But that would probably make the question too broad.) |
Why don't stationary electric charges posses magnetic field, while moving charges do? | For a charge moving in an electric field $\vec E$, its equation of motion is given by the electric part of the Lorentz force $$\frac d {dt}\gamma m \vec v = e\vec E$$This comes from the conservation of relativistic energy in a static electric field. But a magnetic field would still make this conservation law true since the magnetic force is always orthogonal to the velocity of the charge and therefore doesn't change its energy. Is there a simply physical argument that shows why a static charge doesn't create a magnetic field? |
I have a strange problem when positioning table in a big file. I use the option h! to put the table exactly where the code is written. \begin{table}[h!] ... \end{table} The problem is, in the big file, I have 4 table, at different places 'supposodely' separated by pages (with a lot of text in between). At the end, all the tables are regrouped at the end of the chapter, sometimes 5 pages after their supposed placement! This bothers me very much, and I don't understand why. With figure the option h! comes in handy, the figure is always placed as close as possible from the point where I put it... Does it not work in the same way with tables? Thank you very much. Claude. | Is there any package or a method to force LaTeX to keep floating environments like table and figure closer to where they are declared? |
How can I get a List of an Enum's values? For example, I have the following: public enum ContactSubjects { [Description("General Question")] General, [Description("Availability/Reservation")] Reservation, [Description("Other Issue")] Other } What I need to be able to do is pass ContactSubject.General as an argument and it returns the List of the descriptions. This method needs to work with any Enum, not just ContactSubject (in my example). The signature should be something like GetEnumDescriptions(Enum value). | My enum consists of the following values: private enum PublishStatusses{ NotCompleted, Completed, Error }; I want to be able to output these values in a user friendly way though. I don't need to be able to go from string to value again. |
Is there any program like htop which can tell me the GPU RAM consumption when I train a "Deep Learning" model? | I installed CUDA toolkit on my computer and started BOINC project on GPU. In BOINC I can see that it is running on GPU, but is there a tool that can show me more details about that what is running on GPU - GPU usage and memory usage? |
I'm beginner in C and I really need an efficient method to set all elements of an array equal zero or any same value. My array is too long, so I don't want to do it with for loop. | I have a large array in C (not C++ if that makes a difference). I want to initialize all members of the same value. I could swear I once knew a simple way to do this. I could use memset() in my case, but isn't there a way to do this that is built right into the C syntax? |
I have a js function which calls 'generate.php' on click event. The php returns an anchor tag with id 'alert'. the js functions appends this anchor tag to the document. Another js function acts on this dynamically generated anchor. As title says the .on() function doesn't bind the event handler on this anchor tag.Please help me out... My js file is as below $("#generate").click(function(){ // Working Fine :) $.post("generate.php",function(reply){ $("reply").html(reply); } }); $("#alert").on("click",function(){ //Not Working :( alert("hello"); } My html code is as below <a href="#" id="generate">Click TO generate</a> <div id = "reply"></div> My generate.php looks like this <?php //Working Fine echo '<a href="#" id="alert">Click To get alert Box</a>'; echo '<div id="abc">Click The above link to get an alert</div>'; ?> | I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off. This happens on page ready and works just fine. The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound. I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option. |
I have an entity reference view (views block with entity reference display of a list of nodes that have "Certification" checked (boolean)). I am able to use this view from the content type manage fields config, i.e. and it gives me a select list of all entities with that condition. Is there a Drupal function to invoke this view to create a select field programmatically in my custom form? I've searched high and low and can't find anything about this. | I have a view called all_projects_list. This view fetches Fields (not nodes), and i'd like to get it by code, and iterate on it. I managed to do this by using: $view = views_get_view_result('all_projects_list', 'default'); foreach($view as $project){ print_r($project->_field_data['nid']['entity']->field_project_code['und'][0]['value']); } Which as you can see is very, very dirty. Is there a Drupal way of doing this ? Thanks in advance. |
I dissolved one corner of a cube: And got this weird face: It doesn't make sense to me cause it's not a "face" in a geometrical sense. Why do faces like this exist in Blender and is there any usage of them? | Support for N-Gons (polygons consisting of more than 4 vertices) has been in Blender for a while now, but many of us still may not know when to use them, and how to do so effectively. In what situations do N-Gons really come in handy? When should they be just plain left out? Do they have any place in finished models? |
When I run ls * its returning entries delimited by a newline. However my shell is ignoring the newlines to condense the output. I would like each entry on a separate line. Currently: > ls * a b c Ideally: > ls * a b c | I think I may be overlooking a relatively fundamental point regarding shell. Output from the ls command by default separates output with newlines, but the shell displays the output on a single line. Can anyone explain this to me? I had always presumed that the output was simply separated by spaces, but now that I see the output separated by newlines, I would expect the output to be displaying on separate lines. Example: cpoweradm@debian:~/lpi103-4$ ls text* text1 text2 text3 od shows that the output is separated by newlines: cpoweradm@debian:~/lpi103-4$ ls text* | od -c 0000000 t e x t 1 \n t e x t 2 \n t e x t 0000020 3 \n 0000022 If newlines are present, then why doesn't the output display as: text1 text2 text3 |
It is well known that the solution to the optimization problems proposed in Principal Components and Canonical Correlation Analysis are given by the solution to eigenvalue problems and generalized eigenvalue problems respectively. My linear algebra is quite rusty and I wanted to know if anyone could give me a semi-formal, albeit intuitive explanation on why this is so. | How are PCA, LDA, CCA, and PLS related? They all seem "spectral" and linear algebraic and very well understood (say 50+ years of theory built around them). They are used for very different things (PCA for dimensionality reduction, LDA for classification, PLS for regression) but still they feel very closely related. |
(Updated answer choice for High Sierra. See the old answer if you are still on Yosemite) I'm running OS X Yosemite, and I want to disable the notifications from Time Machine. I rarely do a hard-drive backup because all of my essential files are in the cloud. I don't need to run timemachine as often as it suggests/warns/annoys me about. How do I disable the notifications? Time Machine is not in the Notifications preferences, and I don't want to stop using it entirely. | Mountain Lion and later OS X releases have a very useful feature where Time Machine can alternate between multiple backup destinations. I use this to back up to both a network share at home and an external drive I keep offsite. Because I only have physical access to the offsite drive occasionally, I don't back up to it often. After 10 days, OS X gives me a message around the same time each day, such as: Time Machine is still backing up successfully to the network share every hour, so this message is unnecessary (and the second sentence is incorrect). I like being able to see when the last backup was completed, so I'd prefer not to remove the disk from Time Machine's destination list entirely. Likewise, turning Time Machine off (as suggested ) isn't an option because I still need my backups to run on the other drives. Is there any way to disable or delay this message? Ideally I would be able to set it to a longer period of time, so it could remind me to go do an offsite backup every month or so. |
I've seen people change the X, Y ans Z inputs in the mapping node all at once. How is that done? In tutorial, Andrew Price does it at 7:44 | Everytime I change the X axis to 2' it literally only does the x axis and I was wondering if there was a way I could do this proportionally |
Pro Evolution Soccer 2015 does not recognize my GeForce card. I set the settings on my Nvidia card to high performance, but it still uses the intel integrated graphics card. Nvidia driver version v344.15 Laptop Asus n550jk GeForce 750m integrated Intel Graphics. How can I make PES use my Nvidia card instead? | I had PES 2015 game and it's always use Intel(R) HD Graphics as a default How to change that to Nvidia ? |
Alright guys, so I attracted you with the title. Now, to preface the question, I am fully aware of the work of Copernicus, as well as the concepts of Heliocentrism and Barycentric Coordinates. I have a master's degree in Engineering, and have taken many a course in dynamics and kinematics. It is with this experience that this question arises. When studying bodies in motion, it is customary to pick a stationary reference frame for the basis of your calculations. Since the Sun is extremely massive compared to the rest of the planetary bodies, the barycenter of the Solar System (the stationary origin of choice) is extremely close to (and often inside) the sun. Hence why we commonly say that the planets all revolve around the Sun. Although this certainly simplifies drawings of the planetary orbits, allowing for mostly non-intersecting ellipsoids in modeling, the base reference frame is, for all intents and purposes, arbitrary. All motion is relative to it's observer, so who's to say we cannot define the origin to be at the center of Earth? Sure, children would no longer be able to make working models out of hangers and Styrofoam balls, but wouldn't the equations of motion remain the same? I have been searching online for a video, or gif, that illustrated this principle, but was unable to find anyone who took the time to do so. I'd be very interested in seeing what the orbits actually looked like if we re-defined the stationary reference frame from the barycenter to the center of the earth. I'm sure the orbits would look pretty rad! Much like . Is there something I'm missing that would theoretically preclude us from doing so? Edit: Ah hah! Finally found a that shows this simulation. | In history we are taught that the Catholic Church was wrong, because the Sun does not move around the Earth, instead the Earth moves around the Sun. But then in physics we learn that movement is relative, and it depends on the reference point that we choose. Wouldn't the Sun (and the whole universe) move around the Earth if I place my reference point on Earth? Was movement considered absolute in physics back then? |
What makes a "AAA" game. and its engine and technology, so special? Why are they so hard to make, and take so long to make? Why can't an average basement dweller write a game or engine with graphics that are just as good or realistic? Take "Crysis" or "Battlefield 3", for example; if someone knew the techniques, algorithms, and everything else needed, what would stop them? | I tried to find a precise definition. I found clues on and , but I cannot find more than an approximation like: Equivalent of blockbuster movie in cinema, an AAA game is a game with highest development budgets and levels of promotion. The definition seems imprecise. How can I be sure a game is AAA? Let's imagine a small indie studio making games and growing up. They hire more and more people through the years and invest more and more money in their game. At which milestone would their game be considered as AAA? |
