Importance of serialVersionId in Serialization?

Whenever we try to serialize an object of a Class, we always have a unique value for serialVersionId as a private final field, what is its significance with respect to deserialization, can we use it to check whether the object and the values have been deserialized in a proper way ?


What Are The Elements of $e$ in Set Theory?

I saw a comment by Asaf Karagila a while back that remarked on the elements of $\pi$.  I'm aware of how natural numbers get said to have elements in set theory, such as $3$ having the elements $\{\}, \{\{\}\}, \{\{\}, \{\{\}\}\} \}$.  This doesn't quite make it clear to me how rational numbers have elements also, but I'll forego that here. It seems even less clear to me that a number like $\pi$ or $e$ would have elements.  I thought for a moment that using the terms of an infinite series used to compute $e$ might work, but on further reflection this seems suspicious, since it seems that different non-terminating series could get used to compute $e$, as holds for $\pi$. What are the elements of $e$?


I am very inexperienced in electronics, so far I have just done real simple stuff with an arduino. I have a Nema17 (driven through a L293D) stepper motor which has a rated voltage of 12V and current of 0.4A. Now, my understanding of current and voltage is that the current solely depends on the voltage of the power supply and resistance of the motor. Therefore the motor draws a certain amount for a specific voltage. Now, when I connect my power supply to my circuit I only get to 0.4A or anywhere near that by setting to voltage to about 20V which exceeds the 12V rated voltage of the motor. Am I simply understanding this in a wrong way or do I somehow need to convert the voltage to 12V without the current being affected?


How can I get a significant overall ANOVA but no significant pairwise differences with Tukey's procedure?

I performed with R an ANOVA and I got significant differences. However when checking which pairs were significantly different using the Tukey's procedure I did not get any of them. How can this be possible?  Here is the code:  fit5_snow<- lm(Response ~ Stimulus, data=audio_snow) anova(fit5_snow)  > anova(fit5_snow) Analysis of Variance Table  Response: Response           Df Sum Sq Mean Sq F value  Pr(>F)   Stimulus   5  73.79 14.7578  2.6308 0.02929 * Residuals 84 471.20  5.6095                   --- Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1   df<-df.residual(fit5_snow) MSerror<-deviance(fit5_snow)/df  comparison <-  HSD.test(audio_snow$Response, audio_snow$Stimulus, df, MSerror, group=FALSE)  > comparison <-  HSD.test(audio_snow$Response, audio_snow$Stimulus, df, MSerror, group=FALSE)  Study:  HSD Test for audio_snow$Response   Mean Square Error:  5.609524   audio_snow$Stimulus,  means                  audio_snow.Response   std.err replication snow_dry_leaves            4.933333 0.6208034          15 snow_gravel                6.866667 0.5679258          15 snow_metal                 6.333333 0.5662463          15 snow_sand                  6.733333 0.5114561          15 snow_snow                  7.333333 0.5989409          15 snow_wood                  5.066667 0.7713110          15  alpha: 0.05 ; Df Error: 84  Critical Value of Studentized Range: 4.124617   Comparison between treatments means                                Difference   pvalue sig        LCL      UCL snow_gravel - snow_dry_leaves  1.9333333 0.232848     -0.5889913 4.455658 snow_metal - snow_dry_leaves   1.4000000 0.588616     -1.1223246 3.922325 snow_sand - snow_dry_leaves    1.8000000 0.307012     -0.7223246 4.322325 snow_snow - snow_dry_leaves    2.4000000 0.071587   . -0.1223246 4.922325 snow_wood - snow_dry_leaves    0.1333333 0.999987     -2.3889913 2.655658 snow_gravel - snow_metal       0.5333333 0.989528     -1.9889913 3.055658 snow_gravel - snow_sand        0.1333333 0.999987     -2.3889913 2.655658 snow_snow - snow_gravel        0.4666667 0.994348     -2.0556579 2.988991 snow_gravel - snow_wood        1.8000000 0.307012     -0.7223246 4.322325 snow_sand - snow_metal         0.4000000 0.997266     -2.1223246 2.922325 snow_snow - snow_metal         1.0000000 0.855987     -1.5223246 3.522325 snow_metal - snow_wood         1.2666667 0.687424     -1.2556579 3.788991 snow_snow - snow_sand          0.6000000 0.982179     -1.9223246 3.122325 snow_sand - snow_wood          1.6666667 0.393171     -0.8556579 4.188991 snow_snow - snow_wood          2.2666667 0.103505     -0.2556579 4.788991


Subgroups of finitely generated groups are not necessarily finitely generated

I was wondering this today, and my algebra professor didn't know the answer.      Are subgroups of finitely generated groups also finitely generated?    I suppose it is necessarily true for finitely generated abelian groups, but is it true in general?  And if not, is there a simple example of a finitely generated group with a non-finitely generated subgroup?  NOTE:  This question has been merged with another question, asked by an undergraduate.  For an example not involving free groups, please see Andreas Caranti's answer, which was the accepted answer on the merged question.


Finding a subring of $M(2,\mathbb{Q})$ which is isomorphic to a) $\mathbb{Q}\times \mathbb{Q}$ b)$\mathbb{Q}$ c)$\frac{\mathbb{Q}[x]}{(x^2)}$.

I got this classwork but got very confused with the form of answer the question needs, Can anyone please help? Thank you


18.04 clean install GRUB installation failed

I am clean installing 18.04 to a partition. All went smoothly until this error.     The 'grub-efi-amd64-signed' package failed to install into /target/. Without   the GRUB boot loader, the installed system will not boot.   After pressing 'ok'  the following opened:     Installer crashed      We,re sorry the installer crashed. After you close this window, we'll allow you to file a bug report using the integrated bug reporting tool. This will gather information about your system and your installation process. The details will be sent to our bug tracker and a developer will attend to the problem as soon as possible.   Has anybody had the same issue and had a resolution?


Whenever I assign a material to the selected faces of a cube, it paints the entire cube. I've seen questions like this, and I've done everything they say to do in the comments, yet nothing seems to work.


With the command pv it is possible to clone a drive, how do I mount it?

I was able to backup a drive using the following command.  pv -EE /dev/sda > disk-image.img   This is all well and good, but now I have no way of seeing the files unless I use this command  pv disk-image.img > /dev/sda   This, of course, writes the data back to the disk which is not what I want to do. My question is what can I do to mount the .img file itself instead of just writing back to a disk?    I've tried mounting using loop but it seems to complain about an invalid NTFS.  $ mount -o loop disk-image.img mount: disk-image.img: can't find in /etc/fstab. $ mount -o loop disk-image.img /mnt/disk-image/ NTFS signature is missing. Failed to mount '/dev/loop32': Invalid argument The device '/dev/loop32' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?


Blocking programs from reading outside their allocated RAM

I was wondering if I could keep program A from reading my entire ram, as it does not need to monitor what program B is doing.  Also I am on windows 8.1 64 bit.


Determinant game: a generalization of Putnam 2008, A2

The initial question is:  Alan and Barbara play a game in which they take turns filling entries of an initially empty $2008\times 2008$ array. Alan plays first. At each turn, a player chooses a real number and places it in a vacant entry. The game ends when all the entries are filled. Alan wins if the determinant of the resulting matrix is nonzero; Barbara wins if it is zero. Which player has a winning strategy?  Answer: Barbara has a winning strategy by a basic parity argument. Label the rows $r_1,\ldots,r_{2008}$ and partition them into 'slices' of two, say $\{ \{r_1,r_2\},\{r_3,r_4\},\ldots,\{r_{2007},r_{2008}\}\}$. If Alan places an entry in some spot, Barbara places the same entry in the same column in that slice; for instance, if Alan plays $5$ in $a_{332,98}$, Barbara plays $5$ in $a_{331,98}$. This ensures the rows in each slice are equivalent, so the determinant of the matrix is zero.  My question: How can this be modified if instead of a $2008\times 2008$ array, they play on a square array with odd sides ($3\times 3,5\times 5,$ etc., with the $1\times 1$ case discarded)?  I don't know of a winning strategy even for the $3\times 3$ case. I think Barbara's strategy breaks down because Alan isn't forced to complete a row in the same way as he was in the even case, so it isn't clear to me that Barbara can force one row to be a linear combination of another. I also think the strategy of, 'Barbara tries to get a column/row of zeroes,' is easily disrupted, so I don't see that as viable either.


Changing colors of polygon based on numbers in separate Excel sheet using ArcGIS Desktop?

I have a shapefile and a separate excel Sheet.  I want this shapefile to interact with the excel sheet. I have assigned numbers associated with colors on this sheet, what I would like to do is have the shape color change with the numbers in the excel sheet.  I believe this is something I can accomplish in ArcGIS 10 ModelBuilder but I don't know how to go about it.


Query: how to recompile the python file or overcome the cached version (.pyc)

Have the following query:  consider test/auto/gen/init.py has a version field set as 1.1.1  Now start the script which contains:  Step 1: from test.auto import gen as auto_gen  Step 2: open the file test/auto/gen/__init__.py   Step 3: write __version__=1.1.2 to this file  Step 4: now use auto_gen to check the content          auto_gen.__version__ this still points to 1.1.1  But when i exit the script and comeback again then i see after importing the auto_gen.__version__ gives me updated value as 1.1.2  I also tried importing again after writing to the file but still the same problem. (from test.auto import gen as auto_gen)  So this problem i see as a generic one. In the sense if i am running a script and it generates a python file on the fly the object does not get updated.  Exit from the ipython or the script excecution and then running again solves this.  Can any please give some suggestions to this problem.


What is the Economic system of the Potterverse?

The annual student intake of Hogwarts seems about 100. Since in book 7 Hogwarts is declared mandatory for all children, this means that the total magical population of Britain cannot be much more than 10,000.  How do these people make a living?  All jobs mentioned in the books are non-productive occupations (government, stores, sports &c) - not farmers or engineers. There are exceptions - makers of wands/robes/broomsticks - but where do they get the raw materials from?  Who and how "creates goods" in the wizarding world?  Note that if you say "wizards exchange their gold for Muggle money and buy stuff from Muggles (through intermediaries, if necessary)" then you would have to explain where they get their gold: they would either have to mine it, or produce something of value to the Muggles (in which case the separate financial system of galleons/sickles/knuts does not make sense).  PS. A simple issue of maintaining a steam locomotive for Hogwarts express is pretty much insurmountable for 10k people - without Magic, that is. So, I can imagine that the skilled tradesmen can transfigure dirt into raw materials for their trade - except for food, which "is the first of the five Principal Exceptions to Gamp's Law of Elemental Transfiguration".


