The differential equation $ xu_x + yu_y = 2u$ satisfying the initial conditions $y = xg(x), u=f(x)$ with    $f(x) = 2x, g(x) = 1$, has no solution $f(x) = 2x^2, g(x) =1$, has infinite number of solutions $f(x) = x^3, g(x) = x$, has a unique solution $f(x) = x^4, g(x) = x$, has a unique solution   I don't know when a partial differential equation has unique solution, infinite solutions or no solution. can I solve this by Cauchy's method of characteristics? I have no idea. please help.

I was thinking about the following problem : Find out which of the following option(s) is/are correct? The differential equation $xu_{x}+yu_{y}=2u$ satisfying the initial condition $y=xg(x),u=f(x)$, with  (a)$f(x)=2x,g(x)=1$ has no solution, (b)$f(x)=2x^2,g(x)=1$ has infinite number of solutions, (c)$f(x)=x^3,g(x)=x$ has a unique solution, (d)$f(x)=x^4,g(x)=x$ has a unique solution.  My Attempt: Using lagrange's method, we see that $\frac{dx}{x}=\frac{dy}{y}=\frac{du}{2u} $ gives $y/x=c_1,$ and $y=\sqrt uc_2$ ,where $c_1,c_2$ being constants. Now we have to apply to the given initial conditions  and  check the given options.Here ,I observe that $y=xg(x)=x.1=x$,[as $g(x)=1$] and $u=f(x)=2x^2$But,this relation does not satisfy $xu_{x}+yu_{y}=2u$ and so the choice"(a)$f(x)=2x,g(x)=1$ has no solution," is right. Now I am stuck here and could not progress further.Am i going in the right direction? Please help.Thanks in advance for your time.


Hi I am having an issue trying to figure out how to unmerge two objects that weren't even merged to begin with.  I'm creating a 3D character and have made the body. I then added a cube using (Shift+A) to add the new cube shape then off to the side started to make and form the left hand and am using the mirror affect as well so it's the exact same on the other side. Now I haven't merged the two object at all, yet when I hit Tab or A to highlight the Hand object it highlights both the (hand) and the (main body).  I can't move the hand I finished to the arm of the body part to the character I'm creating, instead both the body and the hand move together whenever I try to move the hand anywhere around the grid.  I have looked at videos and read articles to figure out how to have them both as separate objects. I have tried to hit P to un-join them doesn't work, I have tried to hit L to highlight the island of the hand but doesn't work.  I am fairly new at Blender but getting the hang of it so far I'm just stuck in trying to have both object move freely on their own so I can move the hand to the body and join them but instead both the hand and the body move together and I don't know what to do.  Please can you help with this I'm doing this for a friends company and need this project done by next week but this issue is holding me back.  Thank you.

I've just made a set of armor by using a male body mesh model I downloaded and selecting certain faces from the model and duplicating them to create viable armor pieces.   Since the pieces are just duplicated from the same mesh male model, then it's still part of the same object.   How do I separate the armor piece from the model to make the pieces separate?


It seems that when using the Stack Exchange app on iOS, I can't access my profile settings to change my password. Am I just over looking something, or is this the case with everyone else using the iOS app?

The iOS app should allow a user to change passwords. Can this feature be added?


I roasted a chicken at 180 using the fan for 1 1/2 hours, when I got it out of the oven, I pierced it and the juices were clear, I ate some slices of the breast, and the first ones looked fine, but a later one had blood or what looked like blood in it, will I be ok or do I need a doctor?

I've come across this particular recommendation many times in  and cookbooks and probably even given it out myself once or twice.  Poultry is sufficiently cooked when the juices run clear, not red or pink.  In recent months and years, as I've grown more interested in and knowledgeable about the science of cooking, I've learned to be skeptical of such simplistic claims.  This one is repeated everywhere - even the  says it - but I've also run across various .  What I'd like to know is this:  What does it actually mean - chemically or biologically speaking - when poultry juices run clear?  Is it actually a reliable indicator that the food is safe to eat?  P.S. I am quite well aware that the way one is supposed to test for doneness is to use a thermometer and ensure that the internal temperature has reached 165° F / 74° C.  I always do this, but thermometers can break, run out of battery, etc., so I think it is still helpful to know if the juice test is ever a viable alternative.  But most importantly I am interested in understanding what is happening to the meat that causes the juices to change colour, and under what other conditions this can happen.


Let $f: \mathbb{R}^{m\times n} \mapsto \mathbb{R}$ be a mapping from an $m$-by-$n$ matrix to the real numbers. Defining the derivative of $f$ to be: $$\nabla_A f(A) = \begin{pmatrix} \frac{\partial f}{\partial A_{11}} & \ldots & \frac{\partial f}{\partial A_{1n}} \\ \vdots & \ddots & \vdots \\ \frac{\partial f}{\partial A_{m1}} & \ldots & \frac{\partial f}{\partial A_{mn}}\end{pmatrix}, $$ I am given that  $$\nabla_A \mathrm{tr}(ABA^T C) = CAB + C^T A B^T. $$ This was stated in CS229 - Machine Learning without proof. How would I prove this? Is there an easy way (the notes say that it should be simple)?    Edit: I seem to have found a counter-example. If I let $A = B = C = I$, the identity matrix, the left hand side gives me $I$ and the right-hand-side gievs me $2I$. However, throughout the course I've used this rule many times without fail. Have I missed something or is the formula typo-ed? Also, $ABA^TC$ requires $A$ to be $m\times n$, $B$ to be $n\times n$, $C$ to be $m\times n$ for $ABA^TC$ to be $m\times n$. The right-hand-side has the product $CAB$ which doesn't make sense under these dimensions.

Why is $\nabla_A \mbox{tr} (ABA^TC) = CAB + C^TAB^T$?   Here $A, B, C, D$ are all $n \times n$ matrices.  $$\nabla_A f(A) = \left[\begin{matrix} \frac{\partial f}{\partial A_{11}}... \frac{\partial f}{\partial A_{1n}}\\ ...\\ \frac{\partial f}{\partial A_{n1}}... \frac{\partial f}{\partial A_{nn}}\\ \end{matrix}\right]$$      I tried to prove it in this way:  $$\begin{align} \nabla_A \mbox{tr} (ABA^TC) &= \nabla_Atr (BA^TC)A\\ &= \nabla_A \mbox{tr} DA ......let  \ D=BA^TC\\ &= \nabla_A \mbox{tr} AD\\ &=D^T\\ &=B^TAC^T\end{align}$$  Since $B^TAC^T \neq CAB + C^TAB^T$, there must be something wrong in my derivation. How to prove this property?


The search functionality is broken, it seems, e.g.  only loads after more than a minute of waiting. This happens on multiple sites, e.g. also on Stack Overflow.

:  Not ten minutes ago, I received this error, twice:  And also an "Oops, something bad happened" error.  I'm also getting question posting errors.  Can we fix this, please?