So I bought a Nest Thermostat off amazon, I read they used batteries and what not and after I purchased it I was looking at the description on amazon and it said it was a built in rechargeable battery (face palm) I have a 4 wire I don't have a common, I was wondering if it's safe or reasonable that, I have a light switch basically a foot below the thermostat so I was going to install a 40va step down transformer to power the thermostat using the R as the hot from the transformer and the C as the neutral from the transformer, does this pose any issues? I googled it but people seem 50/50 some say it's great some say it's not a good fix and to pull a new wire, but pulling a new wire at this point in time is not an option. If I left the R straight from the furnace and just used the neutral from the transformer would that be worse than setup 1? (Using the hot and neutral from the transformer) as far as I know all the thermostat does is use that power to close and open contacts in the thermostat so it shouldn't matter if the tstat is powered off a transformer, should it? Sorry for poor phrasing wrote on phone. | Update 02/02/2019 I appreciate all the responses and help but unfortunately i must have not seen the emails stating there were responses! I am now looking into a NEST thermostat and was curious if they too, use the same connections. Lastly, looking for a quick recommendation on which WiFi Compatible therms are preferred by the memebers that respond! Thanks again your knowledge is highly appreciated! Bob I Purchased the Honeywell WiFi Prog Thermostat to replace my Round Digital Honeywell Thermostat. I have separate Heating and Cooling (Heating is a Weil McLain Boiler for Hot water baseboard and Hot water(no tank) and Cooling is a separate unit that was added later.) Wires: RC Cool R Heat W Heat Y Cool G Cool 3 wires from AC unit and 2 from Heater. If I were to go the separate transformer route to power the thermostat, where would I land the 2 wires? C and ??? |
Let $ a,b,c$ be lengths of sides triangle $ ABC$. Prove that: $\displaystyle \frac{a}{b+c}+\frac{b}{c+a}+\frac{c}{a+b} <2$ $\bf{My\; Try::}$ For a $\triangle $ with sides $a,b,c$ $a+b>c$ and $b+c>a$ and $a+b>c$ Now let $x=a+b-c>0$ and $y=b+c-a>0$ and $z=c+a-b>0$ So $\displaystyle 2a=x+z$ and $2b=x+y$ and $2c=y+z$ So equality convert into $$\frac{x+z}{x+2y+z}+\frac{x+y}{x+y+2z}+\frac{y+z}{2x+y+z}<2$$ How can i solve above inequality, Help required, Thanks | Let $a,b,c$ be the lengths of the sides of a triangle. Prove that $$\sum_{\text{cyc}}\frac{a}{b+c}=\frac{a}{b+c}+\frac{b}{c+a}+\frac{c}{a+b}<2\,.$$ Attempt. By clearing the denominators, the required inequality is equivalent to $$a^2(b+c)+b^2(c+a)+c^2(a+b)>a^3+b^3+c^3\,.$$ Since $b+c>a$, $c+a>b$, and $a+b>c$, the inequality above is true. Is there a better, non-bruteforce way? |
I started gathering information about Hamiltonian MCMC and I would like to ask if someone knows some good papers or books.If it possible notes that give a detailed explanation of Hamiltonian MCMC. Thanks in advance! | Could you provide a step-by-step for dummies explanation of how Hamiltonian Monte Carlo work? PS: I've already read the answers here, , and here, , and here, and they do not address it in a step-by-step way. |
Once the flooring is pulled up is it necessary to remove the dense paper layer which ultimately glued the linoleum to concrete. If it is not necessary to remove do I rough up the surface to make a more adhesive surface? Or will thinset adhere to the dense paper layer? This paper layer has been exposed on my kitchen floor for over 3 years with spills. It does absorb but no deterioration. Help! thank you for the expert advice. | I have a contractor coming in to tile my home. My floor is a post tension concrete slab, home is only 4 yrs old. The contractor said they could just tile right over the linoleum, but after reading about the risks online, I decided to rip it up and they said they would just tile right over whatever material is left. I can easily rip up the top layer of the linoleum, but the felt/paper layer adheres to the concrete 100%. Should I be spending time/money/energy on getting all the felt paper up as well? or is the contractor right that there will not be any issue? |
Let $f(z)$ be analytic on $\mathbb{D}$ = {${z\in\mathbb{C}:|z-1|<1}$} such that $f(1) = 1$, if $f(z) = f(z^2)$ for all $z\in\mathbb{D}$, then which of the following statements is NOT correct? 1) $f(z) = [f(z)]^2$ 2) $f(\frac{z}{2}) = \frac{1}{2}f(z)$ 3) $f(z^3) = [f(z)]^3$ 4) $f'(1) = 0$ This question is also in . If we will assume $f(z)=1$ for all $z\in\mathbb{D}$ then this function clearly satisfies all the hypothesis so (2) is incorrect. I strongly believe that the only function which satisfy the above hypothesis is $f(z)=1$. But how will I prove this? | Let $f(z)$ be analytic on $\mathbb{D}$ = {${z\in\mathbb{C}:|z-1|<1}$} such that $f(1) = 1$, if $f(z) = f(z^2)$ for all $z\in\mathbb{D}$, then which of the following statements are correct? 1) $f(z) = [f(z)]^2$ 2) $f(\frac{z}{2}) = \frac{1}{2}f(z)$ 3) $f(z^3) = [f(z)]^3$ 4) $f'(1) = 0$ I can't understand how to do solving this problem. please anyone give me some hints. |
Let $n$ be the number of ways in which $5$ men and $7$ women can stand in a queue such that all the women stand consecutively. Let $m$ be the number of ways in which the same 12 persons can stand in a queue such that exactly 6 women stand consecutively. Then the value of $\frac mn$ is (A) 5 (B) 7 (C) $\frac 57$ (D) $\frac 75$ Try Considering the $7$ women as a unit the $5$ men and the unit can be arranged in $6!$ ways. In each arrangement the $7$ women can arrange themselves in $7!$ ways. So total arrangements $n=7!\times 6!$. But I'm stucked in the second part. Please help to understand the underlying counting technique. Thanks in advance. | Let $n$ be the number of ways in which $5$ boys and $5$ girls can stand in a queue in such a way that all the girls stand consecutively in the queue. Let $m$ be the number of ways in which $5$ boys and $5$ girls in such a way that exactly $4$ girls stand consecutively in the queue. Then find $\frac{m}{n}$. I could find $n$ correctly as $6!\times 5!$, but I am finding $m$ as $7!\times 4!\times \binom{5}{1}$, but the book says $m$ is $6!\times 4!\times 5\times \binom{5}{4}$. Where have I gone wrong? What is the proper logic to find $m$? |
What does static mean in import static org.mockito.Mockito.*; I have seen statements like import java.util.*; but it never had static. Thank you | When used like this: import static com.showboy.Myclass; public class Anotherclass{} what's the difference between import static com.showboy.Myclass and import com.showboy.Myclass? |
How can I subscribe to get answers to my question via mail? | Is there a feature on Stack Exchange that will allow me to receive an email notification when someone comments on my question or answer, or answers my question? |
Someone know, how to do this with math only (without string conversions): function Round_M(const aVal: Double): Double; var x: Double; Str: string; begin if aVal < 0 then x := aVal * 100 - 0.5 else x := aVal * 100 + 0.5; Str := FloatToStr(x); if Pos(FormatSettings.DecimalSeparator, Str) > 0 then Str := Copy(Str, 1, Pos(FormatSettings.DecimalSeparator, Str) - 1); Result := StrToInt64(Str) * 0.01; end; It rounds to 0.01 and 0.005 always up. I try get same result with RoundTo, Trunc, Int, SimpleRoundTo... But f.ex 1.005 -> good rounded to 1.01 but 1.015 will be 1.02, and my solutions got 1.01. Same for 1.025, 1.035, 1.045, 1.055. | Consider the following code: 0.1 + 0.2 == 0.3 -> false 0.1 + 0.2 -> 0.30000000000000004 Why do these inaccuracies happen? |
I have some email templates defined in MyTemplates in Exact Target. From the ExactTargetUI, I can create a Template-based Emails in MyEmails. But I am required to do it through API. Is there a way to create an Email in (Contents->MyEmail) by using a template so that I can then just load the contents in the template-based-email ? | I have created a email template in ExactTarget API and I want to use it executing XML from SoapUI. Is there any tutorial or examples of how can this be done? I'm new at this and I'm not sure how ExactTarget really works. |
I'm using a JPG file (8bit unsigned), together with a .jgw and the .jpg.aux.xml having the projection. The image displays well in ArcGIS and QGIS. Now I want to create the image in Geoserver 2.11.0 as a 'WorldImage' store, and then create a Web Map Service around it. But the image doesn't work in 'Layer preview'. You see nothing. When I try to consume the WMS in ArcGIS, this is the error I get. Any ideas? | I'm new to Geoserver, Ubuntu and Java, but have downloaded a virtual machine from gisvm.com and am getting up to speed. I got as far as configuring it with some fairly large shapefiles from a project I've worked on previously. My question is related to a problem which I see if I show the shapefile using the OpenLayers layer preview option. I see an error: OpenLayers map preview code="internalError" Rendering process failed. java.lang.OutOfMemoryError: Java heap space Googling has led me to plenty of Java command line options to increase heap space, but I have no idea if this should be applied to an environment variable, in a startup script or as a part of the Geoserver config. Can you help me to understand what I need to edit to get this working? I'm also wondering if I should be splitting my shapefile into smaller pieces. |
I am currently watching it right now and I was wondering, when they beamed Kirk and Sulu back up from falling onto the Vulcan planet, wouldn't they still have died? Since the speed they were falling before they were beamed? Also, wouldn't the gravitational pull from the singularity (Black Hole) be too strong for Spock to walk on the planet, let alone run? | In Star Trek (2009), when Kirk and Hikaru Sulu are falling from the drill, at the last moment Ensign Chekov locks on them and is able to transport them inside the ship. By the time they were transported, they have gained a lot of momentum due to free fall, but when they are inside the ship they just experienced a mild thud. Where did that much amount of momentum go? Does momentum conservation not apply to Teleportation in the Star Trek Universe? As far as i know from the game 'Portal', momentum was being conserved there. |
Find the solutions to $4x \equiv 16 \pmod{20}$ I managed to determine this by writing $4x = 16 + 20j \implies x =4 +5j \implies x \equiv 4 \pmod{5}$, but the official solution stated that the solutions are $x = 4,9,14,19 \pmod{20}$ which I'm not entirely sure how they got? | I want to ask a question about modular arithmetic. I know, that modular multiplicative inverse exists only if modulo and integer are relatively prime. I want to know, are there any ways of division in modular arithmetic, if modulo and integer aren't relatively prime? I tried to find info about that, but failed. |