Reference an environment counter through label in another counter

I have an implications environment impl whose counter works as intended (1,2...). In a subsequent chapter, I develop a series of hypotheses for each implication, and I want the hypothesis environment hypo to recognize the counter of the implication that it belongs to. So far what I have is:  \documentclass{article} \usepackage{amsmath} %% Implications \newcounter{implcounter} \newenvironment{impl}{ \refstepcounter{implcounter} \textbf{Implication \theimplcounter:} }{\par}   %% Hypotheses \newcounter{hypcounter} \newenvironment{hypo}{ \refstepcounter{hypcounter} \textbf{Hypothesis \thehypcounter:} }{\par} \numberwithin{hypcounter}{implcounter}  \begin{document}  This is one implication:  \begin{impl} \label{impl:a}     Hello \end{impl}  This is another implication:  \begin{impl}      Bye bye \end{impl}  But then:  \begin{hypo}     Not the numberwithin I would like!   % I would like for this to be implication 1.1 \end{hypo}  \end{document}   I would like to have a hypo environment for which the number within is the one referenced by \label{impl:a}, in this case 1.


How to define a type alias for a template in a class

For example  struct Option_1 {     template<class T> using Vector = std::vector<T>; };   I can do  typename Option_1::Vector<int> v;   But I prefer the following  Vector<Option_1, int> v;   or similars without the word "typename". I define an alias  template<class Option, class T> using Vector= typename Option::Vector<T>;   but failed with unrecognizable template declaration/definition. How to fix it?


Formula to generate Critical t-values for t-test (instead of using a look-up array)

I am searching for the formula that will generate the critical values in a t-test instead of using a static critical value table.   I am programming in Java and not R so the qt() function is not what I am looking for.  Any help is appreciated.


What Causes Slanting Pointed Ice Spikes to Form?

Ice spikes are fairly rare but there is a general consensus about how they form from extruded pressurized water in containers subjected to below freezing conditions. This morning as I fed my dogs I found the above pictured ice spike in their outdoor watering dish.  The spike formed near the edge of the dish, was approximately 8-9 cm long, protruded at about a $45^o$ angle, was fairly flat on the upper surface but ovoid on the lower surface, and was very pointed with the base much larger than the rather short tip.   The outside temperature overnight was $2$-$3^o$ C below freezing. There was freezing rain overnight so the relative humidity was near 100 %.  The dish was in a protected corner so no rain hit the surface, but normal outdoor air currents would have prevailed.  The water in the dish was collected by a dehumidifyer, but the dish itself was not particularly clean as the photo shows.  In online searches about this phenomenon I learned that they can be normal to the liquid surface, or slanted like the one I observed.  They are also sometimes wider at the top than at the base unlike the pointed spike I observed. They sometimes look like inverted pyramids. My question concerns the explanation for the diversity of shapes and angles that these ice spikes exhibit. Are air currents the complete explanation, or are there more subtle things involved here?


I have a sun lamp at 90 degrees to a curved mesh. In Eevee, the shadow renders as smooth. However, in Cycles, I get these black artefacts - entire faces on the shadow edge are black. How do I fix this? I've played around with the mesh normals, material settings, etc. No luck.  Update I fixed this with Subsurf modifier. Is there a better way?


How can I prevent my honey cake from splitting open?

I've made honey cake pretty often, and it almost always splits open in the middle. Why does that happen and how can I prevent it?  Edit: attaching a picture of the cakes I just made    Basic recipe (not so exact):  Ingredients 6   eggs 1   glass oil 2   glasses sugar     Pinch of salt 4   teaspoons baking powder 1   cup coffee (glass of water + some instant coffee) 4   cups flour 4   Tablespoons brandy     Pour in cinnamon - teaspoon+ 1   pound honey Directions  Mix first 3 ingredients. Add rest of ingredients besides honey and mix. Put in honey last – pour slowly as it mixes Bake for 1 hour at 350. Cover towards the end


I've installed in Ubuntu bionic the following package in a 64 bits system:  apt install openjdk-11-jdk   Now I try the new java:  /usr/lib/jvm/java-11-openjdk-amd64/bin/java -version openjdk version "10.0.2" 2018-07-17 OpenJDK Runtime Environment (build 10.0.2+13-Ubuntu-1ubuntu0.18.04.4) OpenJDK 64-Bit Server VM (build 10.0.2+13-Ubuntu-1ubuntu0.18.04.4, mixed mode)   The question is why I'm getting Java 10 instead of 11.  With this command, I see that no other java is installed in my system:  # update-alternatives --config java


Simplest way to add a bibliography using a .bib file

I have written a little essay and tried to add a bibliography. I get all kinds of errors and searched the last 5 hours for solutions, only to find out how little I know about latex... I am using Miktex and Texmaker. I made a simple version of my .tex file to post here: \documentclass[]{article} \usepackage[autostyle]{csquotes} \usepackage[ngerman]{babel} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{biblatex} \addbibresource{referenzen}  \begin{document} \section{Introduction} Lorem ipsum \cite{dirac} \printbibliography \end{document}  Bib file: @article{valueSensitiveDesign,     author = {Friedman, Kahn et al},     title = {Value Sensitive Design},     year = "2008" }  @book{dirac,     title = {The Principles of Quantum Mechanics},     author = {Paul Adrien Maurice Dirac},     isbn = {9780198520115},     series = {International series of monographs on physics},     year = {1981},     publisher = {Clarendon Press},     keywords = {physics} }  @article{Lee2009a, author = {Lee, Geun}, journal = {The Korean Journal of Defense Analysis}, number = {2}, pages = {205--218}, title = {{A Theory of Soft Power and Korea's Soft Power Strategy}}, volume = {21}, year = {2009} }  I've setup Texmaker to do 'pdflatex > show pdf'. But then the bibliography is not printed. I researched this and people say that you need to 'latex > biblatex > latex 2x > show pdf', but I don't have that. I have similar options, but the I get the error:  This is BibTeX, Version 0.99d (MiKTeX 20.6.29) The top-level auxiliary file: prototype.aux I found no \citation commands---while reading file prototype.aux I found no \bibdata command---while reading file prototype.aux I found no \bibstyle command---while reading file prototype.aux (There were 3 error messages)  Texmaker doesn't seem to give me an option to do it the correct way (and this gets way to complicated for me). Here is a screenshot of my configuration options (sorry it's in German):  My problem seems to be so simple, but I feel like a need to do a full latex tutorial to get any idea what I m doing. I feel like there might be some conflicting packages. Can anyone please explain whats going on here?


Install 32-bit version of Oracle JDK 7 on a 64-bit Ubuntu?

I am using  to install the 64-bit version of Oracle JDK 7 under Ubuntu 64-bit. Is there a way to tweak this mechanism to install the 32-bit JDK instead?  If not, how do I install a 32-bit Oracle JDK 7 under Ubuntu 64-bit?


What’s the difference between rootkit and RAT?

I know that both can give attacker remote access to computer. Is RAT easier to detect than rootkit? Where are they typically get installed? Can one make more damage than another? Which one is easier to remove?


Does the Distant Spell metamagic apply to the Sword Burst cantrip?

If this has been asked, I could not find it. My Sorcerer has the sword burst cantrip, and I'm thinking of taking the 'Distant Spell' metamagic option. Will it change the range to 10 feet?  Similar to  but not quite answered, though Crawford's tweet seems to imply it would work.  Although the spell has a range of 5 feet, it seems like Distant Spell would increase the area of effect in this case. So RAW it works, but likely shouldn't?


How to get 256 color support in a login shell TTY?

I want to experiment with a fully text-based environment, however, the only thing that is stopping me - is getting 256 colors so my Vim color schemes could work perfectly.  When I enter a TTY by pressing CTRL+ALT+number, and execute tput colors, I always get just 8.  So, in order to get a usable text-only environment, I'd need to have the following questions answered:   How can I configure the TTY to support at least 256 colors? (more if possible) How can I set the font, both family and size? How can I change the color scheme of the TTY, as I can in GNOME Terminal?   Any other tips on using such an environment appreciated.


I have come across strange operators such as &, |, ^ etc. How exactly do these operators work?  >>> 10 | 7 15 >>> 10 ^ 7 13 >>> 10 & 7 2 >>>    The pattern does seem quite odd, and most of the sources out there do not give answers that are easy to comprehend.


Dealing with anxiety about answering questions during presentations

I'm a PhD student in social science. Recently, I have been invited to present my work at a conference and a lab meeting. I'm glad about the opportunities to present my work in front of colleagues. But at the same time, I'm afraid that I won't be able to answer questions from audience and they will think that I'm dumb. To be clear, I don't have anxiety about giving a talk per se, or at least know how to deal with it. I have a script for my talk, rehearse it so many times to the point I almost memorize it. I even practice my facial expressions and voice tone during the talk. I just learn and practice how to present my "ideal" academic self to colleagues. However, when it comes to Q & A after my talk, I sometimes couldn't answer questions professionally. I think there are two reasons for why sometimes I couldn't answer questions.  I'm not a native English speaker. When someone asks me a question that I couldn't understand, I ask the person to repeat the question or ask a follow-up question for clarification. But this strategy doesn't always work. One time, at a conference, I couldn't understand the question after asking the person to repeat the question twice. It was so embarrassing.  When I'm under pressure, my brain stops functioning and I couldn't really think! When people suggest a new idea that I'm not familiar with, I feel like my brain stops working, my mind goes blank and I cannot really provide "sophisticated" answer, which is possible only when I fully understand what their question actually meant and when I know how to connect their idea with my work. Also, it is so hard for me to come up with a good answer in a minute. I cannot really think when everyone is looking at my face waiting for my answer.   Given that how judging academia is, I feel like people will eventually find out that I'm not that smart. My frustration is that I cannot prepare for questions in advance. They are often unpredictable and random. I'm wondering if you have any tips or advice about how to deal with questions after talk or how to overcome anxiety about questions.


How to prevent overflow of row/cell colors in booktabs?

Based on  you know how to easily create rows with background colors. This also works for booktabs. Edit: This is how it looks by default with \begin{tabular}{lccc}:  But we want to change that… So there is a problem if you intend to use @{}. @{} makes the table a little smaller at the left and right side and it looks very professional. Usually… Because with colored rows, it does not, because they (horizontally) "overflow" the table. Here is an example: \documentclass{article} \usepackage{array,graphicx} \usepackage{booktabs} \usepackage[dvipsnames, table]{xcolor}  \begin{document}      \begin{table} \centering         \rowcolors{1}{white}{yellow}                  \begin{tabular}{@{}l ccc@{}}             & Head & Head & Head \\             \cmidrule{1-4}             line 1 & Y & N & Y \\             line 2 & Y & N & Y \\             line 3 & Y & N & Y \\             line 4 & Y & N & Y \\             \rowcolor{red}             line 5 & Y & N & Y \\             \cellcolor{green}%             line 6 & Y & N &              \cellcolor{green}%             Y \\             \cmidrule{1-4}         \end{tabular}     \end{table}  \end{document}


According to the definition a  is defined as the      duration of 9,192,631,770 periods of the radiation corresponding to   the transition between the two hyperfine levels of the ground state of   the cesium-133 atom.   Why specifically 9,192,631,770? Is there a scientific purpose for such?   And if there is a scientific purpose, why is this method (cesium atomic clock) the most accurate for it?


