I have a test scene where a very thin and bright spotlight (almost like a laser) shines on a diagonal mirror in a volume that scatters light, such that the light beam is directly visible. The mirror uses a 100% glossy material. The intention is to make the light bounce on the mirror. However, it seems the light beam disappears after bouncing in the mirror.  This is the scene in the viewport:   And this is the rendered result:   As you can see, the light beam is visible from the light source to the mirror, but then the light beam stops: it doesn't continue from the mirror to the cube. Is this a limitation in Cycles or do I need to enable some options somewhere? As far as I'm aware, I'm using Cycles' default settings. I've already tried increasing the maximum number of volumetric scattering events to no avail.  (I'm aware you could fake the effect by placing another spotlight on the surface on the mirror, pointing in the direction of the cube, but I'd like to do it the "proper" way if possible)
Working in Cycles.  Say I have a "disco ball" with a glossy shader. I'm pointing a spot light to it, and I'm trying to have the reflections of that light illuminate the diffuse material on the walls with the patterns from the ball.    I get this:    but I'd like to get something like:    For the illustration I placed a point light inside the ball an removed faces. But what I'd like to do is move the light around the ball so that the light reflected from it changes like it would do in real life.   Is that possible at this point?  EDIT:  Just for the record here's the image rendered in LuxRender (yet another program to learn...)
Unity remove logo in splash screen Creating a default preamble Since I am using (almost) the same set up for my tex documents, I wonder if there is a way to create a preamble with my default packages and to recall it anytime I want to create a tex document.  If yes, how I can call this "default" preamble?  Thanks in advance Canonical map $R/(I\cap J)\rightarrow R/I\times _{R/(I+J)} R/J$ is an isomorphism I am a platform diver. I am trying to figure out how deep in the water I go depending on which platform I dive from.  The platforms are 1m, 3m, 5m, 7.5m and 10m above the water surface.  By ignoring air resistance (we assume that I do not do any tricks) I can easily compute the energy that my 90 kg body has when it is hitting the water:  E = mgh = 0.5mv^2   My problem is to find the deceleration in water and thus how deep my feet will go into the water before coming to a halt. We can assume that I stand straight and fall straight down and have a height of 190cm.  How do I compute that? I read that     A typical stream cipher encrypts plaintext one byte at a time, although a stream cipher may be designed to operate on one bit at a time or on units larger than a byte at a time.   (Source: , William Stallings.)  A block cipher encrypts one block at a time. The block may be of size one byte or more or less. That means we can also encrypt a block of one byte by help of a stream cipher as a stream.  So, what exactly is the difference between a stream cipher and a block cipher? While traveling in the Berlin Tegel airport (TXL), I wanted to get on Wi-Fi. I found three unsecured networks in addition to a number of password-protected networks.   _Free_TXL_WiFi airberlin Berlin Tegel Airport WiFi   I had no idea which of these were an official Wi-Fi network provided by the airport and which were provided by other people, potentially for malicious purposes like capturing my network traffic. Presumably the official one uses a captive portal to allow internet access.  Is there any way to determine which Wi-Fi network is the official one provided by the airport? Would airport staff such as at the ticketing booths know? Are there official lists available somewhere?  