I am running Kubuntu 17.04 from a USB drive. Since I don't have a PC of my own, I was wondering how can I save changes that I make in my live session, since starting from scratch is starting to get really annoying each time I run on a different PC. Thanks for your help.

I want to make a persistent live Ubuntu USB drive with more than 4GB of storage.   I know there is an option of installing directly on the drive but I don't want to do this as it will restrict the drive from working on different computers.   One option is to make an additional partition with extra space but if I do this how can I get newly installed software to be stored on this partition?


Is there a way to disable certain modules on different environments from settings.php or another means in Drupal 8?  For example, if I am not on prod, I don't want XML Sitemap enabled.

Using the new Drupal 8 Configuration manager, how can I prevent it from installing the Devel module on certain environments? As far as I know, installing it on my local means the next time I export the configuration and move it to my other environments (dev, test, prod), it will automatically be enabled.


I have a bricked usb stick Kingston DT101 G2. I tried the solutions I found on the net without success. The problem seems to be that the capacity is reported as 0 (and not less than actual as in other questions). (Although I don't know a command to explicitly query the capacity.)  Sticking it in, /dev/sdd appears but /dec/sdd1 does not appear.  gparted/parted/fdisk don't recognize it. e.g.   $ sudo fdisk -l /dev/sdd fdisk: cannot open /dev/sdd: No such file or directory     $ sudo dd count=1 bs=512 if=/dev/zero of=/dev/sdd && sync dd: error writing '/dev/sdd': No space left on device 1+0 records in 0+0 records out 0 bytes copied, 0.000316047 s, 0.0 kB/s     $ ls -l /dev/sdd brw-rw---- 1 root disk 8, 48 Jan 30 13:45 /dev/sdd`     $ sudo xxd -l 10 /dev/sdd $   (i.e. nothing)  $ sudo smartctl -i -d scsi /dev/sdd smartctl 6.5 2016-01-24 r4214 [x86_64-linux-4.4.0-109-generic] (local build) Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org === START OF INFORMATION SECTION === Vendor:               GENERIC Product:              USB Mass Storage Revision:             1.00 scsiModePageOffset: response length too short, resp_len=4 offset=4 bd_len=0 scsiModePageOffset: response length too short, resp_len=4 offset=4 bd_len=0 Terminate command early due to bad response to IEC mode page A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.`   [Edit]    sudo lsblk: no mention of sdd.   Output of lsusb -v (relevant portion only) Note that it reports 2GB instead of the actual 16GB.  Bus 001 Device 022: ID 0930:6544 Toshiba Corp. TransMemory-Mini / Kingston DataTraveler 2.0 Stick (2GB) Couldn't open device, some information will be missing Device Descriptor:   bLength                18   bDescriptorType         1   bcdUSB               2.00   bDeviceClass            0 (Defined at Interface level)   bDeviceSubClass         0    bDeviceProtocol         0    bMaxPacketSize0        64   idVendor           0x0930 Toshiba Corp.   idProduct          0x6544 TransMemory-Mini / Kingston DataTraveler 2.0 Stick (2GB)   bcdDevice            1.00   iManufacturer           1    iProduct                2    iSerial                 3    bNumConfigurations      1   Configuration Descriptor:     bLength                 9     bDescriptorType         2     wTotalLength           32     bNumInterfaces          1     bConfigurationValue     1     iConfiguration          0      bmAttributes         0x80       (Bus Powered)     MaxPower              200mA     Interface Descriptor:       bLength                 9       bDescriptorType         4       bInterfaceNumber        0       bAlternateSetting       0       bNumEndpoints           2       bInterfaceClass         8 Mass Storage       bInterfaceSubClass      6 SCSI       bInterfaceProtocol     80 Bulk-Only       iInterface              0        Endpoint Descriptor:     bLength                 7     bDescriptorType         5     bEndpointAddress     0x81  EP 1 IN     bmAttributes            2       Transfer Type            Bulk       Synch Type               None       Usage Type               Data     wMaxPacketSize     0x0200  1x 512 bytes     bInterval             255       Endpoint Descriptor:     bLength                 7     bDescriptorType         5     bEndpointAddress     0x02  EP 2 OUT     bmAttributes            2       Transfer Type            Bulk       Synch Type               None       Usage Type               Data     wMaxPacketSize     0x0200  1x 512 bytes     bInterval             255

I have a 8 GB pendrive. I used to write raw data into the pendrive (without creating filesystem) using the dd command.    Today, when I inserted the pen drive, the I am unable to write anything on to it.  When I open gparted it is showing the total space on the pen drive as 500 MB. I am unable to create a new partition table or a partition on the pen drive now.   Here is the fdisk -l output.   Disk /dev/sdb: 0 MB, 512000 bytes 255 heads, 63 sectors/track, 0 cylinders, total 1000 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00095df6   What's wrong with the pen drive? How can I recover the lost space?   Device Boot      Start         End      Blocks   Id  System   When I open gnome-disks, it shows the total space as 8 GB but when I try to create a new partition using it, it shows the following error:  Error creating partition on /dev/sdb: Command-line parted --align optimal --script "/dev/sdb" "mkpart primary ext2 1MiB 7969177599b"' exited with non-zero exit status 1: Error: The location 7969177599b is outside of the device /dev/sdb.  (udisks-error-quark, 0)


Sarek and Amanda's son Spock is half Vulcan half human but he looks no different from other Vulcans. On the episode Naked Time, Bones was giving him a checkup and the way he explains Spock's anatomy it is full Vulcan. If he is half human why does he have all Vulcan anatomy and no human features?

We know that Spock is biologically half-Vulcan but to me he looks just like full-Vulcans. B'Elanna Torres is half-Klingon and half-human, but in her case you can tell; the Klingon traits like head ridges are about 50% of what they would be were she a full-Klingon. So, shouldn't Spock have only kind of pointy ears, sort of slanted eye-brows, slightly green blood, etc. instead of simply looking just like a full-Vulcan?


Is there a class of LaTeX that does not divide the pages?  I contextualise a bit the question. Some time ago I was talking with some colleagues and we were discussing that most of the time, nowadays, we look at mathematics articles on screen, instead of paper, and the division in pages sometimes feels "weird", while the structure of a webpage (just scrolling without changing pages) would feel more natural, especially on touch devices and small papers.  So, is there a way to produce such a thing in LaTeX, so a long PDF or DVI that is just a very long page with everything inside?  EDIT: The  is not a duplicate of this, since the solution there renders a document with more than one page.  EDIT 2: It is indeed a duplicate of .