I have a HTML interface that shows a dialog when the search button is clicked. The dialog has a text field where the user types a search string, and through Ajax the system uses PHP file to get data from the database and return data inform of a table //code for dialog <script> $(function() { $( ".comment").click(function(){ $( "#dialog-modal" ).dialog({ height: 140, modal: true, width : 440 }); $( "#dialog-modal" ).show(); }); }); </script> <div class="inner2"> <p><button class="more comment " type='button' ></button></p> <div id="dialog-modal" style="display:none"> <input name="searchPat" id="searchPat" type="text" onkeyup="searchPatient(this.value)" /> <input type="submit" id="submit" name="submit" value="Register Patient" /><br /> <div id="newtable" > </div> </div> </div> //searchPatient function <script> function searchPatient(str) { var xhttp; if (str.length < 3) { return; } xhttp = new XMLHttpRequest(); xhttp.onreadystatechange = function() { if (xhttp.readyState == 4 && xhttp.status == 200) { document.getElementById("newtable").innerHTML = xhttp.responseText; } }; xhttp.open("GET", "/clinicosight/lib/getPatient.php?q="+str, true); xhttp.send(); } </script> //getPatient.php $pat_no = $_REQUEST["q"]; $name=""; $query = "select patient_no, surname || ' ' || other_name as name,residence,year_of_birth from hp_outpatient_register where patient_no ilike '%$pat_no%' "; $con = @pg_connect("host=$serverIP dbname=$database user=$username password=$password"); $result = pg_query($con, $query); $tab=""; if ($result) { //$tab=$tab. ""; $tab=$tab. "<table border ='1' width='30%' id='searchtable' style='cursor: pointer;' > <tr>"; if (pg_num_rows($result) > 0) { //loop thru the field names to print the correct headers $i = 0; while ($i < pg_num_fields($result)) { $tab=$tab. "<th>" . pg_field_name($result, $i) . "</th>"; $i++; } $tab=$tab. "</tr>"; //display the data while ($rows = pg_fetch_row($result)) { $tab=$tab. "<tr>"; foreach ($rows as $data) { $tab=$tab. "<td align='center'>" . $data . "</td>"; } $tab=$tab. "</tr>"; } } $tab=$tab. "</table>"; } echo $tab; //code for table listener <script> var table = document.getElementById("searchtable"); //alert("People"); if (table != null) { for (var i = 0; i < table.rows.length; i++) { for (var j = 0; j < table.rows[i].cells.length; j++) table.rows[i].cells[j].onclick = function () { tableText(this); }; } } function tableText(tableCell) { alert(tableCell.innerHTML); } </script> So far, the dialog can display and once the user types text in the search text field, a dynamic table is created from the getPatient.php which is displayed on dialog. The problem is that the table created doesn't respond to the onclick event for the table. Kindly assist on how to go about it, or let me know if there is something i'm missing. | I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off. This happens on page ready and works just fine. The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound. I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option. |
What is the dual category of topological spaces $Top$? I know that the order theoretic dual of a topological space is a closed set system rather than an open set system. However, this doesn't answer my question (I think) since it is just a transformation of the objects, and not of the morphisms. I thought that maybe it would be the same as $Top$ but have morphisms involving closed sets instead of open sets somehow -- however the definition of a continuous function as one for which preimages of closed sets are closed is equivalent to the definition for which preimages of open sets are open, so this doesn't seem to lead anywhere unless $Top$ is self-dual, which seems unlikely. EDIT: let's see if we can start with a simple example and generalize. Consider two copies of the real line, one with the discrete topology (call it $A$), and one with the regular Euclidean/metric topology (call it $B$). The space of continuous functions from $A$ to $B$ is simply the space of all real-valued functions on the real line, i.e. $Hom(A,B)=\{\text{real valued functions on the real line}\}$. So now for $Top^{opp}$, the dual category to topological spaces, $$Hom^{opp}(B,A)=\{\text{relations whose "inverses" are real valued functions on the real line}\}?$$ (since the range of a function doesn't have to be its codomain). This is a simple/special case of two objects and their morphisms in $Top^{opp}$, but already the morphisms seem likely to be pretty useless in general since they aren't even functions in general. Still, now what confuses me is that it seems like this problem wouldn't be unique to defining the dual category of $Top$; any category whose morphisms aren't all invertible would seem to have the same problem. Thus it seems more likely that I am misinterpreting the definitions. EDIT: I am looking for a more precise definition than given in the answer to this question: However, it seems that looking at that question (which I couldn't find before asking this one) that there is no simple answer to what the dual category of topological spaces $Top$ is, which perhaps is unsurprising considering how pathological the simple example given above seems to be. Therefore I am going to vote to close this question as a duplicate. | My question is rather imprecise and open to modification. I am not entirely sure what I am looking for but the question seemed interesting enough to ask: The opposite category of rings is the category of affine schemes. This is usually thought of as the category of spaces. Can we run the construction backwards for categories usually thought of as containing spaces? For instance, does $\operatorname{Top}^{\operatorname{op}}$ have a nice description as some "algebraic" category? Note that it does not seem easy to describe the opposite category of all schemes. Therefore, the above question might be asking too much. Perhaps the following is a more tractable (or not) question: Can we find an "algebraic" category $C$ such that we can embed $C^{\operatorname{op}}$ in $\operatorname{Top}$ such that every topological space can be covered by objects in $C^{\operatorname{op}}$? Perhaps one would like to replace this criterion of being covered by objects by a more robust notion in general. One can repeat the question for other categories of spaces like: Category of manifolds (perhaps closer to schemes than general topological spaces) Compactly generated spaces Simplicial Sets and so on. A perhaps interesting example is the category of finite sets, it's opposite category is the category of finite Boolean algebras. |
I have recently wrote a few questions for Gerrit code review system and with each question being written, I could clearly see, that only tag appears among suggested tags: The tag has now over 400 questions and I put that string in many places in my question, but even though it doesn't appeared as suggested tag. So: what conditions must a tag meet to become visible among suggested tags? Additional information: For past five-six questions about Gerrit, was the only tag that was visible among suggested tags. A few minutes ago, I've asked another question about Gerrit, and this time I saw whole bunch of suggested tags, including: , , , , and , though neither GitHub nor SVN haven't been mentioned even an once in my question. As in above, just added new question, this time for Notepad++ and tag wasn't among suggested, though it has 1800+ questions tagged and though this name is mentioned few times in question body; on contrary, and tags were suggested, though there isn't even a trace of them in question body. This case (my question) becomes more and more interesting... | After you've typed in a question, you get suggested tags that appear that look like this: It appears that you need a minimum amount of characters (): you must have entered a title (any length) and a minimum body length of 220 characters. But other than that, how are the tags chosen? Is it: A match of the title/body with other questions (taking the tags from those questions) A match of the title/body with tag excerpts (taking tags with overlap) A match of the title/body with tag wikis (taking tags with overlap) All of the Above None of the Above Other (please explain) Some additional info from : The suggested tags seem to only pop up on meta.so (they do not work on regular Stack Overflow, or on other SE sites). While we're on the topic, why isn't this feature implemented network-wide? |
What is the explanation of the quantum entanglement in the quantum field theory framework? | I'm a bit confused. QFT is claimed to incorporate both Quantum Mechanics and Special Relativity. Therefore it should address the problem of non-locality caused by entanglement. However when I search for an answer on the Internet, I found nothing. I'm not complaining. But it seems that most people only use QFT to do some fancy particle stuff and forgot we should care more about the more fundamental stuff. |
I am trying to output an image in between every XX post shown on the /category/archive pages for every category. Years ago there was a tutorial online of how to do this, but I can't seem to find it now. I am writing a plugin that allows the admin to upload an image with a link to the image to create an advertisement on the site and have it show between every 10 posts shown on the category page. What hook would I use for this and would I need to loop through the posts before they are shown? Any help would be greatly appreciated. | I have a plugin where I want to output ads after X number of posts on the home page. The home page is step 1, but things like archives should be possible too once I get the code for the home page. How do I hook in to post loops and say something like "after every loop, increment a counter, and then if the counter = my number, output an ad". I can write all the logic for this code myself, but where to hook/implement my code is confusing. |
I'm new to Ubuntu and already have my first problem I just cant understand. I've set chmod 777 on /opt/lampp/htdocs (also set me as owner). When I open index.php, which is located in the htdocs directory via gedit, it works perfect. But when I try to open that file with notepadqq, I don't see its content and I'm also unable to save that file there. What could be the problem? | I have some trouble with the Ubuntu notepadqq package. After opening a file from my apache webroot I cannot see any content. Saving the file is also not possible. I thougt this would be a classic permission issue. Therefore, I changed the group of the webroot from root to www-data and added my user to this group. Permissions are 775, so in theory it should now be possible for me to edit files in my webroot. But nevertheless, when I open a file of this directory with notepadqq, it still only shows an empty file. When using gksudo notepadqq I get the following error message: No protocol specified QXcbConnection: Could not connect to display :0 I figured out that notepadqq is a so called snap application and I wonder if this is the reason for my problems. Can someone give me a hint how I could fix this issue (without using 777 permissions)? |
new to blender, but eager to learn, and spending lots of time with blender now. I am trying to make a simple solar animation in Blender 2.79, Cycles engine. The earth spins around the sun's (scene's) Z axix, but earth also has a constant tilt of 23.4 degrees to the sun. I need to keep this earth tilt constant and make the earth spin around it's own Z axis. I cannot figure out how shift the earth-mesh-objects coordinates. Even if I set the transformation orientation to Local, the earth still spins around the global scene's Z axis when I try to animate or rotate the Z axis of the earth. I have googled and searched but cannot find an answer. BTW! I don't want to change the angle of the sun to the earth to achieve the same effect. I also suppose I could manually apply rotations to all axis of the earth to simulate this, but this complicates things as I also have other objects I need to apply this to. Any tips on how to separate the earths axis from the scene and being able to apply separate/local rotations? As you see in the attached picture the sun and the earth mesh has different axis, but still, when trying to animate the earth it rotates around the scene/suns axis and shifts the poles of the earth around. | As you know, Earth rotates around it's axis in an angle of 23.5 degrees. How do I make a sphere in Blender rotate like this? |
