Is there any application in Ubuntu that can do exactly what Windows DeepFreeze does?  (for example: you are working fine but when you restart the PC it always goes back to the time when you applied deepfreeze)  Example:  When you want to un-deepfreeze you apply password, so that it can be used by anyone but only Admin can un-deepfreeze to upgrade.   Once you logged in you can then tell is it frozen mode or upgrade mode:    How can i do this in Ubuntu please?  EDIT:  DeepFreeze for Windows works as below:  1 - you have installed windows 8.1 pro with drivers, softwares, config, policy etc etc. you are happy with your configuration and you think its final and reliable and its stable. But now you want to allow this KIOSK to be used by Public locations  2 - Because it has to run in Public locations there are many issues. To get prevent from all the issues there is this tool call DeepFreeze. You can install it once and make everything frozen. Which allow the users to work day and night without cause any problem in the PC.  3 - When the PC is rebooted, DeepFreeze automagically restore to the position when DeepFreeze was applied.  This prevent the system to run 24/7 in a public location or in a location where you want to deploy reliable, stable release for not to expect any new surprises.  DeepFreeze provide that solution and its very easy to configure takes about 4 to 5 minutes.
I'd like to know if there is any alternative to Deep Freeze for Linux that still under development, because I've read some things on the internet and looks like the same company which developed Deep Freeze had a Linux version of it, but the project was discontinued.
Integrating $\int_1^2 \int_0^ \sqrt{2x-x^2} \frac{1}{((x^2+y^2)^2} dydx $ in polar coordinates I'm having a problem converting $\int\limits_1^2  \int\limits_0^ \sqrt{2x-x^2}   \frac{1}{(x^2+y^2)^2}  dy dx $ to polar coordinates.  I drew the graph using my calculator, which looked like half a circle on the x axis.  I know that $\frac{1}{(x^2+y^2)^2}  dydx$ turns to $ \frac{r}{(r^2)^2}drd\theta$, which would be $ \frac{1}{r^3}$  The region of integration in  $\theta $ is I guess $0 \leq  \theta  \leq  \frac{1}{4}  \pi $, but I'm stuck for r. The lower boundary is $x=1=rcos\theta \rightarrow r=1/cos\theta=sec\theta$, but what is the upper boundary?? Is it  $\sqrt{2rcos\theta-r^2cos^2\theta}$? I tried this but I couldn't integrate my equation...  Could someone please help me out?  Also, how can I draw the graph of $y= \sqrt{2x-x^2} $? I could only know how it looked like by using my calculator... Evaluate $\int_0^\infty\frac{\ln x}{1+x^2}dx$ Evaluate $$\int_0^\infty\frac{\ln x}{1+x^2}\ dx$$ I don't know where to start with this so either the full evaluation or any hints or pushes in the right direction would be appreciated.  Thanks. Two independent Poisson process question Why do Jedi use lightsabers instead of blasters? Blasters seem to be more practical. Is there a special bond or something between lightsabers and Jedi? Which browsers are officially supported, and what else do I need? Which browsers are officially supported by Stack Exchange?  Also, what else is needed in order to use every feature of the site? Parallel.ForEach Slower than ForEach Every time I install a new Linux kernel, it gets left in the grub_config, making the boot menu longer each time.    I know I can manually search through the installed packages and remove them.  Does Ubuntu provide any easier way to clean them up or keep them from showing in the boot list? I think some good words would be conflicted, or confused. As an example of context, think of someone who believes in freedom of speech, but, at the same time, they would support banning comedians who make jokes about certain issues that person cares about. How align the qedsymbol after of a big formula in display mode? OSX keeps switching to the first space I have come across these three definitions of the limit superior (or upper limit) and the limit inferior (or lower limit) of a sequence of real numbers and I wonder how to establish the equivalence of these.    