How to calculate distance of an object from camera or size of an object in an image? Have to utilise already generated camera parameters to find these
How do I calculate the distance of an object in a photo?
Can the editor for editing tag descriptions get updated to match the normal questions/answers editor? The text editor that is shown when editing tag descriptions still uses the previous behaviour for inserting links and images. Also, the placeholder text for links is still http:// instead of https:// compared to the new editor. Another &quot;nice to have&quot; feature that exists in the main editor is the ability to paste an image from clipboard directly to the text editor without having to press the &quot;insert image&quot; toolbar-icon first. Can it get updated to match the editor we use for questions and answers?  The following screenshot is an example of how it looks if I try to insert a link for a tag description:  In comparison, this is how it looks in the new editor: Maximum area of isosceles triangle with perimeter 6 cm Problem. What is the side lengths of an isosceles triangle with $6cm$ perimeter which has the largest area? I solved this problem as below and I would like to learn  that if there is anything wrong: Let us say that the side lengths are $a$ and the bottom length is $6-2a$. By using pythagorean theorem we can conclude that the height $h$ is equal to $\sqrt{6a-9}$. Then, the area of the triangle can be given as $f(a)=(3-a)(\sqrt{6a-9})$. So $f'(a)=-\sqrt{6a-9}+\cfrac{3}{\sqrt{6a-9}}$. Finally, $f'(a)=\cfrac{12-6a}{\sqrt{6a-9}}$ and $f'(a)=0 \iff a =2$. Prove $\gcd(a+b,a^2+b^2)$ is $1$ or $2$ if $\gcd(a,b) = 1$ Assuming that $\gcd(a,b) = 1$, prove that $\gcd(a+b,a^2+b^2) = 1$ or $2$.   I tried this problem and ended up with $$d\mid 2a^2,\quad d\mid 2b^2$$ where $d = \gcd(a+b,a^2+b^2)$, but then I am stuck; by these two conclusions how can I conclude $d=1$ or $2$?  And also is there any other way of proving this result? How many switches can be stacked/interconnected? Missing argument 2 for wpdb::prepare() Issue Number of normal subgroups of a non abelian group of order $21$... CSIR December $2013$ Question is to :  Find the number of Normal subgroups of a nonabelian group $G$ of order $21$ other than $\{e\}$ and $G$.  What I have done so far is :  As $|G|=21=3\cdot7$  we have :  No. of sylow $3$ subgroups $1+3k$ dividing $7$ leaving out possibilities $1$ or $7$  No. of sylow $7$ subgroups $1+7k$ dividing $3$ leaving out only possibilities $1$.  So, we have a unique sylow $7$ subgroup and so it is normal.  I remember somehow that any normal group should come from a normal sylow subgroup or something like that.  S0, I prefer to conclude there is only one Normal subgroup for a non abelian group of order $21$.  Please let me know if this is true and please help me to fill that gap :      I remember somehow that any normal group should come from a normal sylow subgroup or something like that.   Thank you. "Z-level" in TikZ Getting incorrect slope values from an ASTER DEM in QGIS? I have a DEM layer from ASTER satellite and I want to get the slope information from it.  I use terrain analysis > slope, but the output is so wrong. Why is that?  Here is the DEM:     And here is the "Slope" that is totally wrong. It should stretch the values from 0 - 89.9097 but it does not. How to show that $L^p$ spaces are nested? Suppose $1&lt;p_1&lt;p_2&lt;\infty$, then show $L^{p_1}[a,b] \supset L^{p_2}[a,b]$.  I was able to show $\|f\|_{p_1} \le \|f\|_{p_2} (b-a)^{1/p_1 - 1/p_2}$ but I'm not sure how to proceed from here. Define $S\equiv\{ x\in \mathbb{Q}\mid x^2<2\}$. Show that $\sup S=\sqrt{2} $. How do you integrate $\int \frac{1}{a + \cos x} dx$?  Is it solvable by elementary methods?  I was trying to do it while incorrectly solving a homework problem but I couldn't find the answer.  