When to use % after a command
What is the use of percent signs (%) at the end of lines? (Why is my macro creating extra space?)
When I try to render a wave, it keeps being rendered in extremely low quality. I'm not sure exactly which setting is causing this, but increasing the renderand viewport sampling don't seem to help. If Anakin Skywalker didn't get what he wanted as a Sith (to save Padmé), why was he still a Sith? In the prequels, the primary reason Anakin was willing to become  is because he wanted to save Padmé;     ANAKIN: I will do whatever you ask.       PALPATINE: Good.       ANAKIN: Just help me save Padme's life. I can't live without her. If she dies, I don't know what I will do.      PALPATINE: To cheat death is a power only one has achieved, but if we work together, I know we can discover the secret.       ANAKIN kneels before PALPATINE.       ANAKIN: I pledge myself to your teachings. To the ways of the Sith.   Given that he didn't manage to save her, why did he still become a Sith? I'm not a physicist; I'm just curious about what would happen.  According to this video "" (at 2:50):     "Somebody decided to leave the detectors on but just not take any data. [...] So if it was also going to a magnetic tape - there was no magnetic tape loaded. [...] And what do you think happed? They got this. They got the diffraction pattern."   So the act of measuring (beeing concious of the data) destroys wave-form pattern?  If so lets consider these cases:   What if I'd throw a dice after the experiment to decide if I should look at the data or to destroy it? (e.g. look at the data if the number on dice is even) What if the information about measurement would need to travel longer period of time than the particle would need to hit the wall?    To above cases: Would it mean that information travelled instantly - faster than light or that "the particle can look into the future"? Is tipping mandatory at Restaurants and Bars in Germany? In Bavaria, I paid for my drink, I asked her for "Ruckgeld", but only got the integer part of the money back, the rest of it, she kept it for tip! I looked her in the eye and she understood that I wasn't happy with that "initiative", but wouldn't blink an eye!  My company advised me to let it go, mentioning that if I was going to ask for the change, she would swear.  Notice how she didn't return me the correct amount back and then stare at me, demanding for tip, but she would decide for me!  Since, I will be around for a week or so, I was thinking of paying the exact amount of money next time. Will I get in an uncomfortable situation of having the waiter stare at me, demanding a tip? In other words, is tipping mandatory in Germany?    PS: Having experienced the tipping-cruelty in USA, and having tipped generously waiters across the Mediterranean for their supreme behavior, this Saturday night came as a shock, since I had the impression that this awful habit was only a USA-thing (you know, just like the fake audience laughing they have in USA TV series :) ). What is the difference between Unix, Linux, BSD and GNU? What is the very fundamental difference between Unix, Linux, BSD and GNU?  Unix was the earliest OS, so the term 'Unix like' is understandable, since they have kernel, file system structure, most of the commands, users etc are same as Unix.  Still why are they different? What made them set apart? Is it the kernel? What, exactly, is transferred along supply lines? Do Dragonborn get tails/wings? With the following circuits as examples :    and    How will the current I know how much to flow? Would any other wave travel first in the circuit and then come back and say so much current should flow? Showing there is no ring whose additive group is isomorphic to $\mathbb{Q}/\mathbb{Z}$ Show that there is no commutative ring with the identity whose additive group is isomorphic to $\mathbb{Q}/\mathbb{Z}$. Orthographic Camera Zooming In XNA I am using a spritebatch to render a board. I have created a camera class which can provide me a view and projection matrix. Currently I am supplying the view matrix to my sprite batch when I call begin.  I can get the view matrix to correctly move everything around and do some zooming in and out. My problem is that I want to zoom in on a specific point (for now the center of the screen) but currently zooming just zooms in on the coordinate 0,0.   Here is how I am constructing the view matrix;          _ViewMatrix =             Matrix.CreateTranslation(                 new Vector3(                     (-_Position.X + _Width * _Zoom / 2),                     (-_Position.Y + _Height * _Zoom / 2),                     0) ) *             Matrix.CreateScale(new Vector3(_Zoom, _Zoom, 1));   How could this be altered to make it scale correctly relative to the given point. Later I will probably want to zoom to the mouse position, but if someone has a simple example I'm sure I can work out how to adapt it. I tried to install WPS Office on my laptop (ubuntu 16.10 Gnome, 64 bit) with  Gdebi installer but it said   Dependency is not satisfiable: libpng12-0   Then I tried to open this library as follows  sudo apt-get install libpng12-0   But I encountered an error:  Reading package lists... Done Building dependency tree        Reading state information... Done Package libpng12-0 is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'libpng12-0' has no installation candidate   Can anyone help? Thanks a lot Is there a way to head/tail a document and get the reverse output; because you don't know how many lines there are in a document?  