I am trying to automate the solution proposed by egreg to  by hooking into \begin{document} and \end{document}.  So, egreg's solution works fine:  \documentclass{article} \def\MinimumPaperHeight{12cm} \usepackage{geometry} \geometry{paperwidth=\MinimumPaperHeight,paperheight=\maxdimen,margin=1cm} \usepackage{lipsum}  \begin{document} \setbox0=\vbox{ \lipsum[1-6] } \dimen0=\dp0 \pdfpageheight=\dimexpr\ht0+2cm\relax \ifdim\pdfpageheight<\MinimumPaperHeight \pdfpageheight=\MinimumPaperHeight \fi \unvbox0\kern-\dimen0 \end{document}   But can't seem to get this to work:  \documentclass{article} \def\MinimumPaperHeight{12cm} \usepackage{geometry} \geometry{paperwidth=\MinimumPaperHeight,paperheight=\maxdimen,margin=1cm} \usepackage{lipsum} \usepackage{environ}  \NewEnviron{MyBox}{     \setbox0=\vbox{\BODY}% }{%     \dimen0=\dp0%     \pdfpageheight=\dimexpr\ht0+2cm\relax%     \ifdim\pdfpageheight<\MinimumPaperHeight \pdfpageheight=\MinimumPaperHeight \fi%     \unvbox0\kern-\dimen0% }  \AtBeginDocument{\begin{MyBox}} \AtEndDocument{\end{MyBox}}  \begin{document} \lipsum[1-6] \end{document}   Hooking into \AtBeginDocument is per this solution on .


I have come across 2 questions that are off topic, but there is no option to select a site to which it actually belongs to. and always i have to select some other option other that off-topic and then explain which site.  Suggestion: It would be better if we have general radio buttons as shown as now and other radio button which enables a drop down with all the stack sites.   SE site 1 SE site 2 SE site 3 SE site 4 Other    on Selecting other    SE site 1 SE site 2 SE site 3 SE site 4 Other  <drop down of all stack sites shown>

I think there should be more Stack Exchange networks available when flagging a question to be migrated. For example I'd think that the following question:    ...would be a better fit on unix.stackexchange.com instead of Stack Overflow. But without the option to mark it so, I feel hesitant to mark it.


I am facing problem calculating area and projection in general, using QGIS 3.18.3. preface: I am using EPSG: 32643 projected CRS. I aim to compute area and the result is fine correct in this image.  Calculating Area on Bing Map using Measuring tool When I load another layer as shown in image (EPSG: 32643) then the coordinates changes to (lat,long) and the area also is incorrect. I am sure that this layer is in correct EPSG. Not sure why the coordinates displayed does not give Cartesian coordinates.  The coordinates are not in (X,Y) format Attached is the associated information for the layer.  How to resolve this issue and get the coordinates in correct format?

I have a point layer and a polygon layer that are all in UTM51N projection but do not align. Just want to know when should I use Assign, Reproject, or Define.  Experimented with a polygon in EPSG:4326 - WGS 84 - Geographic, which is the project CRS since this polygon is the first layer I loaded. Target projection is UTM51N.  Reproject - aligned  Assign - not aligned  Define - not aligned  Save layer as - aligned  Using 3.4 so there is no "on the fly projection" feature.


Always considered antimater as negative mass so: $$m1=10kg(matter)$$ $$m2=-10kg(antimater)$$ $$displacement=r=10m$$ $$gravity =\frac{Gm1m2}{r^2}=-1N<0!HOW?$$

I know that the gravitational interaction of antimatter is expected to be the same as normal matter.  But my question is, has it ever been experimentally validated?  I think it would not be a trivial experiment, because electromagnetic effects have to be eliminated, so neutral particles would be needed. Maybe diamagnetically trapped antihidrogen atoms could be examined as to which direction they fall?


I have this starter kit. I first made a fighter (easy in my mind), but now I am making a Wizard. I don't understand how the Hypnotism spell works. I don't throw anything?      Attack:_ (Intelligence) VS Will   My wizard has Intelligence 18.  For example, I use the spell hypnotism on a gnome and then gnome tries to use WILL to Defend? And I don't roll any dice? Does this also mean when using magic missiles only the creature is rolling the dice?

I've just recently started playing D&D 4e through the Red Box, and I am confused about how to fill in the power cards.  So, take Nimbus of Holy Shielding for instance. I understand the Target and Hit components as well as the effect, but my question is about the Attack component. It reads:     Attack: Wisdom vs Will.   Does the mean whatever my Wisdom score is, without the modifier, is compared to the Will score of the enemy? Would I then not even have to roll a d20 to see if it works?


What do you guys think about it?     "Ace Grit is a 16 years old Vestal boy" or "Ace Grit is a 16 year old   Vestal boy"?      "Ace Grit is 16 years old" or "Ace Grit is 16 year old"?   Actually I still guess weird that it is "year old" instead os "years old", I didn't know anything about it, I just want to know please about what is the fact about "year-old-like" somebody, one person or two person, but in an age, younger and/or older.

1) a ten years old boy is sitting on the couch.      2) a ten year old boy is sitting on the couch.      3) a ten-years old boy is sitting on the couch.      4) a ten-year old boy is sitting on the couch.   Which is correct?


