I have a Xenial (upgraded from Trusty) 64 bit Desktop install. I've installed the tasksel package in order to install a LAMP server (required for ZoneMinder). When runing "sudo tasksel", it displays the various package groups, some (e.g. Ubuntu Desktop) being marked with a * to show that they are already installed. LAMP server is not marked with a *. So I move the red marker to the [ ] position opposite LAMP server. However, pressing the Enter or Return keys just exits tasksel. I've tried the * and x keys with no success: they do nothing. Am I missing some packages that tasksel requires?
I found a video on YouTube that shows someone using the command tasksel from the server's boot menu after a fresh install of Ubuntu Server. Simple enough it looked like, but when I go to the options I want to choose for installation it has no information on how to select them, and when I click Enter on one of them it takes me back to the command prompt.  So how do I make a selection of the items listed under tasksel?  I have tried Shift++ to add, but no luck. Anyone know?  I want to install Ubuntu Desktop, as Ubuntu GNOME GUI is not an option in the listing for Ubuntu 17.10 Server.
What are underfull hboxes and vboxes and how can I get rid of them? Often, TeX outputs underfull hbox and vbox warnings when running and in the generated log file. What are these and how can I get rid of them? Find remainder when $f(x^{12})$ is divided by $f(x)$ Word for an event that will likely never happen again I've read , but none of them are what I am looking for. I once read a book that used a word to describe an event that has happened in the past, but the odds were so astronomical that it will likely never happen a second time. The context I read these words in were the creation of the first life on earth (without any theological ideas). Basically, the text said that the scenario for the creation of the first living organism happened on a planet where conditions were just right by complete chance, and that the odds of this were so astronomical that it would likely never happen again anywhere in the universe over any length of time.  Sample sentence: "The creation of the first organisms was incredibly unlikely, the event can be called a _________ event, or an event that will likely never happen again."   I can't pretend to understand the validity of the claims by the text, but the words they used to describe these events were quite clever (and scientific sounding) that it would make a fun hyperbole.  I thought it was something along the lines of singularity event, but that doesn't sound quite right. Is it necessary to explicitly remove event handlers in C# I'm using Terminator version 0.97. Is there a way that I can scroll unlimited? In the current version I only can scroll back limited history There is a lot of lag when I play Minecraft. I think this is due to the low amount of RAM I've allocated to Minecraft. (495MB)  How do you allocate more RAM to Minecraft?  I checked my other computer (Intel i5 Core) and it had the same amount of RAM allocated to Minecraft. However, Minecraft did not lag on that computer.  After I installed Optifine on this computer, the lag stopped (I don't know why cause I read that Optifine splits the load onto 2 cores, but I have only one core (At least I think so, a sticker on the laptop says Intel CORE i7)). Neural networks output probability estimates? Suppose my training data contains ~100 variables, and each example is tagged as "success" or "failure".  I understand how a neural network can be used to try and predict success vs failure based on the variables.  However I am interested in the neural network outputting the posterior probability rather than success or failure. In fact, I evaluate the efficacy of the NN based on how accurate the probabilities are (eg. AUROC over the entire dataset) rather than % of cases with correct prediction.  Are NN's the right tool for the job here and if so how do you structure the NN to output this?  (NOTE: I'm a ML newbie!) possible to access custom labels dynamically? titlesec: loss of section numbering with the new update (2016/03/15) After reinstalling TeXLive distribution (install-tl-20160318, Ubuntu 14.04), a issue occurs with the updated version of the titlesec package: the section numbering is lost.  What could it be missing? Is there a modification I have not seen?  Below is a MWE comparison of the two versions. The prevtitlesec package is a reinstall of the previous version (2011/12/15).  \documentclass{book} \usepackage[margin=2cm,a4paper]{geometry} %\usepackage{prevtitlesec}% 2011/12/15 version \usepackage{titlesec}% 2016/03/15 version \usepackage{lipsum}  \begin{document}  \chapter{Title of the first chapter} \lipsum[1] \section{A test section} \lipsum[4] \subsection{A test subsection} \lipsum[4] \subsection{A test subsection} \lipsum[4]  \end{document}   titlesec package 2011/12/15:    titlesec package 2016/03/15: What is the most "pythonic" way to iterate over a list in chunks? I have a Python script which takes as input a list of integers, which I need to work with four integers at a time.  Unfortunately, I don't have control of the input, or I'd have it passed in as a list of four-element tuples.  Currently, I'm iterating over it this way: for i in range(0, len(ints), 4):     # dummy op for example code     foo += ints[i] * ints[i + 1] + ints[i + 2] * ints[i + 3]  It looks a lot like &quot;C-think&quot;, though, which makes me suspect there's a more pythonic way of dealing with this situation.  The list is discarded after iterating, so it needn't be preserved.  Perhaps something like this would be better? while ints:     foo += ints[0] * ints[1] + ints[2] * ints[3]     ints[0:4] = []  Still doesn't quite &quot;feel&quot; right, though.  :-/ Related question: Representing every positive rational number in the form of $(a^n+b^n)/(c^n+d^n)$ About a month ago, I got the following :      For every positive rational number $r$, there exists a set of four positive integers $(a,b,c,d)$ such that    $$r=\frac{a^\color{red}{3}+b^\color{red}{3}}{c^\color{red}{3}+d^\color{red}{3}}.$$      For $r=p/q$ where $p,q$ are positive integers, we can take    $$(a,b,c,d)=(3ps^3t+9qt^4,\ 3ps^3t-9qt^4,\ 9qst^3+ps^4,\ 9qst^3-ps^4)$$   where $s,t$ are positive integers such that $3\lt r\cdot(s/t)^3\lt 9$.      For $r=2014/89$, for example, since we have $(2014/89)\cdot(2/3)^3\approx 6.7$, taking $(p,q,s,t)=(2014,89,2,3)$ gives us $$\frac{2014}{89}=\frac{209889^3+80127^3}{75478^3+11030^3}.$$   Then, I began to try to find every positive integer $n$ such that the following proposition is true :   Proposition : For every positive rational number $r$, there exists a set of four positive integers $(a,b,c,d)$ such that $$r=\frac{a^\color{red}{n}+b^\color{red}{n}}{c^\color{red}{n}+d^\color{red}{n}}.$$  The followings are what I've got. Let $r=p/q$ where $p,q$ are positive integers.   For $n=1$, the proposition is true. We can take $(a,b,c,d)=(p,p,q,q)$. For $n=2$, the proposition is false. For example, no such sets exist for $r=7/3$. For even $n$, the proposition is false because the proposition is false for $n=2$.   However, I've been facing difficulty in the case of odd $n\ge 5$. I've tried to get a similar set of four positive integers $(a,b,c,d)$ as the set for $n=3$, but I have not been able to get any such set. So, here is my question.     Question : How can we find every odd number $n\color{red}{\ge 5}$ such that the following proposition is true?      Proposition : For every positive rational number $r$, there exists a set of four positive integers $(a,b,c,d)$ such that $$r=\frac{a^n+b^n}{c^n+d^n}.$$   Update : I posted this question on .  Added :  asks the case $n=3$. Pass in an array of Deferreds to $.when() How we can add two date intervals in PHP Why $\sqrt{-1 \cdot {-1}} \neq \sqrt{-1}^2$? I know there must be something unmathematical in the following but I don't know where it is: \begin{align} \sqrt{-1} &amp;= i \\\\\ \frac1{\sqrt{-1}} &amp;= \frac1i \\\\  \frac{\sqrt1}{\sqrt{-1}} &amp;= \frac1i \\\\  \sqrt{\frac1{-1}} &amp;= \frac1i \\\\  \sqrt{\frac{-1}1} &amp;= \frac1i \\\\  \sqrt{-1} &amp;= \frac1i \\\\  i &amp;= \frac1i \\\\  i^2 &amp;= 1 \\\\  -1 &amp;= 1 \quad !!? \end{align} Large braces for specifying values of variables by condition How do I produce a conditional expression with large brackets? For example: X = 0 if a=1, 1 otherwise, with a large left bracket and specifying each condition in a line? How can I find the smallest set of groups of $n$ elements such that every element is in the same group as every other at least once? Background: I'm working on  for , and I've run into a problem with how I'm creating the individual matchups (groups of 4 entries).  Currently, I'm simply generating all combinations of 4 elements (in the combinatoric sense) of entries, but that gets really big really quickly:  $$x \choose 4$$    (from )  Therefore, my question is: How can I choose subsets (of length $n$) of a set such that each element of that set appears in the same subset as every other element at least once, while maintaining a minimal amount of subsets?  I can figure this out for $n = 2$, since the solution is quite intuitive: simply combine the first element with every other element, combine the second element with every other element that comes after it, etc. For a set of length $L$, this yields:  $$\sum_{x=1}^{L-1}(L - x)$$    (from )  which is much smaller and more manageable.  