I am working on a beamer presentation which will include many mathematical symbols. I use MiKTeX 2.9 and the TeXstudio IDE. I have run into a problem when I attempt to use certain mathematical symbols. Here is a MWE: \documentclass{beamer} % Document \begin{document} \begin{frame} \begin{itemize} \item This is normal text \item This item has a greek symbol: $\alpha$ \item This item uses it as a subscript $C_\alpha$ \end{itemize} \end{frame} \end{document} I use \alpha twice, once normally and once in a subscript. However, this only compiles without the third item. If that is included, this produces the error: !pdfTeX error: pdflatex.exe (file mathkerncmssi10): Font mathkerncmssi10 at 657 not found ==> Fatal error occurred, no output PDF file produced! I have made a web search for similar error texts and found nothing. I have no idea how to further proceed, and would appreciate any hints at what is actually going wrong. Update 1 It seems this is not related to the \alpha symbol at all, but instead just caused by any letters I try to typeset in mathmode. Including \item $a$ already causes this error and fails to produce any output document. | I have this problem where I can't built slide documents with beamer every time I include a math environment as simple as $\mu = A$. The log file posts this message at the end: !pdfTeX error: miktex-pdftex.exe (file mathkerncmssi10): Font mathkerncmssi10 a t 657 not found ==> Fatal error occurred, no output PDF file produced! I understand that the file (mathkerncmssi10) that is apparently missing is part of the package sansmathaccent, but the package is already there and updated. This is driving me crazy, I would appreciate any help. Sure, I tried this with several examples. I can post this one \documentclass{beamer} \usepackage[latin1]{inputenc} \usetheme{Warsaw} \title[Make a LaTeX presentation using Beamer]{Introduction to Beamer\\How to make a presentation with LaTeX?} \author{Nadir Soualem -- Astozzia} \institute{Math-linux.com} \date{Jule 13, 2007} \begin{document} \begin{frame} \titlepage \end{frame} \begin{frame}{Introduction} This is a short introduction to Beamer class. $\mu=A$ \end{frame} \end{document} By the way, it turns out that I just tried this one in another PC and works fine. |
Prove that for each $z\in \mathbb{C}$ we have $$\overline{\cos z} = \cos \overline{z}$$ using $ \cos z = {e^{iz}+e^{-iz}\over 2}$. Can you please give me a link or show this proff using the equation i wrote. My english sucks so i can really search for it. | I have a dilemma. I have a task where I'm supposed to show that $|\cos z|^2+|\sin z|^2=1$ if and only if $z\in \mathbb{R} $. In my argument I have that $$\cos z\cdot\overline{\cos z} + \sin z\cdot\overline{\sin z}=\cos z\cdot \cos\overline{z} + \sin z\cdot \sin\overline{z}$$ but my teacher said that $\overline {\cos z} \neq \cos \overline{z}$. Is this true? But $$\overline{\cos(z)} = \overline{\frac{e^{iz}+e^{-iz}}{2}}=\frac{e^{-i\overline{z}}+e^{i\overline{z}}}{2}=\cos(\overline{z})$$ |
Does anybody know how to eliminate the numbering only in sections D and E, whereby the title itself for the Section D or Section E should start exactly at the beginning of the line? Additionally, the section numbers should not appear within the table of contents and should start exactly at the beginning of the corresponding line. Thanks in advance! \documentclass[12pt]{article} \begin{document} \newpage \tableofcontents \section {Section A} \section {Section B} \section {Section C} \section {Section D} \section {Section E} \end{document} | I'm using the report document class for a thesis, and I need to add things like "Acknowledgements" and an "Introduction". I noticed that there is an \abstract command which would have been wonderful if applied similarly. How do I add these without messing up the chapters' numbering while being picked up by the ToC in proper order and page numbering? |
I own a MacBook Pro 2016 and I want to buy a second monitor with a 2k resolution that runs at 144Hz, is it possible? With what cable? I've tried to look up on apple support and it says this: Up to two displays with 5120-by-2880 resolution at 60Hz at over a billion colors Up to four displays with 4096-by-2304 resolution at 60Hz at millions of colors Up to four displays with 3840-by-2160 resolution at 60Hz at over a billion colors Thunderbolt 3 digital video output Native DisplayPort output over USB‑C VGA, HDMI, and Thunderbolt 2 output supported using adapters (sold separately) Still I cant find anythink about 2k resolution(2560 x 1440). I want to buy a monitor with a 2k and to run on 144Hz. I don't know if my macbook suports this, if it suports what type of cable do I need? | How do I find out the number, type, resolution & refresh rate of additional monitors I can attach to my MacBook or MacBook Pro? This is an attempt at a canonical QA, as per the Meta QA - to try prevent the myriad "same but different" questions we get on every possible combination of computers, cable & monitors There are perfectly good resources out there that Ask Different should not have to duplicate the efforts of. |
I try to prove that the open interval $(0,1)$ and $\mathbb{R}_+$ are equivalent sets. I thought maybe if I define a bijective function between those two sets; it would help, but I couldn't. Can you help with it? | I need to construct a bijection from an arbitrary interval $(a,b) \to\Bbb R$. I was thinking of somehow using the tangent function because it's asymptotic, but i'm not sure how to get started. |
I know there is a lot of discussion regarding whether a hard drive should be kept running at all times or turn off after a certain time I purchased a Seagate HDD (), and currently I have it set to turn off after every 1 minute because I do not use it often (I access it once every 1 hr.). I don't really mind the power consumption I just really care about longevity cause I do not have a backup system like RAID. so is this a stupid idea or is it alright? | Hardware description and problem introduction: I'm a Home user and I use Windows in a Home PC, I have 4 internal hard disks connected and running, 1 hard drive is for the OS, and the other hard drives are 'secondary' (They are single partitions, any RAID). For life circumstances I need to keep my PC ON every 24 hours of every day of every week of every year (I don't have money to buy expensive things such as NATs), the PC does not sleep and does not hibernate and does not turn off, but like I've said, I'm a home user, please don't threat this question like an intensive working PC of a company. The hard drive that stores the OS is working every minute all day, the others hard drive aren't but I access to those secondary hard drives like 20 times each day to navigate through their folders. I would like to be sure that I'm doing things the most safe possible that I can, I would like to keep alive the life of my hard drives the maximum time possible, so taking the information that I've explained above I would like to know if in my circumstances it's better to turn off the power of the secondary hard drive devices to save power or not, in the power management configuration that provides Windows. I ask this also 'cause I'm confused about opinions, an expert hardware 'mechanic' (I don't know the English word, sorry) said me that turning off the power of drives is not the most safer decission IN ANY CIRCUNSTANCES 'cause it depletes the total life time of the device each time that the device re-initializes, for example when a disk is turned off automatically by Windows and then I open the Explorer to navigate inside the hard drive folders it needs to wait some seconds to turn on the device to list the folders, and he said me that those insignificant seconds at the end depletes/waste away the total life time of the disk, and it's safer to don't turn off the power of the devices NEVER. The question: Then, what is better and safer for me? let windows power management turn off devices when they are not working, or keep on the power every time? If turning off the power of the devices at the end it's a life-time consumer then why Windows puts an unsafe checkable option in the power management? I'm very worried about the future state of my hard drives by let Windows turned them off/on every day 20 times when I need to read those secondary hard drives, so I'm only searching and I only can accept an answer of a professional hardware expert that could clarify my question. |
We know that if $f:K \to X$ is continuous and injective, $K$ is compact, and $X$ is Hausdorff, then $f$ is a homeomorphism $K \cong f(K)$. So suppose $f:U \to \mathbb{R}^n$ is continuous and injective, where $U$ is an open subset of $\mathbb{R}^n$. Choose an open ball $B$ such that $B \subset \bar{B} \subset U$. By the remark above $\bar{B} \cong f(\bar{B}) \Rightarrow B \cong f(B)$. Finally, since $B$ is open, so is $f(B)$. My instructor said something about not knowing that $f(B)$ is open even though it is homeomorphic to an open set, but I'm not sure I understood at all. | The states that, given an open subset $U\subseteq \mathbb{R}^n$ and an injective and continuous function $f:U\rightarrow\mathbb{R}^n$ then $f$ is a homeomorphism between $U$ and $f$'s image. I tried proving it by using another theorem: if $g:K\rightarrow X$ is injective and continuous, $K$ is compact and $X$ is then $g$ is a homeomorphism between $K$ and $f(K)$. But I'm not sure on how to prove this (sub)-theorem? or perhaps there exists an easier proof of the invariance of domain theorem? |
Just trying to install sssd, getting the following errors: Failed to fetch 404 Not Found [IP: 18.232.150.247 80] thanks Mike | NOTE: This is a Master Canonical Post for the issues observed on February 25, 2020. All issues on Feb 25 relating to Python updates not found should be dupe-linked here. Errors have been seen such as this today, February 25, 2021: Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/p/python2.7/libpython2.7-minimal_2.7.17-1~18.04ubuntu1.3_amd64.deb 404 Not Found Is there something up with the repositories? |
In some contexts, I see the \text command used as follows: $ A_\text B $ , which renders correctly as italics A subscripted by a roman B. However, I recall that I "read somewhere" that the proper usage is $A_\text{B}$ or even $A_{\text{B}}$. In particular, I note that importing packages like breqn introduces errors in the first and second cases. What is correct, and why? | I want to define a macro \ind which let's me set in math mode a subscript in upright letters and when starred (\ind*) in italic letters. Additionally, an optional argument allows me to adjust the kerning between letter and index, i.e. W_{\ind[-2mu]{x}}. This works quite well. But surprisingly, I have to put braces around the \ind-command in order to make it run. Can someone explain me why I have to put braces around the command and how I can modify the macro to avoid this? It's a super big deal but I would like to understand the mechanism behind it. The error is always that a { and a } is missing. MWE: \documentclass{article} \makeatletter \newcommand\ind{\@ifstar{\ind@star}{\ind@nostar}} \newcommand\ind@star[2][]{\mkern \muexpr 0mu #1 #2} \newcommand\ind@nostar[2][]{\mathrm{\mkern \muexpr 0mu #1 #2}} \makeatother \begin{document} $\sigma_{\ind{xy}}$ % works $\sigma_\ind{xy}$ % does not work \end{document} |
I just updated my iPad Air to iOS 8. Now it won't mount any more on my computer running Ubuntu 12.04. When I plug it in, it gives me a message that says, "Unable to mount iphone / Unhandled Lockdown error (-3)". Before the update when I'd mount it, I would see two drives in the file explorer window, "Documents" and "Ipad". The former has the files of all my apps, while the latter has my photos and settings and stuff. Now the "Documents" drive won't mount and I see an unmounted drive icon labled iphone. The Ipad drive mounts as normal. What I need is to get the Documents drive back. My iPad isn't jailbroken. Until now Ubuntu has allowed me to be a proudly iTunes free iPad user. I'd hate to change that. | What ubuntu applications provide support? (guides, how to's, status) Also, specifically, details on support for syncing music to iPhone's and iPod's with the latest OS version: Can you sync music to apple devices using >iOS4? (iPhone & iPod) What applications allow you to do this and how? (guides, how to's, status) What has already been established is: Apple does not support Linux and has no plans to. provides some support, however it currently does not support music/video synchronization with devices >iOS4. Go to and scroll to the section titled "" to see if your device version is supported. |
