I am taking 2 pictures using:     Nikon D3400 APS-C sensor and an APS-C kit lens, 18-55mm set at 50mm   Nikon D850 full frame camera and a full frame lens 50mm that is designed for full frame Nikon camera   Both systems have lenses mounted on them that is specifically designed for them. I am NOT putting FF lens on APS-C camera nor I am putting APS-C lens on FF camera. Shouldn't both 50mm images taken by above 1 and 2 have same field of view? What am I not getting here? Please clarify.
I have a Canon 7D, which has a crop factor of 1.6x.  When using a Canon EF-S lens I get the focal length stated on the lens, when using a Canon EF lens I get the focal length times 1.6 when used on the APS-C body. At least that's what I thought.  I just compared two lenses:   Canon EF-S 15-85mm f3.5-5.6 Canon EF 70-200mm f4   .  The top photo is shot with the 15-85, the bottom photo with the 70-200 - both lenses are set to 70mm. Now why do they look the same?  I thought I would get 112-320mm (70mm*1.6 crop factor). What did I misunderstand about the crop factor calculation? Lightroom also displays the photos as having "70mm" and not 112mm.
jQuery: Selecting and manipulating html elements outside the DOM Active vs passive voice with inanimate object as the subject I have asked the  in ELL Stackexchange forum. There all the answers and comments I received was really helpful, but still I was looking for something more. So I have decided to ask this same question here also.   I have seen some sentences like this -         The film was announced to be released on this coming Friday.   The film was announced to release on this coming Friday.      Both the sentences are used, and I know they are interchangeable and does bear the same meaning. But I have some doubt about the second sentence - why is it "to release", when the film cant release itself.   Some other sentences of similar structure that arises my confusion -         The product sells well.   The book reads well.   The glass broke.      The sentences are understandable, but in each of the sentences the subjects can't perform any job, as they all are inanimate object. The verbs are active, but they acts like they are used as passive.  Now my question is how to decide which verb to use this way and which not? Big tilde in math mode How do I get a really wide tilde?  I need to cover at least  abcdefghijklmnopqrstuvwxyz  The \widetilde command does not work. Nor using \stackrel with \sim. I am running Ubuntu 14.04 on think-pad T450.  When using an external monitor with higher resolution than the in-built laptop screen, the text of dialog boxes are getting messed up.  Looks like I need to replace the Graphic card driver. Anyone found a solution to this?  Updated to add requested information:  lspci -nnk | grep '\[03' -A2   gives the following:  00:02.0 VGA compatible controller [0300]: Intel Corporation Broadwell-U Integrated Graphics [8086:1616] (rev 09)     Subsystem: Lenovo Device [17aa:5034] Kernel driver in use: i915   Below is a screenshot, see how the letters are messed up on the screen. Reflection of sound waves from the open end of an organ pipe & relationship b/w nodes & pressure We know that standing waves are created when any wave traveling along the medium will reflect back when they reach the end. But in an open organ pipe, there is nothing to oppose the wave and reflect it back. So then how are standing waves created in such a case? In standing waves where is the pressure greater, at nodes or anti-nodes? Why "be king", not "be a king"? I've heard people say "be king" (as in "I can't wait to be king") in movies and TV. Why don't they say "be a king"? Which is correct? Proof a set cannot contain its own powerset - Russell's Paradox My question is about $CFT_1$. Page 18 of  says that $$L={\frac{\overset{.