I’d like an answer that is applicable to airports generally, rather than specific to the Berlin Airport. Also, please don’t just give a blanket “don’t use any public Wi-Fi network” answer; I know there are risks associated with it, but sometimes it is a necessity and so I want to know how to identify the airport-provided one.   suggests there are no official Wi-Fi networks, but the answers are six years old, so it’s not clear if things have changed or if none of the networks I saw were official. How do I tell Maven to use the latest version of a dependency? In Maven, dependencies are usually set up like this:  &lt;dependency&gt;   &lt;groupId&gt;wonderful-inc&lt;/groupId&gt;   &lt;artifactId&gt;dream-library&lt;/artifactId&gt;   &lt;version&gt;1.2.3&lt;/version&gt; &lt;/dependency&gt;   Now, if you are working with libraries that have frequent releases, constantly updating the &lt;version&gt; tag can be somewhat annoying. Is there any way to tell Maven to always use the latest available version (from the repository)? real memory usage Prove $\sum\limits^m_{k=0} \frac{2n-k\choose k}{2n-k\choose n}\frac{2n-4k+1}{2n-2k+1}2^{n-2k}=\frac{n\choose m}{2n-2m\choose n-m}2^{n-2m}$ for- I'm using Python, and would like to insert a string into a text file without deleting or copying the file. How can I do that? Error when clipping raster in QGIS: "'ascii' codec can't encode character"? I have done it many times (clipping a raster with a polygon layer or by extension) but today I got an error for the first time and I don't know how to solve it. I am always using the same type of raster layers. When running the clipping tool I got the following message:  gdal_translate -of GTiff -ot Byte -projwin 410282.185971 4694950.41162 410783.882475 4694524.96815 -co COMPRESS=DEFLATE -co PREDICTOR=1 -co ZLEVEL=6 -co TFW=YES "C:/Users/FERRAN ALA/Desktop/Justificació Fontanals/QGIS/Topo 1_5000/bt5mv20sd0f283077st1r031.sid" "C:/Users/FERRAN ALA/Desktop/Justificació Fontanals/QGIS/background/image.tif"   GDAL command output:     'ascii' codec can't encode character u'\xf3' in position 201: ordinal not in range(128) See log for more details   Does anybody know what that is? Spacing around \left and \right Why does the addition of a \left and \right introduces an extra space around the formula? Specifically, why do $\cos(\theta)$ and $\cos\left(\theta\right)$ render differently?  Is there a way to use resizable delimiters without introducing the spurious spaces?  Why did Knuth design it like this?  Edit: This occurs too, if \operatorname{MYOP} or some other operator, like \lim, \min etc. is used. (This edit is basically to make it easier to find this answer.) I looked up a few grammar-teaching websites (in Chinese language). The website says many people do not use the phrase "A xxx of" correctly because they do not identify the subject of the phrase correctly.   The website says phrases like "A range of; A high percentage of" is singular, while "a number of; a group of; a couple of; a total of" is plural.  Therefore according to the website, the correct sentences should be as follows.     A wide range of courses is available. ("A wide range" is the subject)      A high percentage of peptides that are made of amino acids is present   in the sample. ("A high percentage" is the subject)      A number/ group/ couple of people were killed in the earthquake.("people" is the subject )       A total of 230 employees were laid off. ("employees" is the subject)   I don't get the pattern here. All of this looks (or should I use "look"?) arbitrary to me. In fact I thought this phrase is supposed to be arbitrary and whether the phrase is plural or singular should depend on the the person's own judgment.   How do I identify the correct subject in the "A xxx of" phrase? I ask this Question on behalf of my neighbor.   Their 12 year old son saw his parents having sex.  As there is only one room in their home we can't say its the parents' mistake... but now the question is how do they handle the situation? Convergence of the series $\sum_n \frac{n^{\log(n)}}{\log(n)^n}$ I have a rough outline of a proof. Is this correct?  $$\sum_{n \geq 2} \frac{n^{\log(n)}}{\log(n)^n} \to a \in \mathbb{R} \iff  \sum_{n \geq 2} 2^n \frac{(2^n)^{\log(2^n)}}{\log(2^n)^{2^n}} \to b \in \mathbb{R}$$ via dyadic criterion (or Cauchy condensation test).  