I am an Algerian citizen, working as a computer scientist in Paris. I have been refused a tourist visa for UK for the second time despite having strong applying documents, good income, and a rich travel history(I gave all my boarding passes that includes flights to +10 EU countries + canadian visa) The reasons given seem absurd to me, and I really think they just don't want me to visit UK independently from given documents. You state that you intend to visit the UK for 4 days and propose tourism. Am I not free to decide how long I want to visit the country depending on my budget and holidays given by me employer ? In support of this you have submitted your payslips, letter confirming employment and bank statements in French. It is unclear whether your employment is permanent, temporary or fixed term and whether your employer has granted you leave for the stated duration of your trip. I could have agreed with this argument, if I haven't applied with a colleague that has gave the same proof of employment as me(which was in french), and had his visa. Furthermore the visa application required documents are around 50 pages long, and it costs around 50€ to translate one paper, which means I have to spend 2500€ for translating document, this is ridiculous ! For my first application that has been refused too, all documents were in french and this wasn't the reason of the refusal(it was because I applied during summer as a student and I didn't have my new student card yet), they were able to extract information from the application's documents. I note that the bank statements you have submitted do not correspond with the income you have stated on your Visa Application Form (VAF) or your payslips. This is I think the worst reason, some months I'm paid 2000€ instead of 2100€ because it was a month with one less working day(30 instead of 31) The bank documents you have provided show large credits not commensurate with your documented income in the time leading up to your visa application. There is no explanation provided regarding the origin of these funds. I am not satisfied these funds are genuinely available for your use and have been provided to you for the sole purpose of obtaining an entry clearance for the UK. I don't know what to say about this, I have other accounts where that a use to transfer money to for savings. I don't know what more I can do to proof that these funds are mine, since they are here in my account for years. Considering the refusal reasons, the only document I can translate is my certificate of employment and income given by my employer, and since this refusal(one month ago) I have been given an USA visa. So, with these two new elements, is it worth applying again or should I give up ? I'm afraid they will think I'm a bit obsessed if I apply again(which is partially true because UK /Eire is the only part of Europe I haven't visited yet) | Many of the UK visa refusals we see here share a common pattern and the prevailing reasons refer to V 4.2 (a) and (c). I do understand that, while the applicants may describe very different individual circumstances, there's a consistent pattern and, broadly, fall into specific categories: Credibility (lifestyle, lack of ties, visit history, lies & omissions) Funding (insufficient funds, provenance of funds, funds parking) Sponsorship (family, friends, employer) Question: What most commonly triggers a UK visa refusal where V 4.2 (a) and (c) are given as the grounds? Secondarily: Given that there is a clear pattern, to what extent are these refusals predictable? Does sponsorship make a difference? Is there a set of personal circumstances, however abstract, where a refusal is all but guaranteed? For example, why do those we see here on TSE who sought entry for the PLAB or British Army appear to be refused with a common theme? Is there a uniform shortcoming or is it just discrimination? PLAB: What is about applications for a visa, for the purpose of sitting the Professional and Linguistic Assessments Board (PLAB) exam, that seem to invite refusals. After all, the test is given so that international medical graduates can show that they qualify to practise medicine in the UK. The first part, PLAB 1, can be taken in centres outside of the UK. However, PLAB 2 can be taken only in the UK. Why can't you can't get a visa just to sit the exam, promising that you'll leave immediately after? British Army: Since Commonwealth citizens are eligible to apply online to join, even those who don't reside in the UK, why is it so difficult to get a visa just to attend an interview to see whether you are suitable? Even with an invitation from the Army, such visa applications seem to be unsuccessful. Isn't a career in the British Army a valid reason? Lastly: After such a refusal, what approaches would increase the chance of a successful application? |
I have a c++ vector of student objects with each object having an ID(string), name (string) and age(int). std::vector<student> myVector; Lets say the vector looks like this [{"1", "Tom", 12}, {"2", "David", 10}, {"3", "Adam", 15}, {"4", "Jill", 20}] Is there any way I can delete an object in the vector using the student Name like: myVector.deleteObjectWithName(David) such that my remaining vector is now [{"1", "Tom", 12}, {"3", "Adam", 15}, {"4", "Jill", 20}] | I was looking at the API documentation for stl vector, and noticed there was no method on the vector class that allowed the removal of an element with a certain value. This seems like a common operation, and it seems odd that there's no built in way to do this. |
I need to find a bijection between the power set $P(\mathbb{N})$ and the set of functions $J=\{f|f:\mathbb{N}\to \{0,1\}\}$ I considered the map $g:P\to J$ as $g(A)=f $ where $f$ is a function who is mapping $A$ to {0} and $\mathbb{N}\setminus A$ to ${1}$, then i think this will be a required bijection! | I recently got the book "selected problems in real analysis", and I'm stuck solving the very first problem $(u_n)$ is a binary sequence iff it only contains $0$ and $1$ in the sequence Let $A$ be the set of all binary sequences I have to prove that $A$ and ${2}^{\mathbb{N}}$ have the same cardinality, that is to say there exists a 1-1 function from one set to another I've thought about maybe considering integers as base-2 numbers Thanks for your help |
How can I solve this limit without using L'Hopital rule or other advanced methods? $\displaystyle\lim_{x \rightarrow 0}\left(\frac{2^x+8^x}{2}\right)^{\tfrac{1}{x}}$ | I want to calculate the limit of: $$\lim_{x \to 0} \left(\frac{2^x+8^x}{2} \right)^\frac{1}{x} $$ or prove that it does not exist. Now I know the result is $4$, but I am having trouble getting to it. Any ideas would be greatly appreciated. |
In the UK, one needs to pay a council tax regardless of whether you rent or own a house. And unlike the US, there is no prohibitive property tax when you own a house. So, does that mean the only financially smart thing to do is buy a house in the UK regardless of how long one plans to be in the country? Are there purely financial counter-arguments to buying a house in the UK? | I am a 22 year old currently renting accommodation with my partner in the UK, and we are wondering if now is a good time to buy a property, and whether or not we can afford it. As background, my salary before tax is £70,000 p.a. and my partner's is £36,000 p.a. This year I have a guaranteed bonus of £30,000 (i.e. written into my employment contract) before tax. After this, my target bonus is £10,000 p.a. We are looking at houses around £500,000/£550,000 in the area just inside the M25 and when we are ready to buy, we will have savings of £55,000 for a deposit and £20,000 for stamp duty and legal fees. Looking at Mortgage calculators such as provided by , based on these figures it would appear that we may be eligible for a mortgage up to ~£530,000, which should be enough. A mortgage of this amount will require repayments in the order of £2300-£3000 per month. After tax, our joint earnings per month is about £6345, without bonuses. I am aware that interest rates are currently low, and am conscious that recently 3 members of the Bank of England MPC voted in favour of raising the base rate; so I do not want to miss out on preferential mortgage rates. Moreover, if we do not buy a house, we will be spending money on rent, probably ~£1500 per month and this will just be expenditure with no assets at the end to show for it. So my question is: based on this information, should we be looking to buy ASAP, or wait to accumulate more savings and buy a house using a smaller mortgage? |
I just wanted to know because I'm not the best when it comes to commands. These are the things I tried: /effect give @p poison 1 100 true but fast poison doesn't work. Then I tried /attribute base set @p minecraft:max_health 1 attribute base set @p minecraft:max_health 20 To try to mess with the regeneration system. Finally I tried /effect give @a instant_health 1 99 true and summon tnt ~4.5 ~ ~ But I had to be too precise with the tnt. | I want to be able to give an entity damage for a command I’m making, but instant damage effect is way too much, how do I apply other amounts of damage with command blocks? |
How do you compute this integral? $$\int_0^{2\pi} e^{R \cos t} \cos(\sin t+3t)dt \quad R>0.$$ My friend sent this to me the other day, but have not made much progress so far. Maybe using line integrals would be the easiest way to go about, since it looks like it will get messy very fast. He says that the answer should be $0$ which makes me think that this thing is symmetric over $\pi/2$, but not sure. | Calculate: $$\int_{0}^{2\pi}e^{R{ {\cos t}}}\cos(R\sin t+3t)\mathrm{d}t$$ My try: $\displaystyle\int_{0}^{2\pi}e^{R{ {\cos t}}}\cos(R\sin t+3t)dt\\ \displaystyle \int_{|z|=R}e^{\mathfrak{R\textrm{z}}}\cos(\mathfrak{I\textrm{z}}+3(-i\log z)dz\\ \displaystyle \int_{|z|=R}e^{\mathfrak{R\textrm{z}}}\mathfrak{R\textrm{e}}^{(\mathfrak{I\textrm{z}}+3(-i\log z))i}dz\\ \displaystyle \int_{|z|=R}e^{\mathfrak{R\textrm{z}}}\mathfrak{R\textrm{e}^{\mathfrak{I\textrm{z}}}}z^{3}dz\\ \displaystyle \int_{|z|=R}e^{\mathfrak{R\textrm{z}}}\mathfrak{R\textrm{e}^{\mathfrak{I\textrm{z}}}R}z^{3}dz$ and there is nothing here that is not holomorphic, therefore according to Cauchy theorem it must be exactly $0$. |
Is it possible to style the tooltip for the alt attribute? I wish to style the background, font color etc for the html alt attribute. Can anyone help me with this please? | Is it possible to format an HTML tooltip? E.g. I have a DIV with attribute title="foo!". When I have text-size of my browser zoomed in or out in, the text size of the tooltip remains unchanged. Is there a way to make the tooltip font scale with the browser setting? |
I want to change the appearance (size, shape and color) of the mouse pointer. What options are available for me? | I have recently created an Ubuntu 12.04 partition on my Windows 7 laptop. When installing it, I switched to "high contrast" mode, which has rather large cursors (by large I mean about twice as large and thick as they should normally are). Now I have successfully installed the partition, the large cursors have stuck around even after exiting this high contrast mode, but only when I am hovering over stuff e.g. hovering over text inputs, links, and when resizing windows. All of these cursors are too large. They cursor is only normally sized when the computer should be displaying the normal mouse pointer. Does anyone know how I might go about fixing this? |
I am an undergraduate applied math and statistics major and plan on applying to PhD programs after graduation. My research interests are in machine learning, cv, etc.. And do research in the stats and CS department in ML/DL. I am thinking of applying to PhD CS programs, but have only taken 4 CS classes in undergrad, but I have had two internships with Amazon as a software engineer. Can my experience in industry make up for the lack of CS classes as an undergrad? I obviously want to get into the best program possible, but worried that my lack of CS classes might hinder my chances of getting accepted. edit: Not a duplicate. Not worried about weak grades, gre, research, etc.. I am just wondering from a graduate admissions perspective will they look negatively on less CS classes even though I have research and industry experience in CS. | When applying to a PhD program in the US, how does the admissions process work? If an applicant is weak in a particular area, is it possible to offset that by being strong in a different area? Note that this question originated from this . Please feel free to edit the question to improve it. |
