I don't know why My Final Render is all black
Render result is completely blank
Take the manifold: The graph of $|x|$ on $(-1,1)$, with the induced topology from $\mathbb{R}^2$. This is a topological manifold, which is homeomorphic to $(-1,1)$ by projection. Is it a differentiable manifold? I believe it is, because we can take an atlas with only the projection, and then we will have only one transition map which is the identity, and therefore differentiable. But I'm not sure I get the definition of a differentiable manifold right...  Thanks! I tried to install OracleJDK 8 using   sudo add-apt-repository ppa:webupd8team/java   But it's not working.   I searched the problem and found that      "The Oracle JDK License has changed for releases starting April 16, 2019." And  "Oracle Java (JDK) 8 Installer PPA (DISCONTINUED)"   So I installed the OpenJDK8 .   But why oracle cancelled the license of oracle 8 installer? A "friends list" on Stack Overflow would be nice HTML text input allow only numeric input Computing matrix-vector calculus derivatives $x, a$ in $\mathbb R^n$, $A$ in $\mathbb  R^{n\times n}$. Compute $d(x^T a)/dx$ and $d(x^T A x)/dx$.  I'm not sure about how to think about these and how to do these. Can someone explain how to derive the expressions for the two?  Finally, what happens when we have $A$ and $X$, BOTH in $\mathbb R^{n\times n}$, and we want to find $dTrace(XA)/dX$? Give a sequence $(f_n)_{n\in \mathbb{N}}$ of differentiable functions which uniformly converge to $0$, but for which the seqeunce $(f_n')_{n\in \mathbb{N}}$ of the derivatives isn't even pointwise convergent.    I found this one in my textbook marked as "Fun things to solve" and although it may be fun, it's kind of hard to do.   To be honest I already failed at the first hurdle. I couldn't even find a sequence of functions which uniformly converges to $0$.   Is there a certain way of dealing with this kind of problem? Because it seems kind of hard for me to come up with sequences without a mathematical of way of doing so (or maybe there is a mathematical way I just don't know yet). I am developing the backend for a website. I always had the trouble of making an attractive design for my websites and have never hired any graphic designer yet. I have no logo nor web template.  What are the steps to hire a graphic designer? What information should I read about before hiring one in order to make most out of our time? Where should I find him? What questions should I ask him? How much do they charge and what qualifications should I look out for? Should I disclose my business ideas to the designer or could that be risky? Getting coordinates by clicking on QGIS Canvas with PyQGIS? Are there any procedures when working with QgsMapCanvas (pyqgis, qgis) in order to obtain a pair of coordinates by clicking on the map canvas?   Are there any sample Python codes that demonstrate this? Adding newmode with Xrandr - "800x480_60.00" I have 5-inch a 800x480 tft connected to the LVDS connector on a Portwell WADE-8020 mini-ITX embedded system board. I would like to build a XMBC/Kodi box for streming my music from my freenas PC with the tft showing what is been played, I got as fare as this...   sudo xrandr --newmode "800x480_60.00"  29.50  800 824 896 992  480 483 493 500 -hsync +vsync`enter code here   then,  sudo xrandr --addmode LVDS1 800x480_60.00   now that I get the correct resolution, I now have a black band on the top of the screen.  sudo xrandr --output LVDS1 --set "scaling mode"  "Full aspect"   However this did not solve the issue, also I know I need to amend the /bin/sh file with this from googling so I don't need to keep doing this at every boot. But I don't know how to as I'm very new to Linux.  #!/bin/sh xrandr --newmode "800x480_60.00"  29.50  800 824 896 992  480 483 493 500 -hsync +vsync xrandr --addmode LVDS1 800x480_60.00 How would one write object-oriented code in C? Proving convergence of sums: If $\sum_{n=1}^{\infty}a^2_n$ and $\sum_{n=1}^{\infty}b^2_n$ converge then $\sum_{n=1}^{\infty}a_nb_n$ converges Gduated symbology not taking attribute into account using QGIS I m working on a project on QGIS. I have a point shapefile vector that represents my store. In the attribute table, i have bunch of data such as size, unit per transaction and most importantly store turnover. When I want to graduate the symbology, the turnover isn't present in the list I can choose from. Does someone know why, and how to fix it? Derivation of binomial coefficient in binomial theorem. How was the binomial coefficient of the binomial theorem derived?  $$\frac{n!}{k!(n-k)!}$$ How can I unlock a password locked rar file without knowing the password? I have .rar file that is password protected, but I accidentally have forgotten the password. The file extremely important to me.  How can I get my file back? In windows, there was many programs that could remove the password of such a file. Is there one for Ubuntu? Does app review rejection list all issues? Our app was rejected recently with reason Google+ signin, which we understood is not according to Apple policy and need to fix.  While discussing about this issue we came across an interesting question with Apple review process, does Apple review team list all issues (if more than one exists) while rejecting app (or) would they stop reviewing other areas as soon as they found an issue (in our case Google+ signin)? Preposition confusion - Do you learn somthing 'at' school OR 'in' school? I know that we use the preposition at to describe a place. I learned French at school is one of the examples I can think of.   I came across two examples that use the preposition 'in' with 'schools' in the context of 'learning'.   Example #1 from the  website:      Eleven things that you will never learn in school.   Example #2 from      Do you think the skills you learn in school will help you get the job you want?   The use that I had in my mind is here on      Should Parents Control What Kids Learn at School? I have an image with a woman, and I need to make an ad (size 260mmx125mm). I want to put the woman to the left side, but then right side becomes empty. So, how I should solve the problem? I have picked the color from image, but it is definitely different than in the actual picture.  Should I use the Clone Stamp Tool in Photoshop, or there is a better way to do this?  By the way, it will be used in print, so I need a good quality. I am preparing a document in French, using the "babel" package with option "french" and using commands that include colons and semicolons. My problem is, the French spacing before colons and semicolons disappears when the commands are printed. I do not understand why, have not been able to find an answer. Below is a MWE.  \documentclass{article} \usepackage[french]{babel} \newcommand\deuxpoints{Texte: texte} \begin{document} \deuxpoints\ \endgraf Texte: texte \end{document} Alignment issue in Area 51 main site - site switcher, inbox and achievements Emergency mode due to filesystem check On bootup, filesystem check occurs and it stops at 61% and I am redirected to a page with the message you are in the emergency mode. I don't know what to do next.  This is the message that I get at the screen   You are in emergency mode. After logging in, type .......  Press Enter for maintenance (Or press ctrl+D to continue):   But when I press Ctrl+D it again directs me back to the same screen.