Ordnance Survey Master Map font in QGIS 2.14

I have been trying to style some OSMM data using  which include a font with some of their symbology in. I've added the font to my system (ubuntu 14.04 LTS) and when viewed in FontMatrix and other system font tools it looks fine:  But when I come to use it in QGIS the font has no glyphs visible and I end up with ugly rectangles instead of my symbols.  Is there some trick to get QGIS to recognise this font?


How to determine the confidence of a neural network prediction?

To illustrate my question, suppose that I have a training set where the input has a degree of noise but the output does not, for example;  # Training data [1.02, 1.95, 2.01, 3.06] : [1.0] [2.03, 4.11, 5.92, 8.00] : [2.0] [10.01, 11.02, 11.96, 12.04] : [1.0] [2.99, 6.06, 9.01, 12.10] : [3.0]   here the output is the gradient of the input array if it were noiseless (not the actual gradient).  After training the network, the output should look something like this for a given input.  # Expected Output [1.01, 1.96, 2.00, 3.06] : 95% confidence interval of [0.97, 1.03] [2.03, 4.11, 3.89, 3.51] : 95% confidence interval of [2.30, 4.12]   My question is how can a neural network be created such that it will return a predicted value and a measure of confidence, such as a variance or confidence interval?


Freestyle is confusing me - Cycles Blender

I have been trying for the past 3 days to try and get freestyle to work in Blender cycles, but I can only find tutorials for Blender  Internal.  I don't like working in Internal, but I can't figure out how to get the freestyle to work in Cycles!  I am not a seasoned blender-ist, so please explain with pictures


Show that the subgradient of the nuclear norm is given by $$\partial|X| = UV^T + W$$ where $X = U \Sigma V^T $ is the compact SVD of $X$, $W$ is a matrix such that $U^T W = 0$ and $WV = 0$, and $\|W\|_2 \le 1$.   This is exact that question. But I don't know how to get $W$. Can some explain that paper explicitly?


Inexact measurement and wavefunction collapse

As is usually said, measurement of an observable $q$ leads to collapse of wavefunction to an eigenstate of the corresponding operator $\hat q$. That is, now the wavefunction in $q$ representation is $\psi(q)=\delta(q-q_0)$ where $q_0$ is result of measurement.  Now, in reality measurements are never exact, so the wavefunction should not have that sharp peak. Instead it should be broadened depending on precision of measurement. In this case, can we still introduce an operator, an eigenstate of which would the new wavefunction appear? Is it useful in any way? Or does the new wavefunction depend too much on the way it was measured so that each instrument would have its own operator? How would such opeartor look e.g. for a single-slit experiment?


I'd like to override the default style of Leaflet 1.0.0 tooltips, especially the bubble/frame. I don't see any options or methods for this. How do I hook into the CSS? I want to change layers individually, so I need to select each layer's tooltips individually with CSS.


How to make an exe run without the IO window (command line window)?

I'm trying to write an exe that runs with out any window how cat I do that? How can I run/write an exe that will not open any window?  (A code example can be very useful).  Thank you very much!


Mix active and passive voice in the thesis

I am starting to write my thesis and was told not to use passive voice. But the active voice pronouns "I" and "we" do not sound right somehow and I even found this link  encouraging active voice yet instructing not to use first person pronouns.   So I am planing to mix active voice with passive voice, such that when I refer to my work specifically I will use passive voice and else I will use active voice. I am not a native English speaker, but in my language this sounds fine. Moreover this link  says it is okay in English too.  Is this good practice in dissertations?  If not is there any other solution to this problem?  For instance in the abstract I want to say "In this thesis I prove that the...". How can I write this sentence in active voice without using I? Thanks a lot.  I believe my question is different from  as I am asking about mixing two voices in same document specifically and not about using we vs I.


Is there a 2D generalization of the coefficient of restitution?

The  characterizes a collision in one dimension by relating the initial and final speeds of the particles involved,  $$C_R = -\frac{v_{2f} - v_{1f}}{v_{2i} - v_{1i}}$$   In a 2D collision, the velocity can be split into components parallel and perpendicular to the "plane of collision" (the plane tangent to the two objects' surfaces at their contact point), and the equation above applies to the perpendicular components of the velocities only. One could write  $$\begin{pmatrix}v_{2f\shortparallel} - v_{1f\shortparallel} \\ v_{2f\perp} - v_{1f\perp}\end{pmatrix} = \begin{pmatrix}1 & 0 \\ 0 & -C_R\end{pmatrix}\begin{pmatrix}v_{2i\shortparallel} - v_{1i\shortparallel} \\ v_{2i\perp} - v_{1i\perp}\end{pmatrix}$$   My question is, is it useful (i.e. does it produce a more accurate description of realistic 2D collisions) to generalize that matrix? Perhaps by allowing the top left element to be unequal to 1, or allowing nonzero off-diagonal elements? Or is there some nonlinear relation that works better?  As usual, if you know of any relevant published research, references would be much appreciated.


Calling Custom Writers Within Instance Methods: Why is self not implicit?

I am familiar with the conventional way of using attr_accessors within the initialize method:  class Dog     attr_accessor :name      def initialize(name)         @name = name     end end  dog = Dog.new("Denver") p dog.name  => "Denver"   I was playing around with custom writers and readers. I was suprised to realize the following:   Within instance methods: you can call upon a reader method without explicitly specifying self because self is implicit.  Within instance methods: you MUST explicitly call self to call upon a writer method. self IS NOT implicit for attr_writers   Example 1 to show that self is implicit when calling attr_reader methods within instance methods:  class Dog     def name         @name     end      def name=(val)         @name = val     end      def initialize(name)         @name = name     end      def call_name         # no need to say: p self.name         p name     end end  dog = Dog.new("Denver") dog.call_name  => "Denver"   Example 2 to show that self IS NOT implicit when calling upon attr_writers within instance methods.  In other words: the instance variable is not getting set because I did not prepend the writer method below with self:  class Dog     def name         @name     end      def name=(val)         @name = val     end      def initialize(name_val)         # works as expected with: self.name = name_val         name = name_val      end      def change_name         # works as expected with: self.name = "foo"         name = "foo"     end end  dog = Dog.new("Denver") p dog.name  dog.change_name p dog.name  => nil => nil   Question: why isn't self implicit within instance methods when calling attr_writers? Why do I have to explicitly specify self for attr_writers within instance methods?


undefined reference to c++ class constructor

i am using Qt5 creator , all the files are included in the project  (the class "MyCounter" is created using the IDE wizard) i reduced my code to this one, and when i compile and run:           undefined reference to MyCounter<int>::MyCounter()   main.cpp  #include <QCoreApplication> #include"mycounter.h" //if include "mycounter.cpp" instead of "mycounter.h" works fine   int main(int argc, char *argv[]) { QCoreApplication a(argc, argv); MyCounter<int> x; return a.exec(); }   mycounter.h   #ifndef MYCOUNTER_H  #define MYCOUNTER_H   template<class T>  class MyCounter  {    public:       MyCounter();  };   #endif // MYCOUNTER_H   mycounter.cpp     #include "mycounter.h"    #include <iostream>     template<class T>   MyCounter<T>:: MyCounter()  {   std::cout<<"somthing..."; }


I am trying to install internet explorer on my ubuntu 18

So I am trying to install Internet Explorer on my ubuntu 18. I followed these steps from   sudo apt-get install wine cabextract wget http://www.tatanka.com.br/ies4linux/downloads/ies4linux-latest.tar.gz tar zxvf ies4linux-latest.tar.gz   As I got the ies4linux-latest.tar.gz file and tried to gunzip and untar it, I am getting the below error :   gzip: stdin: not in gzip format   Which means that the file is not properly gzipped and its an HTML or binary or some code. In my case it's an HTML code. So I opened it and had a 1800 line of code.  I tried other links to find the source file but I can't.


In /etc/profile I see this:  for i in /etc/profile.d/*.sh ; do if [ -r "$i" ]; then         if [ "${-#*i}" != "$-" ]; then             . "$i"         else             . "$i" >/dev/null 2>&1         fi     fi done   What does ${-#*i} mean. I cannot find a definition of a parameter expansion starting ${-.


Integer i = new Integer(10);     Integer j =10;     System.out.println(i==j); // false      String a1 = new String("abc");     String a2 = "abc";     System.out.println(a1==a2); // false   But to make Java more memory efficient, the JVM sets aside a special area of memory called the "String constant pool." When the compiler encounters a String literal, it checks the pool to see if an identical String already exists. If a match is found, the reference to the new literal is directed to the existing String, and no new String literal object is created. (The existing String simply has an additional reference.) So String literals are immutable. So, both a1 and a2 will have two reference pointing to same memory location then why "==" doesn't return true?


How to split an array to 2 arrays with odd and even indices respectively? For example  int[] a = new int[]{1, 3, 7, 8};   then get two arrays     a1: {1, 7}    a2: {3, 8}


I have an noteboook ASUS X200CA with Ubuntu 12.04 factory preinstalled.  I would like to update the operating system but I'm afraid it is not working properly, consume more resources than my computer can support or have problems with drivers.  Could someone tell me if the new Ubuntu on this computer working properly?  Thanks!


How to obtain/enable Blender 2.8 "shortcut properties"?

I'm trying to add a custom shortcut that enables selecting vertex/edge/face mode inside mesh edit mode. I'm trying to do this inside a custom keymap preset.  The image shows two instances of the same shortcut: The upper part of the image is the custom keymap preset. The lower part of the image is from the preset known as 'industry standard'.  Industry standard preset has the additional option that allows you to select vertex mode (encircled) while the same 'sub-option' is missing inside the custom preset (question mark) despite using the same operator.  How do I enable these 'sub-options'? Why is the name of the shortcut the same as the operator and is there a way to change it?


Filtering a raster by pixel value ? (Qgis)

I have downloaded Globcover data in GeoTIFF format. I want to create a new grid which only has values where the Globcover data (the only band in the TIF file) has one certain value (==190).  Can I do this with GDAL?  If not, which way should I go? The procedure should be callable from a Shell script (Linux). I have QGIS installed (but no clue how to use it).


Next weekend you will be participating in 12km cross country race on a mountain.The average time between  two successive wild animal sightings on the mountain is reported to be 5 minutes  (a) What is the probability that you see at least one wild animal in the 11th minute of the     race given that you will see 3 wild animals since the start of the race?  (b) What is the probability that it will take more than a quarter of a hour before you see a wild animal after ten minutes of running?  Now I have attempted (a) , but I don't know whether my thinking is correct. (b) on the other hand makes little sense to me.  My attempt:  (a)$ X~ Poisson(\frac{1}{5})$ and $Y~Exponential(\frac{1}{5})$  $Pr(X>4) = Pr(X>1)$  (I am thinking that this is some variation of the memoryless property)  $Pr(X>1) =Pr(Y<1)$  $Pr(Y<1)= 1 - (e^{(\frac{-1}{5})})$  Perhaps, I was a bit to vague in my attempt of (a). So here goes my attempt of(b).From my understanding of the question , it is asking what it the probability that the time between events(in this case animal sightings) is more than 25 minutes given you have been running for ten minutes  Now from what I know the fact that you have been running ten minutes is irrelevant this is due to memory-less property of the exponential  distribution   so without further ado  I present my attempt at (b)   let $X $ be exponentially distributed random variable with $\lambda = 1/5$  then  $Pr(X >15) = 1 - Pr(X <= 15)$


Corridor with a dead body turns out to be in a Möbius strip

I'm looking for a book of science fiction short stories. One of the stories describes the experiences of a man who finds himself in a corridor with a dead body. The corridor turns out to be a Möbius strip. I must have read that late 1970s.