I just downloaded ubuntu from the website & had it saved under my documents but i can't seem to figure out how to get to the next phase of it being installed & running on my laptop. Most all the instructions I've come across don't seem to mention anything other than when I reboot I should be given the option to choose to run it or windows...not sure if this is before or after the installer should be done or how it is to be done. A little help & guidance will be appreciated, thank you. | I would like to see a full how-to guide on how to install Ubuntu. |
I'm a senior student in high school and we are learning about Particle Physics in Physics. I wanted to ask a question about neutrons. Is there a possibility that neutrons may not even be a particle, just a bond, relationship or pairing between electrons and protons? Can neutrons just be the cancelling out of electrons and protons charges, forming a neutral charge inside the nucleus and not an actual particle? For example, carbon has 6 electrons, 6 protons and 6 neutrons. Could the 6 neutrons and 6 protons cancel each other out forming 6 neutral charges making the atom stable? The protons and electrons would still exist but they just form a stable atom by being neutrally charged. I know this is extremely unlikely and most likely wrong but I really wanted to know if there was an answer to this or is the theory we have have no correct and there is no need for further debate. | I imagine that there is a pretty simple answer to my question, but I have just never gotten it straight. If a proton is comprised of two up quarks and a down, and neutrons are comprised of two down and an up, how can a neutron be a proton and electron? |
How can I create an Outlook 2013 rule which moves any message that doesn't have me listed as a recipient? It's easy to do this for messages which aren't To me, but I only want it to trigger if I'm not on the To or the Cc. UPDATE: These messages will still arrive, either through BCC, or, more commonly, through certain bulk mailers and mailing lists, which deliver mail without the To: header. | i want a folder with all emails that come to me because i am in distribution list. I see how i can do this individually (1 rule for each specific list) but i wanted to see if i can do this in one rule for all dist. lists without having to specify the list names ? |
Let $l\in\mathbb{Z}$ and $N\in\mathbb{N}$. I need to prove the following: \begin{equation} \sum_{j=0}^{N-1}\cos\left(l\frac{\left(2j+1\right)\pi}{2N} \right)=0 \end{equation} I tried to use Euler formula and then sum the first $N$ terms of the geometric serie I get, but it didn't work. Any ideas? | How can we sum up $\sin$ and $\cos$ series when the angles are in arithmetic progression? For example here is the sum of $\cos$ series: $$\sum_{k=0}^{n-1}\cos (a+k \cdot d) =\frac{\sin(n \times \frac{d}{2})}{\sin ( \frac{d}{2} )} \times \cos \biggl( \frac{ 2 a + (n-1)\cdot d}{2}\biggr)$$ There is a slight difference in case of $\sin$, which is: $$\sum_{k=0}^{n-1}\sin (a+k \cdot d) =\frac{\sin(n \times \frac{d}{2})}{\sin ( \frac{d}{2} )} \times \sin\biggl( \frac{2 a + (n-1)\cdot d}{2}\biggr)$$ How do we prove the above two identities? |
Based on some samples: I'm trying to update my twitter status from command line (via cURL), but always get error. Any idea what I'm doing wrong? curl -u <anonymized> -d status="#curl test" -d source="cURL" https://twitter.com/statuses/update.xml Enter host password for user '<anonymized>': <?xml version="1.0" encoding="UTF-8"?> <errors> <error code="34">Sorry, that page does not exist</error> </errors> Or possibly, do you have an alternative solution for this (maybe not over cURL)? | I would like to tweet a message using terminal. I tried something like: curl -u 'TwitterUsername':'TwitterPassword' -d status=”Your Message Here” https://twitter.com/statuses/update.xml but seems this isn't working anymore. I get a error like this one: <?xml version="1.0" encoding="UTF-8"?> <errors> <error code="53">Basic authentication is not supported</error> </errors> So, how could we tweet from the terminal? PS.: my motivation to this is because I use the Yakuake terminal a lot, and it would be awesome to tweet from there. |
I have been working on something for which a ticket was not yet open. I made multiple checkins but didn't have them associated with a ticket. Now that the ticket has been created I have been trying to find a way to associate my previous checkins with it with no luck. Is this even possible? | Is it possible to go back and tie work items to code that's already been checked into TFS? For example . . . A developer picks the wrong work item, or forgets to pick a work item? I can see work item details for ChangeSets, but the work item page is read-only. |
I've just finished installing Ubuntu 13.10 on my computer. When I start the computer, after the Ubuntu logo fades away, I see this message: the disk drive for /dev/mapper/cryptswap1 is not ready yet or not present Then the login screen appears and when I enter my password I go to my desktop. Is this normal? Do I need to do something about it? | While booting Ubuntu 12.04, the disk drive for /dev/mapper/cryptswap1 is not ready yet or not present is showing. Why is this? |
Recently I scanned my Windows PC using Avast and it showed the presence of some weird malware in the result. It couldn't remove all of them nor it could move all the malware to the chest. Now I am facing some serious trouble: My start menu is not working nor Cortana (search) is opening. Task bar icons are not showing up. I am able to click the task bar icons but I can't see the icons. My internet connection (modem) is getting disconnected by itself. When I click on the personalize settings, it says "This file has no program associated with it." There are some serious troubles. Please help me. Will restoring to a previous point remove the malware? | What should I do if my Windows computer seems to be infected with a virus or malware? What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware? This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits. |
So, I main playing the bot lane, but I like to be capable in all positions. So what DOES make a jungle champion, a jungle champion? I know one key element is self-sustain, but at the same time, I know of several champions that are viable in the jungle, that have no real source of self-sustain. This includes a lot of the champions that are only "Glass Cannon" style junglers, such as Shaco, and a couple others, like Volibear. I know Volibear's passive restores his health, but as it has 2 minute cool down, I don't consider it to be a sustain tool. After looking at Shaco and some other glass cannons, I tried Talon in the jungle, and while it got the job done, it didn't feel like it was as strong as a jungler like Shaco, Kha'Zix or Master Yi. I want to know, is there some sort of common trait I can look for, to see who is the most viable in the jungle. Please keep in mind, that for me Viable doesn't necessarily mean that it works, it means it works well enough to be competitive through all levels of play. Please don't recommend things like jungle Leona or Jungle Sivir. So in general, I guess I'm looking for how to determine if a champion can jungle well. How big a factor is sustain (Lifesteal/Spell Vamp/Mana Restore)? What kinds of damage output are needed? What about defenses? I'm looking for stats, not just general features. | In general, what characteristics should a jungling champion have? |
Let G be a finite group, if $H\lneq G$ and $|G| \nmid ( \, [G:H]! \, ) $ then prove $G$ is not simple. I used contrapositive argument. Suppose $G$ is simple then we need to prove that $ |G| \mid ( \, [G:H]! \, ) $. Now consider the group action $$f:G\times G/H \rightarrow G/H \\ (g,xH) \mapsto (gxH)$$ Note that it is not necessary for $H$ to be a normal subgroup of $G$. This group action is equivalent to a homomorphism $\phi : G \rightarrow S(G/H)$. Then $K=Ker(\phi) \trianglelefteq G$. If $K={1}$ then $|G|$ divides $|S(G/H)|=[G:H]!$ . Now i am not sure how i can exclude the case of $K=G$. Any hints ? | I'm looking for verification: My claim: If $G$ is a finite group and $H$ is a (proper)subgroup of index $k>1$, where $k! \leq |G|$, then $G$ is not simple. Proof: Consider the set of left cosets of $G$ by $H$: $$G/H = \{H,g_1H,\dots,g_kH\}$$ Then $\phi: G \rightarrow S_{G/H}$ is a homomorphism where we define: $$\phi(g)[g_iH] = g g_iH$$ ($S_{G/H}$ is the group of permutations on elements of $G/H$ and of course $S_{G/H} \cong S_k$.) Also $\ker \phi \neq G$ because $\phi(g_1)$ is clearly not the identity in $S_{G/H}$. Because $\phi$ is a homomorphism, $$ G/\ker\phi \cong \text{im}\phi$$ Then $|\text{im} \phi| \leq |S_k| = k!$ and if $k! \leq |G|$ then $|\ker\phi| > 1$ and $\ker\phi$ is a non-trivial normal subgroup of $G$. Example: If a group of order $36$ has a subgroup of index $3$ or $4$ then the group is not simple. |
I'm building a website, and there is a input that allows the user to write some text and search for it on google. I have everything working already, except that the user has to click the search button to make it go to google. I wanted to be able to press enter key and it search. Is there any way? code: <img id="google-logo" src="1280px-Google_2015_logo.svg.png"> <input placeholder="Pesquisar na Web" id="google-search"> <img src="search.png" id="search-img" value="Submit" onClick="javascript: window.location.replace('http://www.google.com/search?q=' + document.getElementById('google-search').value);"> | I have one text input and one button (see below). How can I use JavaScript to trigger the button's click event when the Enter key is pressed inside the text box? There is already a different submit button on my current page, so I can't simply make the button a submit button. And, I only want the Enter key to click this specific button if it is pressed from within this one text box, nothing else. <input type="text" id="txtSearch" /> <input type="button" id="btnSearch" value="Search" onclick="doSomething();" /> |
I'm just working through some flags, and I notice that some answers allow a choice of NAA and VLQ (among others), but some particular questions don't allow VLQ. For example, for , which I think shouldn't be "Not an answer" (because it is, it's correct, it's just very poor on content), so I'd like to flag it as "Very low quality". However, the flag options I'm shown are just these: Where has the "Very low quality" option gone? It's ok for many other answers. | Why is the option very low quality sometimes hidden in the flag menu? About a moment ago, I saw a post of very low quality on Stack Overflow, and I wanted to flag it as very low quality but this option was not in the flag menu. Why? |
So I have find . -name \*.md -type f -exec pandoc --filter ./filter1.py -o {}.html {} And notice the {}.html. The {} returns a filename ending with .md, but I want it to just return the filename without the .md, so say I have a file named index.md, {} should return index, resulting in a file named index.html, rather then resulting in a filename named index.md.html. So how would I go about removing the .md within this command? | I need to create thumbnails from multiple .png files and would like to do this using ImageMagicks convert utility. To recursively find all files that are not thumbnails themselves, I am using the following call (split into two lines to make it readable): find . -type f -name "*.png" -not -name "*thumb.png*" \ -exec convert {} -thumbnail 200x200 {}.thumb.png \;` But this would of course create a file named a.png.thumb.png when running it on a file called a.png. How could I remove the .png extension from the second {} parameter passed to convert? |
