Question about derivations in Sakurai's Quantum mechanics, section 5.8

If anyone is familiar with Sakurai's book, specifically section 5.8 on energy shift and decay width, I am stuck and could use some help. I can't see how he derives 5.8.9 (in the revised edition). He starts with (3) (given below), and derives (1) and (2). The equation is as follows:$$(1){\space}{\space}\space{\space}\space{\space}{\dot c_i\over c_i}\approx{{-i\over \hbar}V_{ii}+{\left(-i \over \hbar\right)}^2{{{\left|V_{ii}\right|}^2}\over \eta}+\left({-i\over \hbar}\right) {\sum_{m\not=i}}{{{\left|V_{mi}\right|}^2}\over {(E_i-E_m+i\hbar\eta)}} \over 1-{i \over \hbar}{V_{ii} \over \eta}} $$ $$(2)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\approx{-i\over \hbar}V_{ii}+\left({-i\over \hbar}\right) {\sum_{m\not=i}}{{{\left|V_{mi}\right|}^2}\over {(E_i-E_m+i\hbar\eta)}}$$ where $$(3)\,\,\,\,\,\,\,\,\,c_i(t)=\lim_{\eta\to 0}\left({1-{i\over \hbar\eta}V_{ii}}{e^{{\eta}t}}+{{\left({-i\over \hbar}\right)}^2}{{\left|V_{ii}\right|}^2}{e^{2{\eta}t}\over 2{\eta}^2}+\left({-i\over \hbar}\right){\sum_{m\not=i}{{{{\left|V_{mi}\right|}^2}}\over 2\eta(E_i-E_m+i{\hbar}\eta}}\right)$$First of all, the expression (3) for $c_i(t)$ itself is strange because in the limit as $\eta\to0$, all three terms dependent on $\eta$ blow up, and the probability interpretation is out the window. Then he discards all kinds of terms in the denominator to arrive at the first expression using (3), and I can't see how he justifies this. Then he seems to multiply top and bottom by the complex conjugate of the denominator in (1), arriving at (2) after discarding a term in the denominator, which is of second order in V. Then he goes on to say the equation is formally correct up to second order. This doesn't make sense to me! Also, soon after, he has this strange expression with $$\lim_{x\to 0} {1\over(x+iε)}=Pr.(1/x)-iπδ(x)$$ What is this Pr symbol? Any help would be much appreciated!


Do Maxwell's equations predict light instantaneously reaches a point one light-year away from the source?

Maxwell's equations don't seem to have any delay between changes in electric field and changes in the magnetic field.  So, do Maxwell's equations predict light instantaneously reaches a point one light-year away from the source (I think light takes one year to reach that point).  Or, in other words, do Maxwell's equations predict the speed of causality?  I understand the electromagnetic wave oscillates at the velocity $c = \frac{1}{u_0c_0}$, but Maxwell's theory seems to predict that if I flip on a flashlight and there are no obstructions, the light can immediately be detected one light-year away.  For example, the wave function for the electric field is $g(kx-wt)$ for some function $g$. So, at any time $t$ for all distance $x$ the electric field is changing, which seems to violate the speed of causality.  Perhaps, Maxwell's equations do not predict the speed of casuality, and we need to use more advanced theories (I'm guessing relativity) to predict this. I would like to know  if this is the case.  Could anyone tell me (maybe, in the comments) how this is a duplicate question?


Is it true that Ackermann's function cannot be implemented without recursion?

Yesterday I got sucked into a bingewatch of Computerphile's and Numberphile's videos on youtube. In particular I ended up watching some on Ackermann's function. While I knew already this function (and the effect it can have on mathematicians if ), I did not know that it was designed to be computable only through recursion (or, at least, that is what  claims).  The thing is that in a  is shown that you can the results can be computed through exponentiation, and  says that it is really easy to write doen the result using Knuth's up-arrow notation.  So here's lie my problem: [stretching for a moment the imagination and assuming that all integers are representable into a computer, avoiding the risk of overflows, that are outside the scope of this question] if it can be represented through Knuth's up-arrow notation, can't a program that does not use recursion be written to compute the value?  Is it any different for the original Ackermann's function? (the one that Wikipedia says it has 3 arguments instead of 2)


(a) $x+40 ≡ 1 \pmod {99}$.  (b) $40x ≡ 1 \pmod {99}$.  Is the answer for a $x \equiv -39 \pmod {99}$ and b $x\equiv\frac{1}{40}\pmod {99}$?  I believe I am doing it correctly.


Why is "bad news seemS" and not "bad news seem"?

In an online English test I found that "bad news seem" is wrong, the correct would be "bad news seems" as in the sentence:     Bad news seems to be more attractive than good news.    I'm considering news is a plural, but I could be wrong. Someone said about uncountable nouns. Other said about news being singular. Could anyone explain to me why the use of the "s" and also if news is both singular what and uncountable and how can I tell if any other word follows the same conjugation?


I am having trouble getting subdirectories to update to commit so I can push them.  My main directory is projects and this is where I created my init to manage a few small projects into one git repo.  I created a directory and a virtualenv and put it into git.  so currently I have  -Project         ->flask-blog/                     fb/                       /bin                       /include                       /lib   I then added blog.py and a static and templates directories into my folder.  -Project         ->flask-blog/                     fb/                        /bin                        /include                        /lib                     static/                     templates/                     blog.py     I then added them to git from the project folder.  git add .   But that didn't work, well it added blog.py but not the new directories. So I tried.  git add -A   and  git add *   and   git add flask-blog/*   but none of these have worked how to I get git to notice my new directories?


set of almost complex structures on $\mathbb R^4$ as two disjoint spheres

The set of almost complex structures on $\mathbb R^{2n}$ is given by $$ M_n = \frac{GL(2n,\mathbb R)}{GL(n,\mathbb C)} = \mathcal C_+ \sqcup \mathcal C_-,$$ taking into account that $\det = \pm 1$ gives two disjoint sets.  How do we show that $M_2=S^2 \sqcup S^2$? Moreover, I'm a bit confused by dimensions: how does $\dim_{\mathbb R}M_2=8$ relates with the latter decomposition?  This is exercise 1.2.1 from the book Complex geometry by Huybrechts.


I'm following this document to install ansible:    I'm try to add ansible to my ubuntu repositories list but this is what happens:   me@mydev:~/Documents$ sudo apt-add-repository ppa:ansible/ansible Cannot add PPA: 'ppa:~ansible/ubuntu/ansible'. ERROR: '~ansible' user or team does not exist. me@mydev:~/Documents$    I've also tried to just clone the repo (following these instructions: ) But that fails with the following:   me@mydev:~/Documents/ansible$ git clone git://github.com/ansible/ansible.git --recursive Cloning into 'ansible'... fatal: unable to connect to github.com: github.com[0: 192.30.252.131]: errno=Connection timed out  me@mydev:~/Documents/ansible$ ping 192.30.252.131 PING 192.30.252.131 (192.30.252.131) 56(84) bytes of data. 64 bytes from 192.30.252.131: icmp_seq=1 ttl=56 time=23.4 ms 64 bytes from 192.30.252.131: icmp_seq=2 ttl=56 time=23.5 ms ^C --- 192.30.252.131 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1000ms rtt min/avg/max/mdev = 23.466/23.511/23.557/0.159 ms me@mydev:~/Documents/ansible$    As you can see, I'm getting a connection timeout error.  I tried pinging the server and it seems to be able to communicate with my box. Not sure what else I could try.   thanks.  EDIT 1  I am behind a proxy.  I ran this command to identify my proxy server:   me@mydev:~/Documents/ansible$ export http_proxy=http://10.20.30.40:8080   and then to test, I ran:   sudo apt-get update   and it ran fine.


Why are we not able to visualize Dimensions beyond 3 (or maximum 4 including time)?

We consciously know and feel the first three dimensions and with some thinking time as well. But according to literature like String theory etc., we have many many more dimensions. We can readily express them in paper. But why can't we realize them? Why can't we experience them like the first three dimensions?  PS. I was pondering on this when I saw the movie Interstellar where even the fourth dimension 'time' is expressed using the first three dimensions for Cooper. PPS. The first three dimesnions being the X, Y and Z axes.


Show that $A[x] \cap A[x^{-1}]$ is integral over $A$.

Let $R$ be a commutative ring,  $A$ a subring of $R$, and $x$ a unit in $R$. Show that every $y \in A[x] \cap A[x^{-1}]$ is integral over $A$.  I'm supposed to use the fact that there exists an integer $n$ such that the A-module $M = Ax +..... +Ax^{n}$ is stable under multiplication by $y$.  How do I prove the existence of such an $n$ and then proceed using the claim?


Adding OpenVPN client connection to cron

I wrote simple server-client OpenVPN config files:  server.conf  dev tun0 ifconfig 10.8.0.1 10.8.0.2   client.conf  dev tun0 ifconfig 10.8.0.2 10.8.0.1 remote 192.168.0.123   which basically is a cleartext OpenVPN tunnel - for now on its ok to me, I just learn it from basics, the point is - yay, it works! :)  I also wrote a tiny simple bash script to automatically run client:  #!/bin/bash openvpn --config client.conf   and saved as run.sh. Then, wanted to add it to cron to allow client connect to vpn server at the time I want.   I did:  crontab -e 11 5 * * * /home/mirx/run.sh   but I dont see any connected client on server site - does my cron entry work or not? On client site I dont see any new tun interface when I check it with ifconfig. Any ideas?


sqlite how to save french characters to a database?

Trying to get a simple insert saving data and the french characters are read back as box characters. How can I fix this?  $query = 'insert into category (category_en, category_fr) values                             ("Seamanship", "Matelotage"),                             ("General - Histoiry", "Généralités - Histoire")),                             ("Sailing", "Voile")';   When I display the results, I am seeing:   G�n�ralit�s � Histoire   I already noted that if I manually change these characters to be &eacute; that I can save them correctly.  However this does not apply when saving directly from input fields in a form. All French characters in this case are being saved correctly.  I tried to apply SQLite3.escapestring to the query above but it still failed.   Just wondering is there a more straight forward way instead of manually changing each character?  SOLUTION   does the trick.  $query = utf8_encode('insert into category (category_en, category_fr) values                                 ("Seamanship", "Matelotage"),                                 ("General - Histoiry", "Généralités - Histoire")),                                 ("Sailing", "Voile")';   Honestly when forms input fields save french characters correctly one would believe a hardcoded statement would be pretty logical. Hope this helps anyone looking for a quick solution.


Validity of an argument with a contradictory conclusion

I have an argument with the conclusion: 'The sky is blue and it is not the case that the sky is blue'.  Without knowing the premises of this argument, am I right in saying this argument is invalid since the this conclusion is necessarily false?


Is it possible to install vim for a user?

I have a SSH Login to a dev computer (used for hosting PHP and Python files). It has vim installed, but a stripped down version of it - it has syntax and whole lot of other stuff disabled .  So, my question is - can I install my own "local" vim without a superuser account?