What exactly is Trunks' new transformation?

Some people say it is a False Super Saiyan God, other people say it is a Super Saiyan God 2, while another group of people say it is something different. Is there any official info on what it is exactly?


Prove that the number of divisors of a number that is a power of a natural number, is odd.

I want to know if the number of divisors of a number is odd or even, I think that will solve me a problem.   The problem, as I see it, asks me to prove that the number of divisors for a number that is a power of a natural number - is odd.   What I tried:  I think to prove it using induction. Not sure I'm doing it the right way.   For $n = 1:$ 1 has only one divisor – itself, and it's the power of itself so its a power of a natural number, so it holds.  For $n = n^2$, take $n^2$, it's surely a power of natural number ($n$). Aassume it holds.   Now prove for $n = (n+1)^2$ again, it's surely a power of a natural number – (n+1). Let's calculate:   $$ (n+1)^2 = n^2 + 2n + 1 $$  From the assumption we know that the number of divisors of $n^2$ is odd, from the base – the number of divisors of $1$ is odd and now we remain with $2n$... not sure what to say on him.   I would like a hint (more than a solution, as it will solve me homework)  Maybe something with prime factorization? But my proof should be general and not for a particular number.   Thank for any help.


I typed Code under MIT documentation under CC as title of my question on Stackoverflow. The suggestions popped up showing all licensing questions as closed. Where shall the questions about licensing be asked? My original question is:  Why some project code is licensed under MIT and documentation under CC? For example


When should I use typename in a template function?

According to , typename should be added to tell compiler that iterator is a type (Is it correct?), e.g.  template <typename T> void print(vector<T> &v) {   for (typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)     cout<<*it<<endl; }   Two questions:   Under what circumstances should a typename be added? Can someone give me another example? Can auto in C++11 replace all these typename xxx cases?


Find pattern using grep and then replace with sed

I have the following lines of code          BalancerMember http://server3:82 status=D         BalancerMember http://server2:80 status=D   I want to search for entries with port 82 and then want to wipe out status=D. So , it will look like this           BalancerMember http://server3:82   Tried this, but this will not work    grep :82 app.conf | sed -i 's/status=D/ /'   sed: no input files   I need the -i option with sed because I would like to make the change in file .  Any suggestions.


Python - extract the 3rd item from a list?

I have a list as per below, it is currently returning the first and the 3rd item in the list, but i only want the 3rd item not the 3rd, how can i achieve this?  >>>list = ['1', '2', '3', '45'] >>>print list[::2] ['1', '3']   Thanks


Question of $\Diamond$ in Generic Extension

Let $M$ be a countable transitive model of $ZFC$, $\mathbb{P}\in M$ a forcing notion and $G$ a $\mathbb{P}$-generic filter over $M$.  Assume $( \mathbb{P}$ is c.c.c and $|\mathbb{P}|\leq \omega_{1})^{M}$  and $\Diamond$ holds in $M$. I want to show  $\Diamond$ is holds in $M[G]$.   How to use $ \Diamond $  in $ M $?


Transporting chicken between refrigerators - how long is too long?

My work lunch routine currently consists of cooking chicken over the weekend and refrigerating it, then cutting up a piece and adding it with rice and vegetables in a refrigerated, sealed tupperware container the night before work. In the morning I take the container out of the fridge and put it in my backpack, where it stays for about 2 and 1/2 hours (or a little more) through my morning commute. As soon as I get to work I put it back in a refrigerator, microwave it and eat it about 4 hours later. Is this too long out of the refrigerator to safely eat?


Attempting to block "wordpress" useragent is overloading CPU

I've had some DDoS issues - specifically the XML-RPC exploit (wordpress) wherein thousands on thousands of Wordpress instances attack my machine.    I have the following in my nginx server block:     if ($http_user_agent ~ WordPress) { return 444; }  While it does terminate all of the wordpress connections, it still overloads the CPU.  Here are my server specs:  Ubuntu 16.04 LTS - E3-1230v5, 16G DDR4, and a SSD.    I would've assumed that it would be able to handle far more, but that doesn't appear to be the case.  I have attempted to block the wordpress useragent automatically using fail2ban, but all that appeared to do is create a few thousand iptables rules and no end in sight.    Is there a more performant way to block this attack?  Thanks.


I'm new to Linux and today I'm trying to install AMD Catalyst™ 15.9 Proprietary Linux Graphics Driver for my HD 7650M.   Everything so far is good, but when I try to install XFree86-Mesa-libGL and XFree86-libs in terminal via sudo apt install XFree86-Mesa-libGL XFree86-libs it shows:  Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package XFree86-Mesa-libGL E: Unable to locate package XFree86-libs   Any ideas how I can install these packages?


How to add mysql-8.0 repository from archive.ubuntu.com/ubuntu/pool/main/m/mysql-8.0/

Official repo for MySQL8  not working.  How to add archive.ubuntu.com/ubuntu/pool/main/m/mysql-8.0/ to source list for Ubuntu 18.04 Bionic for setup MySQL8?  I'm trying to add next list to /etc/apt/sources.list.d/mysql.list  deb http://ua.archive.ubuntu.com/ubuntu/pool/main  bionic main deb-src http://ua.archive.ubuntu.com/ubuntu/pool/main bionic main   but it's not working


How is reputation given/taken for multiple owners' answers?

On several occasions I have seen answers that belong to a list of users (abstract or real) like :  15 revs, 9 users 85% Robert Cartaino   When  owns something, no reputation point changes occur, but in this particular case, there are only real users that "own" the answer.  How are reputation points computed if such an answer is upvoted or downvoted?  Answer based on comment: "Voting on a community wiki post (up or down) does not affect any user's reputation."


How to restore accidentally deleted /etc/bash.bashrc, without reinstalling Ubuntu?

In a brand new system, I mistakenly deleted /etc/bash.bashrc, by creating and redirecting to it, instead just appending.  How could I restore it without reinstalling the system?  As the experts here know, this is an important file in the system and I need it for proper working of the system as well as aliases.  I tried rebooting assuming it will be recreated but it isn't. In a quick Google search I found nothing (I found many results regarding restoring ~/.bashrc but of course it's different).  How could I restore it fast without copying from another PC?   A same-PC minimal, fast, solution.


Transit visa for UK if on Dutch residency permit

I am a South African living in the Netherlands on a residence permit.  My husband is Dutch, and we are going on holiday to South Africa. I have a flight booked back from South Africa to Amsterdam, via Heathrow.  Do I need a transit visa for the UK? The  is not clear about how my Dutch residence permit would apply - and it's very expensive if I do need a visa!


Using a slash (/) between multi-word phrases

How would you suggest using a forward slash (/) between multi-word phrases? Should a slash be even used between multi-word phrases?  For example -      Following are the open/in progress issues.   or     Following are the open/ in progress issues.   or     Following are the open/in-progress issues.   P.S. - The example sentence is just for explaining the problem, I'm not necessarily looking for an alternate way to put the same point forward.


Careers: create PDF is not handling properly the sections Writing and Reading

Scenario #1: no items in the section Writing, a few items in Reading   click on create pdf in the PDF you get your readings under the title "Writing" (should be "Reading")   Scenario #2: one item in the section Writing, a few items in Reading   click on create pdf in the PDF you get:   your readings under the title "Writing" (should be "Reading"), as in scenario #1 there are no writings (there should be one)    Hope it to be clear. Let me know in case it isn't.  Thank you!


The question is:  A monoatomic gas undergoes a process $PV^3=k$ where k is a constant. Find the heat capacity of the gas.  Problem:  I know how to calculate the heat capacity at constant pressure ($C_p$) and ($C_v$) of a gas but this problem does not ask any of them.  I came to know about this formula:  For a process $PV^n=k$,  $C = (\frac{1}{\gamma - 1}-\frac{1}{n-1})R$   as the solution but found no proof or anything. How can I start to prove it myself?


Can Chatter Connect API set createdByUser to other than logged in user?

I know this question has been asked earlier but I could not find the answer.  I am trying to create chatter Feed using Chatter connect API and my need is "Createdby user should be different than logged in User".  Please let me know if it is possible and if so then how.  Thanks


Understanding Lens Viewing Angle and Focal Length Relationship

I have a camera module with a lens viewing angle of 185° and a focal length of 1.8.  But as far as I can tell, this camera module is not classified as a fish-eye lens.  The working distance is specified from 14cm->infinity.  And while I understand that the horizontal FOV (mm) can be calculated from the lens viewing angle and desired working distance, I am confused at how this 184° viewing angle would effect the outputted image (would it be fish-eye?  Is the working distance too small for the fish eye effect to be noticeable?)  Thanks for any clarification.


Why some of my objects suddenly start to move together?

In my scene all of a sudden I must have hit a random hot key, because random objects are now parented and when I move an object others move as well.


If $\mathbf A$ and $\mathbf B$ are Hermitian, when does $\det(\mathbf A-\lambda\mathbf B)=0$ have only real roots?

Let $\mathbf A, \mathbf B$ be Hermitian matrices of the same size. What is the characterization of $\mathbf A, \mathbf B$ such that $p(\lambda)=\det(\mathbf A-\lambda\mathbf B)=0$ has only real roots?   If $\mathbf B$ is positive definite (I corrected this), it is easy to see $p(\lambda)$ has only real roots.


How i can download youtube videos by using cmd

in the first time of learning command line i've saw the quick performance that it presents and its deal with files, directories, and programs efficiently. after all of that i think command line not only surrounded by this feature and i think has to much extra features and i wish from this features to be one for downloading videos from youtube. anyway i have tried numerous of website and programs that can do that but often is not with required qualifications. finally, i want something can do it by cmd prompt anything other i don't. thanks all of you


How to download 360 photos from Facebook and view them on Windows 10?

Searched the web for few hours but barley found any information. How to download 360 photos from Facebook? Could they be viewed via Windows 10 photo viewer?


Domain controller failed on domain, how do I remove it?

We had a server called DC01 set as a domain controller. Then we got another server and added it to the domain as a backup domain controller DC02. Months after adding DC02 to the domain DC01 had a catastrophic failure and was unplugged/taken off the network. But DC02 still things DC01 exists and I get errors like     The specified domain controller could not be contacted. This affects the following domain in the console.       Domain: domain.com   The error was: The specified domain either does not exist or could not be contacted.   Please choose from the following options:   [ ] Choose a different domain controller   [ ] Retry   [ ] Remove this domain from the console   Choosing a different domain controller leads me to the following:     Current domain controller: (blank)   Look in this domain:   domain.com   Change to:   [x] The domain controller with the Operations Master token for the PDC emulator   [ ] Any available domain controller   [ ] Any available domain controller running Windows Server 2003 or later   [ ] This domain controller:   dc01.domain.com   dc02.domain.com   I select This domain controller and choose dc02.domain.com and the pop up goes away.  How do I get rid of the references to the old primary domain controller, dc01? And what must I do to dc02 to make it the new primary domain controller?


