ubuntu: clean, 287617/30875648 files, 13277437/12398240 blocks
"dev/sda1: clean, ..." This message appears after I startup my laptop, then it won't continue booting
Converting ArcGIS (*.mxd) file to QGIS (*.qgs) file? How come if $\ i\ $ not of the following form, then $12i + 5$ must be prime? I know if $\ i\ $  of the following form $\ 3x^2 + (6y-3)x - y\ $ or $\ 3x^2 + (6y-3)x + y - 1, \ \ x,y \in \mathbb{Z}^{+},i \in \mathbb Z_{\ge 0}$,  then $\ 12i + 5\ $ must be composite number, because:  $12(3x^2 + (6y-3)x + y - 1) + 5 = 36x^2 + (72y - 36)x + (12y - 7) = (6x + 12y - 7)(6x  + 1)$  How come if $\ i\ $ not of the following form $\ 3x^2 + (6y-3)x - y\ $ and $\ 3x^2 + (6y-3)x + y - 1\ $,  then $12i + 5$ must be prime? $\ x,y \in \mathbb{Z}^{+},i \in \mathbb Z_{\ge 0}$.  For example: $\ 5 = \ 3*1^2 + (6*1-3)*1 - 1\ $ ,when $\ x = y = 1\ $, as proved before,$\ 5*12+5\ $ must be composite number;  $\ 0, \ 1. \ 2.\ 3.\ 4\ $ can't of the following form $\ 3x^2 + (6y-3)x - y\ $ and $\ 3x^2 + (6y-3)x + y - 1\ $,  $\ 12*0 + 5 = 5\ $, $\ 5 $ is prime,$\ 12*1 + 5 = 17\ $, $\ 17 $ is prime, and so on, Is there a --parents option for mv like for cp? cp has a useful feature --parents that allows a file's directory structure to be copied to another directory:  $ cp -v --parents source/directory/from target/ ‘source/directory/from’ -&gt; ‘target/source/directory/from’   How do I similarly move a file? When you energise a taut string, the following resonant modes of vibration occur:    Plotting on the frequency domain, you can see their corresponding frequencies:    But what is the underlying physical principle? Why does this happen?  Is there any way of explaining it that could be understood by a smart 15 year old?  EDIT: I'm going to give my best attempt so far. Here goes:   We can start with sympathetic resonance. Sounding a particular frequency, a pure sinewave.  And noticing the string resonates sympathetically at the frequency of each harmonic. Say this is explained and understood. Now imagine that plucking a string is equivalent to a burst of white noise, which contains frequencies all the way through the spectrum. This could be approached backwards, by starting with random frequencies and noticing that resultant wave produced looks like white noise.   If the above is scientifically correct, then it restricts the domain of the question.  I would really like to be able to understand it scientifically and also be able to explain it intuitively.  PS Images from Can I configure it to allow:   select right-click to copy right-click or ctrl-v to paste? filling area between 2 functions, with shading How do I get my C# program to sleep for 50 msec? How do I get my C# program to sleep for 50 milliseconds?  This might seem an easy question, but I'm having a temporary brain failure moment! Switching languages in bibliography with biblatex I would like to have a bibliography with both Cyrillic and Latin and the main document language being English. How can I make biblatex to automatically switch between languages? (without using XeTeX as suggested by some) The minimal example returns an error if the main language is English. However, with the main language being Russian the document works.  \documentclass{article}  \usepackage[utf8]{inputenc} \usepackage[russian,english]{babel}  \usepackage[backend = biber,babel=other]{biblatex} \usepackage{csquotes} \addbibresource{library.bib}  \begin{document} %\selectlanguage{russian} %if the main document language is Russian the bibliography is compiled without any problem. This is a test. \parencite{Bara2006,Baranov2001}  \printbibliography  \end{document}   The .bib entries are  @book{Bara2006, address = {New York}, author = {Bara, Judith}, publisher = {Routledge}, title = {{English Citation entry}}, year = {2006} }  @book{Baranov2001, address = {Санкт-Петербугр}, author = {Баранов, Николай А}, title = {{Эволюция взглядов}}, year = {2001} } I know that the harmonic series $$\sum_{k=1}^{\infty}\frac{1}{k}  = \frac{1}{1} + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + \cdots + \frac{1}{n} + \cdots \tag{I}$$ diverges, but what about the alternating harmonic series   $$\sum_{k=1}^{\infty}\frac{(-1)^{k+1}}{k}  = \frac{1}{1} - \frac{1}{2} + \frac{1}{3} - \frac{1}{4} + \frac{1}{5} - \frac{1}{6} + \cdots + \frac{(-1)^{n+1}}{n} + \cdots \text{?} \tag{II}$$  Does it converge?   If so, what is its sum? Marking plural of code words In my blog (which is about programming) I often use reserved words from different programming languages.  Like this:     When column is nullable in both tables, this query won't return a match of two NULLs for the reasons described above: no NULLs are equal.   