I am having difficulty with \cite,  would not compile some of the cites.  It is save in a file with extension .bib and the rest of the cites work fine but these ones do not. Any help?  @ONLINE{nistasd,       title  = "",       author = "",       note   = "\url{https://physics.nist.gov/PhysRefData/ASD/levels_form.html}",       year   = ""     }   @MastersThesis{lopez,     title    = {No wayout},     school   = {Universidad de Pamplona},     author   = {P. Lopez},     year     = {2007},  }   MWE:  \documentclass[a4paper,12pt]{report}  %%%%%figure beyond 100 %\usepackage[titles]{tocloft} %\cftsetindents{figure}{0em}{3.5em} %\cftsetindents{table}{0em}{3.5em} %%%%%%%%%%%%%%%%%%%%%%%%%  \usepackage{graphicx,rotating} \usepackage{multirow} \usepackage{siunitx,booktabs}%for table decimals number \sisetup{separate-uncertainty}% \usepackage[export]{adjustbox} \usepackage[sectionbib]{chapterbib} \usepackage{setspace} \onehalfspacing \usepackage{amssymb}%checkmark on table \usepackage{parskip}%paragraph separation \setlength\parskip{5pt}%separation after title    \usepackage{fancyhdr} \fancyfoot{} \fancyhead{} \pagestyle{fancy}  \fancyhead[R]{\textbf{\cfoot{\thepage}}}{\slshape \rightmark}   \renewcommand{\headrulewidth}{0pt} %lets the head rule disappear. \lhead{\textbf{\nouppercase{\rightmark}}} %\addtolength{\oddsidemargin}{2.cm} \usepackage[left=3.5cm,right=2.5cm,top=3.5cm,bottom=4cm,headheight=1cm]{geometry} \usepackage{wrapfig}  \usepackage{nccmath} \usepackage{tabularx,ragged2e,booktabs,caption,makecell} \usepackage[section]{placeins} \usepackage[textfont=normalfont]{subcaption} \usepackage{url} \urlstyle{same} \newcommand\apj{1925ApJ....61...38R}  % Journal abbreviations  \addtolength{\topmargin}{.25in}  %topmargin control \setlength{\parindent}{0pt} \setcounter{secnumdepth}{3}  %to include subsection in table of cont. \setcounter{tocdepth}{3} \pagenumbering{roman}       %change page number style \flushbottom   \begin{document}  This is given problem to compile  \cite{browning2008basic} and this \cite{Siegman:98}. and this \cite{lopez}   and this \cite{nistasd} and this \cite{doi:10.1063/1.2142102}     \bibliographystyle{ieeetr}\newpage\cleardoublepage \bibliography{sourcespectra}  \end{document}   Here are some entries in the file sourcespectra.bib:   @book{browning2008basic,   title={Basic Plasma Physics},   author={Browning, B.},   isbn={9781409219194},   url={https://books.google.ie/books?id=pItUOwAACAAJ},   year={2008},   publisher={Lulu.com} }   @inproceedings{Siegman:98, author = {A. E. Siegman}, booktitle = {DPSS (Diode Pumped Solid State) Lasers: Applications and Issues}, journal = {DPSS (Diode Pumped Solid State) Lasers: Applications and Issues}, keywords = {}, pages = {MQ1}, publisher = {Optical Society of America}, title = {How to (Maybe) Measure Laser Beam Quality}, year = {1998}, url = {http://www.osapublishing.org/abstract.cfm?URI=DLAI-1998-MQ1}, doi = {10.1364/DLAI.1998.MQ1}, abstract = {}, }    @MastersThesis{lopez,     title    = {No wayout},     school   = {Universidad de Pamplona},     author   = {P. Lopez},     year     = {2007},  }  @ONLINE{nistasd,       title  = "",       author = "",       note   = "\url{https://physics.nist.gov/PhysRefData/ASD/levels_form.html}",       year   = ""     }     @article{doi:10.1063/1.2142102, author = {Shinsuke Fujioka and Hiroaki Nishimura and Katsunobu Nishihara and Masakatsu Murakami and Youngces-G Kang and Qincui Gu and Keiji Nagai and Takayoshi Norimatsu and Noriaki Miyanaga and Yasukazu Izawa and Kunioki Mima and Yoshinori Shimada and Atsushi Sunahara and Hiroyuki Furukawa}, title = {Properties of ion debris emitted from laser-produced mass-limited tin plasmas for extreme ultraviolet light source applications}, journal = {Applied Physics Letters}, volume = {87}, number = {24}, pages = {241503}, year = {2005}, doi = {10.1063/1.2142102}, URL = { http://dx.doi.org/10.1063/1.2142102}, eprint = {http://dx.doi.org/10.1063/1.2142102} }      [![enter code here][2]][2]

I've browsed the forums and found a number of posts that have addressed this issue, but none of the solutions seem to work for me. I have the following script that I just copied from the bibtex home page to get familiar with it. Instead of the citation number I get a question mark. I compile using Latex+Bibtex+Latex+Latex+PDFLatex+ViewPDF just as has been previously suggested and the problem persists.   \documentclass[11pt]{article} \usepackage{cite}  \begin{document}  \title{My Article} \author{Nobody Jr.} \date{Today} \maketitle  Blablabla said Nobody ~\cite{Nobody06}.  \bibliography{mybib} \bibliographystyle{plain} \end{document}   My bibliography (Bib.bbl)  @misc{ Nobody06, author = "Nobody Jr", title = "My Article", year = "2006" }    Looking at previous posts one thing that is concerning is that my .bbl looks empty as shown below. Further, I don't have a .blg  \begin{thebibliography}{}  \end{thebibliography}


I'm sure this is a really stupid question and it's probably already been asked a dozen times on this site, and I just don't know which keywords to search. I'm still really new to managing a server and new to the command line in general, but it's something I've been wanting to try for a long time.  Right now I have Ubuntu Server (no GUI) running a Node.js web server.  How can I keep Node running while executing other commands on the command line?  For example:  node /var/www/my_app.js  This command prevents me from running other commands until I terminate it with Ctrl + C. But what if I want to run a redis-cli command while leaving Node running in the background? In other words:   How can I exit out of the Node.js context without stopping the Node server? and After I do (1), how can I return to the Node context?   I don't know if (2) makes sense for the node command, but, for example, if I ran nodemon instead, I can run a rs (restart) command while nodemon is running.  Thanks, and apologies if this is a duplicate and/or really obvious question.

How do I run a program in the background of a shell, with the ability to close the shell while leaving the program running? Lets say my UI is having problems or for some reason, I need to boot up a program from the terminal window, say, nm-applet:  nm-applet   When it's started, it occupies the foreground of the terminal window.  Is there any simple way to run the program in the background without needing to leave the terminal open or have it occupy the whole terminal?  On that note, I did find a way to run programs from the terminal and have it allow for other inputs, by appending an ampersand (&) to the command as such:  nm-applet &   But this isn't much use as any processes started in the terminal are killed once the terminal is closed.


I feel intimidated in learning TikZ. I was wondering if there are some nice materials (or just your replies) at different level:   for providing big picture, which is important to beginners to not lose direction during learning. for comprehensive reference.   Examples are important, but only examples are not always clear for understanding the big picture and organization.


I already read other questions like this but nothing seems to work. I just had my ASUS UX31A recovered from factory with Windows 7. Everything is fine there, so I tried to reinstall Ubuntu 12.04 LTS (the first time installation worked fine, so I was confident it would have worked this time as well). I shrik volume from my second Windows partition to make it unallocated, boot the Ubuntu live USB and when I try to install it tells me that there's no other operating sistem to install Ubuntu alongside. If I proceed with the manual operation to create the swap area and the OS partition, it doesn't make me choose whether it should be logical or principal, so I don't dare to go on. If I look at GParted it doesn't show the label OS on C:, while on the disk manager in Windows everything seems ok. What should I do? I DO NOT want to reinstall Windows, any other clue? Thanks  EDIT 1 I tried to launch os-prober in my Terminal and the only option I get is   /dev/sda5:Windows Recovery Environment (loader):Windows1:chain   while Windows 7 (mounted on dev/sda3) is not showed.  This is what I see in my Disk Manager inside Windows 7:   Click for a full-resolution image.  (Sorry for the Italian Language, C: basically is the partition with Windows system's file, while the D: one is for data), while this is what I see when I launch GParted:   Click for a full-resolution image.

I'm having a problem installing Ubuntu 12.04 on my ASUS UX31A alongside Windows 7; I tried to launch os-prober in my terminal and the only option I get is:   /dev/sda5:Windows Recovery Environment (loader):Windows1:chain   while Windows 7 (mounted on dev/sda3) is not shown.  This is what I see in my Disk Manager in Windows 7:    C: basically is the partition with Windows system's file, while the D: one is for data), while this is what I see when I launch GParted:     May it be because Windows is installed on SSD? How do I know that? Is it safe if I proceed with the installation for computers with UEFI, SSD and HDD? I'm not sure that's my case.