Prove that $$\sum_{n=0}^\infty \frac{(-1)^n}{3n+1} = \frac{\pi}{3\sqrt{3}}+\frac{\log 2}{3}$$   I tried to look at $$ f_n(x) = \sum_{n=0}^\infty \frac{(-1)^n}{3n+1} x^n $$  And maybe taking it's derivative but it didn't work out well.  Any ideas?


Defining New Command with regular text inside math mode (Notation)

I would like to denote the volume of a lattice as vol $L$ and the determinant similarly as det $L$, so that the words "vol" and "det" are in the normal/regular text format but the L is in mathmode.  However, when I need to write it that way in an equation, it takes longer to type and I make more errors.    I want to write a new command so that I can type it all in mathmode similar to:  $\vol L = ...$ and $\det L= ...$.    QUESTION 1:  Since \det is already a command, I cannot overwrite it.   What kind of font does it form when using $\det\ M$ versus det $M$?  This is what I came up with for the Volume:  \documentclass[english]{article} \newcommand{\vol}{\text{vol }} \begin{document} $\vol L = \sqrt{\left|\det(G\cdot G^{T})\right|}$ \end{document}   QUESTION 2:  Does it look okay if I use my new command $\vol L$ and \det\ L together in the paper or should I use $\vol L$ along with with det $M$?


What does it mean when my neural network always gets stuck at the exact number 8.6791 when I use binary-crossentropy loss? Some strange local minimum?  It happens regardless of my learning rate, initialization, activation function, regularizer, or choice of optimizer.   The only thing that changes it is a change of architecture or a new loss function, which are things I don't want to change...


NetGear A6100 AC600 wireless adapter not working in Ubuntu 20.04. Worked fine in 18.04. Not same problem as previously

Firstly, I know very well there are answers to this already. But, in my case, it is installed and shows in the terminal as such Bus 001 Device 007: ID 0846:9052 NetGear, Inc. A6100 AC600 DB Wireless Adapter [Realtek RTL8811AU]  It says it is installed in  as well.  I have tried downloading the driver for this adapter from several guides online, linking to GitHub, but no luck there either...  Any help is greatly appreciated! Thanks in advance!  EDIT: The answer from sudo dkms status command reads:  rtl8812au, 4.3.8.12175.20140902+dfsg, 5.4.0-31-generic, x86_64: installed  The other command  modinfo 8812au | grep 9052   spits out the following:  alias:          usb:v0846p9052d*dc*dsc*dp*ic*isc*ip*in*


If $\sin x + \cos x +\tan x + \cot x +\sec x +\csc x=7$, then $\sin 2x$ is a root of $x^2 -44x + 36$ .

If   $$\sin x + \cos x +\tan x + \cot x +\sec x +\csc x=7$$   then show that $\sin(2x)$ is a root of the equation $x^2 -44x + 36$.   How do I solve this question?


Best Algebraic Topology book/Alternative to Allen Hatcher free book?

Allen Hatcher seems impossible and this is set as the course text?  So was wondering is there a better book than this? It's pretty cheap book compared to other books on amazon and is free online.   Any good intro to Algebraic topology books?  I can find a big lists of Algebraic geometry books on here. On a very old thread on Maths overflow someone recommended that a person should read James Munkres Topology first, then you should read Allen Hatcher book.   It just seems like Rudin's book but crammed with ten times more material.


I want to add background color to my table, but do not want any borders  \documentclass[12pt, landscape]{article} \usepackage{colortbl}  \begin{document}  \begin{table}[h]   \begin{tabular}{cl}   \rowcolor{black}   \textcolor{white}{A}  &  \textcolor{white}{B} \\   \rowcolor{black}   \textcolor{white}{a} & \textcolor{white}{b} \\   \end{tabular} \end {table}  \end{document}     As you can see there is a very thin line which appears between the columns and rows, which I believe is due to the space between cells. I do not want these lines.   How to remove them?  Thanks.  -Alok


using urllib2 to execute URL and return rendered HTML output, not the HTML itself

urllib2.urlopen("http://www.someURL.com/pageTracker.html").read();   The code above will return the source HTML at .   What do I need to do to actually return the rendered HTML that you see when you visit google.com? I essentially trying to 'execute' a URL to trigger a view, not retrieve the HTML.  To clarify a few things:   I'm not actually concerned about the visual output of the page I'm concerned about the page rendering as it would inside of a proper browser so that I can track a Google Analytics goal via the JavaScript on that page.


npm installed packages are not accessible

I installed nodejs with the instructions from  on ubuntu 13.1 All went smooth. After that I installed  by issuing the command  npm install express   which result in  express@3.4.4 node_modules/express ├── methods@0.1.0 ├── range-parser@0.0.4 ├── cookie-signature@1.0.1 ├── fresh@0.2.0 ├── debug@0.7.4 ├── buffer-crc32@0.2.1 ├── cookie@0.1.0 ├── mkdirp@0.3.5 ├── commander@1.3.2 (keypress@0.1.0) ├── send@0.1.4 (mime@1.2.11) └── connect@2.11.0 (methods@0.0.1, uid2@0.0.3, pause@0.0.1, raw-body@0.0.3, qs@0.6.5, bytes@0.2.1, negotiator@0.3.0, multiparty@2.2.0)   but when I now type something like   express demo   I get     The program 'express' is currently not installed. You can install it   by typing: sudo apt-get install node-express


Converting between GPT and MBR hard drive without losing data

NOTE: I don't know a lot about hard drives so you're going to have to work with me here.  My question: Can I change my hard drive from GPT to MBR without losing data on it?  NOTE: there isn't an operating system on the laptop which I'm going to do this on. I'm going to boot from a USB and try to convert it.


Solve in $R$ the following equation :  $3x^4+x^3-10x^2-x+3=0$  Im try use sub   $y=x+\frac{1}{x}$  But I don't understand whene and where I use this sub   Please give me ideas or hint to approach it


Prove that, for any $a, b, c \in \mathbb{N}$, $\bigl\lfloor \frac{a}{bc} \bigr\rfloor = \Bigl\lfloor \frac{\bigl\lfloor \frac{a}{b} \bigr\rfloor}{c} \Bigr\rfloor$.  I have no idea how to prove this. Can you help me, please? Thanks!


Will my Live USB stick work if it already has another OS on it?

I'm wanting to install with a Live USB stick, but it already has an OS on it that's run for working at home. Can I have both OSs on it at once and choose which one I want to install?  EDIT: The OS that's already on my USB is Windows 7. Can I put the Ubuntu ISO on that same USB and install it without a problem?


let $f,g$ be contiunous, bounded on $\Bbb R$. Suppose that  $$f(x+y)=f(x)f(y)-g(x)g(y),\quad g(x+y)=f(x)g(y)+f(y)g(x),\ \forall\ x,y\in\ \Bbb R.$$ $f(0)=1$, $g(0)=0$. Show that for some $a\in\Bbb R$, $f(x)=\cos ax, g(x)=\pm \sin a x$.


I am using tar file. I am extracting using tar xvjf filename then I am doing ./configure and getting error to install package fetch. Now what to do?


Why does the /run directory have inode 2?

It's well known that the / directory has inode number 2 (see also ). And we also know that hard links share the same inode number. So far so good.  Here's the confusing bit (notice the Inode: part):  $ stat /run   File: /run   Size: 940         Blocks: 0          IO Block: 4096   directory Device: 16h/22d Inode: 2           Links: 32 Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root) Access: 2018-09-10 10:22:18.198727482 +0800 Modify: 2018-09-10 02:47:58.655999930 +0800 Change: 2018-09-10 02:47:58.655999930 +0800  Birth: -   The simple question is "Why do they have the same inode?" The /run directory is different from / and /run is not hardlink to /.


Why tags stats are not getting updated after script was supposed to run

I have noticed that for at least a couple of days, the tag stats have not been updating.  It is possible identified in  and marked as  has returned.  After spot checking a few of my lower score tags:    - I have answered 3 questions, including 1 yesterday, but my tags only show 2 answers.  Additionally, my tag score is shown as 7 but the net total score of my 3 answers is 8.   -  I have answered 5 questions, including 2 posts 2 days ago, but my tags only show 3 questions.  Additionally, my tag score is shown as 8 but the net total score of my 5 answers is 12.    This suggests it has been at least 72 hours since the script ran


can HTML onSubmit / onClick handler function have another parameter except event?

I face with some cases onClick or onSubmit functions needs both event and parameter. Can I do with this in react, or vanilla html tags? Or, Just do something side effect using another functions?  const CustomFC = ({}) => {   const [ id, setId] = useState("");   const [password, setPassword] = useState("");      type FormParams = {     id: string;     password: string;    }   const customClickHandler = useCallback((params: FormParams) =>    {     dispatch(params);    }, [id, password]);    const onChangeId = useCallback((id) => setId(id),[]);   const onChangePassword = useCallback((password) => setPassword(password),[]);         <Form      onClick ={customClickHandler}      onChange={{onChangeId, onChangePassword}}   /> }  // Form.tsx const Form = ({   onSubmit,   onChange, }) => {   const { onChangeId, onChangePassword } = onChange;    const handleSubmit = ( e, params ) => { // <- can this be possible?      e.preventDefault();     onSubmit(params);   }   return (     <form onSubmit={handleSubmit}>       <input ... />       <input ... />     </form>   ) }


$\int \dfrac{w^2}{(w^2+1)^2(w^2+2w+2)}=\dfrac{p \pi}{q}$, limits are from minus infinity to infinity.


Android 4.4 comes with an app button in the bottom panel. If it gets deleted, how do I get it back?


How do I put mods on my minecraft server?

I know how to set a Minecraft server and I already know about plugins, but how do I install mods on it?   For example; Deathchest, Pokemobs, Mo' Creatures, Recipe Book, TooManyItems, and all the things necessary to make them run.   I've looked everywhere.  wont give out how they set their servers up with mods but they have  and  and some others. I only found a custom thing needed to play on their server.   Is this related to the version I'm running? If i have to downgrade my Minecraft from 1.2.5 this isn't a problem.


