Display is upside down but cursor is ok but the cursor clicks elsewhere as it were upside down as well.  You can see cursor in the pic
I just did a clean installation of Ubuntu 18.04.1 on a tablet which was previously running Ubuntu 17.10. Back then just after the installation the screen was rotated, but I was able to get it to work (I think it was running on Wayland).  Now with 18.04.1 the situation is similar: when Ubuntu first boots the login screen is upside-down, but that's not a problem. This time, after login, the screen is correctly oriented but the mouse cursor is upside down and mouse movements are inverted with respect to both axes. The problem is that when I try to click on something the click is registered on the position on the other side of the screen (symmetrically with respect to the center).   It almost seems like the screen (desktop, application, etc.) is correctly displayed, with also the mouse positioned correctly and moving as it should, but then the mouse cursor which is shown to the user is inverted, like if the screen had been inverted just before drawing the cursor.  I already tried the answers I could find, but none worked for me. Anyone have an idea of what's going on?  Thanks
Why is the even root of a number always positive? Let $n \in \mathbb N$ be a natural number and $a \in \mathbb R$ be a real number. The $n$-th root of the number $a$ is defined as follows:  Case I: $n$ is an odd number. In this case the $n^{\text{th}}$ root of $a$ is defined to be that number $b \in \mathbb R$ such that $b^n = a$.  Case II: $n$ is an even number. In this case the $n^{\text{th}}$ root of $a$ is defined to be that number $b \geq 0$ such that $b^n = a$.  Why is it that when $n$ is even, we only consider $b \geq 0$. For example, both $+2$ and $-2$ squared equal $4$, but when we say the square root of $4$ is $2$. Is there a reason for this? Story where the hero ends up having his eyelids removed and being hooked up to some kind of virtual reality machine Trying to identify a short science fiction story where the protagonist is some kind of policeman or investigator, and at the end he chooses to live his life out hooked up to some kind of virtual reality machine. The ending describes him having his eyelids removed as he is attached to the machine, and then as the machine starts working he "becomes" a cowboy or some other western figure riding his horse downhill in a desert scene. Epsilon delta proof for $\lim_\limits{x\to a} \sqrt{x} = \sqrt{a}$ where $a>0$ $f(x) = \sqrt{x}$. For right limit, $x-a &gt; 0$. Let $x-a &lt; \delta$ then $(\sqrt{x}-\sqrt{a}) \lt \frac{\delta}{\sqrt{x}+\sqrt{a}}$. Then chose we must choose $\epsilon $ so that $\epsilon &gt; \frac{\delta}{\sqrt{x}+\sqrt{a}}$. Is this correct? How would I conclude the proof?  Edit - Follow up  From answers, I try a proof for the same limit but this time Left side:  For left side limit, $x-a &lt; 0$ so $a-x &gt; 0$. Let $a-x &lt; \delta$ then $\sqrt{a}-\sqrt{x} \lt \frac{\delta}{\sqrt{a}+\sqrt{x}} \lt \frac{\delta}{\sqrt{a}}$.   So let me begin the proof by saying to choose $\delta = \epsilon \sqrt a$ then $a-x \lt \delta $ so $(\sqrt a - \sqrt x )(\sqrt a + \sqrt x) \lt \epsilon \sqrt a$ so $\sqrt a - \sqrt x \lt \epsilon$ A current I flows through a solenoid (with n turns). Self inductance is $L$. If the magnetic flux is $\phi$, I am taught that $-n\phi=LI$  I dont understand the part with $n$, why do we have multiply by $n$? $\phi$ itself represents the whole magnetic flux there, if $\phi$ implied the flux only occurred by one coil, then it would be correct.   Moreover, flux change by a coil ($n$ turns) in $dt$ time is $d\phi$, so the induced electromagnetic force is   $$dE=n \cdot \frac{d\phi}{dt}$$   Why do we multiply by $n$ here? If $\phi$ means the whole flux, then why multiply? Travel to Romania with a residence permit of Germany I am a student in Germany and i have a residence permit here for 2 years, which is also a Schengen visa, I suppose. Do I need a separate visa if i wish  to travel to Romania? Why are objects at rest in motion through spacetime at the speed of light? What does "...from nonmagical attacks not made with silvered weapons" mean? I'm sure your first thought is, that's perfectly clear.  Unfortunately my group who aren't normally rules lawyers disagree.  Party encounters a  (MM p.211).  