So I've been attempting to solve the 3SUM problem and the following is my algorithm  def findThree(seq, goal):     for x in range(len(seq)-1):          left = x+1         right = len(seq)-1          while (left < right):             tmp = seq[left] + seq[right] + seq[x]             if tmp > goal:                 right -= 1             elif tmp < goal:                 left += 1             else:                 return [seq[left],seq[right],seq[x]]   As you can see it's a really generic algorithm that solves it in O(n2).  The problem I've been experiencing is that this algorithm doesn't seem to like working with floating point numbers.   To test that my theory is right, I gave it the following two array  FloatingArr = [89.95, 120.0, 140.0, 179.95, 199.95, 259.95, 259.95, 259.95, 320.0, 320.0] IntArr = [89, 120, 140, 179, 199, 259, 259, 259, 320, 320]   findThree(FloatingArr, 779.85) // I want it to return [259.95, 259.95, 259,95] >> None // Fail findThree(FloatingArr, 777) // I want it to return [259,259,259] >> [259, 259, 259] // Success   The algorithm does work, but it doesn't seem to work well with floating point numbers. What can I do to fix this?   For additional information, my first array is originally a list of string of prices, but in order to do math with them, I had to strip the "$" sign off. My approach in doing so is this  for x in range(len(prices)):     prices[x] = float(prices[x][1:]) // return all the prices without the "$" sign. Casting them to float.    If there is a much better way, please let me know. I feel as if this problem is not really about findThree() but rather how I modified the original prices array.  Edit: Seeing that it is indeed a floating point problem, I guess my next question would be what is the best way to convert a string to int after I strip off the "$" ?

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


When both Cobb and Ariadne go down to Limbo near the end of Inception, it's essentially the same as Cobb had left it. But if Ariadne went herself and hadn't heard about Cobb's limbo (so her subconscious wouldn't build it), would it be an ultimately different place?

In the ending of  (2010), there is some doubt that Cobb is in the real world. But if he is not in the real world then at which level of the dream he is in?  Starting at the presumed 'real world' as the first level of the story, I think the final scene it's the fifth level (limbo) because at the fourth level they save Fischer, but I need clarification.


I've been searching through various types of sites that I can create using SharePoint 2010, and it seems that the only one I can't use (a simple list view in a web part) is the only one that will accept non "http" links.   A Document Library won't even let me create non-http links, so I went with a Wiki, thinking that surely this would let me enter whatever I want. But it's not so! It let me create mms:// links (about 50 of them, before I saved), but once I save+closed the page, SharePoint decided that it would do me a favor and remove all the addresses from the hyperlinks! Now I have 50 empty links that only open a new tab when clicked. Of course, I tested this with an http:// link to Google and, sure enough, that one worked after save.   My question is: is there any way for me to avoid Microsoft's walled garden approach here and use mms:// for some of my links using native options? Or will I have to alter the HTML directly?  There was  on Sharepoint.SE nearly a year ago, but it got zero answers. Hopefully this one will garner more attention.

I have a client that has a Links page in SharePoint 2013. On the page is a column called URL that is set as a hyperlink column, but they want the column to accept pw://example.com/... instead of just ...  Is there a way to change the hyperlink column to allow for this behavior? I considered creating it as a single line of text and then making that text box a hyperlink-enabled box. Is there another native option? If not, which of these would be easiest? I am new to SharePoint so any help would be appreciated! Thanks in advance!   URL    Type the Web address: (Click here to test)  pw://test  Invalid URL: pw://test


I have this proposition.   Let X,Y be a metric spaces and let $f:X \to Y$ be a map. Then f is continuous if and only if $f^{-1} (V)$ is closed in X whenever V is closed in Y.  How would you go about proving this?

Here is the question:     Prove that the function $f: E \rightarrow E'$ between metric spaces is continuous iff whenever $ C\subset E'$ is closed, $f^{-1}(C)$ is a closed subset of $E$.   What I was thinking of doing is this following:  First, assume F is continuous. So we want to show that whenever  $ C\subset E'$ is closed, then $f^<(C)$ is a closed subset of $E$. To do this, do we just need to show that whenever $C^c \subset E'$ is open, then $f^<(C^c)$ is open?


It might be a silly question but if $$a+\sqrt{a^2+1}= b+\sqrt{b^2+1},$$ then can I conclude that $a=b$? I thought about squaring both sides but I think it is wrong! Because radicals will not be removed by doing that! Can you help me with proving that $a=b$ or not? Actually I'm going to prove that $x+\sqrt{x^2+1}$ is a $1$-$1$ function.

I have a function  $y = \sqrt{x^2 + 1}− x$ and I need to prove if it's a Injective function (one-to-one).  The function f is injective if and only if for all a and b in A, if f(a) = f(b), then a = b  $\sqrt{a^2 + 1} − a = \sqrt{b^2 + 1} − b$  $\sqrt{a^2 + 1} + b = \sqrt{b^2 + 1} + a$  $(\sqrt{a^2 + 1} + b)^2 = (\sqrt{b^2 + 1} + a)^2$  $a^2 + 1 + b^2 + 2b\sqrt{a^2 + 1} = b^2 + 1 + a^2 + 2a\sqrt{b^2 + 1}$  $2b\sqrt{a^2 + 1} = 2a\sqrt{b^2 + 1}$  $b\sqrt{a^2 + 1} = a\sqrt{b^2 + 1}$  $(b\sqrt{a^2 + 1})^2 = (a\sqrt{b^2 + 1})^2$  $b^2(a^2 + 1) = a^2(b^2 + 1)$  $b^2a^2 + b^2 = a^2b^2 + a^2$  $b^2 = a^2$  $\sqrt{b^2} = \sqrt{a^2}$  $b = \pm a$  then the function is not injective because $b$ in not equal to $a$, but using online  the function is injective.


Is cooking garlic is the important part of curry.This huge use of garlic in our dishes wants the easy method to peel of garlic.

How should I approach peeling a clove of garlic to get the skin off most quickly?  Is it different if I'm doing a bulb whole?


I recently installed win 7 32bit as dual boot (to Win 10 64bit) on my Alienware 17 R3. I forgot what a pain manual driver installation used to be and probably got something wrong. 32bit is usually limited to 3.25 GB ram, right? But for me it's showing up as 16 GB (855mb usable) - I have no clue why. It's showing correctly in the BIOS (and the Win 10 system).  I might still be missing quite a few drivers, but I don't remember needing drivers for RAM in the past... Any ideas on how I might solve this?