What I basically want to is make so that any one of my family members can log on at any of our Pc/Laptops and still assess their files. I know kinda of know what to do but not completely. Would this be called a server or a network. If any one could help/guide me I'll be very thankful.  PandaGlasses


for (x in y) VS for (i = 0; i < y.length; i++) Where x is an array of objects

Where y is an array of objects,  y = [     {property:"",property2:""},     {property:"",property2:""},     {property:"",property2:""},     {property:"",property2:""},     {property:"",property2:""} ]   could someone please tell me why,  for (x in y) {     console.log(x[y].property); }   is so many times slower than,  for (i = 0; i < y.length; i++) {     console.log(x[y].property); }


I am facing this situation. I have a dual boot system with Windows 10 and Ubuntu 18.04 Since yesterday, I am stuck into Windows. When rebooting, my screen stays black, until it boots into Windows again. Not going into bios or grub. So i cant even start from a bootable USB or disc. Last week i installed grub customizer, and recently I set it up to boot into the last used operating system. Any ideas, while it seems that I can't even format my disk, while i can't change boot order?


How do I show this Mobius transformation maps the unit disk onto itself?

I am struggling to show that, for any $\alpha, z \in \mathbb C$ such that $|\alpha|<1$ and $|z|<1$:  $$\left | \frac{z - \alpha}{1-\bar\alpha z} \right | < 1$$  This should be doable with simple algebric manipulations, without using the properties of Mobius transformations, but I cannot figure out how.  Thank you for your time.


Inconsistent connection and super slow speed with RTL8723BE

I just installed Ubuntu on my laptop with a RTL8723BE adapter and the Wi-Fi is really spotty.  Sometimes available wireless networks won't even show up in the menu, and other times just the network in my household will show up and just barely function (I can ping, sites like Stack Exchange usually manage to load, etc.)  I saw online some people suggest in a terminal entering echo "options rtl8723be fwlps=N ips=N" | sudo tee /etc/modprobe.d/rtl8723be.conf and rebooting, but it didn't work.  I saw someone suggest updating the driver with:  sudo apt-get install build-essential git git clone https://github.com/lwfinger/rtlwifi_new/ cd rtlwifi_new make sudo make install sudo modprobe -r rtl8723be sudo modprobe rtl8723be   Rebooted, and it still didn't work.  I also found this, and it didn't work:  sudo add-apt-repository ppa:hanipouspilot/rtlwifi  sudo apt-get update  sudo apt-get install rtlwifi-new-dkms linux-firmware   I have no problems with Windows on this laptop. Do I just have to accept I can't use Ubuntu on it?


Okay, I need some clarification. The  state this about natural attacks:     You do not receive additional natural attacks for a high base attack bonus. Instead, you receive additional attack rolls for multiple limb and body parts capable of making the attack (as noted by the race or ability that grants the attacks).   Let's say that I can shape into an . My BAB is +8/+3 and STR 5. An Oliphant has two natural attacks: Gore and Stomp (x2).  Reading the rules, it seems that I can't do two Gore attacks, like:   1st attack: AB +13. DAM 2d8 + 5 2nd attack: AB +8. DAM 2d8 + 5   because I don't get additional attacks for a high BAB. Does that mean I need to combine attacks instead? Example:   (Gore) 1st attack, AB +13. DAM 2d8 + 5 (2 Stomps) 2nd attack, AB +6*. DAM 2d6 + 5 * With the Multiattack feat, reduces secondary weapon penalty to −2.   Also, does the damage from the two stomps equal 2d6 + 5, or should I roll damage for each stomp? (1st foot = 2d6 + 5, 2nd foot = 2d6 + 5).


Disable screen capture in windows forms desktop applications using c#

I am developing a windows desktop application in C# and I want to disable screen captures of this application.  Can I get suggestions for this?


What is the most appropriate way to cluster respondents based on their rankings of some items?

I have ~30 observations of individuals ranking 20 different products from top to bottom (1-20). I would like to have a way to "cluster" these individuals based on their rankings of the different products.  For example, I would like to cluster respondents with similar high rankings of the same products. This can be done looking at only the top 3 products ranked by each respondent, if that's simpler.  What would be an appropriate way to perform this analysis?


Library for video conversion from one format to another format

Are there any libraries in Ubuntu for converting video files into another format??


has now probably made around 15 accounts. He consistently uses the , , ,  and  tags, and does not ever do anything constructive.  was his latest.  Unfortunately I haven't been bookmarking his other questions, but here are some of his previous accounts:          He has also gone by many other names (Iraq War Veteran is the one that comes to mind), but those accounts have been deleted.    Is there nothing we can do about this? Deleting and suspending his accounts just seems to give him more reason to create other accounts. Is there a way to block him entirely?    Edit:  seems to have been deleted by Community ♦


What the title says when I try to start nautilus on terminal this is the output:  (nautilus:5593): GLib-GIO-CRITICAL **: g_dbus_interface_skeleton_unexport: assertion 'interface_->priv-    >connections != NULL' failed  (nautilus:5593): GLib-GIO-CRITICAL **: g_dbus_interface_skeleton_unexport: assertion 'interface_->priv->connections != NULL' failed Could not register the application: Timeout was reached  (nautilus:5593): Gtk-CRITICAL **: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed  (nautilus:5593): GLib-GObject-WARNING **: invalid (NULL) pointer instance  (nautilus:5593): GLib-GObject-CRITICAL **: g_signal_connect_object: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed   PS: Krusader works fine though


How can I add a texture to a specific face?

I have a cylinder (imported from Creo, in .obj), to which I've added a material, steel and rendered it. It looks great.  I've now cut it in half, and want to see a different texture on the cut face, how do I do that in Cycles?  I tried diffent tutorials from that site but doesn't work with Cycles and imported .obj.  Here is an outside view:    Then, when cut, the blueish part should show the cutting tool path leaving marks in the metal.    Marks or scratches could be like .


What is the recommended order for the books and the games of the Witcher?

With the (relatively) recent release of the third game and the recommendation of a friend, I'd like to discover this universe.  I know there are several media; the books, the video games (though to be honest, I don't intend to play the first video game) and a TV series (also still unsure about that one), but I know almost nothing about how they intervene together storywise.  The books alone have me a little confused, given that the numbering of the edition I'm planning to buy (from the french editor Milady) doesn't seem to exactly match the original order of release:     Season of Storms (2013)   1. The Last Wish (1993)   2. Sword of Destiny (1992)   3. Blood of Elves (1994)   4. Time of Contempt (1995)   5. Baptism of Fire (1996)   6. The Swallow's Tower (1997)   7. Lady of the Lake (1999)   So, what is the best order, potentially mixing the various media, to discover the saga ?


Lp space contained in the intersection of Lq, where 1≤q≤p.

Let $(X, \Sigma, \mu)$ be a measure space with $\mu$(X) $< \infty$. Let $p \in [1,\infty)$.    I would like to prove that $L^p \subseteq \underset{1 \leq q \leq p}\cap L^q$. I'm not sure how to go about this question, so would appreciate any help. Thanks!


How to kill script run through SSH when the local bash script is killed

I have the following script called exec.sh which runs a python script remotely on node01:  #!/bin/bash ssh node01 "python2.7 /home/user/run.py"   If I kill exec.sh using either CTRL+C or kill -9, then the python script that I was running through ssh is still executing on node01.  What I want is to kill the process that I was running on node01 whenever I kill the exec.sh script.


The only good way of creating circles in ArcMap is using true arc, (compound curves) but I need to convert those to vertex (densifying) because of a compatibility problem. I need info for geodatabase and SDO_geometry (arcsde)  and yes there is a way. I use:  UPDATE layer1 a SET arctype = 'compound' WHERE has_compound_curves(a.shape) <> 0;   and then using ET Geotools to densify  layer by layer.  But there should be easier way of doing this straightforward in Oracle or ArcMap, and I just want to densify the features that have true arc. I don't want any unnecessary vertices on straight lines and so on.  How can I identify true arcs in ArcMap, and how can I densify them as fast and easy as possible?  Same for Oracle SQL.


I can't seem to get the idea of point mass into my head. Why are equations of physics applicable on only point masses and should be altered while dealing with object that has a collection of points? We don't see point objects in the real world, so why consider using it in a physical science?


Tangent Points for Common Tangents between Two Ellipses (Ellipses described with rotation and translation coefficients)

The Problem:  Looking for the tangency points (where the lines would touch) between 2 ellipses (already rotated and translated). I have found generalized equations for standard ellipses but don't know how to adapt them. The ellipses may or may not overlap as well. I'm basically pulling the equation from a cad system and generating the tangent lines automatically.  Example of the information I have:  109.41x^2 + -278.93xy + 317.56y^2 + -33.04x + 48.67y = -1.57  1341.05x^2 + -868.64xy + 647.25y^2 + 6.06x + 12.59y = 0.89    The coefficients on the equations above have been rounded to 2 decimal places.  My background is mainly in programming, so a simplistic explanation would be wonderful as I need to "convert" the math/logic to code.  Thank you!!


How to find the files on my AWS linux instance that are filling it up?

I have a free tier linux instance on AWS running a bitnami ubuntu parse dashboard that is the backend for an iOS app and website.  When I log on to my instance it says that I am using 100% of the 9.76gb available when I run the df command: df -h bitnami@ip-172-31-22-220:~/apps/parse/htdocs/logs$ df -h / Filesystem      Size  Used Avail Use% Mounted on /dev/xvda1      9.7G  9.7G     0 100% /  I have found other posts about searching for what files are filling up the file server but was hoping someone may be able to offer insights into the specific set up of AWS/Ubuntu/Bitnami parse-platform.  This is my first question on this board, so before voting down please let me know if there are ways to improve my question. For example when I noticed when running du -ah there were a series of files that looked like AWS specific log files like /usr/src/linux-aws-headers-4.4.0-1109.  Does AWS write out some files that I need to clear out or back up to S3 to keep my server from filling? My website is down because of this and I am not sure what commands I can run that will help me find what is taking up all the space.  I did some research on the du command but wasn't quite sure how I could use that to track down where the space has accumulated.  I stumbled on one log file area that I try to clean out but it was only filling up about 1.6gb.  Is there a way I can run a command on unix that will list out which directories are > a 1gb or something?  I suspect that there is another place like the folder I found du -h /home/bitnami/apps/parse/htdocs/logs where log or error files exist that need to be cleaned out and I just don't know how the ubuntu bitnami parse instance stores those things.  I am new to AWS so I am pretty sure that I need to upgrade my account or something so I have more then 9.76 gb in filespace before I release my app for general use, so you if you happen to have any advice for what an AWS instance that is the backend for an iOS should be set up as I would appreciate any insights on that topic as well.


Why is the minipage indented on the left?

