OS: Lubuntu 16.04  I recently had a problem with login to TTY (1-6). When I press ENTER after the username a newline character seems to repeat every 3 seconds or so.  Halfway through typing the password, a newline occurs and I get Incorrect Login. This continues to repeat a newline every few seconds until I press Ctrl+C.  Has anyone come across this before? It does not happen in a Terminal window or GUI login, only when pressing Ctrl+Alt+F2 to F6.
I upgraded from 16.04 to 18.04. When I press Ctrl+Alt+F3 I get the terminal which prompts for the username. When I type my username and press Enter, it doesn't wait for my password (its as if I pressed Enter without entering anything). Even if I enter something, the text shown in plaintext and then it keeps on saying my password is wrong. After few times, the screen is cleared and it prompts for my username again and the same loop goes on.
How to obtain a confidence interval for a percentile? I have a bunch of raw data values that are dollar amounts and I want to find a confidence interval for a percentile of that data.  Is there a formula for such a confidence interval? Transpose/Unzip Function (inverse of zip)? Subdivision Surface not making things smooth as they are in the tutorial I am following Is my US visa still valid after change in name? I'm a Malawian national and I got US Visa years back.  Recently, due to some reasons, I had to get my first name partially changed on my passport. I have got an affidavit certificate stating the reason and proof.  Since the visa on my old passport has still not expired, but there is a difference in first name, will I face any problem? Capacitance of a single charged plate? Lets say we have a single plate that has a charge of $+Q$ on it. A plate with charge $-Q$ is infinite distance away. Will the plate with $+Q$ have a capacitance associated with it? Why or why not? I was thinking that because the distance between the plates is infinity, the capacitance is zero, but according to my TA, that is not the case. There is always some sort of "absolute" capacitance for the plate with $+Q$ (a capacitance will exist between the plate and air?). Can someone help me out in understanding this? Windows Explorer sort method I'm looking for an algorithm that sorts strings similar to the way files (and folders) are sorted in Windows Explorer. It seems that numeric values in strings are taken into account when sorted which results in something like  name 1, name 2, name 10   instead of  name 1, name 10, name 2   which you get with a regular string comparison.  I was about to start writing this myself but wanted to check if anyone had done this before and was willing to share some code or insights. The way I would approach this would be to add leading zeros to the numeric values in the name before comparing them. This would result in something like  name 00001, name 00010, name 00002   which when sorted with a regular string sort would give me the correct result.  Any ideas? My &quot;hat&quot; is shown twice in my answer, once in my sig, and again above. MacOS 10.14.6; Safari Version 14.0.2 (14610.3.7.1.10) Interpretation of log transformed predictor and/or response Electric charge is lorentz invariant I know that electric charge is lorentz invariant quantity and I can easily think of experiment to check that. Is a though experiment that can prove that also? I would like to use Zapf's Palatino font for the text in my document, which also includes a lot of maths. And I would like a good font for the maths. This is a snapshot of what I am doing.  \documentclass[10pt,letterpaper]{memoir} \usepackage{amsmath} \usepackage{amssymb} \usepackage{mathpple} \usepackage{upgreek} \usepackage{mathpazo} \usepackage{lipsum}  \begin{document}  \chapter{Demo}  Some regular text. \lipsum[1]  Now for some maths.  \begin{displaymath} P_{N-1 + m} = \frac{C}{N-{1} + m} \binom{N_{2} - N_{1}}{m}         \alpha^{m}\beta^{(N_{2} - N_{1}) -m} \end{displaymath}  The number 27 is the sum of the first 5 odd prime numbers: $27 = 1+3+5+7+11$  \end{document}   To me the text and math fonts seem a good fit but the text does not look like Palatino. We have this large database (>1TB) that we intend to "shrink".  The database revolves around one main entity, let's call it "Visit".  For discussion, let's say it is a database for a medical practice.  There are a total of 30 visit "types", such as procedure, annual, follow-up, immunisation etc, each of which is a subsidary table to "Visit", e.g. "visit_immuno".  The database has accummulated some 12 years of data since 2000.  Someone has proposed that we keep about 3 years of data in the "live" version and have the rest live in an "old_data" database.  The date is ONLY stored in the "Visit" table since it is normalised.  