Walter Rudin: PRINCIPLES OF MATHEMATICAL ANALYSIS, 3rd edition:  Definition 3.16: Given a sequence $\{s_n\}$ of real numbers, let $E$ be the set of numbers $x$ (in the extended real number system) such that $s_{n_k} \to x$ for some subsequence $\{s_{n_k}\}$. This set contains all subsequential limits ..., plus possibly the numbers $+\infty$, $-\infty$. We now ... put  $$s^{*} = \sup E,$$ $$s_{*} = \inf E.$$ The numbers $s^{*}$, $s_{*}$ are called the upper and lower limits of $\{s_n\}$; we use the notation  $$ \lim_{n \to \infty} \sup s_n = s^{*}, \, \, \, \lim_{n \to \infty} \inf s_n = s_{*}.$$ Tom M. Apostol: MATHEMATICAL ANALYSIS, 2nd edition:  Sec. 8.3: Definition 8.2: Let $\{a_n\}$ be a sequence of real numbers. Suppose there is a real number $U$ satisfying the following conditions:    i} For every $\epsilon &gt; 0$ there exists an integer $N$ such that $n &gt; N$ implies $$a_n &lt; U + \epsilon.$$ ii) Given $\epsilon &gt; 0$ and given $m &gt; 0$, there exists an integer $n&gt; m$ such that $$a_n &gt; U - \epsilon.$$ Then $U$ is called the limit superior (or upper limit) of $\{a_n\}$, and we write $$U = \lim_{n \to \infty} \sup a_n.$$ Statement (i) implies that the set $\{a_1, a_2, a_3, \ldots \}$ is bounded above. If this set is not bounded above, we define $$\lim_{n\to\infty}\sup a_n = +\infty.$$ If the set is bounded above but not bounded below and if $\{a_n\}$ has no finite limit superior, then we say $\lim \sup_{n\to\infty} a_n = -\infty$. The limit inferior (or lower limit) of $\{a_n\}$ is defined as follows: $$\lim_{n\to\infty}\inf a_n = -\lim_{n\to\infty}\sup b_n,$$ where $b_n = -a_n$ for $n= 1, 2, 3, \ldots$.    Robert G. Bartle and Donald R. Sherbert: INTRODUCTION TO REAL ANALYSIS, 3rd edition: Exercises for Section 3.3: Problem 10: Let $(x_n)$ be a bounded sequence of real numbers, and for each $n\in \mathbb{N}$ let $s_n \colon= \sup \{x_k \colon k \geq n\}$ and let $t_n \colon= \inf \{x_k \colon k \geq n\}$. Prove that $(s_n)$ and $(t_n)$ are monotone and convergent. Also prove that if $\lim (s_n) = \lim (t_n)$, then $(x_n)$ is convergent. [One calls $\lim (s_n)$ the limit superior of $(x_n)$ and $\lim (t_n)$ the limit inferior of $(x_n)$.]   Now how can one show that the above three definitions are equivalent (i.e. these three definitions are of the same pair of numbers)? Update: Universal login is in place and considered &quot;done&quot;. If you see anything weird, please submit new bug reports.   As y'all know, our current flavor of &quot;global authentication&quot; leaves a few things to be desired. It's flaky, requires a page refresh, etc. etc. Wouldn't it be nice if you could just sign in once and be automatically logged in across the network?  We are ready to roll out Stage 1 of Project &quot;Make Authentication Suck Less&quot;. It is live as of a few minutes ago. What this means right now:  When you log into any Q&amp;A site on the stackexchange.com domain, you will be automatically logged into all other Q&amp;A sites on the stackexchange.com domain + stackexchange.com itself.   is excluded from this.   , , and other Q&amp;A sites with their own domains will still use the old flow.  We are going to recognize you in some ways on sites where you don't have a profile. This is still a work in progress, but most notably you will see &quot;join this community&quot; in the top bar instead of &quot;sign up&quot; and &quot;log in&quot;.   But I use multiple accounts! What do? We aren't intending to break the ability to run multiple accounts. The same guidelines as before still apply — we don't officially support that, you might end up with an accidental automatic merge if you're not careful with your credentials, any interaction between the accounts is right out, and so on. If you're already using different browsers or different browser profiles for your accounts, nothing will change for you. If you are somehow logged into multiple accounts in the same browser... I'm sorry to say, but that's a bug even for our current global auth setup. You will now only be able to log into one at a time, and you'll need to log out when you want to switch. (Or start using different browsers.) What's next:  Remember  we tested a few months ago? It's coming back. Stage 2: bring other domains into the fold (this is also live now) Stage 3: make cross-domain experience smoother and support browsers that reject third-party cookies in all conditions (looking at you, Safari) - this is not currently feasible. Safari users and users who reject third-party cookies will need to sign in separately to every second-level domain (e.g. stackexchange.com, stackoverflow.com, etc).  