My dock tells me I have 8 available updates:    I also got the notification asking to install updates. However, when I open App Store, I only see recently installed updates (with no updates to apps or software visible):    If the updates are real, how do I update, and if not, how do I get rid of the bubble?  Edit (more information):  $ defaults read com.apple.appstore {     "NSWindow Frame Preferences" = "0 116 1277 661 0 0 1280 777 ";     "NSWindow Frame window_prefs" = "20 51 1240 726 0 0 1280 777 ";     SeenOSUpdates =     (     );     Storefront = "143441-1,13 ab:WJ6jMoo1";     appStoreBadgeCount = 7;     "com.apple.appstore.WebKit2DeveloperExtrasEnabled" = 1;     "com.apple.appstore.WebKit2ShowsToolTipOverTruncatedText" = 1;     "com.apple.appstore.WebKit2SuppressesIncrementalRendering" = 1;     "com.apple.appstore.WebKit2UserInterfaceDirectionPolicy" = 1;     "primary.WebKit2DeveloperExtrasEnabled" = 1;     "primary.WebKit2ShowsToolTipOverTruncatedText" = 1;     "primary.WebKit2SuppressesIncrementalRendering" = 1; } $


Example of function in $H^1(U)$ which is not continuous, where $U \subset R^2$ has a smooth boundary.

Does anyone have a nice geometric example of function in $H^1(U)$ which is not continuous, where $U \subset R^2$ and has a smooth boundary. I want something that is easy to remember.


How to get the value of previous and current profile assigned to a user using trigger?

I do have a requirement like I need to write a trigger on user object.The trigger must be before update, which should give the value of previous and current profile assigend to a user.  any help??  This is what I have done, but not getting anything in debug log  trigger UserProfileTrigger on User (before update) {  for(Integer i = 0; i< Trigger.new.size(); i++) {         if(Trigger.new[i].Profile!= Trigger.old[i].Profile){          System.debug('***SFDC: Trigger.old is: ' + Trigger.old[i].profile);          System.debug('***SFDC: Trigger.new is: ' + Trigger.new[i].profile);           }     } }


I tried to load base map from OpenLayers, but it doesn't work at all. QGIS popped up an error message showed below. What I noticed the slash foreword different way. I guess something wrong with the connect to Python.   How can I re-set it?     An error has occurred while executing Python code:       Traceback (most recent call last):   File    "C:/Users/.qgis2/python/plugins\openlayers_plugin\weblayers\weblayer.py"      ......      Python version:      2.7.5 (default, May 15 2013, 22:44:16) [MSC v.1500 64 bit (AMD64)]      Python path:   ['C:/PROGRA~1/QGISPI~1/apps/qgis/./python/plugins\processing',       ......


I have two models - we'll say a sphere and hollow cylinder - that I'm working with.  Effectively, I want to 'subtract' the hollow-cylinder shape from the sphere.  I know from certain orientations (the top of the sphere) this is fairly easily done, just a matter of deleting and creating new faces.  However, from other orientations the edges/geometry doesn't line up so easily.  Is there an automatic (or at least, not terribly difficult/manual) way to 'subtract' one mesh from another?


A finite group of even order has an odd number of elements of order 2

Need some help with this, i'm a bit stuck:  Show that if $G$ is a finite group of even order, then $G$ has an odd number of elements of order $2$. Note that $e$ is the only element of order $1$.


Recommendation for installing Ubuntu (or variant) on old hardware like HP Omnibook XE3

I want to install Ubuntu on an old HP-Laptop (Omnibook XE3 - Pentium III generation).   Which Ubuntu version is appropriate? Is there some documentation for installation? Where can I download the selected Ubuntu version?   Thanks, Martin


write a small text in an equation environment after the symbol "="

I wanto to write something like this  c dt = average probability that a particular 1-2        molecular pair will react according to R        in the next infinitesimal time interval dt.   I tried with \\ but it does not work.  How can I do such a thing?


On a complex manifold we have the differential operators  $$\partial:A^{p,q}\to A^{p+1,q}$$ $$\bar\partial:A^{p,q}\to A^{p,q+1}$$ which both square to zero. Hence one can define cohomology groups $$H^{p,q}_\partial=\frac{\ker\partial:A^{p,q}\to A^{p+1,q}}{\partial A^{p-1,q}}$$ $$H^{p,q}_{\bar\partial}=\frac{\ker\bar\partial:A^{p,q}\to A^{p,q+1}}{\bar\partial A^{p,q-1}}$$ But for some reason I only ever see people discussing the $H_{\bar\partial}^{p,q}$, i.e. Dolbeaut cohomology. What makes this more interesting the the $H_\partial^{p,q}$ groups?


Commands ping and ipconfig are not recognized

Why are the commands ipconfig and ping not recognized in the command prompt on my windows 10 PC? How do I recognize this commands? Here you've a screenshot.  (Click on image to watch in full screen)


Is this sentence correct?  If an employee experiences an ethical dilemma, they can request a reassignment.  Is it correct to use 'they' when talking about 'an employee'? Or should the subject be plural?


How does one calculate frictional force for an object sliding down a wall?

Let's say that there is a book sliding down a vertical wall such that the only fundamental force acting on it is gravity. I want to say that there is a frictional force slowing the book down; however, I can't find a normal force acting on it, so I can't calculate the kinetic friction force.  Is there any frictional force?  For reference, the book has a mass of $3.5kg$ and a coefficient of kinetic friction of $0.13$.


I was doing a Hackerrank python problem the task was to print 123...N (where N is the input) without using any string function.  Someone commented a solution which is:                              print(*range(1, int(input())+1), sep='')   My question is:   What is the use of * here with this range() function? Why we can't do it by only using range() function inside the print? Is there any other way to do this?


How do you calculate probability of rolling all faces of a die after n number of rolls?

Possible Duplicate:             Im pretty new to the stackexchange, and posted this is statistics, and then discovered this site, and thought it was much more appropriate, so here I go again:  It is fairly easy to figure out what is the average rolls it would take to roll all faces of a die [1 + 6/5 + 6/4 + 6/3 + 6/2 + 6/1 = 14.7], but that got me thinking of a seemingly more complicated problem.  Say you roll a die 1-5 times, the is the odds of ALL faces showing, is obviously 0. If you roll a die 6 times, the odds of all faces showing can easily be calculated like so:  1 * (5/6) * (4/6) * (3/6) * (2/6) * (1/6) = .0154 or 1.54%  Now is where I get stuck. How to do 7, or more times, and calculate it with n.  Any tips is helpful!


$ cd / /$ ls bin   dev  home        initrd.img.old  lib64       media  opt   root  sbin  sys  usr  vmlinuz boot  etc  initrd.img  lib             lost+found  mnt    proc  run   srv   tmp  var  vmlinuz.old  /$ cd // //$ ls bin   dev  home        initrd.img.old  lib64       media  opt   root  sbin  sys  usr  vmlinuz boot  etc  initrd.img  lib             lost+found  mnt    proc  run   srv   tmp  var  vmlinuz.old //$ pwd //  //$ cd /// /$ /$ pwd /   What is this trickery? What is //?


Question of type: "What is the best..." ==> Why not, where to go?

I recently had one question put on "Hold" on Stack Overflow and was really sad, shocked and confused. It turns out that I modified my question, another user also improved it a lot and it was reopened.   But I'm still amazed and disturbed by the fact that I cannot ask question like "What is the best...".  This type of question has some negatives:   Create emotional reactions Attracts spams Attracts non objective answers, sometimes by creators of products/software Could lead to inappropriate exchange/words Generate lots of unnecessary information It is subjective   But these kinds of questions also have their positives:   It create debate where lots of useful information came out Brings new information that could lead to change some minds / a new vision to readers In most case, those questions lead to a solution that will save a lot more time than any other kind of question In most case, those questions lead to a solution that will save a lot more of money than any other kind of question (usually related to products) Brings creator reaction that would bring additional useful information on the product, reason of certain design decision, ...   In summary:  Considering the negatives and the positives, and also considering that Stack Overflow has a really good system for rewarding/penalizing users, I think that the acceptance of this type of questions would be a lot more beneficial for users than anything else. It is only because Stack Overflow has this rewarding system that it could support those type of questions easily whithout too much drawbacks. Also, Stack Overflow has the best reputation and is recognized as the best question/answer system now for programmers (it is subjective I know, but don't be blind, be honest and admit it), then I think that it returns to Stack Exchange to offer that type of question for the benefits of everyone.  If Stack Overflow does not support this type of question, what can we do? Where can we go to have lots and good reactions to this type of questions? Who will do it?


I'm a newbie Ubuntu user. Every time I log in to my OS, I always add:  xhost +si:localuser:root   How can I add Xhost to root permanently?  My kernel version is 4.13.0-46-generic.  I have tried , to edit something in /etc/pam.d/..., but this doesn't work for me.


So essentially does margin collapsing occur when you don't set any margin or padding or border to a given div element?


Sometimes when I work I write something like  \begin{proposition} \label{my new result} ... \end{proposition} ... blah blah in Proposition \ref{my new result} blah...   but then I realize that the Proposition should actually become a Lemma. So I change it to  \begin{lemma} \label{my new result} ... \end{lemma}   The problem is that I then have to hunt down all the places where I wrote Proposition and change it to Lemma, which is tedious and error-prone. Well, we have search facilities in editors, so it is not really that complicated, but still it feels the wrong way to do this. I would be happier to write  \begin{proposition} \label{my new result} ... \end{proposition} ... blah blah in \labelNameFor{my new result} \ref{my new result} blah...   where labelNameFor is a hypothetical magic command which outputs "Proposition". Then I could forget about all the places where I reference the result and just make any changes I wish.  Is there a way to do something like this? As far as I understand the label/ref mechanism is simply based on counters, so I do not see a straightforward way, but maybe someone more clever and industrious then I am has given the problem some thought.


What am I doing wrong in calculating $i^2$?

$$i^2 = i \cdot i = (\sqrt{-1}) \cdot (\sqrt{-1}) = ({\sqrt{-1}})^2 = -1   \tag{1}$$ $$i^2 = i \cdot i = \underbrace{\sqrt{-1}\cdot\sqrt{-1} = \sqrt{(-1)\cdot(-1)}}_{?} = \sqrt{(-1)^2} = 1   \tag{2}$$  What are the conceptual or logical errors here?  TIA


Is working in symlink directory identical to working in the directory directly?

In  my home directory, I have a folder named symlinks in which all my symlinks live. I've added this folder  to my CDPATH, so that I can do:  ~$ cd FarAwayDirectory ~/symlinks/FarAwayDirectory$   I’ve noticed that if I pwd, I get:  ~/symlinks/FarAwayDirectory     ->    A  rather than:  .../.../.../FarAwayDirectory    ->    B  which is what I would've gotten through consecutive cd’s.  So my question is: Is working in directory A identical to working in directory B?


Is there a faster way to erase a pen (USB) drive using dd command?

I am using the dd command to erase a pen drive with this: sudo dd if=/dev/zero of=/dev/sdd bs=4k && sync  where /dev/sdd is the designated device.  The pen drive is 16GB in size and this process takes a very long time. Using dd, is there a way to speed up the erasure process?


How do I use ARandR to create a permanent monitor layout in Lubuntu 12.10?