However, I still have not been able to figure out: How can I generalize this to any $n$? Is there any criterion (theorem or algorithm) to find out a given polynomial $f(x)$ is irreducible over the field $\mathbb{F}_2$? Django set default form values I have a Model as follows:  class TankJournal(models.Model):     user = models.ForeignKey(User)     tank = models.ForeignKey(TankProfile)     ts = models.IntegerField(max_length=15)     title = models.CharField(max_length=50)     body = models.TextField()   I also have a model form for the above model as follows:  class JournalForm(ModelForm):     tank = forms.IntegerField(widget=forms.HiddenInput())       class Meta:         model = TankJournal         exclude = ('user','ts')   I want to know how to set the default value for that tank hidden field. Here is my function to show/save the form so far:  def addJournal(request, id=0):     if not request.user.is_authenticated():         return HttpResponseRedirect('/')      # checking if they own the tank     from django.contrib.auth.models import User     user = User.objects.get(pk=request.session['id'])      if request.method == 'POST':         form = JournalForm(request.POST)         if form.is_valid():             obj = form.save(commit=False)              # setting the user and ts             from time import time             obj.ts = int(time())             obj.user = user              obj.tank = TankProfile.objects.get(pk=form.cleaned_data['tank_id'])              # saving the test             obj.save()      else:         form = JournalForm()      try:         tank = TankProfile.objects.get(user=user, id=id)     except TankProfile.DoesNotExist:         return HttpResponseRedirect('/error/') How can I find the source of a mysterious bad smell? We have recently moved home, and all is fine appart from a mystery smell which I'm unable to track down. It's driving me crazy (actually, my wife thinks I am crazy as she can't smell it).  I'm hoping someone on here could offer some tips on how to track it down, or what it might be.  Here's some info:  Background: The house is a two floor (plus basement) block/concrete construction.  There is a wide hallway on the groundfloor connecting the rooms (including kitchen, toilet/shower room, stairwell).  The stairs are wood-board on concrete.  The floor in the hall and kitchen  is tiles over concrete, the rest woodblock/parquet over concrete.  Location of the smell: I usually smell it when coming down the stairs, seems to be strongest about half way down.  However sometimes it doesn't smell on the stairs at all, but rather in the ground floor hallway.  Seems to move around quite a lot. Occasionally I have felt it upstairs, but assume this is it drifting. The basement smells fine.  The Smell: The best description of the smell I can give is something like old rubbish.  What I've investigated so far:  1) Something died somewhere?  This was my initial thought, and since I usually notice the smell on the stairs I thought I'd try there first.  I've taken up some of the wood on the stairs (not all yet) but not looking promising, as there really isn't much space between the wood boards and the concrete.  Not really sure where else something could have gotten, as everything seems to be tight against the concrete.  2) Smell from kitchen moving into rest of house? I never really detected a bad smell in the kitchen, but thought I'd rule it out anyway. I thought maybe it was the bin under the kitchen sink that might be causing it.  So I moved the bin to a small storage room at the back of the kitchen (and kept the door closed) and thoroughly cleaned inside the cupboard under the sink. No change.  I also looked behind all of the cabinets for a problem, but could not see anything.  3) Gas from drains? The sink doesn't smell in the kitchen, and it's got a P-bend trap on the pipe - so I can't see a problem there.  Cant detect a smell from the plugholes in the bathroom either.  The bathroom sink waste pipe has a bottle-trap on it.   Don't know if there is a trap on the shower as it's a sealed unit, but I'm guessing yes (and can't smell anything).  Can any one think of something I might have missed, or give any advice? In the Upcoming Halloween Update Posted By SOOPUR SELL (supercell), there have been sneak peeks released showing new skeleton traps for TH 8+. I also remember the Santa Strike from one of the Christmas Updates. My question is when these holiday events finish, do we lose the money we spent on the Traps or do we keep them forever?