The Ubundu screen resolution 640*480 and not able to chnage.  I installed the virtual machine in windows 10
I've recently installed Ubuntu on Oracle's Virtualbox.  Now I want to install the guest additions.  I started up my Ubuntu guest OS, clicked "Devices" and chose "Install Guest Additions". Nothing happened, and I don't see the CD icon on my desktop.  How can I make this work?
I use a 7805 for a project where the circuit needs a higher current (~2.8&nbsp;A) at 5&nbsp;V. So I assume that if I use both ICs in parallel I can increase the maximum current capacity. Would it work? What are the units of entropy of a normal distribution? I have a random process that follows a normal distribution. It's parameters are mean = 35 units, std.dev. = 8 units. I've seen from the  for the normal distribution that there is a formula to calculate the entropy. So plugging in the figures as:- $$     .5\log\left(2\pi e^1 8\cdot 8\right) $$ I get a value of 1.52, which I take to be  per sample.  My question is what are these units?  What thing do I have 1.52 of?    is (typically) measured in units of bits, after Claude Shannon's definition.  So can I take it that each sample generates 1.52 bits of entropy?  Clearly recording those samples generates information and therefore occupies a real and discrete amount of storage space. Ergo entropy cannot be unit less. How to connect and disconnect to a network manually in terminal? Since the network manager is troubling me so much I want to replace it (possibly wicd orNM from ppa:volanin).  I do not know how to connect and disconnect to the network through the terminal without using network manager.  I would like a command-line way of managing the network. How to turn cheats on or off How can top principal components retain the predictive power on a dependent variable (or even lead to better predictions)? Suppose I am running a regression $Y \sim X$. Why by selecting top $k$ principle components of $X$, does the model retain its predictive power on $Y$?   I understand that from dimensionality-reduction/feature-selection point of view, if $v_1, v_2, ... v_k$ are the eigenvectors of covariance matrix of $X$ with top $k$ eigenvalues, then $Xv_1, Xv_2 ... Xv_k$ are top $k$ principal components with maximum variances. We can thereby reduce the number of features to $k$ and retain most of the predictive power, as I understand it.   But why do top $k$ components retain the predictive power on $Y$?   If we talk about a general OLS $Y \sim Z$, there is no reason to suggest that if feature $Z_i$ has maximum variance, then $Z_i$ has the most predictive power on $Y$.   Update after seeing comments: I guess I have seen tons of examples of using PCA for dimensionality reduction. I have been assuming that means the dimensions we are left with have the most predictive power. Otherwise what's the point of dimensionality reduction? Brie Cheese and expiration date I have a Brie Cheese that has not been opened. It shows an expiration date that is 6 weeks ago. Is it still safe to eat? Caps-lock remapping stops working I have caps-lock key remapped to control, which usually works fine, but after some uptime and one/more suspend/awake cycles* this mapping breaks, and caps-lock reverts back to the default behavior -- i.e. turning on the led and capitalizing whatever I type. (Even though the Tweaks UI still shows it as being mapped to Ctrl -- see picture below.)  Questions:  Is this a known issue (with maybe a known fix)? (Could not find anything relevant with a quick search.) Is there a way to debug the problem, preferably from the command line?  *Remark: I'm not sure it is the suspend/awake cycle that causes the problem, but I can't connect it to anything else... Remark2: removing and readding the mapping (or rebooting) solves the problem, but it would be nice to find a more permanent solution. Reference undefined I receive the a Reference "LastPage" undefined error when trying to compile a document with this syntax:  \fancyfoot[R]{\thepage/\pageref{LastPage}}   What is necesarry to prevent this error? I'm using TeXworks Version 0.4.3 (MiKTeX 2.9) and pdfLaTeX. What made the Ministry admit Sirius was innocent? dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) nginx The Software up-to-date Option automatically download the upgrade for nginx. but While installing it's giving me the following error:  Reading package lists... Done Building dependency tree        Reading state information... Done The following NEW packages will be installed:   nginx 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/434 kB of archives. After this operation, 977 kB of additional disk space will be used. (Reading database ... 