Here, NULL is a programming language keyword.  For numerous reasons, I mark them with &lt;code&gt; tag so they are rendered with a fixed width font, not translated into the foreign languages by Google Translate, can easily be seen on the page etc.  In the example above, which would be the best way to mark the plural?   NULLs NULL s NULL's NULLs NULLS   Option 1 looks ugly on the page (the word and the plural marker are rendered in different colors and fonts)  Option 2 adds a space between the word and the plural marker  Option 3 looks nicest but is not correct  Options 4 and 5 may leave the reader under impression that NULLS is a reserved word (which is not true) and this may be confusing. Also, Google Translate would leave the word as is which would be definitely wrong in other languages.  What would be the least of 5 evils? Calendar month view is unresponsive on iOS 9 How to find string position within another string in C recursively? What would be the optimum design/structure for product data database, where each product have many variations and many attributes? Attribute sets vary between products, and some attributes have values common for all variations of a given product. A typical example of product variations &amp; attributes table is in the image below:    (The 'ATTRIBUTE X' is here to give you and idea of a different attribute type than for 'Product 1').   Would it be practical to try to 'group' some of the attributes (to save time and minimise errors when creating new product entries)? If so, how complicated would it need to be?  If it's relevant - I'm thinking of using mySQL engine, but I'd be happy to see any applicable example from other engines.  EDIT : More information: at the moment we have over 400 variations in a spreadsheet, each one about 15-20 attributes, so that would give about 6000-8000 'data points'. It would be great to be able to list all possible values for a given attribute (to create a dropdown menu when adding new entries), and also to have a choice of possible attributes for a given product. It would be great to be able to specify which attributes are applicable for product variations of each product. How does chain fishing work? Should I set the title attribute for content DIV's to explain what they contain? I have a number of DIV's that break up a page into logical elements for styles and positioning, etc.  As part of optimizing my site for search engine spiders, should I include a title attribute within these DIV's?  (Yes I have a title as part of the whole page, I'm curious on individual structual elements)  Ex  ... &lt;div id="SearchOptions" title="Search filters and options - Type in a name or pick a business and Click 'Search' to get started" &gt;   .... &lt;/div&gt; ... The Boolean modifier is not working I'm trying to model an , but it's not going so well when it comes to the magazine of the weapon.   Next to the magazine is a mesh. I want to cut holes in the mag with that mesh. But the magazine just goes invisible or connects with the mesh when trying to execute the Boolean Modifier. I have tested to invert the normals and some other stuff, but it isn't working. What is the best way to initialize a private, static data member in C++?  I tried this in my header file, but it gives me weird linker errors:  class foo {     private:         static int i; };  int foo::i = 0;   I'm guessing this is because I can't initialize a private member from outside the class.  So what's the best way to do this? How to disable notifications for a single mailbox in Mail? How can I manipulate field-based data from the commandline? For example   How can I print only lines whose Nth field is foo? How can I print only lines whose Nth field isn't foo? How can I print only lines whose Nth field matches foo? How can I change field N to foo?   Is there a standard approach or toolset that facilitates manipulating field-based data on *nix systems? As we all know that Kurama's chakra is of the healing nature type. This is known from many mentions about it in the wiki page of .  My question is, what is the nature type of the chakra of the other Tailed beasts?  Note: This is my thinking why there should have been a nature type to each of the tailed beasts.   As we all know that when Rikudō Sennin was about to die, he split his powers among his two sons (the older son inherited his powerful chakra and spiritual energy, and the younger son inherited his powerful life force and physical energy). Similarly, when creating the nine tailed beasts from the Shinju, he must have split the chakra based on their nature so that each tailed beast had a unique natured chakra.  Any insight on this would be very much welcomed.