I am trying to create a CV and for the heading information I am using a minipage to display my name and Curriculum Vitae inline with smaller text containing my contact information.  The code works fine, but I cannot figure out why the left edge of the minipage is indented further than the section heading and text and which come below it.   Any ideas and help would be very appreciate.  Here is the code:   %------------------------------------------------------------------- % PACKAGES AND OTHER DOCUMENT CONFIGURATIONS %------------------------------------------------------------------- \documentclass[10pt]{article} \usepackage{array, xcolor, lipsum, bibentry} \usepackage[     paper=letterpaper,     includefoot,            % Uncomment to put page number above margin     marginparwidth=1in,     % Length of section titles     marginparsep=.05in,     % Space between titles and text     margin=1in,         % 1 inch margins     ]{geometry}  \usepackage{showframe}    % Shrink spacing around section headings \usepackage{titlesec} \titleformat*{\section}{\large\bfseries} \titlespacing\section{0pt}{12pt plus 4pt minus 2pt}{0pt plus 2pt minus 2pt}  % Break tables across pages \usepackage{supertabular}  % Set column sizes and color \definecolor{lightgray}{gray}{0.8} \newcolumntype{L}{>{\raggedleft}p{0.1225\textwidth}} \newcolumntype{R}{p{0.81\textwidth}} \newcolumntype{X}{>{\raggedleft}p{0.05\textwidth}} \newcolumntype{Y}{p{0.9\textwidth}}  % Commands to simplify starting a table \newcommand\VRule{\color{lightgray}\vrule width 0.5pt} \newcommand\smalltab{\begin{supertabular}{L!{\VRule}R}} \newcommand\medtab{\begin{supertabular}{X!{\VRule}Y}} \newcommand\longtab{\begin{supertabular}{L!{\VRule}R}}  \begin{document} %-------------------------------------------------------------------  % NAME AND CONTACT INFO %-------------------------------------------------------------------  \begin{minipage}[b]{0.65\textwidth} \begin{flushleft}     \Huge{\textsc{Here is my name\\}}     \Large{Curriculum Vitae} \end{flushleft}  \end{minipage} \begin{minipage}[b]{0.35\textwidth}     \small{Street Address\\     City, State 12345\\     emailaddress@gmail.com\\     www.website.com\\     1-555-555-5551} \end{minipage}  %------------------------------------------------------------------- % EDUCATION %------------------------------------------------------------------- \section*{Education} \smalltab     2011--present & PhD in Stuff, Very Awesome School.\\[2.5pt]     2009--2011 & Masters in Stuff, Just OK School.\\[2.5pt]     2004--2008 & Bachelors in Things, Relatively Awesome School.\\ \end{supertabular}  \end{document}


Command substitution: splitting on newline but not space

I know I can solve this problem several ways, but I'm wondering if there is a way to do it using only bash built-ins, and if not, what is the most efficient way to do it.  I have a file with contents like  AAA B C DDD FOO BAR   by which I only mean it has several lines and each line may or may not have spaces.  I want to run a command like  cmd AAA "B C DDD" "FOO BAR"   If I use cmd $(< file) I get  cmd AAA B C DDD FOO BAR   and if I use cmd "$(< file)" I get  cmd "AAA B C DDD FOO BAR"   How do I get each line treated a exactly one parameter?


Counting items in itemize or enumerate environments

Is there any way to obtain the number of items that appear in an enumeration? My intention is to have that number updated automatically when I add a new item anywhere in my list, so something like this would be ideal: Here are the \numitems{mylist} points I wanted to address: \begin{itemize}\label{mylist}     \item important issue;     \item another important issue;     \item oh, and yet another critical thing. \end{itemize}


I was asked this question during an interview for a trading position with a proprietary trading firm. I would very much like to know the answer to this question and the intuition behind it.  Amoeba Question:  A population of amoebas starts with 1. After 1 period that amoeba can divide into 1, 2, 3, or 0 (it can die) with equal probability. What is the probability that the entire population dies out eventually?


What is the emergency phone number in different countries?

I know that the emergency services can be called FREE in the UK by dialing 999 and in the US by dialing 911.   What I don't know is the number to call in other countries and if there is a cost involved. This is something I think most people should find out before travelling but many don't (including me). Hopefully this will help me and other people.


I have been playing around with Ubuntu installing new themes and and docks. Sometimes during the installation, whole screen just hangs. What is the best way in Ubuntu to Kill a process/application? Anything similar to Ctrl + Alt + Del of windows?


showing that $\sum_1^n \frac{1}{\sqrt{n^2+k}}$ is increasing

Define $u_n$ as :  $$u_n=\displaystyle\sum_{k=1}^n \dfrac{1}{\sqrt{n^2+k}}$$  From first values, $(u_n)$ seems to be increasing.  From squeezing, its limit is $1$.  $$ \dfrac{1}{\sqrt{n^2+n}} \le \dfrac{1}{\sqrt{n^2+k}} \le \dfrac{1}{\sqrt{n^2+1}}$$   (summing from $k=1$ to $k=n$)  How can one show that it's indeed increasing (if it is) because no terms cancel out when setting $u_{n+1}-u_n$.  thanks.


Is there a phrase that means sleeping with someone without sex?

The phrase "sleeping with someone" often means "having sex." What is the origin of this sexual connotation? Is there a non-sexual equivalent of this phrase to express sleeping with someone without sexual intercourse?


My wall plate won't come off - I've removed the screw on it, I can force the bottom part away from the wall as shown in the picture, but it seems there is some attachment behind the the top part. Has anyone run into this kind of wall plate? How should I remove the wall plate from the wall? (I need it come off so that I could check the wiring - Originally it was used as a phone jack, now I would like to ).


About compactness and completeness of set $X = \mathbb{R}$ with the metric $d(x, y) = \frac{|x-y|}{1+|x-y|}$

What can we say about the compactness and completeness of the  set $X = \mathbb{R}$ with the metric $$d(x, y) = \frac{|x-y|}{1+|x-y|}\;?$$  I tried by showing that  $d(x, y)<1$ and thus it is bounded. But how to show rest of the things? Can anybody help me? Thanks


Storing the last value and comparing changes in async function?

I have a Tensorflow.js model making predictions and I want to send a certain websocket message each time the predicted label changes. I have tried to store the latest label in a variable and compare that to the newest one. However, my "cat" websocket message is still activated each second even if the predicted label stays the same. Problem is probably some newbie mistake regarding the use of async function or storing the values - I would really appreciate any directions! Thank you so much. Code (cleaned to include only relevant bits):  let newLabel; let oldLabel;   async function app() {    const model = await tf.loadGraphModel(MODEL_URL);   console.log('Successfully loaded model');   const labels = ["cat", "dog", "human"];   console.log(labels);    const webcam = await tf.data.webcam(video);     var myPredict;     async function predictFunction () {     myPredict = setInterval (predictLoop, 1000);     }    async function predictLoop () {      ...      const result = await model.predict(t4d);      result.print();      result.as1D().argMax().print();      const labelIndex = result.as1D().argMax();      const predictionLabel = result.as1D().argMax().dataSync()[0];     newLabel = labels[predictionLabel];     const predict = await result.data();     const value = predict[predictionLabel];        document.getElementById("demo").innerHTML = `     I can see a: ${newLabel}\n     Confidence is: ${value}\n     `;      if (newLabel== "cat" && newLabel !==oldLabel){        var data = {         speed: 100       }       socket.emit("cat", data);       sendParam ("/sound", 1);   }      else {       socket.emit("other");        sendParam ("/sound", 2);     }        img.dispose();       result.dispose();       smalImg.dispose();       resized.dispose();       t4d.dispose();       tf.engine().endScope();       await tf.nextFrame();    }     oldLabel = newLabel;    predictFunction();   }   app();


Convergence of the series $\sum_{n=1}^{\infty}{\frac{1}{2^n n (3n-1)}}$

this series has been driving me crazy, the thing is I need to determine if the series converges or not, and if it does I need to find the value at which converges.  $\displaystyle{\sum_{n=1}^{\infty}{\frac{1}{2^n n (3n-1)}}}$  I know that this series converges by the ratio test, but I can't find yet at which value converges, I tried to find the partial sums but I couldn't get anywhere.   I would appreciate any advice that you guys could give me. Thank so much.


Can the human body create glucose out of fat?

I read conflicting views about whether or not the human body can create glucose out of fat. Can it?


How can I setup a Material in Cycles for Z-Transparency?

After converting to nodes in order to render using Cycles I've no idea where to enable the z-transparency. I guess the image textures alpha channel needs to be pluged somewhere but I've no idea which node would be suitable.   The question is how could I correctly setup the nodes to have the same effect as when using z-transparency in BI?      The materials original settings for BI are:    Which renders like:    I had no luck with DarenWs suggestion:


In characteristic $p$, the field extension $k(X,Y)$ over $k(X^p,Y^p)$ is not simple

Let $k$ be a field with characteristic $p>0$, $L=k(X,Y)$ be the field of rational fractions of two variables over $k$. Let $K=k(X^p,Y^p)$. Then $[L:K]=p^2$ (for a proof see ). Show that $L^{p}\subseteq K$ and $L$ is not a simple extension over $K$.  Thank in advance.


Machine name set to new-host-X instead of the name set in Preferences

My machine name is set shiny in System Preferences/Sharing/Computer Name.  From another machine on the network, I can only use shiny.local to refer to this machine. In the past, I used only shiny.  In a terminal, I have new-host-7 instead of the machine name.  I don't know if this is relevant, but the computers are connected to an internet box, on which a DHCP server is activated. I assigned a static IP address to the Mac. The internet box can see the name I gave to the Mac.  Is there something I can do to refer to the Mac as shiny on the network ?


EDIT  After a second attempt using EasyRE I could get rid of BSoD, but then it wouldn't boot anymore. Even before Windows starts to boot it loaded a screen as the recovery media was inserted (couldn't get over this).  Checked a few minidumps on  and it pointed, it seems, to some driver failure.  It was too late anyway. Was avoiding, but ended reformatting.    Notebook always reboots after a blue screen, right after of showing Windows logo ("Starting Windows").  None of these work:   Safe Mode Last Known Good Configuration Low-resolution video (VGA Mode) in Windows Disable driver signature Debugging Mode Directory Services Restore Mode   DID NOT SOLVE   CHKDSK /F/R EasyRE – Tried , but can't get to really use it. I've made a bootable USB drive, but I'm stuck on this error "grub_divmod64_full". sfc /scannow – it returns the old fashioned error: "There is a system repair pending which requires reboot to complete. Restart Windows and run sfc again" any repair attempt (using HP Built in recovery tools)   BLUE SCREEN MESSAGE  STOP: 0x000000F4 (0X0000000000000003, 0XFFFFFA800A439B10 ...)     SYSTEM   HP Pavilion dm4-2175br Windows 7 Home Premium, 64-bit


Let $p$ be a prime. Why is ${p^mn \choose p^m}$, where $p \nmid n$, not divisible by $p$?   $${p^mn \choose p^m} = \frac{(p^mn)!}{p^m!(p^mn-p^m)!} = \frac{p^mn(p^mn-1)(p^mn-2)\cdots(p^mn-p^m+1)}{p^m(p^m-1)(p^m-2)\cdots(p^m-p^m+1)}$$  I can see $p^m$ cancel out in the first term, but why is this not divisible by $p$?