My girlfriend bought a laptop last week. It's a core 2 duo with 4 GB  We installed vista 64bit, and one of the first things we did was right click on "My computer" to see gthe properties. Immediately we noticed something strange about her RAM, the line said: Installed memory (RAM): 4,00 GB (3,68 GB usable)  I told her not to worry, thinking it must be something about the laptop hardware (considering her vista installation came from the same DVD as mine, and I never noticed anything like that on my 4 GB desktop). One hour ago, it got worse. We looked at Properties again, and it now says: Installed memory (RAM): 4,00 GB (2,98 GB usable)  What does that mean? Are those 1,02 GB missing or being used by the system?  EDIT: There is a possibility that the sytem information is wrong. I just noticed that it reports an intel T6500 processor, when it's actually a T6400.  How can I find out how much RAM is really available to the system?  EDIT2: Checking the resource monitors, it says 1003 MB are reserved for the hardware. Is that good or bad? Thanks


I'm looking for the rules concerning when you use possessive pronouns combined with a verb of "-ing" form. What's the combination called and how does it work?  Examples:    Thanks to my going to school I know a lot of things. I object to his going to the dentist.   Can you also say this?   Thanks to me going to school I know a lot of things. I object to him going to the dentist.

The rule says that we can use a possessive adjective or an object pronoun before a gerund. Is there a rule  that says when to use each or are they interchangeable? Some say that it's wrong to use an object pronoun before a gerund.


I'm quite accustomed with integration and all those calculus involved in finding moment of inertia as well as center of mass. But a random thought is wiggling in my mind. Why do we take $dm$ instead of $dr$ in finding moment of inertia and center of masses of continuous bodies?

When computing the moment of inertia, I observed that people usually use the following logic:  $$d I=r^2 dm,\\ \therefore I=\int r^2 dm$$  My question here is, why not use $dI=m  ~d(r^2)$?   I acknowledge that integrating $dI$ means that I am summing up all the small I's ($\Sigma I_i$). What I find strange is that viewing $dI$ as $md(r^2)$ seems to make no sense when viewed from such perspective.  Is there a reason why no textbook seems to view $dI$ that way?


I have a server running multiple web hosts (all internally managed) which was the subject of what looked like a dos attack last night. I blocked the attacking IP in IPTABLES for both input and output chains.  That seemed to solve the problem and I went home.  This morning the server died again - this time it seems from netstat that it was sending multiple SYN's to the attacking IP.  Obviously they were dropped by IPTABLES OUTPUT chain, but there were so many in the stack that it failed.    I am worried that the server is sending syn's to the attacker. Presumably it's trying to establish a new outbound connection to the attacker IP on port 80, but why?  Does this mean the server is compromised?  How can I find what is causing this?  I have tried netstat -p but it just shows the owner of the outgoing attempts as httpd.  There are some big sites in the web directory so my attempt at grep'ing for the attacker IP in all the web files would take days.    What to do?  Many thanks in advance....

This is a  about Server Security - Responding to Breach Events (Hacking)   See Also:                  Canonical Version I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism:   What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", are there other initial considerations? How do I go about getting services back online? How do I prevent the same thing from happening immediately again? Are there best practices or methodologies for learning from this incident? If I wanted to put a Incident Response Plan together, where would I start? Should this be part of my Disaster Recovery or Business Continuity Planning?   Original Version       2011.01.02 - I'm on my way into work at 9.30 p.m. on a Sunday because our server has been compromised somehow and was resulting in a    attack on our provider. The servers access to the Internet   has been shut down which means over 5-600 of our clients sites are now   down. Now this could be an FTP hack, or some weakness in code   somewhere. I'm not sure till I get there.      How can I track this down quickly? We're in for a whole lot of   litigation if I don't get the server back up ASAP. Any help is   appreciated. We are running Open SUSE 11.0.            2011.01.03 - Thanks to everyone for your help. Luckily I WASN'T the only person responsible for this server, just the nearest. We managed   to resolve this problem, although it may not apply to many others in a   different situation. I'll detail what we did.      We unplugged the server from the net. It was performing (attempting to   perform) a Denial Of Service attack on another server in Indonesia,   and the guilty party was also based there.      We firstly tried to identify where on the server this was coming from,   considering we have over 500 sites on the server, we expected to be   moonlighting for some time. However, with SSH access still, we ran a   command to find all files edited or created in the time the attacks   started. Luckily, the offending file was created over the winter   holidays which meant that not many other files were created on the   server at that time.      We were then able to identify the offending file which was inside the   uploaded images folder within a  website.      After a short cigarette break we concluded that, due to the files   location, it must have been uploaded via a file upload facility that   was inadequetly secured. After some googling, we found that there was   a security vulnerability that allowed files to be uploaded, within the   ZenCart admin panel, for a picture for a record company. (The section   that it never really even used), posting this form just uploaded any   file, it did not check the extension of the file, and didn't even   check to see if the user was logged in.      This meant that any files could be uploaded, including a PHP file for   the attack. We secured the vulnerability with ZenCart on the infected   site, and removed the offending files.      The job was done, and I was home for 2 a.m.            The Moral   - Always apply security patches for ZenCart, or any other CMS system for that matter. As when security updates are released, the whole   world is made aware of the vulnerability.   - Always do backups, and backup your backups.   - Employ or arrange for someone that will be there in times like these. To prevent anyone from relying on a panicy post on Server   Fault.


I am a physics high-school student so my knowledge is not very deep on the subject. We started learnning about quantum mechanics and on some processes that my teacher described as random. I began to think on the concept of randomness and question it, thinking how can a process or an outcome be determined without any cause, how an outcome be determined at all in complete randomness?  I searched the internet and figured the scientific community does not agree with me. I'd really like to understand how can true randomness exist? Why the scientific community rejects the idea that ''random'' events may just have a cause we are not aware of? What am I missing?  Thanks for answers and sorry for bad English.

I'm not sure if this is the right place to ask this question. I realise that this maybe a borderline philosophical question at this point in time, therefore feel free to close this question if you think that this is a duplicate or inappropriate for this forum. Anyway, I'm an electrical engineer and I have some basic knowledge of quantum mechanics. I know that Schrödinger's equation is deterministic. However, quantum mechanics is much deeper than that and I would like to learn more. If this question is not clearly answerable at this point than can anyone point out some recognized sources that try to answer this question. I would appreciate it if the source is scientific and more specifically, is related to quantum theory.


How can I open a file in LibreOffice Writer from terminal and be back at terminal to continue with other tasks?  For instance, if I insert     libreoffice CV*.odt   it will open the file in LibreOffice but I will be unable to proceed with further commands in that instance of terminal.

How do I run a program in the background of a shell, with the ability to close the shell while leaving the program running? Lets say my UI is having problems or for some reason, I need to boot up a program from the terminal window, say, nm-applet:  nm-applet   When it's started, it occupies the foreground of the terminal window.  Is there any simple way to run the program in the background without needing to leave the terminal open or have it occupy the whole terminal?  On that note, I did find a way to run programs from the terminal and have it allow for other inputs, by appending an ampersand (&) to the command as such:  nm-applet &   But this isn't much use as any processes started in the terminal are killed once the terminal is closed.