It has:     Damage Immunities: bludgeoning, piercing, and slashing from nonmagical   attacks not made with silvered weapons.   My reading of that is if the weapon has to be magical and silvered to hurt it.  So a +1 silver dagger will hurt it, but a +1 regular dagger or a +0 silver dagger won't.  The group's interpretation was that all three of those weapons would hurt and only a +0 regular dagger would be ineffective.    I would also note my interpretation would mean something like blade barrier would also not harm it since you could argue they're magical blades but nothing indicates that they're silvered.    This also appears to be the same wording for some undead so I'm not looking for a lycanthrope specific interpretation but something general for every time that wording is used.    Thanks in advance. I have a file with values organized in columns, and separated by commas, as in the file below:   324,01,1,113333600000,1,, 016,01,1,134954200000,1,, 770,01,1,109069200000,1,, 853,01,1,111518800000,1,,   When I use the following awk command, the delimiter is being changed from commas to spaces   Code:  awk -F, '{$4=$4/1024}{print $0}'   The output becomes:   324 01 1 110677343.75 1   016 01 1 131791210.93 1   770 01 1 106512890.62 1   853 01 1 108905078.12 1    How can I change the value of the field without changing the delimiter? Publicity badges might be taking internal links into account? Prove that for any natural number $n>1$, we have $(2n)!<(n(n+1))^n$ Prove that for any natural number $n&gt;1$, we have $(2n)!&lt;(n(n+1))^n$    I tried using induction, but I failed in that approach, I rather found it was untrue, but on several case testing, I found it to be true. I am out of ideas here, please help. Thank you. I want to type Arabic text in Photoshop, but the text appears disjointed and the letters do not connect at all. For example محمد appears as م ح م د.   I'm using Photoshop CS6 on OSX Mountain Lion. I thought this would be really simple, but it's presenting some difficulties. If I have std::string name = &quot;John&quot;; int age = 21;  How do I combine them to get a single string &quot;John21&quot;? What is the Linux equivalent to Windows' Program Files? I am trying to print a large quantity (several megabytes) of UTF-8 encoded text which consists of Chinese and Latin characters (and maybe a sprinkling of others). I would like to print it in several columns per page, in a very small, condensed font, preferably with control over line spacing. I'd quite like inter-column lines, but I can live without them. The aim is to print to PDF for transfer, as well as to paper.  I have tried enscript and a2ps, but neither of these support Unicode.  I have also tried paps, but this produces bitmapped outputs which cannot be PDF'd effectively, and also look terrible.  Is there a modern way to print UTF-8 text like this without resorting to something like constructing it manually in Python? If I create just a basic hello.tex file an compile it using   pdflatex hello.tex   The pdflatex program is creating a plethora of file which is a little annoying. Currently it writes all those files about which I really don't care:  hello.aux, hello.log, hello.nav, hello.out, hello.snm, hello.toc   Is there a way to tell pdflatex to only write hello.pdf if the build is successful ? If not, can I specify the output directory of those files ? Maybe I could just write them in /tmp. Why does connecting a battery's positive terminal to the negative terminal of another battery not create a short circuit? How to programmatically remove a field from a node? In the header of my document I set the maximal author names to 2:  \usepackage[style=authoryear-icomp, maxbibnames=9, maxcitenames=2, backend=biber]{biblatex}   Now, when I cite texts with two authors, LaTeX gives me the following:     (Author_A/ Author_B 2012: 232)   When I have three authors or more, LaTeX makes it:     (Author_A/ Author_B et al. 2012: 232)   But I want LaTeX to just name the first author if there are more than two authors ... like this:     (Author_A et al. 2012: 232)   Any tips on how to achieve this ? Editable fields in views Valid characters in a Java class name What characters are valid in a Java class name? What other rules govern Java class names (for instance, Java class names cannot begin with a number)?