I have a table data as shown below.  +---------+----------+-------+--+ |  Name   | Semester | Score |  | +---------+----------+-------+--+ | John    | Sem 1    |    80 |  | | Michael | Sem 1    |    90 |  | | Dennis  | Sem 1    |    65 |  | | Peter   | Sem 1    |    70 |  | | John    | Sem 2    |    65 |  | | Michael | Sem 2    |    85 |  | | Peter   | Sem 2    |    95 |  | | George  | Sem 2    |    85 |  | | Michael | Sem 3    |    80 |  | | Peter   | Sem 3    |    70 |  | | George  | Sem 3    |    75 |  | | Dennis  | Sem 3    |    70 |  | +---------+----------+-------+--+   I want to execute a query and get the following resultset.  Name    Sem 1   Sem 2   Sem 3   Avg Total John    80      55              67.5 Michael 90      85      80      85 Dennis  65              70      67.5 Peter   70      95      70      78.33 George          85      75      80   Help me to build the query.  Thanks in advance


I have a desktop with no battery power with a very simple surge protector.  I am running Ubuntu 64-bit 12.04. Apt-get needed a restart of my computer to finish installing the latest updates I had downloaded. Before I was able to do that, the power went out.  Now when I boot up, all I see is a black screen after I select Ubuntu in the grub menu.  I am able to get to the recovery options from the grub screen. I tried loading the failsafex version but that also failed.  I have never posted anything to a forum before but I have to get this working ASAP because of a work project due for a client.  I'll be up all night until I can get this fixed.  Thanks for any and all help.


Prove that $1 + nx ≤ (1 + x)^n$ , for all real numbers $x > −1$ and integers $n ≥ 2$ by mathematical induction.  My attempt (1) $n=2$ $x > -1 \Rightarrow (1+2x > -1) \land (x^2 \ge 0)   \Leftrightarrow (1+2x) \le (1+x)^2 $ Hence p(2) is true.  (2) We must show that for all integers $k \ge 2, p(k) \Rightarrow p(k+1)$   Suppose for inductive hypothesis, $k \ge 2, p(k)$. That is $1 + kx ≤ (1 + x)^k$ Then, $1 + kx + x = 1 + (k+1)x ≤ (1 + x)^k + x$    I should get $1 + (k+1)x ≤ (1 + x)^{k +1} $. It seems when I multiply each side by (1+x), the left side gets complex and far away from desired inequlity. On the other hand, when I add 1, it doesn't help since we have to get $(1+x)^{k+1}$ on the right side, $(1 + x)^k + x+1$ doesn't increase the exponent of $(1+x)$.  What should I do next to get out of $1 + kx + x = 1 + (k+1)x ≤ (1 + x)^k + x$?   $1 + kx + x = 1 + (k+1)x ≤ (1 + x)^k$


I created a custom view field with the hook _views_data and a custom Class who extends FieldPluginBase.  With the render method, I can return a sample string :  class MyCustomClassViewsField extends FieldPluginBase { ...     public function render(ResultRow $values) {       $node = $values->_entity;       return $node->id(); // My view field shows the nid of the current node     } ...   Now, I want shows a link with my field. I tried :   class MyCustomClassViewsField extends FieldPluginBase { ...     public function render(ResultRow $values) {       $node = $values->_entity;       return "custom link"     } ...   But my field in my view shows :   custom link   and not     How can I show the link as an html element, not a sample text ?   Thank you =)  UP  This code work :   return array('#markup' => \Drupal::l("test",\Drupal\Core\Url::fromUri("http://www.example.com")));   ut the l() function is deprecated. If I use Link::fromTextAndUrl instead :   return array('#markup' => \Drupal\Core\Link::fromTextAndUrl("test",\Drupal\Core\Url::fromUri("http://www.example.com")));   I get the error :      [Sun Sep 18 22:17:59.444188 2016] [:error] [pid 2143] [client   192.168.1.48:53322] Recoverable fatal error: Object of class Drupal\Core\Link could not be converted to string in   /var/www/xxxxx/core/lib/Drupal/Component/Utility/Xss.php   on line 67, referer:         [Sun Sep 18 22:17:59.446098 2016] [:error] [pid 2143] [client   192.168.1.48:53322] PHP Fatal error:  Uncaught Error: Call to a member function get() on null in   /var/www/xxxxx/core/lib/Drupal/Core/Session/SessionHandler.php:76\nStack   trace:\n#0   /var/www/xxxxx/vendor/symfony/http-foundation/Session/Storage/Handler/WriteCheckSessionHandler.php(89):   Drupal\Core\Session\SessionHandler->write('BTaHaVF0t-bMk2Z...',   '_sf2_attributes...')\n#1   /var/www/xxxxx/core/lib/Drupal/Core/Session/WriteSafeSessionHandler.php(75):   Symfony\Component\HttpFoundation\Session\Storage\Handler\WriteCheckSessionHandler->write('BTaHaVF0t-bMk2Z...',   '_sf2_attributes...')\n#2   /var/www/xxxxx/vendor/symfony/http-foundation/Session/Storage/Proxy/SessionHandlerProxy.php(77):   Drupal\Core\Session\WriteSafeSessionHandler->write('BTaHaVF0t-bMk2Z...',   '_sf2_attributes...')\n#3 [internal function]:   Symfony\Component\HttpFoundation\Session\Storage\Proxy\SessionHandlerProxy->write('BTaHaVF0t-bMk2Z...',   '_sf2_attributes...')\n#4 [internal function]:   session_write_close()\n#5 {main}\n  thrown in   /var/www/xxxxx/core/lib/Drupal/Core/Session/SessionHandler.php   on line 76, referer:      How can I replace the l deprecated function ?


extract part of column to make cp command

I wan to create copy command to copy files from one directory to just back of it with removing suffix date. There are multiple files are there.   eg file LOAN.DAILY.20191204  want to create command   cp LOAN.DAILY.20191204 ../LOAN.DAILY   My attempt   ls -lrt | awk ' /DAILY/{ print "cp " , $9 , "../" , sub(/\.20191204$/,""); $9 }'   getting output   cp  LOAN.DAILY.20191204 ../ 1   why this 1 is coming


How to correctly use validation and test sets for Neural Network training?

I am in the machine learning business for a long time, but still, this fundamental fact gets me confused, since every paper, article and/or book describe different kind of usages for validation and test sets. I aim to set my mind at ease forever on this issue:   Let's say I have a relatively small Convolutional Neural Network and I want to train it on MNIST dataset. Naturally, I want to learn the best hyperparameters for the given CNN, like the weight decay coefficient $\lambda$, the learning rate $\alpha$, etc. Naturally, MNIST has 60K training images and 10K test images. The basic practice is allocating 10K of the training set as the validation set for MNIST.   Assume that we are doing a grid search on $\lambda$ and $\alpha$ hyperparameters and assume that we have fixed a $(\lambda^*,\alpha^*)$ pair. Then we start training the CNN using SGD, using the 50K training set and measuring the performance on the 10K validation set in the end of each epoch (a complete pass over the 50K training set). Usually we either stop training if a fixed budget of epochs has been depleted or we start to lose accuracy on the validation set. And then, only for a single time in the training process of the CNN with the $(\lambda^*,\alpha^*)$ pair, we measure the real performance on the test set. We pick the one with best performance. This usage is intuitive and does not cause the network to unfairly overfit on the test set. But the problem is, we did not ever used the 10K validation set in the actual training with SGD.  So, now, what is the correct way to use the validation set here? After we finish training with the $(\lambda^*,\alpha^*)$ pair, either by running out of allowed epochs or early exiting due to overfit on validation set, should we merge the validation set and training set, and train a few epochs more? At this point, our learning rate may already be very small due to decaying it gradually. Should we train everything from scratch by using the 60K training + validation set, setting the learning rate to its initial value?   Another alternative may be to train the CNN with every $(\lambda,\alpha)$ pair in consideration of our grid search, using only 50K training samples in the SGD and 10K validation samples for measuring the accuracy. No interaction with the test set is allowed. Let's assume that after we train with every $(\lambda,\alpha)$ pair, we pick the pair which yields the highest accuracy on the validation set. Then we train the CNN with the picked hyperparameters, from scratch, this time using the 60K training + validation samples directly in SGD, for an amount of fixed epochs. After the training ends, we use the test set once and for all to declare our final accuracy performance.  This method, in my mind, would cause the following issue: The hyperparameters we have picked would be the optimal ones for the 50K training samples! Since we have used a smaller subset of the actual training set, most probably the model would more easily overfit, seeing a lower data variation, so our hyperparameter search may tend to find a higher $\lambda$. And with this $\lambda$ we would probably see a lower accuracy on the actual test set with the full 60K training samples, since the model won't be able to compensate for the variation of the extra 10K samples, due to high $\lambda$.  So, I am not certain what the ultimately correct way to use the validation-test sets. What would be the valid - logical approach here?


Given a square matrix $A$, form the Lie series of it, which is defined by: $$ e^A = I + A + \frac{1}{2} A^2 + \frac{1}{3!} A^3 + \cdots + \frac{1}{n!} A^n = \sum_{k=0}^\infty \frac{1}{k!} A^k $$ Is there a simple expression for the determinant of $\,e^A$ ?  This question is motivated by:  What does shear mean?  Where I've proved for the 2-D case: $$ S = e^{\large t \begin{bmatrix} 0 & p \\ p & 0 \end{bmatrix}} = \begin{bmatrix} \cosh(p t) & \sinh(p t) \\ \sinh(p t) & \cosh(p t) \end{bmatrix} \quad \Longrightarrow \quad \det(S) = 1 $$ I'd like to know if the determinant equals one for the 3-D case as well, where $$\,S = \exp\left(t \begin{bmatrix} 0 & p & q \\ p & 0 & r \\ q & r & 0 \end{bmatrix}\right)$$


How can I install Windows XP from a USB drive?

I have image file of Windows XP installation and I need to know how to create a  bootable USB drive with it so I can install Windows XP?  I am currently using a Linux operating system.


Cheapest way to get from Germany to India and back with flexible dates

I want to travel to Vandenmedu, India from Bochum, Germany. Starting date would be around 20DEC15, return should be about 2 weeks later, i.e. 04JAN16    What bothers me: I am flexible in both start- and return-dates, as well as the airports in both Germany and India, as long as I save money but I'm having a hard time finding a search-engine that takes that flexibility into account.    I am looking for a search-engine that allows me to use a range of dates for both trips, with bonus points if I can just use regions instead of airports.


C# program that overlays an image and saves the new image

I'm fairly new at C# but want to make a program which imports a background image then a partially transparent image and combines the two into a new image. Then the image is saved. How would I do this?


Is there an intuitive explanation for why Lorentz force is perpendicular to a particle's velocity and the magnetic field?

The Lorentz force on a charged particle is perpendicular to the particle's velocity and the magnetic field it's moving through. This is obvious from the equation:  $$ \mathbf{F} = q\mathbf{v} \times \mathbf{B} $$  Is there an intuitive explanation for this behavior? Every explanation I've seen simply points at the equation and leaves it at that.  I can accept mathematically why $\mathbf{F}$ will be perpendicular to $\mathbf{v}$ and $\mathbf{B}$ (assuming the equation is correct, which it is of course). But that doesn't help me picture what's fundamentally going on.  Trying to create an analogy with common experiences seems useless; if I were running north through a west-flowing "field" of some sort, I wouldn't expect to suddenly go flying into the sky.  I'm hoping there's a way to visualize the reason for this behavior without a deep understanding of advanced theory. Unfortunately, my searching for an explanation makes it seem like something one just has to accept as bizarre until several more years of study.


Ubuntu is a derivative of Debian. It uses the same package format.  In what ways is Ubuntu different from Debian?


If $a, b$ are positive real numbers and $a + b = 1$, prove that $$ \left(a +\frac{1}{a}\right)^2 + \left(b +\frac{1}{b}\right)^2 \geq \frac{25}{2} $$  Thank you.