}{Q}^2}{2} - \frac{g}{2Q^2}}\tag{1.11}$$ is the most general Lagrangian that preserves time translation and scale invariance in $CFT_1$. How does one prove that? How to prove that $a \cdot b$ is not divisible by 5 for $\frac{1}{1} + \frac{1}{2} + ... + \frac{1}{99} + \frac{1}{100} = \frac{a}{b}$? What is $\arctan(x) + \arctan(y)$ I know $$g(x) = \arctan(x)+\arctan(y) = \arctan\left(\frac{x+y}{1-xy}\right)$$  which follows from the formula for $\tan(x+y)$. But my question is that my book defines it to be domain specific, by which I mean, has different definitions for different domains:  $$g(x) = \begin{cases}\arctan\left(\dfrac{x+y}{1-xy}\right), &amp;xy &lt; 1 \\[1.5ex]  \pi + \arctan\left(\dfrac{x+y}{1-xy}\right), &amp;x&gt;0,\; y&gt;0,\; xy&gt;1 \\[1.5ex]  -\pi + \arctan\left(\dfrac{x+y}{1-xy}\right), &amp;x&lt;0,\; y&lt;0,\; xy &gt; 1\end{cases}$$  Furthermore, When I plot the function $2\arctan(x)$, it turns out that the book definition is correct. I don't understand how such peculier definition emerges. Thank you. I'm having some problems with listings and UTF-8 in my document. Maybe someone can help me? Some characters work, like é and ó, but á and others appear at the beginning of words...  \documentclass[12pt,a4paper]{scrbook} \KOMAoptions{twoside=false,open=any,chapterprefix=on,parskip=full,fontsize=14pt}  \usepackage[portuguese]{babel} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{listingsutf8}  \usepackage{inconsolata} \lstset{     language=bash, %% Troque para PHP, C, Java, etc... bash é o padrão     basicstyle=\ttfamily\small,     numberstyle=\footnotesize,     numbers=left,     backgroundcolor=\color{gray!10},     frame=single,     tabsize=2,     rulecolor=\color{black!30},     title=\lstname,     escapeinside={\%*}{*)},     breaklines=true,     breakatwhitespace=true,     framextopmargin=2pt,     framexbottommargin=2pt,     extendedchars=false,     inputencoding=utf8 }  \begin{document} \begin{lstlisting} &lt;?php  echo 'Olá mundo!'; print 'Olá mundo!'; \end{lstlisting}  \end{document} \end{lstlisting} xdg-open on debian 9 fails to open browser I decided to try lxdm (was using fluxbox and xfce), and discovered that for many programs the url handler was failing, producing this error message;   Quite strange as you can see, it's prepending the user directory to the url.  The example here is from telegram, but it happens in discord, as well as when executing from the command line; xdg-open https://www.google.com produces a similar error. xdg-settings get default-web-browser output's firefox.desktop which works as a link in both xfce and lxdm.  More information; I ran bash -x on it and...  $ bash -x /usr/bin/xdg-open http://www.google.com + check_common_commands http://www.google.com + '[' 1 -gt 0 ']' + parm=http://www.google.com + shift + case "$parm" in + '[' 0 -gt 0 ']' + '[' -z '' ']' + unset XDG_UTILS_DEBUG_LEVEL + '[' 0 -lt 1 ']' + xdg_redirect_output=' &gt; /dev/null 2&gt; /dev/null' + '[' xhttp://www.google.com '!=' x ']' + url= + '[' 1 -gt 0 ']' + parm=http://www.google.com + shift + case "$parm" in + '[' -n '' ']' + url=http://www.google.com + '[' 0 -gt 0 ']' + '[' -z http://www.google.com ']' + detectDE + unset GREP_OPTIONS + '[' -n LXDE ']' + case "${XDG_CURRENT_DESKTOP}" in + DE=lxde + '[' xlxde = x ']' + '[' xlxde = x ']' + '[' xlxde = x ']' + '[' xlxde = xgnome ']' + '[' -f /run/user/1000/flatpak-info ']' + '[' xlxde = x ']' + DEBUG 2 'Selected DE lxde' + '[' -z '' ']' + return 0 + case "${BROWSER}" in + case "$DE" in + open_lxde http://www.google.com + pcmanfm --help -a is_file_url_or_path http://www.google.com ++ file_url_to_path http://www.google.com ++ local file=http://www.google.com ++ echo http://www.google.com ++ grep -q '^file:///' ++ echo http://www.google.com + local file=http://www.google.com + echo http://www.google.com + grep -q '^/' ++ pwd + file=/home/nesmerrill/.local/share/applications/http://www.google.com + pcmanfm /home/nesmerrill/.local/share/applications/http://www.google.com + '[' 0 -eq 0 ']' + exit_success + '[' 0 -gt 0 ']' + exit 0   The important part seems to be pcmanfm --help -a is_file_url_or_path http://www.google.com but, that command if that's how it was used, doesn't seem to do much of anything?  $ pcmanfm --help -a is_file_url_or_path http://www.google.com Usage:   pcmanfm [OPTION…] [FILE1, FILE2,...]    