I have a point shapefile and a line shapefile like these:   Each point has a numerical attribute that I would like to transfer to the line (The lines represent directional data). I broke already the line at each point, but I don't know how to transfer the attribute from each point to the line.  Does anyone know how to do it?

I have two shapefiles, Point and Polyline. I'm trying to populate my polyline layer with the point data ID (systemID) where the lines start to where they end; eg. create two columns (from and to). The lines already have flow direction assigned to them. I am using ArcHydro tools but Arcpy is also fine.  In ArcHydro I have tried using Attribute Tools > Generate From/To Nodes for lines but it creates values for To and From that are not from my point data. My other alternative was using Feature to Vertices and joining the result to my point data table to get the systemID. But then I would have to update the polyline layer as well. I am sure there is a easier way of doing it.  Note: not all the lines have points at the vertices, blank values are fine for them.


I am managing a Dell R710 server used for some very large non-linear finite element analysis (FEA) computations. Occasionally, these runs will take upwards of 500GB of allocated memory. Since this machine only currently has 132GB of RAM, this additional memory allocation comes through the paging file.  The paging file is current on a spinning HDD array and is causing a huge bottleneck. I have investigated maxing out the memory (288GB) and adding a 400GB Intel 750 NVMe SSD as a dedicated pagefile disk. This should free up some of the pagefile IO bottleneck, but I want to make sure that we don't max out the pagefile and crash a large run.  Short of getting the 800GB Intel 750 for the understood max page file size of 864GB (3x 288GB), can I tell Windows to use the HDD array as a failover for extra pagedisk space? Is there any way to prioritize the SSD as primary for the pagefile? Thanks.

Suppose I have a 6 GB page file on an SSD and another 6 GB page file on a traditional mechanical 5400rpm SATA drive.  Does Windows take into account the difference in the performance characteristics between the two drives when deciding which page file to use?  If it matters, I'm asking about Windows 7 and higher.  I reviewed this  but it doesn't appear to factor in the case of dissimilar storage speeds.


Some Background and Motivation: In , it is shown that an integral domain $D$ such that $F \subset D \subset E$, $E$ and $F$ fields with $[E:F]$ finite, is itself a field.  However, a significantly more general result holds and seems worthy, of independent address; hence, Let $F \subset E \tag 1$ be fields with $[E:F] < \infty; \tag 2$ if $R$ is a ring such that $F \subset R \subset E, \tag 3$ show that $R$ is in fact a field.

This is an exercise in some textbooks.     Let $E$ be an algebraic extension of $F$. Suppose $R$ is ring that contains $F$ and is contained in $E$. Prove that $R$ is a field.   The trouble is really with the inverse of $r$, where $r\in R$. How to prove that $r^{-1}\in R$, in apparent lack of a characterization of $R$.  It occurred to me to use the smallest field containing $R$ ($R$ is easily shown to be an integral domain), that's the field of quotients, and proving that it's $R$ itself, but I don't really know how to proceed.  A not-too-weak, not-too-strong hint will be much appreciated.   Beware $ $ Readers seeking only hints should  beware that there is now a complete answer.


The smooth shading mode is nice, but often times it seems to leave ugly marks where edges are. it doesn't do that between every face, but it does for some faces. I tried flipping normals but all that does is make it lighter or darker, but doesn't actually smooth it out. I tried making all the faces merged, but that didn't help.

I frequently come to the problem of having a mesh with parts I would like to render smooth and "hard" edges connecting them.   How can I set the mesh to show the sharp edges but render everything else smooth?  In the example I would like the sides of the individual cylinders render smooth but the intersection between bottom and top to be sharp/flat


I just don't get it. Isn't snow just another form of water? Also are all ices transparent or do they go white after a certain temperature?

There are many things with different textures that appear white – salt, beer foam, paper, shaving cream, snow, talcum powder, white paint, etc. The most common answer is all of the frequencies must be reflected in order for us to perceive white, which I already know. There must be more underlining details why such a huge variety of things are white. Furthermore, if you wet paper, snow or talcum powder, they appear off-white or gray. Why is this?


This is the implementation of the Edit distance problem.  Here is the recursive version without any memoization   def edit_distance(str_a, str_b, len_a, len_b):     # bot strs consumed     if len_a == 0 and len_b == 0:        return 0      if len_a == 0:        return len_b      if len_b == 0:        return len_a      i_a = len_a-1     i_b = len_b-1      if str_a[i_a] == str_b[i_b]:        return edit_distance(str_a, str_b, i_a, i_b)      replace = edit_distance(str_a, str_b, i_a, i_b)     delete = edit_distance(str_a, str_b, i_a, len_b)     insert = edit_distance(str_a, str_b, len_a, i_b)      return 1+min(replace, delete, insert)   Now here is the memoized version where I cache the results of call.  def edit_distance_memo(str_a, str_b, len_a, len_b, cache):   if cache[len_a][len_b] != -1:     return cache[len_a][len_b]     if len_a == 0 and len_b == 0:     cache[len_a][len_b] = 0     return 0    if len_a == 0:     cache[len_a][len_b] = len_b     return len_b    if len_b == 0:     cache[len_a][len_b] = len_a     return len_a    if cache[len_a][len_b] != -1:     return cache[len_a][len_b]    i_a = len_a-1   i_b = len_b-1   if str_a[i_a] == str_b[i_b]:    cache[len_a][len_b] =  edit_distance_memo(str_a, str_b, i_a, i_b, cache)    return cache[len_a][len_b]   replace = edit_distance_memo(str_a, str_b, i_a, i_b, cache)  delete = edit_distance_memo(str_a, str_b, i_a, len_b, cache)  insert = edit_distance_memo(str_a, str_b, len_a, i_b, cache)   best_option = min(replace, delete, insert)   cache[len_a][len_b] = 1 + best_option   return cache[len_a][len_b]   Here is the calling code:   from time import time  str1 = "Shakespeare"  str2 = "shake spear"  s1 =  time()  print edit_distance(str1, str2, len(str1), len(str2)), "edit_distance"  print "diff---", time()-s1   rows = len("Shakespeare")+1  columns = len("shake spear")+1   cache = [[-1] * columns] * rows  st  = time()  print edit_distance_memo("Shakespeare", "shake spear",len("Shakespeare"), len("shake spear"), cache)   For some reason the memoized version, seems to be giving a wrong answer (7 instead of 3). What is wrong here?  Thanks in advance.

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I;m trying to generate a tuple list from a larger list. how do I do it in pythonic way?  c = ['A1','B1','C1','A2','B2','C2']   Output required is something like this:  c = [('A1','A2'),('B1','B2'),('C1','C2')]   I tried to iterate through the list and put a regex to match for mattern and then added that to a tuple but that doesn;t look convincing for me.. Any better way to handle this?