So ARandR is great for setting up my monitor layout in Lubuntu 12.10 but even if I save the layout to the  ~/.screenlayout   it doesn't seem to save that layout no matter what I call the file.


import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException;  public class Example {      public static void main(String[] args) {         BufferedReader input = null;         BufferedWriter output = null;         try{             int c;             input = new BufferedReader(new FileReader("readfile.txt"));             output = new BufferedWriter(new FileWriter("writefile.txt"));             while ((c=input.read())!= -1) {                 output.write(c);             }         } catch (FileNotFoundException fnfe){                 System.err.println("The file was not found.");                 fnfe.getMessage();         } catch (IOException ioe) {             System.err.println("The file could not be read.");             ioe.getMessage();         }finally {             try {                 output.close();             } catch (IOException e) {                 System.err.println("The file was not opened.");                 e.printStackTrace();             }             try {                 input.close();             } catch (IOException e) {                 System.err.println("The file couldn't be closed.");                 e.printStackTrace();             }          }       }  }   The above code throws an unexpected exception - NullPointerException in one of the try block on the following line: output.close();. Can anyone explain the reason for that? Any help would be appreciated. Thanks in advance.


Don't understand this Null Pointer Exception

StudentTest.java: Has my Main(), tests the classes I've set up.  public class StudentTest {      public static void main(String args[])      {         Student s1 = new Student("Matt", "Patitz");         s1.setMidterm(78, "B");   Only the first couple lines because the error is on that last line.  Student.java: The Student class, includes the setMidterm(int, String) method I'm trying to call  import java.util.Scanner;  public class Student {     Scanner input = new Scanner(System.in);     private String FirstName;     private String LastName;     private Exam Midterm;     private Exam FinalExam;     private Coursework Homework;     private Coursework InClass;      public Student(String firstName, String lastName){         FirstName = firstName;         LastName = lastName;     }     public void setMidterm(int score, String grade){          Midterm.setScore(score);         Midterm.setLetterGrade(grade);     }   Again, not the whole class file. The error is on Midterm.setScore(score);  Exam.java: The Exam class, includes the setScore(int) method.  public class Exam {      private int Score;     private String LetterGrade;      public Exam(int score, String letterGrade){         if(score>100){             Score=100;         } else if(score<0){             Score=0;         } else {             Score=score;         }         if(letterGrade=="A" || letterGrade=="B" || letterGrade=="C" ||              letterGrade=="D" || letterGrade=="F")              LetterGrade=letterGrade;         else{              System.out.println("Invalid Grade");              LetterGrade="F";         }     }           public void setScore(int score){         if(score>100){              Score=100;         } else if(score<0){              Score=0;         } else {             Score=score;         }     }   That should be everything that's relevant from my project. Here's the error message itself:     Exception in thread "main" java.lang.NullPointerException         at Student.setMidterm(Student.java:19)         at StudentTest.main(StudentTest.java:6)   The 19 and 6 lines are the ones I pointed out. Thanks for any help!


C++ overridden virtual function not getting called

I have the following setup:  main.cpp:  int main() {     vector <Tour> tourList;     Tour* tour_ptr;      for (unsigned int i = 0; i < tourList.size(); i++)     {         tour_ptr = &tourList[i];         tour_ptr->display();     } }   Tour.h:  class Tour {    public:     virtual void display(); };   Tour.cpp:  void Tour::display() {     cout << "Tour ID: " << getID() << "\n";     cout << "Description: " << getdescription() << "\n";     cout << "Tour Fee: $" << getfee() << "\n";     cout << "Total Bookings: " << getbookings() << "\n\n"; }   GuidedTour.h:  class GuidedTour : public Tour {     public:             void display(); };   GuidedTour.cpp:  void GuidedTour::display() {     Tour::display();     cout << "Max Tour Group Size: " << getMaxTourists() << "\n";     cout << "Tour Guide: " << getGuideName() << "\n";     cout << "Tour Date: " << getTourDate() << "\n\n"; }   GuidedTour inherits from the Tour class, and I've specified the display() function as virtual in the base Tour class, but for some reason, the GuidedTour display() function never gets called, only the base function gets called every time. What am I doing wrong?


I have Vagrant 1.8.1 installed but apparently I need a higher version    As instructed  I downloaded the latest release 2.0.1, opened it and pressed install, but nothing has changed.    I also did apt-get update but nothing changed.  How can I upgrade vagrant?


what is the function of prefix "a" of parameter in java?

for example,sometimes I see function like this:  public void changeColor(Color aColor){ }   what is the function or meaning of "a" in parameter "aColor"?


AirPods 2nd Gen. with firmware 2A364 dropped volume level in non-iOS Devices

When I bought new Airpods 2nd gen, the firmware it came with was 1A673. The volume level on my android phone (OnePlus 6T) when connected was quite loud and everything was good.  But when I connected my Airpods to my iPad with iOS 13.1 the firmware on these got updated to 2A364 and then when connected to my android phone, music volume started getting low. I tried with other android phones too.  But the thing is during the phone calls the volume comes out loud but low only on music or videos.  How do I fix this?


Commutative diagram with parallel arrows using Tikz (with matrix)

I have used the next code to get a commutative diagram:  \documentclass[10pt,a4paper]{article}  \usepackage[spanish]{babel} \usepackage{amsmath} \usepackage{tikz-cd}% diagramas  \begin{document}  %-----Diagrama------- \deactivatequoting \[ \begin{tikzpicture} \matrix(m)[matrix of math nodes, row sep=4em, column sep=3em, text height=1.5ex, text depth=0.25ex] { M   &   TN \\     &    N \\ }; \path[->] (m-1-1) edge node[auto] {$\psi\circ Y$} (m-1-2); \path[->] (m-1-1) edge node[left] {$\psi$} (m-2-2); \path[->] (m-1-2) edge node[right] {$\pi$} (m-2-2); \path[->] (m-2-2) edge node[left] {$Y$} (m-1-2); \end{tikzpicture} \] \activatequoting %-------------------  \end{document}   However, I would like two vertical parallel arrows and not a "leftrightarrow".  What is the solution?


How to update VS code to the latest version in Ubuntu?

I saw many solutions like  wget https://vscode-update.azurewebsites.net/latest/linux-deb-x64/stable -O /tmp/code_latest_amd64.deb sudo dpkg -i /tmp/code_latest_amd64.deb Buts its not too good. I want to update VS code in Ubuntu in a single command.


Why is the past simple used in this sentence?

We haven't gotten a lot of Finnish groups that we liked here at Bananas but I'm pretty happy with this four tracker from Helsinki, apparently recorded in the same place where the Ramones played in the 70's.   I know my question has already been answered. liked is past simple because it is a single action. But I don't agree with it or have not well understood  the answer.  'Bananas' is a music magazine. Every time they receive a record they make a review(like it or not) so this is not a single action and maybe in the future there will be some Finnish band they will like. It may change !!!


Usage of that: There are many reasons [that] I am confident [that] I will excel at this job

I always find it hard to see when it's best to use "that". Which of these sounds best?  There are many reasons I am confident I will excel at this job. There are many reasons that I am confident I will excel at this job. There are many reasons I am confident that I will excel at this job. There are many reasons that I am confident that I will excel at this job.  Are there ways of looking at this that I can apply elsewhere? Is there a completely different formulation that works better?


Number of vertices present in all maximum matchings

Given a graph $G$, we need to find the cardinality of the largest set of vertices so that each of them are present in every maximum matching possible.   Is there a solution beside the obvious remove each vertex and find the maximum matching to see it reduces?


The second law of thermodynamics and collapse of the wavefunction?

I recently thought what if I wrote the $2$'nd law of thermodynamics as:  $$ dS_{\text{universe}} \geq 0 $$  Note when it is written in this form it is time asymmetric. Let, $dS = S(t+ d t) - S(t)=$ where $dt \geq 0$. Dividing both sides of the inequality with $dt$:  $$  \frac{S(t+ d t) - S(t)}{dt} \geq 0 $$  However, if time flows in the opposite direction , $ dS= S(t -dt) - S$, then:  $$ S(t-dt) - S(t) \geq 0$$  Dividing both sides with $-dt$ again:  $$ \frac{(S(t)- S(t-dt)}{dt} \leq 0$$   Hence, if time flows the other direction then one will see entropy decreasing.   However, there is an obvious flaw to this which is the limit will not be continuous unless $\frac{dS}{dt}=0$ (for example a system which has reached maximum entropy.) But all of known physics is essentially continuous and time symmetric with the exception of the collapse of the wave-function. Does this mean the collapse of the wave-function is responsible for the $2$'nd law of thermodynamics?


How to import module libraries in PyCharm?

a newbie to python. I have the following code on pycharm  import requests import gzip import shutil import os import Libraries  from Libraries import Dictionaries as dicts  And after running it I get the following error  ModuleNotFoundError: No module named 'Libraries  And when I try to install the Libraries package, it fails to install it. Any suggestions? ps: I get the same error both on PyCharm and on Jupyter Notebook


Sort a map having arraylist as values based on property in java

I have a complex custom object like public class MySortedObject {   private static class Employee {         public String name;         public String ssn;                  public Employee(String name, String ssn) {             super();             this.name = name;             this.ssn = ssn;         }     }  public static void main(String[] args) {          Map<Integer, List<Employee>> map = new HashMap<>();          Employee empl1 = new Employee("XYZ", "22DEC2019");     Employee empl2 = new Employee("ABC", "22DEC2019");                                                          Employee empl3 = new Employee("GHI", "18APR2019");     Employee empl4 = new Employee("DEF", "18APR2019");                                                          Employee empl5 = new Employee("WXY", "15OCT2019");     Employee empl6 = new Employee("JKL", "15OCT2019");          List empList1 = new ArrayList<>();     List empList2 = new ArrayList<>();     List empList3 = new ArrayList<>();          empList1.add(empl1);     empList1.add(empl2);          empList2.add(empl3);     empList2.add(empl4);          empList3.add(empl5);     empList3.add(empl6);          map.put(1, empList1);     map.put(2, empList2);     map.put(3, empList3);  }  My object is a map of <Integer,List>. The list is having objects which contain a value(i.e. ssn). I want to sort my map based on this ssn value. The order of the map should be "1,3 and 2"


Is $M_a=\{f\in \mathcal C[0,1]:f(a)=0\}$  where $\mathcal C[0,1]$ denotes the ring of continuous functions in $[0,1]$ a Principal ideal?   My try: Let $M_a=\langle f_1\rangle$ .Consider $f(x)=\sqrt {|f_1(x)|}$ then $f(x)=g_1(x)f_1(x)$ .  Now $|g_1(x)|\le M$ since image of a continuous function on  a compact set is bounded.  Also by continuity of $f_1(x)$ at $a$  if we choose $\epsilon=\frac{1}{M^2}$  then there exists $U$ an open set containing $a$ such that $|f_1(x)|\le \frac{1}{M^2}$ $\forall x\in U$.  Now for all $x\in U$ , $|f(x)|\le M|f_1(x)|\le M\frac{1}{M^2}=\frac{1}{M}$  But I am not getting any contradiction from here.Please suggest some steps


Synchronize the clock the same way I do in Settings with a powershell command

On my Windows 10, I need to synchronize my clock at every startup, to do that I go into Settings → Time & Language → Synchronize your clock → Sync now I am wondering if there is a powershell command to do the same (without elevated privilege) I found some solutions with w32tm but as the service is not started and need elevated privilege I would prefer sticking to the same mechanism I use manually.