Just what the title says, Do Blink, Blur, normal concealment & Displacement stack? Do any of them stack? Do all of them stack? Which ones, if any?


Change the screen resolution of my desktop in WPF

Okay, after an hour of search, I hope asking myself will give me some answer. Basically, I want to write a tiny program that can swap my desktop resolution between 1920x1080 and 1280x800 automatically by running a simple script.  I started with:  public partial class MainWindow : Window {     public MainWindow()     {         InitializeComponent();          this.Loaded += SwapResol;     }      private void SwapResol(object sender, EventArgs e)     {         double width = System.Windows.SystemParameters.PrimaryScreenWidth;         if(width == 1920)         {             //set it to 1280x800         }         if(width == 1280)         {             //set it to 1920x1080         }          this.Close();     } }   When I realized that System.Windows.SystemParameters.PrimaryScreenWidth (and height) both only have getters implemented. If I run any script as an admin, is there a way to change the resolution in code? I have found tons of questions about getting the resolution and using it for the program but nothing on setting it. Does Windows even allow changing it some other way than using the 'standard method'?   question already exists, but the suggested answer seems to refer solving the problem in C++ by not using .NET.


I had to remove a new kernel version after Ubuntu refused to boot. Since then the update manager has not been working and I get the following error. How do I get the update manager to work again?  W: The repository 'http://ppa.launchpad.net/kernel-ppa/ppa/ubuntu xenial Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. W: The repository 'http://ppa.launchpad.net/tiheum/equinox/ubuntu xenial Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. W: http://archive.canonical.com/ubuntu/dists/precise/Release.gpg: Signature by key 630239CC130E1A7FD81A27B140976EAF437D05B5 uses weak digest algorithm (SHA1) E: Failed to fetch http://ppa.launchpad.net/kernel-ppa/ppa/ubuntu/dists/xenial/main/binary-i386/Packages  404  Not Found E: Failed to fetch http://ppa.launchpad.net/tiheum/equinox/ubuntu/dists/xenial/main/binary-i386/Packages  404  Not Found E: W: Some index files failed to download. They have been ignored, or old ones used instead.


I have a problem with a webserver that runs Centos4 with DirectAdmin.  Since a few weeks some websites hosted on it are not redirecting on search engines properly, they are redirected to some malware site, resulting in a ban from google.  Now I have used 3 virusscanners: ClamAV: Didn't find anything Bitdefender: Found a 2-3 files with JS infection, deleted them AVG: Finds lots of files, but doesn't have the option to clean!  The virus that it finds is: JS/Redir JS/Dropper  Still the strange thing is: website a (www.aa.com) does not have any infected files (have gone through all the files manually, is a custom PHP app, nothing special) but does still have the same virus. Website b (www.bb.com) does have the infected files as only one.  I deleted all these files and suspended the account, but no luck, still the same error.  I do get the log entries on the website from the searchengines so the DNS entries are not changed.  But now I have gone through the httpd files but cannot find anything.  Where can I start looking for this?


every infinite set of points in M has a accumulation point in M => M is compact?

The answer in the textbook says no. But I have a proof for it, so wanna know where the mistake is.  proof :  supposed M not compact.  Let { Ui } be a open sets covering of M, which doesn't have a finite subcovering.  Let {Uj} be a minimal subset of {Ui} such that {Uj} is still a covering of M. (in other word : when you remove any element from {Uj}, the remained {Uj} don't cover M any more.)  { xj : xj is an element of Uj , xj is different from xk when j is not k} You take a point xj from each Uj, which is different from any other points from other Ujs( in other word : which is not contained in any other Uj).  it's possible because {Uj} is minimal.  This set of xj has a accumulation point p in M.   Since {Uj} cover M, there exist a Uj which contains p.  because p is a accumulation point of xj and Uj contains p, Uj contains infinate many xj. This is a contradiction to the choice of xj. (since each xj is contained in only one Uj)  Hope to find my mistake. thank you very much.  --------------replies to comments-------------  (I can't post comment so I have to write it here)  @Max   My question is not that, is actually the reverse implication.


Does a Barbarian's Fast Movement affect non-walking speeds?

So a baseline Barbarian in D&D 5e gets Fast Movement at 5th level (Player's Handbook, p. 49):  your speed increases by 10 feet while you aren't wearing heavy armor.  The Storm Herald Barbarian subclass gets a feature at 6th level that can grant you a new, non-walking, movement speed if you pick the Sea environment ability (Xanathar's Guide to Everything, p. 10, emphasis mine):  Sea You gain resistance to lightning damage, and you can breathe underwater. You also gain a swimming speed of 30 feet.  Does the Fast Movement feature interact with this swim speed for an overall swimming speed of 40 feet? Does Fast Movement in general interact with non-walking speeds? If so, would it apply to a swim or climb speed granted through a different method, like a spell or magic item?


Neural Network for input values optimization

I have electric machine, which parameters I measure by 10 sensors. 8 of them measures "input" values and 2 of them result (output). I've got tons of historical data of all of these sensors. I built a Neural Network and train it to aproximate 2 outputs given these 8 inputs (simple multilayer perceptron). It works very well (Error is very small). But the question is: I have got trained model of my process. Can I now somehow train this model to give it 2 outputs as inputs and train it to give me the best combination of input values? I thought about autoencoders. I built some of them to recognize anomallies in this system, but I don't actually see how I can implement them to optimize my input values.  Has anybody done something before?  Maybe I should build some kind of generative model, like GAN? to learn network the distribution of particular input values?  Thanks,


How to prove the trigonometric formula $a \sinθ + b \cosθ = R \sin(θ + α)$?

I recently learnt the formula $a \sinθ + b \cosθ = R \sin(θ + α)$ at school. How to prove it? Thanks.


Why can't I create a file in a directory where I have group write access?

There's a situation I don't quite understand. I have this directory, where the group 'webadmin' has rwx rights :  $ ls -la total 8 drwxrwxr-x 2 root webadmin 4096 Aug 27 12:17 .      ⋮                                       ⋮   I am in the group webadmin :  $ groups eino eino : eino sudo webadmin   however, I can't create any file in the directory :  $ touch test.txt touch: cannot touch 'test.txt': Permission denied   How come? Shouldn't the rwx permissions give me right to do it?


Prove the convergence of the following sequence: $$x_1 = \sqrt{a}$$  $$x_{n+1} = \sqrt{a + x_n}$$


$f(x)=x^n+5x^{n-1}+3$ can't be expressed as the product of two polynomials

Let $f(x)=x^n+5x^{n-1}+3$ where $n\geq1$ is an integer. Prove that $f(x)$ can't be expressed as the product of two polynomials each of which has all its coefficients integers and degree $\geq1$.   If the condition that each polynomial must have all its coefficients integers was not there, then I needed to show only that $f(x)$ is irreducible over real numbers. But since this condition is given,therefore, we can't exclude the case when $f(x)$ is reducible over real numbers but not with polynomials of integer coefficients. Anyone with idea how to proceed? Thanks in advance!!


Here's the output from Blender python console:  >>> from numpy import * Traceback (most recent call last):   File "<blender_console>", line 1, in <module>   File "/usr/lib/python3/dist-packages/numpy/__init__.py", line 153, in <module>     from . import add_newdocs   File "/usr/lib/python3/dist-packages/numpy/add_newdocs.py", line 13, in <module>     from numpy.lib import add_newdoc   File "/usr/lib/python3/dist-packages/numpy/lib/__init__.py", line 8, in <module>     from .type_check import *   File "/usr/lib/python3/dist-packages/numpy/lib/type_check.py", line 11, in <module>     import numpy.core.numeric as _nx   File "/usr/lib/python3/dist-packages/numpy/core/__init__.py", line 6, in <module>     from . import multiarray ImportError: cannot import name 'multiarray'   It seems that Blender is trying to use my system Numpy instead of its own version. If I try importing numpy in a regular python console, it works just fine. However, the regular python console seems to use numpy from a different path than Blender:  >>> import numpy >>> print(numpy.__path__) ['/usr/local/lib/python3.4/dist-packages/numpy']   How to solve this?  EDIT: Inside Blender, sys.path gives:  >>> print(sys.path) ['/usr/share/blender/2.78/scripts/addons_contrib', '/usr/share/blender/2.78/scripts/addons', '/usr/share/blender/2.78/scripts/startup', '/usr/share/blender/2.78/scripts/modules', '/usr/lib/python3.5', '/usr/lib/python3.5/plat-x86_64-linux-gnu', '/usr/lib/python3.5/lib-dynload', '/usr/lib/python3/dist-packages', '/usr/share/blender/2.78/scripts/freestyle/modules', '/usr/share/blender/2.78/scripts/addons/modules', '/home/myhome/.config/blender/2.78/scripts/addons/modules']   In normal python console, I get:  >>> print(sys.path) ['', '/usr/lib/python3.4', '/usr/lib/python3.4/plat-x86_64-linux-gnu', '/usr/lib/python3.4/lib-dynload', '/usr/local/lib/python3.4/dist-packages', '/usr/lib/python3/dist-packages']


How to remove the directory which shows "resource busy"?

I used the following command rm -rf inttergat to remove the directory. But I get stuck with following errors:  rpa-vd1-296: rm -rf inttegrat/ rm: cannot remove ‘inttegrat/.nfs0000000005d154320000000b’: Device or resource busy


Gradient of least-squares cost — how to compute it?

I have a system $A x ~ b$ where vector $b$ is not actually in the span of matrix $A$. I want to use a least squares approach to minimize the distance between the two vectors. $$\begin{aligned} \min_x \Vert \mathbf Ax - b\Vert ^2 &= (\mathbf Ax-b)^T (\mathbf Ax-b) \\ &= x^T \mathbf A^T \mathbf A x - (\mathbf Ax)^Tb - b^T \mathbf Ax + b^Tb \\ &= x^T \mathbf A^T \mathbf A x - 2b^T \mathbf Ax + b^Tb \end{aligned}$$ I'm struggling to understand how to arrive at $$0 = 2 \mathbf A^T \mathbf Ax -2 \mathbf A^T b$$ I understand that some sort of derivative with respect to $x$ has been taken in order to minimize the distance, but what does it mean to take a derivative of a matrix product with respect to a vector? I have never come across such a calculation? Thanks in advance.


Why do universities/research agencies allow their employees to do free peer reviewing which financially benefits a third party?

Following up with this question  and this   I understand that peer reviewing probably started when there were relatively fewer article submissions than today and when the academic system was going at a slower pace and was less cluttered with people.   But given how the system has evolved, I am wondering why do employers let their employee work for free for the monetary benefit of a third party?  As far I as know no employer pays its employees to make someone else rich. It seems against any economics principle. Wouldn't it be more efficient to pay reviewers so they would be more motivated, quicker to review, and universities/grants/governments would not pay someone to work for free for the economic benefit of someone else? This might also offset the cost of salary of professors. Any economic return to the employer seems very low considering the working hours devoted to reviewing.