291344 files and directories currently installed.) Unpacking nginx (from .../nginx_1.4.7-1~precise_amd64.deb) ... ----------------------------------------------------------------------  Thanks for using nginx!  Please find the official documentation for nginx here: * http://nginx.org/en/docs/  Commercial subscriptions for nginx are available on: * http://nginx.com/products/  ---------------------------------------------------------------------- dpkg: error processing /var/cache/apt/archives/nginx_1.4.7-1~precise_amd64.deb (--unpack):  trying to overwrite '/etc/logrotate.d/nginx', which is also in package nginx-common 1.4.6-1+precise0 dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Errors were encountered while processing:  /var/cache/apt/archives/nginx_1.4.7-1~precise_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   Actually that file /etc/logrotate.d/nginx does not exist in this folder. Looking for intro to Conformal Bootstrap Mid 2012 MBP shuts down claiming no power with charge at 30% or 40% or more I have two mid 2012 MBPs. Sometime last year they both started randomly shutting down and showing the 'please plug me in to power' image when trying to start them up. That would be fine if the batter was at 1% or less but this happens when the battery is at anywhere from 30% to as high as 48% full. The power cycle info says 500 cycles or so. Both of them do this. They are both patched current, always. I asked Apple they suggested NVRAM PRAM and SMC reset, as expected, which had no effect. Any ideas? I know in TNG that all computer interfaces are now touch-screen, and that got me thinking: when was the first reference to touch-screen computer interfaces in Sci-Fi made? I wonder if this is a bug, or if I missed something... When a light hits tangentially convex surfaces with "smooth shading", the shadow on this surface seems to "partially ignore" the smoothness of the surface. Here is an example with a simple cylinder :    On the left, a cylinder with "flat shading". Everything's ok. On the right, the same with "smooth". We can see an edge, bad shadowed.  With or without the "Edge split" modifier, no matters, the edge is still there. The shader is a simple white diffuse shader with no texture nor displace.  I have to add a subsurf modifier with at least 2 levels, which will insanely increase the vertex count... And I can't do that for my project.  I hope someone already saw it, and have a little tip to share. Or if someone already know it's a bug, or a limit of the current Cycles renderer ? Why is there a magnetic field around a magnet if there are no charges moving? Limit of $2^{1/n}$ as $n\to\infty$ is 1 How do I prove that:   $\lim \limits_{n\to \infty}2^{1/n}=1$  Thank you very much. When using the Text Editor, what is the best command to include inside a script which will abort the script at that line?  quit() and sys.exit() stop the script, but also kill Blender. How to Store Design Data in Unity including Formulas? My team is switching to Unity 3D for an upcoming project. I'm tasked with converting our game data system into Unity.  Our existing games use spreadsheet documents (Google Docs) for designers to set values and formulas. This is then exported into an XML doc (and obfuscated) and read in by our game client. I'm trying to figure out a way to accomplish this same thing but solely through Unity. Storing, exposing, and reading data through Unity is pretty straightforward but I'm not sure on supporting formulas.  I realize I can write a custom parser and interpreter which can handle formulas but I'm wondering if there is already a way to do this in Unity.  For example, let's say I have a unit with various stats: Level, Max HP, HP, Damage, Victory Reward, etc. That unit may receive a reward after combat which is based on its Level and remaining HP. A designer would be able to enter into the Victory Reward field either a flat value, like 3, or a formula such as "Floor({Level} * ({HP} / {Max HP}))", something like that.  My question is basically, is there an existing solution for handling data with formulas in Unity, via a downloadable asset or something in Unity itself, or is there a simple framework or technology which already can do something like this which can be easily integrated (example: some kind of JSON extension which supports self-referencing other values and basic mathematical/logical operations)? Can someone tell me how to get a closed form for  $$\sum_{k=1}^n k^p$$  For $p = 1$, it's just the classic $\frac{n(n+1)}2$.   What is it for $p &gt; 1$? What is this noisy shadow overlay that stays with the camera?