I want to be able to temporarily enable non-free or contrib but I don't want to keep them enabled all the time as I try to utilize open source software as much as possible. | How do I get to the Universe Repository in supported versions of Ubuntu? |
The number of subgroups of order 2 of $S_4$ is nine? In fact I have : {1,(12)}, {1,(13)}, {1,(14)}, {1,(23)}, {1,(24)}, {1,(34)}, {1,(12)(34)}, {1,(14)(23)}, {1,(13)(24)} | I am trying t prove that there are only 9 subgroups of $S_4$ isomorphic to $S_2$ but I only find 7 different ones( fix 12, 13, 14, 23, 24 34 and swap the remaining two + identity). Which cases am I missing? And also is there a subgroup of $S_4$ isomorphic to $Z_6$ ? |
I run a web development firm and a hosting company and we are launching new blogs for each company. Should we launch our blog within our sites (like domain.com/blog) or should it be a stand-alone site/blog (like siteblog.com with its own design design of the site, but as if it were a separate site? Why would you go with either over the other? | I'm adding a blog to a site. Would it be better for SEO to put it at blog.example.com or at www.exampleblog.com? I already own www.exampleblog.com . Would combining the words together to exampleblog have a negative effect? |
There are several Q&A threads that explain how to download youtube videos using the terminal. However, I would also like to learn how to extract the video's soundtracks as MP3 files--also using only the terminal. Answers briefly explaining how to use youtube-dl or other similar utilities before explaining how to extract the MP3 would be ideal for the sake of having all the information in one place--even though this aspect has been covered in other posts. | What are instructions on how to download videos from YouTube? Notice: Terms of Service Violation Please be aware that by following any of the answers below, you will be violating YouTube's . In particular, from Section 5.B.: Content is provided to you AS IS. You may access Content for your information and personal use solely as intended through the provided functionality of the Service and as permitted under these Terms of Service. You shall not download any Content unless you see a “download” or similar link displayed by YouTube on the Service for that Content. You shall not copy, reproduce, distribute, transmit, broadcast, display, sell, license, or otherwise exploit any Content for any other purposes without the prior written consent of YouTube or the respective licensors of the Content. YouTube and its licensors reserve all rights not expressly granted in and to the Service and the Content. |
I have a class called run_c which is being used to initialize and execute the run of a kinematics simulation. I assign default values to the attributes of run_c, such as x, before run_c.__init__() is executed. All __init__() is doing is extracting user-input values, aggregated into a dictionary, and assigning them to corresponding attributes in run_c if they exists. For example... import vars.Defaults as dft class run_c: ... dt = dft.dt x = dft.x0 states = [ [], [], [], [] ] ... def __init__(self, input): for key in input.keys(): if hasattr(self, key): setattr(self, key, input[key]) ... self.execute() run_c.states is a list of lists that is being used to record the values of run_c attributes as they change with timesteps. Later, within run_c.execute(), I am storing x values in states[1], incrementing the timestep dt, and updating x using velocity and timestep. It's pretty simple stuff, right?... Here's where the problem begins, though. The first time that the instance of run_c is created, initialized, and executed, it runs perfectly. However, I am operating this simulation by creating, initializing, and executing multiple runs based off of list read from a JSON file. As such, in the driver module... from Run import run_c def main(): ... for runEntry in runList: currRun = run_c(runEntry) ... ... What happens is that all the values that were stored in run_c.states do not get wiped after each iteration of the loop. I thought that new instances of run_c are being created every time I run the loop so as to execute __init__() fresh with new information. Why are the data values, such as old values for x, being retained after the end of each loop? Update: When I add in a line of code to reset the values of states back to empty lists within __init__(), the problem goes away. But this shouldn't be a necessary step in what I want to do...should it? | Is there any meaningful distinction between: class A(object): foo = 5 # some default value vs. class B(object): def __init__(self, foo=5): self.foo = foo If you're creating a lot of instances, is there any difference in performance or space requirements for the two styles? When you read the code, do you consider the meaning of the two styles to be significantly different? |
As you can see in the snippet below, I have a 2x2 grid made in flex. The problem I have with it is that the text inside the top right and bottom right <p> elements are on the left side of the <p> and I would prefer if I could push them to the right side. I've tried fiddling with justify-content: flex-end; but it doesn't seem to do anything in my case. .stats-container { display: flex; flex-wrap: wrap; } .stats-container > p { flex-basis: 50%; } <div class="stats-container"> <p>Likes</p> <p>Views</p> <p>Comments</p> <p> <a class='downloadImage' href=""> <span class='specific-image-text'>Download</span> </a> </p> </div> | I have a couple of <p> tags that I want to right align. Does anyone know how to do this? |
The following code gives the error UnboundLocalError: local variable 'Var1' referenced before assignment: Var1 = 1 Var2 = 0 def function(): if Var2 == 0 and Var1 > 0: print("Result One") elif Var2 == 1 and Var1 > 0: print("Result Two") elif Var1 < 1: print("Result Three") Var1 =- 1 function() How can I fix this? Thanks for any help! | The following code works as expected in both Python 2.5 and 3.0: a, b, c = (1, 2, 3) print(a, b, c) def test(): print(a) print(b) print(c) # (A) #c+=1 # (B) test() However, when I uncomment line (B), I get an UnboundLocalError: 'c' not assigned at line (A). The values of a and b are printed correctly. This has me completely baffled for two reasons: Why is there a runtime error thrown at line (A) because of a later statement on line (B)? Why are variables a and b printed as expected, while c raises an error? The only explanation I can come up with is that a local variable c is created by the assignment c+=1, which takes precedent over the "global" variable c even before the local variable is created. Of course, it doesn't make sense for a variable to "steal" scope before it exists. Could someone please explain this behavior? |
Let me redo this, I was accessing a sever via ssh, i can access the server easily from my system (the server is in my local network). I tried copying a file from my local system to my server and it failed due to an error (permission denied). And now I do not want to dig whats wrong and instead want to get that file(which is on my system) from my server directly to which I am ssh'd into. Old questions: /* I am using scp as a root, tried all the things but unable to copy files from my system to the remote server (to which I am logged-in via ssh from the same system). Let say i want to get the files from my system while being on ssh'd server, how do i do it.* | It's driving me nuts! I just want to transfer one simple file from laptop to server. I'm using ubuntu on both machines. So I have: -rwxr-xr-x 1 sandro 414622 2011-10-14 23:42 sandrophoto-html.tar.gz And I'm sending it using: sudo scp -P XXXX sandrophoto-html.tar.gz [email protected]:/media/xx/xx/xx And I get: scp: /media/xx/xx/xx/sandrophoto-html.tar.gz: Permission denied p.s. I might be doing this other way around - I want to send file tar.gz that is located on my desktop, to remote server into the folder /media/yadayda |
Is it possible to print a certain field in the bibliography while omitting it in the (footnote) citations? For example: \usepackage[backend=bibtex,style=verbose-trad1,natbib=true,doi=false,isbn=false,url=false]{biblatex} \addbibresource{x-mendeley.bib} ... \renewcommand{\mkbibnamefamily}[1]{\textsc{#1}} \printbibliography Prints this citation and bibliography: I can get the url, isbn etc. in there by using: \usepackage[backend=bibtex,style=verbose-note,natbib=true]{biblatex} This is what I want for the bibliography, but I don't want all these long urls etc in the footnote citations. Is there a way to differentiate between the two? And could I for example add the isbn's to the citation but not the url? | I am using Biber and the verbose IBID style setting to generate my footnotes. Here is my bibliography settings \usepackage[citestyle=verbose-ibid, bibstyle=authoryear, backend=biber, labeldate]{biblatex} Some of my book entries in the bib file contain URL data (e.g. the Google book reference). I like the fact that these are showing up in the bibliography section at the back of the document, but I do not want them showing up in the full version of the first citation of a work. Is there some way to de-activate URL printing in the main matter, but not in the back matter, e.g. by redeclaring some macro? Thanks! |
I would like to install my Epson Scanner ( model WP-4535 ) in Ubuntu 16.04 (had it installed in 15.10). I installed this sudo apt-get install sane libltdl7 then iScan from the epsonpage (1), which is supposed to be an all-in-one package. I installed it via ./install.sh which results in having the following iscan parts: x@y:~$ dpkg -l iscan* | grep ii ii iscan 2.30.3-1 amd64 simple, easy to use scanner utility for EPSON scanners ii iscan-data 1.39.0-1 all Image Scan! for Linux data files ii iscan-network-nt 1.1.1-1 amd64 Image Scan! Network Plugin iScan still cannot communicate with the scanner, though it can be identified via the following command scanimage -L device `epson2:net:192.168.0.7' is a Epson PID 087D flatbed scanner If I recall it from 15.10 (worked after hours of meh) , epkowa was the solution not epson2, but adding it manually via sudo nano /etc/sane.d/dll.conf doesn't work. The ubuntuuser page (2), suggests installing ltdl7 packages, which seems to be important, but I have no clue, how to find it (same with the plugin): iscan_2.X.X-1.ltdl7_i386.deb (32 bit) / iscan_2.X.X-1.ltdl7_amd64.deb (64 bit) ggf. iscan-plugin-gt-1500_2.1.2-1_i386.deb (allgemein iscan-plugin-SCANNER_VERSION_ARCHITEKTUR.deb) oder z.B. etwas wie esci-interpreter-perfection-v330_0.1.1-2_i386.deb Also installed xsltproc (3), because of reasons, but didn't change it. Any suggestions?; help appreciated! (1): hxxp://support.epson.net/linux/en/iscan_c.php?version=1.0.4 (2): hxxps://wiki.ubuntuusers.de/Hardware/Epson/#Verwendung-von-iScan (3): hxxps://wiki.ubuntuusers.de/Scanner/Epson/ | I have the Epson SX218 with a built-in scanner. The printer works fine but if I want to scan something simple scan says no scanner found. Any ideas what I can do? By the way, how can I check the ink level of the printer?? |
I was confused about why in anime, high school students were not allowed to work. I understand in real life that they have to have permission from the school. Maybe I'm just reading into it too much as a Westerner. | In Hana and Hina After School (Hana to Hina wa Houkago) one of the main plot points it that neither Hana or Hinako are actually allowed a job and if discovered they could be expelled, to the point that Hinako quit her job as a Model and in Chapter 14 (still reading) Hinako quit her job with Hana because Maiko posted online about buying something where Hinako worked. Is this really something in Japan? that students like Hana and Hinako aren't allowed jobs and would actually get expelled for having one, even if it doesn't interfere with their school works? (as shown how Hana's and Hinako's work scheduled were changed so they could do their exams) |
I'm trying to find out where does the word OK come from? | I've heard lots of varying histories of the term "OK". Is there any evidence of the true origin of the term? |