Derivation of the Kubo formula in Ashcroft & Mermin

I've been trying to rederive (13.37) from Ashcroft & Mermin:  $$ \sigma_{xy}(\omega+i\eta) = \frac{-ie^2}{\hbar^2(\omega + i\eta)} \sum_{n\neq n'} (f) \left( \frac{\langle n\mathbf k|\nabla_x|n'\mathbf k \rangle \langle n'\mathbf k|\nabla_y|n\mathbf k \rangle}{\hbar\omega + i\eta + \varepsilon_{n\mathbf k} - \varepsilon_{n'\mathbf k}} + \frac{\langle n\mathbf k|\nabla_y|n'\mathbf k \rangle \langle n'\mathbf k|\nabla_x|n\mathbf k \rangle}{-\hbar\omega - i\eta + \varepsilon_{n\mathbf k} - \varepsilon_{n'\mathbf k}} \right).$$  So I understand (pretty much) all derivation steps, but at some point the authors mention the use of time-dependent pertubation theory, p. 252, between (13.36) and (13.37).  I'm assuming the same applies as in appendix E (pp. 765-766), where a Hamiltonian about $\mathbf  k + \mathbf  q$ is considered, $$ H_{\mathbf  k+\mathbf q} = H_{\mathbf k} + \frac{\hbar^2}m \mathbf q \cdot\left(\mathbf k + \frac\nabla i\right) + \frac{\hbar^2}{2m}q^2 $$ where the second and third terms are treated as pertubation $H_1$, and the eigenvalues can correspondingly be $$ \varepsilon_{\mathbf k+\mathbf q} = \varepsilon_{\mathbf k} + \sum_i \frac{\partial\varepsilon}{\partial k_i}q_i + \frac12 \sum_{ij} \frac{\partial^2\varepsilon}{\partial k_i\partial k_j} q_i q_j+ \dots $$  So far so good. I'm assuming I again want to match the orders of q. So since equation (13.34) requires the second order derivative (factors of q of order 2), I will only consider those in the pertubation.  Now I'm getting into territory where I'm not sure I understand. I have $$ A_0(t) = 1$$ and the other coefficient zero. First order approximation gives $$ A_1(t) = 1\quad\text{and}\quad B_1(t) = -\frac i\hbar\int \langle u_{n\mathbf k}| H_1 | u_{n'\mathbf k}\rangle e^{i\frac{\varepsilon_{n\mathbf k} -\varepsilon_{n'\mathbf k}}{\hbar}t}dt$$  This yields three terms for $B_1$, of which two I believe are zero (since the Bloch wave functions are orthogonal), leaving me with $$ B_1(t) = -q\frac{\hbar^2}{m}\frac{\langle u_{n\mathbf k}| \frac{\nabla}i | u_{n'\mathbf k}\rangle}{\varepsilon_{n\mathbf k} - \varepsilon_{n'\mathbf k}} \left[1-\exp\left(i\frac{\varepsilon_{n\mathbf k}-\varepsilon_{n'\mathbf k}}\hbar t\right)\right] $$ Repeating the procedure again, I get $$ A_2(t) = q^2\left(\frac{\hbar^2}{m}\right)^2\frac{\langle u_{n\mathbf k}| \frac{\nabla}i | u_{n'\mathbf k}\rangle\langle u_{n'\mathbf k}| \frac{\nabla}i | u_{n\mathbf k}\rangle}{\varepsilon_{n\mathbf k} - \varepsilon_{n'\mathbf k}} \int \left[\exp\left({i\frac{\varepsilon_{n\mathbf k} - \varepsilon_{n'\mathbf k}}{\hbar} t}\right)-\exp\left(2i\frac{\varepsilon_{n\mathbf k}-\varepsilon_{n'\mathbf k}}\hbar t\right)\right] dt $$ for the $q^2$ term, thus $$ A_2(t) = q^2\left(\frac{\hbar^2}{m}\right)^2\frac{\langle u_{n\mathbf k}| \frac{\nabla}i | u_{n'\mathbf k}\rangle\langle u_{n'\mathbf k}| \frac{\nabla}i | u_{n\mathbf k}\rangle}{\varepsilon_{n\mathbf k} - \varepsilon_{n'\mathbf k}} \left[\frac1{\varepsilon_{n\mathbf k}-\varepsilon_{n'\mathbf k}} - \frac2{\varepsilon_{n\mathbf k}-\varepsilon_{n'\mathbf k}}\right], $$ but I don't think this is correct. The expressions in the multi-level system don't differ very much, so I think the fault in my derivation is more fundamental, but I can't find it.


Is quantum entanglement affected by time dilation? Let's say one of the entangled pair is accelerated to very high speed. When both the entangled particles are observed at the same time, will they have the opposite spin?


I searched on web about this question and mostly, I found that 14.04 is a way better than 12.04.  but only one answer I found, that say "I am using an old computer and weirdly, I found that 12.04 works better than 14.04"  so I got a doubt, and I want to ask here, this laptop have:  2 GB memory (DDR2) Intel® Core™2 Duo CPU T5450 @ 1.66GHz × 2 Processor Intel® 965GM x86/MMX/SSE2 Graphics 32-bit OS type  which version of Ubuntu, you prefer?


Site review shows me a disabled "add comment" link, and tells me I need a reputation of at least 50

I was looking at a question shown for the  on English Language Learners, and noticed the "add comment" link was disabled because I needed at least 50 points of reputation.    As the screenshot shows, my reputation is more than 50.  The link should not appear, if commenting is not allowed, or I should be allowed to comment.


Converting Enumeration for loop from Java to C#? What exactly is an Enumeration in C#?

I'm converting a project from Java to C#. I've tried to search this, but all I come across is questions about enums. There is a Hashtable htPlaylist, and the loop uses Enumeration to go through the keys. How would I convert this code to C#, but using a Dictionary instead of a Hashtable?   // My C# Dictionary, formerly a Java Hashtable. Dictionary<int, SongInfo> htPlaylist = MySongs.getSongs();  // Original Java code trying to convert to C# using a Dictionary. for(Enumeration<Integer> e = htPlaylist.keys(); e.hasMoreElements(); {     // What would nextElement() be in a Dictonary?      SongInfo popularSongs = htPlaylist.get(e.nextElement()); }


I'm a first time dungeons and dragons dungeon master. I've played the game only a couple of times before. Basically I am using the starter set that I got at the bookstore. Characters are premade as well as mission. So far it's working out fine because all of the adventurers are first time players.    I guess my question is does anybody have any advice on how to enhance gameplay further? I do a couple things like award some random loot every now and then for good ideas the group or solo players come up with.    Any tips would be great. Thanks.


Won't render animation after having already rendered a version

I'm very new to blender and not a very techy person. I rendered out a simple animation of a logo as a sequence of png files, then edited it in the video sequence editor. I was able to do this with no problems.   Next, I made edits to the original blender file of the logo, adding text and lights, and creating different camera moves. This time, when I tried to render out the png sequence, nothing happens. I tried to trouble shoot using questions people have asked in the past, but I still have no luck.  Can anyone help? Thanks.


Rate limiting out of whack in Android App

I was asked to wait for 900 seconds (!) when I tried to submit a second question from the Android app. Got bugged, went over to the mobile website and had no problems.    Please have the messages in readable terms ? (seconds /hours etc)  why the inconsistent rate limiting?


What is the reason for the shift in balance between neutrons and protons in the early universe?

In the book of The First Three Minutes by Weinberg, on pages 106-107, it is stated that  SECOND FRAME. The temperature of the universe is 30,000 million degrees Kelvin [...] The nuclear particle balance has conse- quently shifted to 38 per cent neutrons and 62 per cent protons. [...] THIRD FRAME. The temperature of the universe is 10,000 million degrees Kelvin. [...] The decreasing temperature has now allowed the proton-neutron balance to shift to 24 per cent neutrons and 76 per cent protons.  What is the reason for this balance shift between neutrons and protons? And what determines the rate of change of the neutron/proton ratio?


How was Neville Longbottom qualified to be the Chosen One?

I have read the whole series and watched every movie, but I never caught how Neville could have been the chosen one. Can somebody please explain?


What is the difference in meaning: "tried singing" vs "tried to sing"

For me the following sentences seems identical. But I am not sure. Would you please explain the differences, if any?     She tried singing.      She tried to sing.


Is your mount an enemy of your target in terms of triggering sneak attack?

I was working on building a Zorro character and this question came up: if a rogue is riding on a mount, is that mount considered an ally, or, specifically, an "enemy" of your target?  One of the ways Sneak attack can be trigged is...     "... if another enemy of the target is within 5 feet of it, that enemy   isn’t incapacitated, and you don’t have disadvantage on the attack   roll."   My assumption is yes. Every mount I'm aware of has some kind of attack at its disposal, and thus they represent a threat to your target in addition to the increased threat potential they grant you as the rider. Moreover, if a gnome can proc a sneak attack by acting as a distraction, I don't know why a warhorse wouldn't be able to. That said, is there anything in the books or elsewhere that defines what "enemy of the target" is allowed to include?


My wooden cutting board bent. Is there a way to fix this?

I'm not sure about the humidity in the apartment, but I don't think this was a problem. However, the board took quite some water one day and slightly bent on the front and back (so it has a slight U shape when seen from the side). It seems to have receded a little bit but it is still noticeable.


First-order logic advantage over second-order logic

What is the advantage of using first-order logic over second-order logic? Second-order logic is more expressive and there is also a way to overcome Russell's paradox...  So what makes first-order logic standard for set theory?  Thanks.


Sometimes a tag wiki excerpt or body ends up with unacceptable or useless content: plagiarized text that must be removed, or a totally unhelpful dictionary definition. (For example:  — and I've seen this situation many times before.)  The only way to get rid of that content is to submit replacement text that meets the minimum length requirement. This is not always easy as writing a decent wiki, and especially a decent excerpt, requires subject knowledge.  Currently the users or even moderators who are alerted to unacceptable content in a tag wiki cannot remove that content without providing their own, which they are not always in a position to do. Yet these wikis would be better off with no content than with either unacceptable or unhelpful content, or some content written by a non-expert in a hurry.  Please provide a way for users to blank a tag wiki excerpt or body. I'm not sure what the reputation requirement should be: same mechanism as for tag wiki edits (suggested edits with approval), or only done directly by a user with the trusted user (20k) privilege, or moderator-only.


Time constraint before allowing low-rep users to delete own question with an answer

I would like to propose that new users not be able to delete their own questions too soon after receiving an answer. If we're going to prohibit a user from deleting their own question with an up-voted answer (as described by ), it seems that we have to give the community a chance to actually see the answer and vote.  This question () is not a great example (because it's not a great question, a little too localized), but I not only posted an answer, but did at least two additional substantial iterations of the answer as the user added additional constraints (as the question evolved from "how do I draw semi-circles" to "how do I do that in drawRect" to "how do I do that with CoreGraphics"). But as soon as I answered all of his follow-up questions, he promptly deleted the original question, probably less than two hours after he posted the original question and certainly before many people had a chance to see (much less vote on) my answer.  But I'm not looking for feedback on that particular question (while I have sinking suspicion that I just did someone's homework, but it's not clear that question is truly worthy of undeleting). I'm wondering about the broader practice. It strikes me that if up-voting is going to be a criterion for prohibiting deletion, then we have to have a window that lets the community see the answer and vote. Perhaps only let the user "vote" for the deletion of their question within the first few hours (if there is an answer).  It's just frustrating to invest so much time helping someone out, only to have it deleted with not so much as a "by your leave." (I was thinking of a more colorful metaphor, but I'll leave it there.)