The Visit table also contains a ROWVERSION column and a BIGINT pseudo-identity (clustered) column.  For all intents and purposes, let's say the clustering key is populated by a SEQUENCE (SQL Server 2012 Enterprise) - we shall name it cid.  The visit.date is not always in the same order as the clustering key, for example when a doctor goes on extended visitations and returns with his "briefcase" of data, it gets merged into the main table.  There are also some updates to the "visit" table that will cause the ROWVERSION column to be out of sync with both the cid and date columns - to put it simply, neither ROWVERSION nor cid would make suitable partition keys for this reason.  The business rule for removing data from the "live" is that the visit.date must be greater than 36 months and a child visit_payment record must exist.  Also, the "old_data" database does not contain any of the base tables except visit%.  So we end up with:  Live DB (daily use) - All tables Old-Data DB - older data for the visit% tables  The proposal calls for a Combined DB that is a shell containing Synonyms to ALL the base tables in the Live DB (except visit%) plus Views that UNION ALL across the visit% tables in the two databases.  Assuming the same indexes are created in the Old-Data DB, will the queries perform well on the UNION-ALL Views?  What type of query patterns might trip up the execution plan for the UNION-ALL Views? Access denied for user 'root@localhost' (using password:NO) Are there integer solutions to $9^x - 8^y = 1$? This came up in proving non-regularity of a certain language (powers of 2 over the ternary alphabet). Any clue to the above equation could help me move forward.  Edit: Of course, $x = 1, y = 1$ is a solution. I am looking for non-trivial solutions. What is the best way to explain how to choose between "its" and "it's"? Probably one of the most frequent grammar mistakes in the English language is:     The dog sat on it's mat.   Since spelling checkers don't catch it, and it is even logical, since you would correctly write:     The dog sat on Fluffy's mat.   What is the best way to explain to a learner of English how to choose between it's and its? I can't play online. I can only play solo. I have bought Minecraft so it should work fine, but, when I try to connect to a server, it says:  Internal client error: java.net.UnknownHostException: session.minecraft.net   I have tried over 20 different servers and it says the same thing for every single one.   Note: These are not Hamachi servers. I'm attempting a direct connection. I got this $$ f=a(x-1)(x-2)...(x-101) $$ knowing a and that $1 ,2 \ldots ,101$ are it's roots ... I need the roots of $f'$ , how should I do it ? More specifc how can I derivate a polynomial like that, is there a formula or something ? How do I install applications in Ubuntu? How can I install applications like Google Chrome on Ubuntu?  Are there any commands to install an application?    Index of answers: I've just upgraded from Ubuntu 18.04 to its newest LTS version - 20.04. While it comes with some interesting changes, the Desktop icon system was messed up in my opinion. When you hover the mouse cursor over the icons, you see a huge space marked around them that cannot be violated (as you can see in the image below) so that they need to be placed very far apart from each other.  18.04 allowed you to place icons much closer to each other and didn't have that marked space around them. This new way leaves much less space on the Desktop to organize large amounts of icons - including folders, files and shortcuts. Is there a way I can significantly reduce the size of icons and their "spaces" or go back to the old system of organizing files? On "Settings", there is a tool to change the size of Dock icons, but not of Desktop icons.  Also, every time I move or delete something, the Desktop "flashes" and the icons seem to rearrange themselves automatically, nothing of which happened in 18.04. I also can't move anything directly to the Desktop; I need to move to the Desktop folder on Nautilus. This makes me start to think about downgrading Ubuntu back to 18.04. Center Gravity in Unity A few months ago I set full disk encryption during installation of Ubuntu 17.10. Now, I've decided to upgrade. The upgrade ran to the end without any problems. However, after reboot I am not able to log into my encrypted disk.  Where can be the problem? I am 100% sure I press the "right keys" on the keyboard, but technically I don't know what I am writing because of "*" characters and maybe after upgrade my keyboard layout changed. I use some characters which might be somewhere else on the keyboard. What language is default after upgrade?   By the way, I've already tried Caps-lock, but still no luck.  Help will be really appreciated. I am not a fan of installing my system and all backups over and over again.