If you see any issues… Good luck, because you probably can't log in to report them here. =) But seriously, let us know via the contact form linked at the bottom of any page. If you are able to log in, report issues here on meta as normal. So, in conclusion… Whilst I understand how the RSA algorithm works, I don't understand how the CPU operates when it needs to use the mod function with a huge number $n$, for example.  $n = 8192$ bits; $c = m^e \mod n$;  In essence my question is how does the CPU deal with this huge modulus? Ubuntu stuck/freeze on install I've been trying to replace my current Windows 10 installation with Ubuntu 16.04. My computer is a Lenovo Thinkpad T470. I've formatted my 15GB USB-dongle. Downloaded the software Rufus, and burned the ISO onto the USB. I've tried the settings "MBR Partition for BIOS or UEFI", "MBR Partition for UEFI" and "GPT partition for UEFI". I've tried using memtest86+ to test if I have any memory errors, I have not. I've tried disabling Secure boot, and Fast startup. I've tried using other software than Rufus, and I've tried entering the "nomodeset" in the boot options, as well "acpi=off", nothing works.   When I boot from my USB. I choose "Install Ubuntu" from the grub menu. And then select my language in the installer. It is from this point on, it gets problematic. Sometimes when I try to connect to my WIFI, it connects successfully, but when I press the "continue" button, the installer freezes and nothing happens. Sometimes I get past this point, but it then freezes later on in the installation progress - typically right when I press the "Install now" button.   It should also be mentioned that, if I press the "Quit" button in the install. I get to a black screen with a lot of text saying something like squashfs error.   Can someone please help me? When I tried booting memtest86+ it only worked when I changed my boot mode from UEFI to Legacy. Could this be it? Are there any downsides to installing an operating system in legacy?   If anyone has any other suggestions, it would be greatly appreciated!  Thank you :-) Why are there so many close votes to review and so few of the others? In Random forest algorithm, Breiman (author) constructs similarity matrix as follows:   Send all learning examples down each tree in the forest If two examples land in the same leaf increment corresponding element in similarity matrix by 1 Normalize the matrix with number of trees   He says:     The proximities between cases n and k form a matrix {prox(n,k)}. From their definition, it is easy to show that this matrix is symmetric, positive definite and bounded above by 1, with the diagonal elements equal to 1. It follows that the values 1-prox(n,k) are squared distances in a Euclidean space of dimension not greater than the number of cases.    In his implementation, he uses sqrt(1-prox), where prox is a similarity matrix, to convert it to distance matrix. I guess it has something to do with the "sqaured distances in a Euclidean space"-quoted above.  Can somebody shine a little light on why it follows that 1-prox are squared distances in a Euclidean space and why he uses squared root to get distance matrix? Unit Test - Creating Custom Metadata I have three questions that I'd like to be clarified.   Is their anyway we could create Custom Metadata in Test Classes? I tried to create on my Test Class but I got an error saying the fields of the metadata could not be writable.  If not, then does that mean we should declare real values in our Custom Metadata and use that instead in our test classes? If (2) is correct, then does this mean we have to create the Custom Metadata in the environment we'll be deploying our code before doing the actual deployment? Is there any way to have BibTeX or biblatex insert a bibliography without having citations in the body of the document itself? Maybe a way to hide the in-text citations, so that BibTeX still sees them and includes them in the bibliography, but does not print them in the body? How to create nested loops in x86 assembly language Alternatives to 'respectively'