Keep only first two digits after decimal with no rounding

i would like to keep only first two digits after decimal but i don't want to round or convert the value.  For example:   143,655 -> 143.65 547934,945 -> 547934,94   Converting or rounding the values doesn't work, it modifies the values.


Why I can't set vertical-align middle for img tag

Hello I am very new to HTML and CSS and I am trying to do a site for just learning. I just made a header and I put logo in it but I can't set it's vertical-align. Can someone explain it?  Here is HTML file:  <!DOCTYPE html>          <link href="https://fonts.googleapis.com/css?family=Open+Sans&display=swap" rel="stylesheet">     <link rel="stylesheet" type="text/css" href="style.css">     <title>Scienitive</title>

Scienitive

      Here is CSS file:  .header { width: 100%; height: 80px; display: block; background-color: #FF5733; } .logo-container { height: 100%; display: table; float: left; } .logo-container h1{ color: white; height: 100%; display: table-cell; vertical-align: middle; font-family: "Open Sans"; font-size: 48px;  } .logo { display: table; height: 80px; } .logo img{ width: 48px; height: 48px; vertical-align: middle; display: table-cell; }   Here is how site looks like


I need some help understanding if statements.  How do I make the following pseudocode in LaTeX.  \newcommand{\@leader}{} \newcommand{\leader}[1]{\renewcommand\@leader{#1}}  \newcommand{\donow}{     \if \@leader == {}        %aka blank, null, empty         this is the false     %do false     \else            \@leader              %do leader     \fi }   Such that when a user adds the following to their document  \leader{     \begin{itemize}         \item this is an item         \item this is also an item     \end{itemize} }  \donow  \leader{}  \donow   print the following  *This is an item  *this is also an item  this is the false   My only question about variables is, is the solution I have really the best way to do make variables?


I am trying to read Mathematical Analysis I by Zorich on my own. Here is an exercise that I could not solve:      For all $l \in \mathbb{R}$ that is not of the form $\frac{1}{n}$ for some $n \in \mathbb{N}$, there exists a continuous function $f: [0, 1] \Rightarrow \mathbb{R}$ such that $f(0) = f(1)$ and the graph of $f$ contains no horizontal chord with length $l$.    I was wondering how to prove this? Thanks in advance.


Is the relation between Hamilton's and Lagrange's equations the same as that between conservation of energy and the equations of motion?

Conservation of energy is, usually, a $\textbf{first order}$ non linear differential equation, generally written as  $$ \frac{m\dot{q}^2}{2} +V(q) = cte. $$  Taking the derivative yields the usual equation of motion.  $$ m\ddot{q} + V'(q) = 0 $$  (The $\dot{q}$ term vanishes.) Which is a $\textbf{second order}$ ODE. Since the non linear term $\dot{q}^2$ vanishes, this is easier to solve. There are hints for a kind of duality between first order and second order equations.  The same system could be described by Lagrange's equations  $$ \frac{d}{dt}\left(\frac{\partial L}{\partial\dot{x}}\right) = \frac{\partial L}{\partial x} $$  or Hamilton's equations,  $$ \frac{dp}{dt} = -\frac{\partial H}{\partial q}\quad ,\quad \frac{dq}{dt} =\frac{\partial H}{\partial p} $$  Again, there is the same hint about duality. Lagrange's equations are second order, and Hamilton's equations are first order. $\textbf{Is this the same duality as before?}$ Or is it a coincidence?


divisor of a product of integers is a product of divisors

I read this recently on the web and can't manage to understand it. Not homework -- I haven't done math homework for years.  If $d\mid ab$ then $d=d_1 d_2$, that $d_1|a$, that $d_2|b$ and, further, if $(a,b)=1$ then $(d_1,d_2)=1$.  I know it's the same question... if $a = a_1 a_2 ... a_n$, why can't $d$ divide some $a_i$ and only $a_i$?


If integers $a$ and $b$ are not both zero, then $\gcd(a,b)=\gcd(a-b,b)$   Assume either $a=0$ or $b=0$. If $a=0$, then $\gcd(a,b)=\gcd(0,b)=b$ and $\gcd(a-b,b)=\gcd(-b,b)=-b$, so $\gcd(a,b)\neq\gcd(a-b,b)$.  If $b=0$, then $\gcd(a,b)=\gcd(a,0)=0$ and $\gcd(-b,b)=\gcd(a,0)=0$.  So, what can I say? Can you help? Can you check my proof-trying?


All my flags that were raised before April 2011 are marked as "active", except spam/offensive flags which are marked helpful:        Checking some, they were obviously helpful (e.g. post deleted as result) so most likely the "helpful" bit was not recorded yet back then.  I don't think it should stay "pending" forever, better just remove it and put "status not recorded" or something like that.  Worth also to mention, this is causing a mis-calculation in the new flag history, as reported here:


ls command operating differently depending on recipient

How does commands like ls know what its stdout is?  It seems ls is operating different depending on what the target stdout is. For example if I do:  ls /home/matt/tmp    the result is:  a.txt b.txt c.txt   However if I do  ls /home/matt/tmp | cat   the result is (i.e. new line per result):  a.txt b.txt c.txt   The process is passed a file descriptor 1 for stdout right? How does it determine how to format the result? Does the file descriptor reveal information?


"May I have a glass of water" vs. "Can I have a glass of water": which is better, "may I" or "can I", when asking for something?

What is the correct sentence when asking for something like while flying asking for a glass of water :     May I have a glass of water     or      Can I have a glass of water


Proper order of optimizing hyperparameters in ANN

I have built a neural network for approximating a certain function and decided on a metric how to evaluate the performance. Now, where do I start with optimizing to get the optimal result? I need to decide on number of layers, hidden neurons, learning rate, learning algorithms and all other hyperparameters. What is the usual  procedure and order in which to optimize all network's parameters? I guess I am looking for some kind of general guidelines to follow to obtain the best possible performance


Solving $x^p + y^p = p^z$ in positive integers $x,y,z$ and a prime $p$

The question is from Zeitz's ''The Art and Craft of Problem Solving:"      Find all positive integer solutions $x,y,z,p$, with $p$ a prime, of the equation $x^p + y^p = p^z$.   One thing I noticed is that   $$ \frac{x^p + y^p}{x + y} = \sum_{i=0}^{p-1}x^{(p-1)-i}(-y)^i \implies (x+y) |p^z \implies x + y = p^n, \text{ }n < z   $$  It is also not hard to determine all solutions for $p =2$. After this, however, I am at a loss. I don't know what restrictions I can impose to try to narrow down the solution set; for example, the class of solutions  $$ p=3, x = 3^n, y = 2\cdot3^n, z = 2 + 3n $$  for $n \ge 0$ show that $x+y = p^n$ cannot be sharpened. (Let me note that these are the only other solutions I have found besides the ones for $p = 2$.)  Could anybody give me a push in the right direction on this problem?


Suppose $A,B,C$ are sets.  Prove that $A\mathbin\triangle B\subseteq C \iff A\cup C=B\cup C$.  I proved that for $x\in A\setminus B$, $x\in A\cup C$ and for $x\in B\setminus A$, $x\in B\cup C$. How do I show that $A\cup C=B\cup C$, and that $A\mathbin\triangle B\subseteq C \iff A\cup C=B\cup C$?


meaning of the line: buf = ((buf >> 21));

I use  code for Cryptography home work assignment and can't understand line# 59 thanks for the helpers.


I had submitted a Manuscript in a good journal which has given me the reviews as " Accepted for publication pending revisions"? What does this review actually mean? Is it accepted?   FYI, I have created a response letter in which I have given justification for some concerns and also made the changes that were asked to be made in the figures.  Can anybody please help?


Running Windows 7 Professional. It appears that the proper patch/update for me to protect against the wannacrypt virus is KB4012215.  I reviewed my Windows Update history and see that I tried to install that update on 3/18/17 but the installation "failed."  I right-clicked on it and the Error Code is 80070020.  Questions:   Is KB4012215 the proper update to guard against wannacrypt? If not, please tell me the proper update and where and how to download and install it. If so, please tell me where and how to download and install it.   Thank you.


"So must the X be" vs "So must be the X" vs Neither

I am not sure whether either of the following sentences (in quotations) are grammatically correct. They both sound awkward to me. Is anyone able to judge whether they are?  "Since the latter is large, so must the former be."  or  "Since the latter is large, so must be the former."


What to do after accidental deletion of Python3

As you may guess, Ubuntu desktop Interface namely menu bar is not shown and Terminal is not reachable.   However, there is still hope. Via Ctrl-Alt-F1, I can type commands.  Problem is, Python3.6.3 and related programs i.e. Unity are severely broken and when I try to (re)install the unmet dependencies, it is almost an endless chain.  I followed the chain until it reaches to a point where no other dependencies exist, yet installation is not successful for some reason.   I suspect that I need to manually direct files to a correct directories.   Before I do something, I thought a proper guidance would be helpful.   P.S. I am aware that in the worse case scenario, I need to install fresh Ubuntu.  P.S.2. I have gone through many sources, yet I could not find any proper walk through.


/usr dir with all permissions denied even from root

First, I ran:  sudo chmod -R -777 /usr    Now, my /usr dir permissions looks like this:  d---------   So nobody has permissions I can't even get in the dir or run bash commands.


No. of distinct matrices satisfying a certain equation

[TIFR-GS 2011, Part B, problem no. 1] Let $A$ be a $2×2$ matrix with complex entries. The no. of $2×2$ matrices A with complex entries satisfying the equation $A^3=A$ is infinite. They asked if the statement is true or false.   From the given equation, I've found that the eigenvalues of $A$ can be $0$, $1$, and $-1$. Now I took a trial matrix and tried to satisfy the equation, but it doesn't help in any way. Any help would be appreciated.


What would a suitable justification be to use 'log(exports)' as a dependent variable instead of solely 'exports'?

I am doing a diff-in-diff analysis, looking at whether a regulation had an impact on British pollution-intensive exports. Initially I used 'total exports of pollution-intensive goods' as my dependent variable but to get my treatment effect as a percentage, I was thinking of making this dependent variable as the 'natural log of total exports of pollution-intensive goods'. Apart from giving a straightforward percentage change interpretation, what other justification would there be to use the natural log for exports? Is it appropriate to use the natural log for exports in the first place?


Why has a lot of software disappeared from Ubuntu Software in Ubuntu 16.04?

For example there is no VirtualBox, Texmaker, LyX, calibre, Redshift.  I have ran sudo apt update and sudo apt full-upgrade. I have not used BleachBit. The only thing wrong in my computer seems to be that I often get an error message like this one when I run sudo apt update:  AppStream system cache was updated, but problems were found: Metadata files have errors: /var/cache/app-info/xmls/fwupd.xml Reading package lists... Done E: Problem executing scripts APT::Update::Post-Invoke-Success 'if /usr/bin/test -w /var/cache/app-info -a -e /usr/bin/appstreamcli; then appstreamcli refresh-cache > /dev/null; fi' E: Sub-process returned an error code   , which I would also like to fix by the way.  Things I tried that did not help:  As advised in , I ran sudo apt install --reinstall libappstream3 and then sudo apt purge libappstream3, and then I also restarted my computer. Then I ran sudo apt install --reinstall libappstream3 again sudo apt install --reinstall libappstream4 and I restarted the computer again.


