try{} catch(Exception e){} VS try{} catch(Exception e){ throw;} - What the difference?
The difference between try/catch/throw and try/catch(e)/throw e
Grub: reboot to specific kernel I'd like to ask for help getting grub-reboot to work.  The theory: According to  (and other sources) I should be able to choose the kernel for the next reboot, using grub-reboot. However, this does not work for me; grub always boots to the default kernel.  Here's what I tried:  $ grep GRUB_DEFAULT /etc/default/grub GRUB_DEFAULT=saved $ grep "menuentry " /boot/grub/grub.cfg  menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-f3a807d1-3fd6-4970-b741-5382e9801060' {     menuentry 'Ubuntu, with Linux 4.4.0-43-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.4.0-43-generic-advanced-f3a807d1-3fd6-4970-b741-5382e9801060' {     menuentry 'Ubuntu, with Linux 4.4.0-43-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.4.0-43-generic-recovery-f3a807d1-3fd6-4970-b741-5382e9801060' {     menuentry 'Ubuntu, with Linux 4.4.0-36-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.4.0-36-generic-advanced-f3a807d1-3fd6-4970-b741-5382e9801060' {     menuentry 'Ubuntu, with Linux 4.4.0-36-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.4.0-36-generic-recovery-f3a807d1-3fd6-4970-b741-5382e9801060' {  # Version 1, using the name $ sudo grub-reboot "Ubuntu, with Linux 4.4.0-36-generic"  # Version 2, using the id $ sudo grub-reboot gnulinux-4.4.0-36-generic-advanced-f3a807d1-3fd6-4970-b741-5382e9801060  # Version 3, counting $ sudo grub-reboot 3   Neither of these commands seem to have an effect; after reboot, I always end up with the 4.4.0-43 kernel.  Note: This is on Ubuntu 16.04 Xenial. It is a server machine and I don't have access to the console during boot, so I can't look at the grub menu :( If $f:\mathbb{R}\rightarrow \mathbb{R}$ is differentiable and $\lim_{x\to \infty } f^\prime(x)=0$ show that $\lim _{x\to \infty } (f(x+1)-f(x))=0$. Having some trouble proving this:     If $f:\mathbb{R}\rightarrow \mathbb{R}$ is differentiable and $\lim_{x\to \infty } f^\prime(x)=0$ show: $\lim _{x\to \infty } (f(x+1)-f(x))=0$   Attempt: from $\int \lim _{x\rightarrow \infty } f^\prime(x) \mathrm{d}x=0$ we can say that $f^\prime(x)=const$ would we then have to show that  $\lim _{x\to \infty } (f(x+1))$ is also a constant? From there if we show that both are equal then the difference is zero. I am on the right track?  Thank you for the help. There are so called "point releases" for LTS versions of Ubuntu. 10.04.3 for instance.  What are those "point releases" releases? I installed an Ubuntu alpha or beta and have been keeping it up to date.   So, Should I presume that my system has automatically updated to the next alpha or beta, and will be running the official release when it's finished? Proof of continuity of Thomae Function at irrationals. From what I know, it is unknown whether $x_n=x_{n-1}^2 + 1$ has a closed form. Is there a recurrence relation which is known to have no closed form with a proof of inexistence?  Assuming a closed form is a non recursive description using the elementary operations of addition multiplication and power, or, assuming any other good definition of "closed form".  Edit  There are similar questions out there, but the answers are a little bit going around the question.   So is there one with proof or is it unknown? And if it depends on the definition of a closed form, then what are the (or some) options? How strong can a closed form definition be to still have a recursive relation that can be proved to not being able to have its form?  Update  Because it is a big question, and I don't want to open a new small one, I think a good representative small question about this subject is:  Is there a recurrence relation with a domain of the natural numbers, described by elementary functions, which has no closed form defined as:  A closed form of a recurrence relation with a domain of natural numbers is a function $f$ that can be described as a composition of a constant number of elementary functions without reccursion. i.e, $f(n) = f_1(f_2( \dots (f_k(n))) \dots) $ where $f_i$ is elementary for all $1 \leq i \leq k$   I think this definition is the most intuitive and basic.  For example, the relation $x_n = x_{n-1}+1$ has a closed form in this sense: $$f(n) = f_1(f_2(f_3(f_4(n))))$$  Where $f_1$ is division, $f_2(n)=(n,2)$, $f_3$ is multiplication and $f_4(n) = (n,n+1)$   Is there a recurrence relation which has no closed form in this sense? How can I change the language of the QGIS Interface? I want the QGIS interface in English, in order to share information with the GIS community. Using another language, when chatting with the GIS community, makes things more difficult. When I installed QGIS, it automatically set the language to French. It's very frustrating not having the opportunity to select my preferred language.   I am using Windows XP in French, but I want QGIS in English. How do I update my TeX distribution? I'm trying to compile a document that only works with an up-to-date distribution, so I'd like to know: how do I update my distribution? Please provide screenshots where appropriate.  List of answers           To keep an eye on what’s going on at CTAN you may subscribe to the  or the RSS feed feed://www.mail-archive.com/ctan-ann@dante.de/maillist.xml How does DC work with natural 20? The interval [0,1] andd [3,5] are equivalent. Is my proof correct? DEF file syntax error in visual studio 2012 Highlight some words of a beamer Mac OS X Darwin: how to reset admin password? Today I bought an ibook G4 from a garage sale. The people who sold it to me didn't know the password for the 2 accounts on it. Apparently it was the guys late father's laptop. Any suggestions on how to get into the laptop and set a new admin account and password? Intuitive explanation for formula of maximum length of a pipe moving around a corner? For one of my homework problems, we had to try and find the maximum possible length $L$ of a pipe (indicated in red) such that it can be moved around a corner with corridor lengths $A$ and $B$ (assuming everything is 2d, not 3d):    My professor walked us through how to derive a formula for the maximum possible length of the pipe, ultimately arriving at the equation $L = (A^{2/3} + B^{2/3})^{3/2}$.  