I'm trying to define a function prem_dern that returns the first index and last index of an input real number ( by the user ). When executing, the intitializing part works fine but not the prem_dern function ( program exits right after compiling. The program doesn't return any errors when compiling.Here is what I did : #include <stdio.h> #include <stdlib.h> void prem_dern(float t[], int n, float r) { int i,j; printf("donner le reel pour savoir les positions "); scanf("%f",&r); for(i=0;i<n;i++) { if (t[i]==r)printf("la premiere position %d:",i); break; } for (j=n-1;j>0;j--) { if(t[j]==r) printf("la derniere position %d:",j); break; } } int main() { int i,n; float r; float t[100]; printf("donner le nombre des elements : \n"); scanf("%d",&n); for(i=0;i<n;i++) { printf("donner un element :"); scanf("%f",&t[i]); } prem_dern(t,n,r); return 0; } | Why does everyone tell me writing code like this is a bad practice? if (foo) Bar(); //or for(int i = 0 i < count; i++) Bar(i); My biggest argument for omitting the curly braces is that it can sometimes be twice as many lines with them. For example, here is some code to paint a glow effect for a label in C#. using (Brush br = new SolidBrush(Color.FromArgb(15, GlowColor))) { for (int x = 0; x <= GlowAmount; x++) { for (int y = 0; y <= GlowAmount; y++) { g.DrawString(Text, this.Font, br, new Point(IconOffset + x, y)); } } } //versus using (Brush br = new SolidBrush(Color.FromArgb(15, GlowColor))) for (int x = 0; x <= GlowAmount; x++) for (int y = 0; y <= GlowAmount; y++) g.DrawString(Text, this.Font, br, new Point(IconOffset + x, y)); You can also get the added benefit of chaining usings together without having to indent a million times. using (Graphics g = Graphics.FromImage(bmp)) { using (Brush brush = new SolidBrush(backgroundColor)) { using (Pen pen = new Pen(Color.FromArgb(penColor))) { //do lots of work } } } //versus using (Graphics g = Graphics.FromImage(bmp)) using (Brush brush = new SolidBrush(backgroundColor)) using (Pen pen = new Pen(Color.FromArgb(penColor))) { //do lots of work } The most common argument for curly braces revolves around maintance programming, and the problems that would ensue by inserting code between the original if statement and its intended result: if (foo) Bar(); Biz(); Questions: Is it wrong to want to use the more compact syntax which the language offers? The people that design these languages are smart, I can't imagine they would put a feature which is always bad to use. Should we or Shouldn't we write code so the lowest common denominator can understand and have no problems working with it? Is there another argument that I'm missing? |
For an oscillating string that is clamped at both ends (I am thinking of a guitar string specifically) there will be a standing wave with specific nodes and anti-nodes at defined $x$ positions. I understand and can work through the maths to obtain the fact that the frequency is quantised and is inversely dependent on $L$, the length of the string, and $n$, some integer. If I pluck a guitar string, this oscillates at the fundamental frequency, $n=1$. If I change to a different fret, I am changing $L$ and this is changing the frequency. Is it possible to get to higher modes ($n=2$, $n=3$ etc)? I don't understand how by plucking a string you could get to 1st or 2nd overtones. Are you just stuck in the $n=1$ mode? Or would the string needed to be oscillated (plucked) faster and faster to reach these modes? | In physics textbook, we can calculate the nth harmonic of a vibrating string of a fixed length. How can we do this in a real guitar? For example, if I just pick a single open string, how can I get any arbitrary harmonic for this? More precisely, the first harmonic has 2 nodes and 1 anti nodes the second harmonic has 3 nodes and 2 anti nodes the nth harmonic has n+1 nodes and n anti nodes |
In my profile I add and "Save And Copy To All Stack Exchange Accounts". On Meta Stack Exchange [tag:status-completed] linked to , as it should.But on other sites it is linked to status-completed tag posts on them - in my Stack Overflow profile it is linked to . I tried to place it in hyperlink: <a href = "https://meta.stackexchange.com/questions/tagged/status-completed"> [tag:status-completed] </a> or [ [tag:status-completed] ](https://meta.stackexchange.com/questions/tagged/status-completed) but it doesn't work. Is it possible to link [tag:some-tag] to specific Stack Exchange site? | The tag in my Stack Exchange profile links to different sites depending on where it's being viewed: Profile on StackOverflow: [tag:CSS] => https://stackoverflow.com/questions/tagged/css Profile on StackExchange: [tag:CSS] => https://stackexchange.com/questions/tagged/css Profile on CodeReview: [tag:CSS] => http://codereview.stackexchange.com/questions/tagged/css I'd like to have these all link to https://stackoverflow.com/questions/tagged/css. You can ; why not add the ability to specify the site with tags? <!-- tag: stackoverflow -->[tag:css] <!--tag: meta -->[tag:feature-request] The current behavior also cause a bug on my : All tags send me to find a Panda aka 404 Page Not Found. |
let there be $\{z_1 ,..., z_n\}$ a group of complex numbers. Show that there's a subset $J \subset \{1,...n\}$ so that $$\lvert \sum_{k \in J}z_k \rvert \ge \frac{1}{4\sqrt2}\sum_{i=1}^n\lvert z_i \rvert$$ I've tried playing around with it, like squaring it and I got up to $$2^5 \sum_{k \in J}\lvert z_k \rvert ^2 -\sum_{i=1}^{n}\lvert z_i \rvert^2 \ge \sum_{i \neq k \in J} \lvert z_i \rvert \lvert z_k \rvert -2^6Re \sum_{i \neq k \in J} z_i \bar z_k$$ and here is where I got stuck | Consider the following problem. Fix $n \in \mathbb N$. Prove that for every set of complex numbers $\{z_i\}_{1\le i \le n}$, there is a subset $J\subset \{1,\dots , n\}$ such that $$\left|\sum_{j\in J} z_j\right|\ge \frac{1}{4\sqrt 2} \sum_{k=1}^n |z_k|.$$ I believe I proven have a stronger statement. Is this proof correct, and if so, what is the optimal constant? My proof. Consider all the $z_i$ with positive real part. Call the real part of the sum of these numbers $X^+$. In a similar way, form $X^-$, $Y^+$, and $Y^-$. Without loss of generality, let $X^+$ have the greatest magnitude of these. Note that because $|\operatorname{Re}(z)|+|\operatorname{Im}(z)|\ge |z|$, we have $$ \left(\sum_{k=1}^n |\operatorname{Re}(z_k)|+|\operatorname{Im}(z_k)| \right) \ge \sum_{k=1}^n |z_k|.$$ But note that $\sum \limits_{k=1}^n |\operatorname{Re}(z_k)|+|\operatorname{Im}(z_k)| = X^+ + |X^-|+ Y^+ +|Y^-|$, so we have $$ 4X^+ \ge \sum_{k=1}^n |z_k|.$$ By choosing $J$ to be the set of complex number with positive real part, this proves a stronger statement, because the factor of $1/\sqrt 2$ isn't needed. |
Well, I know that $\sqrt{2}$ is an irrational number and I am also familiar with the proof by contradiction method, but I'm confused by this notation as we can divide $\sqrt{2}$ by $1$ (as $\sqrt{2}$ is a real number and for a real number it is possible) and will get $\sqrt{2}$, so can't $\sqrt{2}$ be written as $\frac{\sqrt{2}}{1}$, and in that case $\sqrt{2}$ should be a rational number. | $$\Bbb{Q} = \left\{\frac ab \mid \text{$a$ and $b$ are integers and $b \ne 0$} \right\}$$ In other words, a rational number is a number that can be written as one integer over another. For an integer, the denominator is $1$ in that case. For example, $5$ can be written as $\dfrac 51$. Is $5$ a rational number? Or is $\dfrac 51$ a rational number? I'm not able to figure out what the definition is actually saying. What are the numbers that cannot be written as one integer over another? Irrational numbers are the numbers that cannot be written as one integer over another. Roots of numbers that are not perfect squares are examples of irrational numbers. However, what is this then: $\dfrac {\sqrt 7} {2}$? |
Most examples of logistic regression uses a cutoff (for classification) of 0.5. But I suspect this is a reasonable starting point only if you have equal number of positive samples and negative samples. Suppose we want to classify whether someone will get a disease or has a disease. We randomly draw 1000 people from the population. Only 50 (5%) of the 1000 people have the disease, while the other 95% don't. Suppose we train a logistic model based on various attributes of the 1000 people. Would it be reasonable to use a cutoff of 0.05 for this case? Any prediction greater than 0.05 gets classified as "disease." I understand the threshold should be determined by acceptable number of false positives/negatives, but I'm just talking about a starting point here. Suppose the ground truth is that 5% of population has this disease. But in a 2nd case, we sample in such a way so that we have 500 people with the disease and 500 don't, and train another model. We would expect the output from the logistic model to be a lot closer to 0.5 than 0.05 in this 2nd case right? This makes me think that the logistic regression uses the distribution of the different classes in the training data as their prior probabilities. And the output is the posterior probability. Is this a way to understand it? | PREFACE: I don't care about the merits of using a cutoff or not, or how one should choose a cutoff. My question is purely mathematical and due to curiosity. Logistic regression models the posterior conditional probability of class A versus class B and it fits a hyperplane where the posterior conditional probabilities are equal. So in theory, I understood that a 0.5 classification point will minimize total errors regardless of set balance, since it models the posterior probability (assuming you consistently encounter the same class ratio). In my real life example, I obtain very poor accuracy using P > 0.5 as my classifying cutoff (about 51% accuracy). However, when I looked at the AUC it is above 0.99. So I looked at some different cutoff values and found that P > 0.6 gave me 98% accuracy (90% for the smaller class and 99% for the bigger class) - only 2% of cases misclassified. The classes are heavily unbalanced (1:9) and it is a high-dimensional problem. However, I allocated the classes equally to each cross-validation set so that there should not be a difference between the balance of classes between model fit and then prediction. I also tried using the same data from the model fit and in predictions and the same issue occurred. I'm interested in the reason why 0.5 would not minimize errors, I thought this would be by design if the model is being fit by minimizing cross-entropy loss. Does anyone have any feedback as to why this happens? Is it due to adding penalization, can someone explain what is happening if so? |
I am working with example code from Stroustrup's book(Programming: Principles and Practice using C++").I have downloaded std_lib_facilities.h from http://www.stroustrup.com/Programming/std_lib_facilities.h When I try to compile on Ubuntu 14.04 with gcc,I got this: d19.cc:1:32: fatal error: std_lib_facilities.h: No such file or directory #include <std_lib_facilities.h> Then I have doublechecked,file is in my directory. milenko@milenko-HP-Compaq-6830s:~/cplus$ ls -l std_lib_facilities.h -rw-r----- 1 milenko milenko 5667 Jul 4 09:35 std_lib_facilities.h I have changed <> to "" and works fine,but still lingers a question why do we use <iostream> and "std_lib_facilities.h" | In the C and C++ programming languages, what is the difference between using angle brackets and using quotes in an include statement, as follows? #include <filename> #include "filename" |
I already have the Taken King. What will happen if I install the Legendary Edition? Will it delete my save file? | I'm a year one Destiny player; I bought The Dark Below, House of Wolves, and I'm thinking about buying the Legendary Edition. My only concern is that I'm not sure if the data from my original Destiny game would be overwritten or ignored by the Legendary Edition. Would it create its own save files like a completely different game? I don't want to get Legendary if that's the case, because all of my items would be completely gone, along with god knows how much play time. |
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