Thanks! Do I need to use The Loop on pages? I'm writing my first WordPress theme and have a question about the use of The Loop in page templates. The page templates I've looked at all follow basically the same pattern (example from Twenty Twelve):  &lt;?php while ( have_posts() ) : the_post(); ?&gt; &lt;?php get_template_part( 'content', 'page' ); ?&gt; &lt;?php comments_template( '', true ); ?&gt; &lt;?php endwhile; // end of the loop. ?&gt;   But a page will only have one post associated with it so iterating through the posts seems unnecessary. My page template is more readable and seems to work fine:  &lt;?php the_post(); the_title('&lt;h1&gt;', '&lt;/h1&gt;'); the_content(); ?&gt;   Is this a good practice? Are there any downsides? Python Script to Add Fields to Feature Classes I have to try to add a field called 'Name' to a bunch of different feature classes using python, and then access the name of the feature class to fill in the field. I have no idea how to even start this! I know I need a loop but that's all I know. How do you join or create a server in multiplayer? How to use maths symbols in text mode? I try to add a center dot with \circ but it fails to compile. How to use maths symbol in text mode? The error message is   ovak, slovenian, spanish, swedish, turkish, turkmen, ukrainian, uppersorbian,  welsh, loaded. (/usr/local/texlive/2012/texmf-dist/tex/latex/base/article.cls Document Class: article 2007/10/19 v1.4h Standard LaTeX document class (/usr/local/texlive/2012/texmf-dist/tex/latex/base/size10.clo)) (./untitled-1.aux) ! Missing $ inserted. &lt;inserted text&gt;              $ error when adding user to wheel group in CentOS 7 I am trying to grant sudo privileges to a user of a CentOS 7 devbox by typing gpasswd -a user wheel, but the attempt is failing.  What am I doing wrong?    Here is what I typed:    I discovered that the user is not in the wheel group as follows:    [user@localhost git]$ sudo yum install git [sudo] password for user:  Sorry, try again. [sudo] password for user:  Sorry, try again. [sudo] password for user:  user is not in the sudoers file.  This incident will be reported.   I then logged in as root and typed the following to add the user to the wheel group:    [user@localhost git]$ su - Password:  Last login: Thu Aug 20 17:11:31 PDT 2015 on pts/0 [root@localhost ~]# gpasswd -a user wheel Adding user user to group wheel [root@localhost ~]# exit logout   I finally tried to use the sudo command again but it failed as follows:    [user@localhost git]$ sudo yum install git [sudo] password for user:  user is not in the sudoers file.  This incident will be reported. [user@localhost git]$ I have a graphic on the clipboard on OS X.  What's the quickest way to get it onto disk as a png or jpg? I want my Qt application to be able to save simple vector graphics to clipboard in a compatible way. On windows I want to be able to paste the graphics into Microsoft Word or Powerpoint. On Linux I want to be compatible with the Open Office.   Which format would you recommend? Can Qt generate EMF in an easy way? Is SVG an option?  Update:  My current plan is to add a piece of native win32 code to render the graphics to emf on windows. This code will not be available on linux. Route SSH to host through interface Is it possible to route all outgoing requests for SSH (port 22) to mydynamicdns.afraid.org via wlan0 instead of eth0 when both are connected?  Since my IP is dynamic, I would like to use a name instead of IP. Why not use a WAMP stack? This is a  about  the use of a *AMPP's stack.    I recently had a talk with some experienced people and they suggested to me not to use a WAMP stack, and instead install apache, mysql and php separately.  I don't understand why they have suggested this, though, so can anyone tell me?  Is there a particular disadvantage of WAMP, or a particular advantage to installing all of them separately?  Since a WAMP stack itself is composed of apache, mysql and php, then what's the difference between using the WAMP stack and installing them all separately?