The issue I have is understanding intuitively why this formula works, and exactly what it's doing. I understand the steps taken to get to this point, but there's an odd symmetry to the end result -- for example, is the fact that $\frac{2}{3}$ and its inverse are the only constants used just a coincidence, or indicative of some deeper relationship?  I also don't quite understand how the formula relates, geometrically, to the diagram. If I hadn't traced the steps myself, I would have never guessed that the formula was in any way related to the original problem.  If possible, can somebody give an intuitive explanation as to why this formula works, and how to interpret it geometrically?    Here's how he found the formula, if it's useful:  The formula is found by finding the maximum possible length of the pipe by expressing the length in terms of the angle $\theta$ formed between the pipe and the wall, and by taking the derivative to find when $\frac{dL}{d\theta} = 0$, which is the minimum of $\frac{dL}{d\theta}$ and is therefore when $L$ is the smallest:  $$ L = \min_{0 \leq \theta \leq \frac{\pi}{2}} \frac{A}{\cos{\theta}} + \frac{B}{\sin{\theta}} \\ 0 = \frac{dL}{d\theta} = \frac{A\sin{\theta}}{\cos^2{\theta}} - \frac{B\cos{\theta}}{\sin^2{\theta}} \\ 0 = \frac{A\sin^3{\theta} - B\cos^3{\theta}}{\sin^2{\theta}\cos^2{\theta}} \\ 0 = A\sin^3{\theta} - B\cos^3{\theta} \\ \frac{B}{A} = \tan^3{\theta} \\ \theta = \arctan{\left( \frac{B}{A} \right)^{\frac{1}{3}}} \\ $$  At this point, we can substitute $\theta$ back into the original equation for $L$ by interpreting $A^{1/3}$ and $B^{1/3}$ as sides of a triangle with angle $\theta$ and hypotenuse $\sqrt{A^{2/3} + B^{2/3} }$:  $$ \cos{\theta} = \frac{A^{1/3}}{ \sqrt{A^{2/3} + B^{2/3} }} \\ \sin{\theta} = \frac{B^{1/3}}{ \sqrt{A^{2/3} + B^{2/3} }} \\ \therefore L = A^{2/3} \sqrt{A^{2/3} + B^{2/3} } + B^{2/3} \sqrt{A^{2/3} + B^{2/3} } \\ L = (A^{2/3} + B^{2/3}) \sqrt{A^{2/3} + B^{2/3} } \\ L = (A^{2/3} + B^{2/3})^{3/2} \\ $$  The equation for the formula for the maximum length of the pipe is therefore $L = (A^{2/3} + B^{2/3})^{3/2}$. Is it possible to upgrade a BGA 1224 CPU? I want to upgrade the CPU of my T430s laptop from i7-3520M to i7-3632QM. I'm sure i7-3632QM is supported (same socket (BGA1224), same TDP (35W) and microcode found in BIOS (306A9.PAT)).  So my question is: 1) is it possible to de-solder the current CPU without damaging it, and to solder the new CPU without damaging it and the motherboard ? 2) if so, what tools are necessary? who can do that at a reasonnable cost?  Until now, I was unable to find anyone able (or willing) to do that (I'm located in France, and I have tried a local fablab, electronics shops, TV repair shops, ...). Any hint would be appreciated. Make "compact view" as a default directory view instead of "icon view" How can I make "compact view" the default for all directory views in File Manager, instead of "icon view" ? How to set up a wi-fi hotspot with an Ubuntu laptop (access point mode)? I've read , and carefully followed the instructions provided. I am sure the wireless card in my laptop supports going into wireless access point mode. But unfortunately, when I use the following command to start hostapd service it throws an error:   $ sudo service hostapd stop  Starting advanced IEEE 802.11 management hostapd                      [fail]    The instructions mentioned above said this could possibly be because my wireless card does not support the g mode, and provided the wiki of hostapd. But what is g mode? I tried to switch to a, or b mode, but it just didn't work.  Can anyone help with this or recommend a tool like connectify in windows ?  ps. I am using Ubuntu 12.04, 32 bit. I have an ADSL wired network, and I want to share it by setting my laptop into a WiFi hotspot with  my windows phone. Show that a group of order $180$ is not simple. Paucity of words for relationships Please refer the following questions asked elsewhere on this site:       I am a native Hindi speaker; Hindi has a plethora of terms referring to relationships. To take a trivial example, the term uncle may refer to father's elder brother, father's younger brother, mother's brothers, father's sister's husband, mother's sister's husband, all of which have specific addresses in Hindi.  I discussed the same with one of my teachers. She had the opinion that the development of language mirrors the cultural moorings of the society that uses the language. Now, since all of the above relationships have distinct status and reverence in the Hindi speaking society, that calls for different addresses. That may well not be the case in English speaking societies.  Is that correct? What other linguistic reasons may account for such a dearth of vocabulary in English in this area? How do I stop Outlook Out-Of-Office from replying to certain addresses? When I am out of the office, if I turn Out-of-Office on, it auto-replies to the automated emails I get from our Bug Tracking system, which leads to our Bug Tracking system getting full of message about my holiday.  With Outlook Out-of-Office, how do I set it to not respond to certain 'From' addresses? I see its something to do with the optional Rules in the O-o-O dialog, but its not that clear how to stop it from replying using the rules.  I'm on Outlook 2003 and Exchange 2003 but advice for any version will probably be useful to people.