Analyzing the right-hand side:  $$\sum_{n \geq 2} 2^n \frac{(2^n)^{\log(2^n)}}{\log(2^n)^{2^n}} = \sum_{n \geq 2} 2^n \frac{(2^n)^{n\log2}}{(n\log2)^{2^n}} = \sum_{n \geq 2} \frac{(2^n)^{n\log2 + 1}}{(n\log2)^{2^n}} = \sum_{n \geq 2} \frac{2^{n^2\log2 + n}}{(n\log2)^{2^n}} = (\ast). $$  We know for some sufficiently large $N$, $n \log 2 \ge 2$ for all $n\ge N$, so we can bound the series above by:  $$(\ast) \leq C_N + \sum_{n \geq N} \frac{2^{n^2\log2 + n}}{2^{2^n}} = \sum_{n \geq N} 2^{n^2\log2 + n - 2^n} = (\ast\ast),$$  where $C_N$ is the finite sum of the original series until $N$. And once again, for sufficiently large $M$, $m^2\log2+m - 2^m \leq -m^2$ for all $m \ge M$. Hence  $$ (\ast\ast) \leq C_{\max(N,M)} + \sum_{n \geq \max(N,M)} 2^{-n^2} &lt; \infty.$$  We then use the $p$-test to conclude that the sequence does converge. After the last update of TeXLive 2018 (pretest) I get an error with csquotes' macro MakeAutoQuote:  \setcounter{errorcontextlines}{100} \listfiles \documentclass[fontsize=11pt,paper=a4,pagesize,ngerman]{scrartcl} \usepackage[utf8]{inputenc} \usepackage{babel} \usepackage[T1]{fontenc} \usepackage{csquotes} \MakeAutoQuote{»}{«}  \begin{document} ABC \end{document}   The error:  ! Package csquotes Error: Invalid argument.   My versions:  inputenc.sty    2018/04/06 v1.3b Input encoding file babel.sty    2018/02/14 3.18 The Babel package csquotes.sty    2018/02/11 v5.2c context-sensitive quotations (JAW)   I use pdfLaTeX. What is wrong here? Changing Locale within the app itself Get dateformat based on Locale Clone internal HDD to new SSD I recently installed an SSD into my machine. The machine itself is a Lenovo thinkpad W520, and it previously had an internal HDD. I moved the internal HDD into an expansion bay (replacing the CD-ROM), and put the new SSD into the internal bay.   The problem I'm having is that I have my Ubuntu configuration EXACTLY the way I want it - I originally spent many hours configuring it to get it to the way it is now. I'd rather not do this again. But, I'd also like the boot-up gains I would get from the OS being on the SSD.  So, what I'd like to do is clone my Ubuntu partition onto the SSD. The catch is that the standard HDD is significantly bigger than the SSD. And it has a windows partition that I don't need on the SSD (I never use Windows, so if it boots off of the other hard drive, that's fine). The layout of my hard drives are as follows:  /dev/sda (SSD):     Model: ATA M4-CT256M4SSD2 (scsi)     Disk /dev/sda: 256GB     Sector size (logical/physical): 512B/512B     Partition Table: msdos  Number  Start   End    Size   Type     File system  Flags  1      1049kB  147GB  147GB  primary  ext4         boot   /dev/sdb (HDD): Model: ATA ST9500420AS (scsi) Disk /dev/sdb: 500GB Sector size (logical/physical): 512B/512B Partition Table: msdos  Number  Start   End     Size    Type      File system     Flags  1      1049kB  1259MB  1258MB  primary   ntfs            boot  2      1259MB  269GB   268GB   primary   ntfs  4      269GB   483GB   214GB   extended  5      269GB   416GB   147GB   logical   ext4  7      416GB   475GB   58.9GB  logical   linux-swap(v1)  6      475GB   483GB   8470MB  logical  3      483GB   500GB   16.8GB  primary   ntfs   What I've tried so far:  1) Resizing the partitions /dev/sdb5 and /dev/sda1 to be the same size. 2) Booting into Ubuntu 11.04 (from /dev/sdb5) and running dd if=/dev/sdb5 of=/dev/sda1 (of course this causes problems with booting, so I had to reinstall grub.. I can get it to boot, but then I have problems with initrd not finding some files ... presumably it can't load some partitions I think).  Now, I think those two steps are the wrong approach, because it will clone /dev/sdb5 EXACTLY - including references in fstab which point to the wrong hard drive. I'm not sure exactly how to rectify this. I could install Ubuntu 11.04 onto the SSD, then try and copy over all of my configurations, but I'm concerned that I'm going to lose something, or that I'm going to overwrite something like fstab that points back to the original hard drive.   Note that currently, I can still boot from the HDD, so it's not imperative that I get this figured out right away, but I do want it to be exactly how it is right now, so that I can maintain my current level of productivity (it's a work laptop).  Suggestions on how I might be able to overcome this difficulty?   Thanks in advance! Is it possible to resize an image in an answer? For example,  has  that should have the image in the answer, but it's too big.  Is there a way to handle resizing?