Help Options:   -h, --help                   Show help options   --help-all                   Show all help options   --help-gtk                   Show GTK+ Options  Application Options:   -p, --profile=PROFILE        Name of configuration profile   -d, --daemon-mode            Run PCManFM as a daemon   --no-desktop                 No function. Just to be compatible with nautilus   --desktop                    Launch desktop manager   --desktop-off                Turn off desktop manager if it's running   --desktop-pref               Open desktop preference dialog   --one-screen                 Use --desktop option only for one screen   -w, --set-wallpaper=FILE     Set desktop wallpaper from image FILE   --wallpaper-mode=MODE        Set mode of desktop wallpaper. MODE=(color|stretch|fit|crop|center|tile|screen)   --show-pref=N                Open Preferences dialog on the page N   -n, --new-win                Open new window   -f, --find-files             Open a Find Files window   --role=ROLE                  Window role for usage by window manager   --display=DISPLAY            X display to use How can I visualize boxes? This question led to a new package:      Some of you may know the Web Developer Toolbar for Firefox that can outline the block level elements of a page like this:  Is there a way to do something similar with TeX boxes for a complete document? What is the difference between linear regression and logistic regression? What is the difference between linear regression and logistic regression?  When would you use each? $ p(x)\in\mathbb{R[X]} $ is a polynomial of degree $n$ with no real   roots. Show that: $$\int\limits_{-\infty}^{+\infty}\dfrac{(p'(x))^2}{(p'(x))^2+(p(x))^2}\,dx \leq n^{3/2}\pi.$$   It's easy to see that the degree of $ p$ has to be even. For $n=2$ this integral is at most $2\pi$. For $n&gt;2$ the maximum value of this integral is obtained when all the imaginary parts of the roots of $p(x)$ tend to $0$, but I couldn't go further.    Any help would be appreciated, thanks.    Edits by David Speyer: It seems very likely now that the optimum bound is $n \pi$, not $n^{3/2} \pi$. As pointed out in the comments below, and further in , this is the value we get in the limit where $p$ has double roots on the real axis.   It seems likely that  moving the roots of $p$ away from the real axis can only make the integral less. Write the roots of $p$ as $a_j \pm i b_j$, so $p(x) = \prod ((x-a_j)^2 + b_j^2)$ and  $$\frac{p'(x)}{p(x)} = \sum \frac{2 (x-a_j)}{(x-a_j)^2 + b_j^2}.\quad (\ast)$$  So making the $b_j$ larger tends to make $p'(x)/p(x)$ smaller, which makes the integral smaller. But this argument is not rigorous, because the terms of $(\ast)$ can have both positive and negative sign, so it could be that making the individual terms closer to $0$ makes the absolute value of $(\ast)$ larger.  I don't see how to beat this issue easily.  Thus, I'm putting up a bounty for proving or disproving   $$ \int_{-\infty}^{+\infty}\dfrac{(p'(x))^2}{(p'(x))^2+(p(x))^2}\,dx \leq n\pi.$$ How could I find $x$ in this equation $x^2-x+6 \equiv 0 \pmod {9}$ This equation is like this: $$x^2-x+6 \equiv 0 \pmod{9}$$  I want to find x by using modular arithmetic. How I could do that?   My solution was:     $$\begin{align*}  x(x-1) &amp;\equiv -6 \pmod{9}\\ x(x-1) &amp;\equiv 3 \pmod{9} \end{align*}$$      So $x$ is either:   $$ x \equiv 3\pmod{9}$$      or       $$x - 1 \equiv 3 \pmod{9}$$      Which is $x \equiv 4 \pmod{9}$   I know what I have done is very dumb. So what is the correct solution? Give me the instructions also please. error: no such partition. Grub rescue Output from ls has newlines but displays on a single line. Why? 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 How can I install Steam? How can I install and run  on Ubuntu? In the following snippet:  public class a {     public void otherMethod(){}     public void doStuff(String str, InnerClass b){}     public void method(a){         doStuff("asd",             new InnerClass(){                 public void innerMethod(){                     otherMethod();                 }             }         );     } }   Is there a keyword to refer to the outer class from the inner class?  Basically what I want to do is outer.otherMethod(), or something of the like, but can't seem to find anything.