I.e. I just want to get everything but the first 2 lines of foo.txt to append to another document. About free quarks and confinement I simply know that a single free quark does not exist. What is the reason that we can not get a free quark?  If we can't get a free quark then what is single-top-quark? The characteristic and minimal polynomial of a companion matrix of a monic polynomial $f \in \mathbb F\left[x\right]$ in $1$ variable $x$ over a field $\mathbb F$ plays an important role in understanding the structure of finite dimensional $\mathbb F[x]$-modules.  It is an important fact that the characteristic polynomial and the minimal polynomial of $C(f)$ are both equal to $f$. This can be seen quite easily by induction on the degree of $f$.  Does anyone know a different proof of this fact? I would love to see a graph theoretic proof or a non inductive algebraic proof, but I would be happy with anything that makes it seem like more than a coincidence! Update: (Originally this was a comment, but I thought it was worth sharing here at the top.)   In the original question, I asked if there was a polite, socially-acceptable way to ask an Indian co-worker not to use the phrase "do the needful", as I didn't care for it.   In the years since I asked this question I've asked many people about the phrase. To the Indians I've asked in-person, it's not rude in any way. To Americans I've asked it varies anywhere from "I don't like it, but I don't mind it" to "It's very rude and makes me angry when I see it".   Through a long series of edits the question morphed and I wasn’t able to delete it because it had upvoted answers. The question, as it stands now, has no other answer.  I guess, though, if you're non-Indian and you find it rude, or if you're Indian and you've never realized someone might find it rude, this post may still have merit. Hopefully it does. It certainly has gotten a lot of views. Best wishes, folks.  End Update. See below for what's left of the actual question.    "Do the needful."   It's a phrase that I've only seen used in email, and I find it . . . presumptuous (maybe even rude). Regardless of prefacing with "please", one is commanding rather than asking for assistance.  I've only seen it used by those of Indian origin, so I've simply not mentioned it at all rather than worry about any cross-cultural offense that may come of bringing it up.  But still, I don't understand why it's used. Why not request rather than make two statements, one factual, one imperative?  For example, why would one use:        I'm told you have Jane's email address. Please do the needful.      instead of,        Would you send me Jane's email address? Get last n lines of a file, similar to tail I'm writing a log file viewer for a web application and for that I want to paginate through the lines of the log file.  The items in the file are line based with the newest item at the bottom. So I need a tail() method that can read n lines from the bottom and support an offset.  This is hat I came up with: def tail(f, n, offset=0):     &quot;&quot;&quot;Reads a n lines from f with an offset of offset lines.&quot;&quot;&quot;     avg_line_length = 74     to_read = n + offset     while 1:         try:             f.seek(-(avg_line_length * to_read), 2)         except IOError:             # woops.  apparently file is smaller than what we want             # to step back, go to the beginning instead             f.seek(0)         pos = f.tell()         lines = f.read().splitlines()         if len(lines) &gt;= to_read or pos == 0:             return lines[-to_read:offset and -offset or None]         avg_line_length *= 1.3  Is this a reasonable approach?  What is the recommended way to tail log files with offsets? Deleting multiple elements from a list Is it possible to delete multiple elements from a list at the same time? If I want to delete elements at index 0 and 2, and try something like del somelist[0], followed by del somelist[2], the second statement will actually delete somelist[3].  I suppose I could always delete the higher numbered elements first but I'm hoping there is a better way. Difference between modelAttribute and commandName attributes in form tag in spring? How can I prove that every planar graph can be expressed as a union of (maximum) five edge-disjoint forests?  Only thing I can think about is going somehow like the $5$ color theorem but I get stuck in the middle. Or with induction, but still something doesn't fit. Can you help? If $U_1$, $U_2,\ldots,U_n$ are proper subspaces of a vector space $V$ over a field $F$, and $|F|\gt n-1$, why is $V$ not equal to the union of the subspaces $U_1$, $U_2,\ldots,U_n$?