Problem with VirtualBox and vboxdrv
Could not load 'vboxdrv' after upgrade to Ubuntu 16.04 (and I want to keep secure boot)
Why $\gcd(qb+r,b)=\gcd(b,r)$? Present perfect for past action with present effect If I seem tired, can I say: "I haven't slept last night"? If not, why have I been told that we use present perfect for actions that have present effects? Is 'clamp' a formally recognized mathematical function? I was surprised to find the clamp function absent from  and . Is this mainly a concept particular to computer programming? Is it known by another name in mathematics? I'll be editing the Wikipedia shortly to include a reference to this function but I want to make sure I'm not omitting some synonymous terms I'm currently unaware of.  $$   \operatorname{clamp}(x) = \max( a , \min( x , b ) ) \in [a,b] $$ Priority and timing between enchantments and instants If I have priority and cast an  on a just summoned 2/3 creature, then, passing priority, my opponent casts a  on that creature, does my creature survive? The first spell that resolves is obviously the bolt, that deals 3 point of damage to the creature; but immediately after, will the  Unholy Strength resolve (giving +2/+1), allowing the creature to survive? Using `\input` to insert a section of a document into another When do I use a dot, arrow, or double colon to refer to members of a class in C++? Can airlines deny boarding if my port of entry is different than the country which issued the Schengen visa? Few days back I did a Europe tour from India. As stated by many (I haven't confirmed official documents), I can apply for a visa from the country which is either my first port of entry in this case Paris or the longest stay which in this case was Italy.  Now following is what happened with me.   My flight was New Delhi to Paris via Istanbul with Turkish Airlines I Traveled from New Delhi to Istanbul (no problem here). When I was boarding to flight Istanbul to Paris, zhe airlines officials (the ones who checks the boarding pass before boarding the flight) told me that I could not board the flight because my visa was issued by Italy and I need to go to Italy First. They were denying the longest stay option of the visa. Moreover NONE of the staff of Istanbul airport were able to understand English so I had to go to a lot of problems before I managed to get tickets to Venice. I somehow managed to fly to Venice from Istanbul after almost 24 hours of struggle at Istanbul airport (without food and water).   So, my question is do the airlines staff have a right to deny flight boarding in this case? If $[\cdot]$ denotes greatest integer function, then what is the value of natural number $n$ satisfying the equation $$[\log_21]+[\log_22]+[\log_23]+\dots[\log_2n]=1538 ?$$   My try:  Note that  $$0+1\times2+2\times2^2+3\times2^3+4\times2^4+5\times2^5+6\times2^6+7\times2^7=1538$$  But the answer is $$n=\sum_{i=0}^72^i=255.$$  How is it derived? Chat flag notification, but no flag It appears  is back. Upon refreshing any chat page (even when dumping the cache and hard reloading), a chat flag notification is displayed, but there is no chat flag. Material Opacity in viewport? I'd like to do motion graphics type work in blender and it would be really helpful if I could see the results of keyframing material opacity to cut items in and out of view.  Blender internal is sufficient, using shadeless materials.  I could have swore there used to be something in view options.  Any ideas? What is the difference between shell, console, and terminal? Prove that for for all $p,q\in \mathbb{Z}$, $q&gt;0$ we have: $$ \left| \sqrt{2}-\frac{p}{q} \right| &gt; \frac{1}{3q^2}. $$  To be honest, I do not know where to start - any help would be appreciated. How to force a table into page width? How can I give a script its own icon in the Unity launcher? With Ubuntu 16.04, if you create a launcher (desktop file in ~/.local/share/applications) with a custom icon for a terminal application (so with Terminal=true) then when you start it, it will spawn a new standard terminal icon, and your custom icon will pulse and disappear within a few seconds.  In 14.04, it just worked as expected. (it would not start a new standard terminal icon).   Any idea what to do to change this behaviour? I have a few terminal apps that I want to launch from unity and the new behaviour is problematic (I lose trace of which is which since they all end up with the standard terminal icon)... Why did the Jedi want to bring balance to the Force? During the Prequel trilogy, the Jedi wanted to bring balance to the Force, in accordance with a prophecy.  There seemed to be a general agreement that this was a 'good thing', but a disagreement with the assertion that Anakin was the one to do it.  Why did the Jedi Council believe it was good to bring balance to the Force?  The Republic was mighty (in theory), the Council was established as THE source of Force users, the Sith were thought extinct, and the number of Dark Jedi was apparently very, very low.  It seemed, for all intents and purposes, as if the Force was strongly imbalanced in favor of the Light side...so why did the Council want to 'balance' it? How often is the password asked for sudo commands? Where can I set it up? Is this algebraic identity obvious? $\sum_{i=1}^n \prod_{j\neq i} {\lambda_j\over \lambda_j-\lambda_i}=1$ If $\lambda_1,\dots,\lambda_n$ are distinct positive real numbers, then  $$\sum_{i=1}^n \prod_{j\neq i} {\lambda_j\over \lambda_j-\lambda_i}=1.$$ This identity follows from a probability calculation that you can find at the  top of page 311 in the 10th edition of Introduction to Probability Models by Sheldon Ross.   Is there a slick or obvious explanation for this identity?   This  question is sort of similar to ; clearly algebra is not my strong suit! How do you measure pedal axle/spindle size?  Replacement pedals and accessories specify a size like 9/16" or 1/2".  How do I measure my current pedal to see what I need?  Is it just a matter of putting the pedal threads in a caliper and measuring the outer diameter of the threads across the axle/spindle?  Or do you need to measure the solid part, excluding the threads? In Ruby on Rails, how do I format a date with the "th" suffix, as in, "Sun Oct 5th"? Take a look on a website with specified viewport size, that is bigger than physical size?