How do I create a Linked List Data Structure in Java?

What's the best way to make a linked list in Java?


I want to check out  which you can deploy using  .  znx does not seem to open correctly in Fedora, which is why I would like to deploy it using the terminal. The how-to says that I should install it on a partition that has at least 4 GB.   I have one big free partition on my computer which has about 200 GB. Do you know if the entire partition will be "blocked" by Nitrux, if I will deploy it on that partition? Or will znx assign it 4 GB of that partition and let me use the rest?  Thanks!


What is the difference between started to do and started doing?  For example        I started to run a few months ago.   I started running a few months ago.      Does the second sentence mean that I run every day/ 3 times a week and I never stopped doing that?  Does the first sentence imply that I  do not run every day or certain times a week and I must have stopped/ stopped for a period during this period of time (a few months)?  I can see there are explanations for "start to do" and "start doing" but my question involves tense.


What are the differences between $H_n(X/A)$ and $H_n(X,A)$ for $A\subset X$?

I want to get a better intuition on relative homology groups, but while I see that the definitions of relative homology groups $H_n(X,A)$ and the homology group of the quotient $H_n(X/A)$ have no reason to generally be the same, I struggle to find rules for when they would be different. Are there certain rules for when these groups differ or are equal?


Staff and percent. Which one of these two statements is correct?

Which one of these two statements is correct?  60% of staff work or 60% of staff works


Class used to assign a variable is different from class used to declare it

Are the following two versions of "pane" the same in Java?  Pane pane1 = new HBox(); HBox pane2 = new HBox();   What is the difference between the two and why would you declare pane1 this way?  Thank you very much.


Before Voldemort, who was the last Horcrux creator?

Horcruxes are rare (and then seven come along at once...) and only a few people know about them.  But when was the last Horcrux before Voldemort's? 50 years before him? Centuries? Millennia?


My in-law applied for UK visit visa with his wife and only son. He is self employed and employed part time with a Korean company. And also employed freelancer with another company in Nigeria. He submitted his business registration certificate, his bank statements for his business and his personal bank statement and his dollars account. All his account statement reflects all the payments he receives. He submitted his payslip. Can someone help explain each paragraph of the refusal. And the eco said he is traveling with his wife and children instead of child


I have little experience coding, most of what I did was done with VBA and there you have arrays. On python you apparently do not use arrays but lists of lists if I'm not mistaken and I seem to have trouble with these. Here a sample of what I did:  array=[["string"]*2]*2   So essentially I wanted to create a 2x2 array. This I wanted to fill using a loop, for the minimal example I fill it with a string b+a:  for b in range(0,2):     for a in range(0,2):         array[b][a]=b,"+",a         print(array[b][a])  print(array[0][0], array[1][0],array[0][1], array[1][1])   The first print command gives what I expected:  (0, '+', 0) (0, '+', 1) (1, '+', 0) (1, '+', 1)   But the second print command is strange:  (1, '+', 0) (1, '+', 0) (1, '+', 1) (1, '+', 1)   When printing array[0][0] I would expect to receive (0, '+', 0) but instead I get what I would expect to be array[1][0]. It looks like when using print inside the loop I get the results that I expect but if I print the exact same element outside of the loops I get strange results.  array[0][0]   should have the exact same content as  array[b][a]   for when I just started the loop (first print command), no?  I'm sorry I don't really know how to describe the problem more precisely, I hope you see what my problem is.


StackExchange is way too confusing and frustrating

There are many sites on StackExchange. Way too many. You have a problem with your code, you don't know if you have to go to StackOverflow, CodeReview, Unix or any else website.  This is both confusing and frustrating.  People write questions on StackOverflow and they're told they have to open a new account (even if it's easy once the first is made, the thought of it can disturb most) on another website they've never heard of to ask their question. There is no indication that those websites exist. They have no indication that their question should be posted on another website.  I now even see SE sites on Arduino or Drupal development. What is wrong with merging those into a more general website? They have so much less questions than SO questions over Javascript or C. Why aren't there specific sites on Javascript or C, then? It makes absolutely no sense.  That's for the confusing part.  But SE sites are also frustrating because you're focused on your own problem which is to solve an answer and then what happens? People are nitpicking about which website your question should be posted on. This is just ridiculous: people take the time to nitpick about this nonsense and they don't help you because your question is not bad for this site but would be better on that one. It's just frustrating.  What should be done?   Merge the websites meaningfully. Use tags. Tags are useful and help everyone filter what they want and in search engines, they can scope the question. Focus on giving a better experience to users rather than pushing on the nitpicking and dividing the community.


Correct way to apply patches to your kernel?

I am following the instructions located  to setup my server. It states that I have to apply a patch which I've downloaded onto the machine. My question is, the article says to use the following command:  /usr/src/linux # patch -p1 < file.diff //note I replace file.diff w/ routes-2.6.36.16.diff   This returns:  -bash: /usr/src/linux: No such file or directory   I go on to assume that /linux # should be replaced with the actual linux kernel version/dir. I've tried this using the following command:  /usr/src/linux-headers-2.6.35.22 patch -p1 < file.diff   This returns the same. When I view the contents of /usr/src I only have two directories linux-headers-2.6.35.22 and linux-headers-2.6.35.22-generic-pae I need guidance as to the correct way to apply a patch to the kernel.   Edit  If I execute /usr/src/linux-headers-2.6.35.22/ patch -p1 file.diff I get -bash: /usr/src/linux-headers-2.6.35.22: is a directory. I need to know how I go about finding the specific file that needs to be patched here...


If so, in what conditions? Look at the . It's a duplicate hell. It can't be true that they were all posted in same minutes(I didn't check). There wasn't so many duplicates when I read the whole thread a while ago. What has happened? Are we supposed not to flag them?


I use this function to make mysql backup it work fine but my problem is i have some data with utf-8 encode in my database and when use this function data change to "?????" how can i fix it ?  function backup_tables($host,$user,$pass,$name,$tables = '*') {        $link = mysql_connect($host,$user,$pass);     mysql_select_db($name,$link);     if($tables == '*')     {         $tables = array();         $result = mysql_query('SHOW TABLES');         while($row = mysql_fetch_row($result))         {             $tables[] = $row[0];         }     }     else     {         $tables = is_array($tables) ? $tables : explode(',',$tables);     }     foreach($tables as $table)     {         $result = mysql_query('SELECT * FROM '.$table);         $num_fields = mysql_num_fields($result);          $return.= 'DROP TABLE '.$table.';';         $row2 = mysql_fetch_row(mysql_query('SHOW CREATE TABLE '.$table));         $return.= "\n\n".$row2[1].";\n\n";          for ($i = 0; $i < $num_fields; $i++)          {             while($row = mysql_fetch_row($result))             {                 $return.= 'INSERT INTO '.$table.' VALUES(';                 for($j=0; $j<$num_fields; $j++)                  {                     $row[$j] = addslashes($row[$j]);                     $row[$j] = ereg_replace("\n","\\n",$row[$j]);                     if (isset($row[$j])) { $return.= '"'.$row[$j].'"' ; } else { $return.= '""'; }                     if ($j<($num_fields-1)) { $return.= ','; }                 }                 $return.= ");\n";             }         }         $return.="\n\n\n";     }     $handle = fopen('db-backup-'.time().'-'.(md5(implode(',',$tables))).'.sql','w+');     fwrite($handle,$return);     fclose($handle); }


I am a Linux newbie trying to setup Lubuntu 16.10 on my Dell desktop. This forum has helped me learn a good bit about Linux and Ubuntu in the last few days.   I'm now having trouble getting app packages to install and was wondering what I'm doing or not doing wrong. I have a couple of applications I've downloaded, they are:   VirtualBox-5.1_5.1.12-112440-Ubuntu-yakkety_i386.deb. audacity_2.12-1build1_i386.deb   When I try to install them, it opens software manager app, I click on " install and it does nothing. Doesn't confirm install, nothing seems to be added to the system. Then I back out of the software app and on the top of the window where it has 3 tabs - •All, •Installed, and •Updates I see under •Installed tab there is a blue 2 highlighted. Also I am not connected to the internet and a message popped up saying a software update was needed to show all installed apps. Could this be why?


How to transit through Delhi without a visa?

I have read a lot on this subject on the Lonely Planet forum and it looks like the staff on ground can transfer your bags through the Delhi airport if you have a connecting flight without you having to go out to check them in again and therefore needing a visa. I refer of course to the situation when you go with 2 different airlines, because otherwise the luggage is transfered automatically.  I posted a  and mentioned it briefly there, however I think this subject deserves a separate question and a detailed answer.  Does it depend on the type on an airline? I have read that Jet is no problem, what about AirIndia and IndiGo? And what about the incoming flight to Delhi from Europe or USA, do they all can hand over you luggage to the Indian airlines and pick it up again on the way home? Do you have to contact them before and explain your situation? Or check in your luggage directly to your desired destination?


We've just been learning about complex numbers in class, and I don't really see why they're called numbers.  Originally, a number used to be a means of counting (natural numbers).  Then we extend these numbers to instances of owing other people money for instance (integers).  After that, we consider fractions when we need to split things like 2 pizzas between three people.  We then (skipping the algebraic numbers for the purposes of practicality), we use the real numbers to describe any length; e.g. the length of a diagonal of a unit square.  But this is when our original definition of a number fails to make sense- when we consider complex numbers, which brings me to my main question: what is a rigorous definition of 'number'?  Wikipedia claims that "A number is a mathematical object used to count, label, and measure", but this definition fails to make sense after we extend $\mathbb{R}$.     Does anyone know of any definition of number that can be generalised to complex numbers as well (and even higher order number systems like the quaternions)?


There´s a way of grouping SVG objects in blender like in Illustrator or Inkscape, where when I have to move the object the entire group move´s on together, without having to append that object to the main object?


What is EV, when used as an absolute measurement?

I know there is already a question about EV, but it doens't quite answer my question. I understand EV as a relative measurement, 1 EV being one stop (doubling or halving the amount of light), but what is 0 EV? What does it mean when Nikon claims that a camera can autofocus in -2 EV?


It's a nice book but it's 'too' expensive. I'm not going to buy it. I would buy it if it weren't 'so' expensive.   These are from the book 'English Grammar in Use'.  So, I'm sure that these are the perfect sentences. However, is it okay to use 'so' rather than 'too' in the first sentence and 'too' rather than 'so' in the second one?


How to convert a working Ubuntu 14.04 to virtual disk so that i can distribute to fellows?

I have installed Ubuntu 14.04 on laptop. I want to convert it to virtual disk so that my fellows could also use it. I have read forums, some have listed VM Ware converter but its installation helping material is for windows, some people also mentioned that's for server only. Is there any easy way to do this?


Black hole gravity vs parent star gravity

In the cases of black holes that form from supernova and collapse of a massive star, I understand that in most of these cases, the star loses significant amounts of mass from the explosion. Presumably, after this point as the remaining mass becomes more dense as it further collapses unto itself, it eventually becomes a black hole with gravitational force greater than that of its parent star. But, if gravity is based on mass, how can the black hole have greater gravitational force than the star from which it is formed?