Why do we say " talk show" not " talking show"?

In English, why do we usually say "talk show" not "talking show"?


Need explanation of Pseudocode and code - Python 3+

I have this code that acts as a recursive function which just prints out all the possible combinations of a string: def permut(head, tail = ''):      if len(head) == 0:         print(tail)     else:                 for i in range(len(head)):              # Need help explaning this part             permut(head[0:i] + head[i+1:], tail + head[i])   # Print the string permut('xy')  This will print out:  xy yx  I just need help explaining what is going on, on this part:  permutations(head[0:i] + head[i+1:], tail + head[i])


why does shell use executable in /usr/bin and not in /usr/local/bin

Given:  /usr/local/bin/cmake /usr/bin/cmake $ cmake # runs /usr/bin/cmake  $ echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin   Why this, and how do I make the shell run the executable /usr/local/bin/cmake when I type cmake (without aliases and the like)?


Does knowing Primordial mean you understand all the different languages of elementals?

I'm wondering if knowing the language Primordial means that you understand all different languages of elementals?


When I'm Using "sudo apt update" I'm getting

sudo apt-get update Err:1 http://your.repo.domain/repository bionic InRelease   Could not resolve 'your.repo.domain' Hit:2 http://packages.microsoft.com/repos/vscode stable InRelease                                                                                Hit:3 http://download.opensuse.org/repositories/home:/strycore/xUbuntu_18.04 ./ InRelease                                                                                Hit:15 http://ppa.launchpad.net/webupd8team/java/ubuntu bionic InRelease            Err:16 http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu bionic Release   404  Not Found [IP: 2001:67c:1560:8008::15 80] Reading package lists... Done E: The repository 'http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu bionic Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.


Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


Have Ubuntu 14.04. loaded Kdenlive from the Software Center. It works from icon on DASH and from Terminal. However, I have no idea how to put icon on desktop. I looked in usr/share/applications-no icon. Also checked /usr/bin/kdenlive. I found the executable, but no icon startup to copy. Would appreciate anything to point me in right direction. Thanks


I want to save a user's email and username when a button is clicked. I assume I have to do this via PHP but I can find the user column at localhost/phpmyadmin. Where is the users' information being stored and which is the MySQL query to achieve that?


Is the total variation function uniform continuous or continuous?

I have been doing some excercises on total variation when the following questions came up to my mind:  (1) Let $f$ be continuous on the interval $[0,1]$ and be of bounded variation. Is it true that its total vatiation function $TV(f_{[0,x]})$ is uniformly continuous? i.e. Is it true that for $\forall\space\epsilon>0$, $\exists\space\delta>0$, such that for arbitrary interval $[a,b]$ with $|b-a|<\delta$, we have $TV(f_{[a,b]})<\epsilon$?  (2) Alternatively, if it is not uniformly continuous, can I say that for $\forall\space{}x\in[0,1]\text{ and } \forall\space\epsilon>0$ , $\exists\space\text{ nondegenerate interval }I \text{ such that }x\in{}I\text{ and } TV(f_{I})<\epsilon$?  Thank you!


I have imported assets in blender and saved it. After I have added some assets and deleted the old ones. But the file size keeps on increasing.


Is Ubuntu compatible with Dell n4050 laptop?

I have dell n4050 laptop. Do i have to install drivers after ubuntu installation? which version of ubuntu will support my laptop?


What is the difference between a ConcurrentHashMap and a Hashtable in Java?  Which is more efficient for threaded applications?


Is there a way to flat plane object affecting by proportional edit?

As in question title, is there a way to flat plane object affecting by proportional edit without creating new plane object?  here my image :    I don't know how to flat this object except create new plane object or edit position of vertex to z=0 individually.


Overpaying on mortgage - How is term reduction calculated?

Just for some example figures:   Original Term: 25 Years Loan Amount: £100,000  Interest rate: 2%   I'm trying to make an excel table which keeps track of my mortgage payments including overpayments. When making an overpayment I was asked if I would like to use this payment to reduce my future payments or keep future payments the same and reduce the term.  I selected to reduce the term (this seemed smarter) but I can't work out how the bank has calculated my term reduction as a result of my over payment.  For example, I made an overpayment of £500 and they said "As a result of this payment, your term has been reduced by 1 month". What equation did they use to come to this figure please?


beleive it or not, I typed sudo rm -r * in / by mistake! anyway to undo

lol is there anything more to ask about it?! when I try "sudo bla bla bla" it asks me who are you? :)) I wanted to do it IN a folder in root, but I did it in only ne upper level which is, GOD, the root folder!


Method chaining is the only way I know to build fluent interfaces. Here's an example in C#: John john = new JohnBuilder()     .AddSmartCode("c#")     .WithfluentInterface("Please")     .ButHow("Dunno");  Assert.IsNotNull(john);    [Test]     public void Should_Assign_Due_Date_With_7DayTermsVia_Invoice_Builder()     {         DateTime now = DateTime.Now;          IInvoice invoice = new InvoiceBuilder()             .IssuedOn(now)             .WithInvoiceNumber(40)             .WithPaymentTerms(PaymentTerms.SevenDays)             .Generate();          Assert.IsTrue(invoice.DateDue == now.AddDays(7));     }  So how do others create fluent interfaces. How do you create it? What language/platform/technology is needed?


In regression, Why correlated error terms makes overconfidence?

I cannot understand about this sentence. "If in fact there is correlation among the error terms, then the estimated standard errors will tend to underestimate the true standard errors." Why? Please give me a mathematical explain if you can.


Prove that if a function's average is nondecreasing then the function is nondecreasing.

Let $\omega:\mathbb{R}_+\to\mathbb{R}_+$ such that $\omega(0) = 0$ and $\xi(s) = \frac{1}{s}\int\limits_{0}^s \omega(t)dt$ is nondecreasing, i.e., $\forall s,s': s\leq s'$, $\xi(s)\leq \xi(s')$. Show that $\omega(t)$ is nondecreasing a.e., i.e. find a function $w(t)$ such that $w$ is nondecreasing and $\omega = w$ a.e.  I was able to show the reverse implication easily, that if $\omega$ is nondecreasing then $\xi$ is nondecreasing. This way seems more difficult.


What is the difference between single, double, and triple quotes in Python?

In other words, how do I know which one to use?  I know when I use strings. I would do      string = "This is a string"   When would I use ' ' or """ """?


I've used  String[] red = linija.split("(?!^)");   and now in this String array I want to know if red[0] is "/". Tried (red[0] == "/") and with "//", please help.


++ operator overload - loop does not terminate without reference

Can someone explain why the below loop in main() does not terminate  #include <iostream>  enum day { Sunday,     // 0 Monday,     // 1 Tuesday,    // 2 Wednesday,  // 3 Thursday,   // 4 Friday,     // 5 Saturday,   // 6 not_a_day   // 7 };  day operator++(day d) {     d = (day)(d + 1);     return d; }  int main() {     day d;     d = Sunday;     while (d <= Saturday) {         ++d;     }     std::cout << d << std::endl;     return 0; }   When I change the overloaded operator to use references, it works as expected, returning 7.  day &operator++(day &d) {     d = (day)(d + 1);     return d; }   Example taken from .  I also do not understand why the compiler is able to cast day to an int with the + operator, but is not able to do so for ++?


What is the origin of Dol Goldur, and why did Sauron start there?

Who built the fortress of Dol Goldur, and when was it built? And was it always a place for evil, or Sauron just occupied it?  Despite the fact that Mordor is much better fortified; artificially by the old fortifications,  and geographically, as it is surrounded by the mountains. Also considering the presence of mount doom that seem to enhance Sauron's power, Sauron chose to start his campaign from Dol Goldur, despite Mordor being ready for quite some time.  Why did he choose this enigmatic fortress, and not go straight for Mordor or even go earlier?


How to screen mirror android phone to Ubuntu PC?

I need to screen mirror my android phone to Ubuntu PC. Is there any tool or package available in Ubuntu to do this?


Use of '? extends ' and '? super ' in Collection generics

Can anybody explain why we use ? in Collection generics.  As for example :   List<? extends Number> numberlist;  List<? super Integer> numberlist;


Using Georeference information stored in tfwx (from ArcGIS) in QGIS?

I have georeferenced some images (ArcGIS -> Update Georeferencing) which creates a *.tfwx file with the new parameters for georeferencing.   I renamed it to *.tfw but QGIS is not able to read the georeferencing information.   Does anybody has any useful tips how to fix this?


strategies, for a beginner, to write code (to answer homework question)

There will be a file called replacewords.txt  This will contain data like   Apple Orange Banana Guava   etc.  There will be another file called data.txt. Word in this file will be replaces, such that, the first column words (from replacewords.txt) should be replaced by second column words.  For example if we find Apple (in data.txt), then replace it by Orange and Banana by Guava etc.    The result should be stored in Results.txt


How to electronically generate exponential and logarithmic functions

i mean, it is possible to generate with Op amps, or diodes, etc, to generate complex exponential and logarithmic functions, like one can create sinusoidal signals using a Wien bridge oscillator.  Thank you very much, if it does what devices can help me on that?


Showing that the Distribution of a Random Variable Must be Standard Normal using Characteristic Functions

Question     Let $X$ and $Y$ be i.i.d with means $0$ and variances $1$. Let $\phi(t)$ be their common characteristic function and suppose that $X+Y$ and $X-Y$ are independent. Show that $\phi(2t)=\phi(t)^3\phi(-t)$ and deduce that  $X$ and $Y$ are standard normal random variables.   The above question is from Grimmett and Stirzaker.  My attempt  I was able to show the first part but unable to fully justify the second part. For the first part here is a proof. Note that $$ \begin{align} \phi(2t)=Ee^{it2X}&=E\exp\{it(X+Y+X-Y)\}\\ &=E\exp\{it(X+Y\}E\exp\{it(X-Y\}\\ &=E\exp(itX)E\exp(itY)E\exp(itX)E\exp(-itY)\\ &=\phi(t)^3\phi(-t) \end{align} $$ by the independence assumptions.  My Problem   For the second part, it is easy to show that $e^{-t^2/2}$ (the cf of a standard normal) satisfies the equation $\phi(2t)=\phi(t)^3\phi(-t)$ but I am unable to show that this is the only choice of $\phi$ that satisfies this equation. I tried taking derivatives and setting up a differential equation but it got messy.  Any help is appreciated.


I've processed this file with PDFLaTeX and got a PDF with a raster font. I need vector fonts. What I did wrongly?  \documentclass[english]{article} \usepackage[T1]{fontenc} \usepackage[latin9]{inputenc} \usepackage{babel} \begin{document} xxx \end{document}   Debian Linux "testing".


What is a good substitute for oyster sauce (for someone with a shellfish allergy)?

I've recently developed a shellfish allergy, and I'm not sure what the best substitute for oyster sauce would be. I've read that the flavor of it is not really easily substitutable.  What is the best way to substitute the flavor without inducing an allergic reaction?