I have a list of arbitrary length, and I need to split it up into equal size chunks and operate on it. There are some obvious ways to do this, like keeping a counter and two lists, and when the second list fills up, add it to the first list and empty the second list for the next round of data, but this is potentially extremely expensive.  I was wondering if anyone had a good solution to this for lists of any length, e.g. using generators.  I was looking for something useful in itertools but I couldn't find anything obviously useful. Might've missed it, though.  Related question:


Food that is being cooked/boiled will possess no chance for the virus to stick to them while cooking. But what precautions should be taken after the process of cooking?

What general rules do I need to follow to keep my food safe? How do I know what temperature to cook something to, or whether my food is safe at room temperature?


The 11th Doctor (Matt Smith), which was the last of his regenerative cycle, gets a new one on Trenzelore. Then he changes to the 12th Doctor (Peter Capaldi), but he still remembers all his adventures in his first cycle. How does the 12th Doctor remember all of the adventures in his first cycle (his past 13 incarnations)?

At the end of The Time of the Doctor, it is shown that Matt Smith has received an entire new regeneration cycle and using it he regenerates into Peter Capaldi. Capaldi's first question to Clara is about how to fly the TARDIS. Does this mean there has been a memory reset for the Doctor?  If so, has he forgotten his true name?  If he has forgotten his true name, then he can't bring back the Time Lords now can he?


I want to use the diode 1N4571 (Vbrkdn=6.4V) and 1N4761 (Vbrkdn= 75V) in my circuit. Please help me design these zener diodes in LTSPICE.

I would like to simulate the behaviour of a zener diode in LTspice. Consider the following schematic         – Schematic created using   I'm interested in simulating its performance when Vcc changes from the rated value (say 12V), for example when Vcc varies from 11 to 15 V.  Now, I know how to simulate this behaviour in LTspice for a generic diode or even for a particular diode which is available in the model library, but when it comes to using a custom diode, I have no idea on how to specify the diode parameters.  Looking into the documentation I was able to come up with a setup that is the correct one, that is, I can specify a custom diode model but now I'm having problems in understanding where to find all the parameters since the datasheet of my diode of choice does not provide all of them. In the LTspice model shown below I've picked a 4.7 V zener diode that was available just to have a base model to edit (and a 1k resistor just for reference).    The diode I'd like to use is a 3V . How can I simulate, as realistically as possible, the behaviour of this diode given the few parameters available in the datasheet?


If $x + \sqrt{x + \sqrt{x + \cdots}} = 2$, what is the value of $x$?

$$\sqrt{x + \sqrt{x + \sqrt{x + \cdots}}}= 5$$


I have a views page that is continually updated using views_autorefresh.  My setup works fine except for the occasional error message:  AJAX Request terminated abnormally  This only happens if the user tries to navigate away from the page during an update.  Is there a way to suppress this message?  Because I know that this message will happen (repeatedly) I do not want for there to be a log entry of it.

How can I prevent ajax failure popups and instead route the failure to the console log instead?  Is this something I can do with Drupals implementation of jQuery?


I know this must be a common question but I have a problem with my site.  Its been up for about four months and its working fine on other search engines but not on Google. Its a very unique name so not much competition. And I have a dashboard component to this product and this shows up on the first page without any content or effort.  I have done the following to resolve the issue.     1. Used google webmaster to check that its being indexed and fixed all errors.  2. Added google site verification  3. Checked the domain is not blacklisted 4. Changed content regularly. 5. Moved the hosting from AWS S3 to normal Apache hosted site. 6. Ensured no duplicate content, did redirect to main domain from ip and dns addresses 7. Created a google add campaign  8. Linked all social sites including google+ business 9. Used seo sites to test for errors. The score is 65 so still working on some issues. There are some issues like only 12% content to html. 10. Removed animation from the site 11. Checked it is being indexed using site:fiskl.com   I am looking for some pointers to where I can go from here.  It so strange that it doesn't appear at all and that my dashboard without any links or effort is on or near page 1 with a search for fiskl The only way I can have any google presence is to run an add campaign.   --EDIT--   Improved the page speed to 90% using google  Check different regions using googles ncr (Non country redirect). So if you want to see what your results are in the .com you can load  or to check in the Neterlands for example     Still 100% omission from results for an exact company search although my dashboard login page is on page 1.

It's been sometime and Google has yet to index my site. How can I get Google to index my website?


Mathematics course, and I love this science, I am very curious, and these days, studying a book of calculus found in (book from the library of the University) a sheet full of challenges, to share with a colleague, he gave me this challenge, which he also failed to respond ... I tried, I tried, I used the formulas of quadratic equation, and I've been trying since Friday (here in Brazil is Sunday at 22:33), and could not, and I ask your help, and please believe me, I struggled, tried to make substitutions, tried both, and I'm confused ... I must find the values of $ a, b $ and $ c $?  Consider a parabola whose roots, $x'$ and $x''$, are such that $x'=-x''$ where $x'> 0$.  Define $$A = (x', 0)$$ $$B = (x'', 0)$$ and let $V$ be the vertex of the parabola. If the equation of this parabola is $$y = ax^2 +bx+ c$$ calculate the value of the discriminant $$\Delta=b^2-4ac$$ so that the triangle AVB is equilateral.

Good Night ... Here I am editing the question and explaining the purpose of the same ... Mathematics course, and I love this science, I am very curious, and these days, studying a book of calculus found in (book from the library of the University) a sheet full of challenges, to share with a colleague, he gave me this challenge, which he also failed to respond ... I tried, I tried, I used the formulas of quadratic equation, and I've been trying since Friday (here in Brazil is Sunday at 22:33), and could not, and I ask your help, and please believe me, I struggled, tried to make substitutions, tried both, and I'm confused ... I must find the values of $ a, b $ and $ c $?  Consider a parabola whose roots, other are $x'$ and $x''$, and such that $x'=-x''$ where $x'> 0$. Let $$A = (x', 0)$$ $$B = (x'', 0)$$ and $V$ the vertex of the parabola. Suppose that the equation of this parabola is $$y = ax^2 +bx+ c$$. Calculate the value of the discriminant $$\Delta=b^2-4ac$$, so that the triangle is equilateral AVB.


This round medallion is held by someone in the . It looks familiar but I can't place it.  Is it something from existing Star Wars lore?

What award/medal is this -  I have been searching  to try and find what medal this is, but i have not found it, does anyone know what this medal/award was and why it would be given (eg- bravery, serving in the battle of Yavin)?


I have this code:  booleans.put(varToSet, choiceResponse);   and it throws a NullPointerException. The error it shows is this:  Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException     at com.salsagames.prometheus.code.Compiler$2.either(Compiler.java:120)     at com.salsagames.prometheus.code.message.YesNo.lambda$new$2(YesNo.java:73)     at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)   The two variables I use are:  varToSet test  choiceResponse true  I am using the right types for the Map, (String in, Boolean out).  My Map needed to be declared as new HashMap<>()

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I recently read an article on dark matter and I could understand this things given as follows  All the ordinary matter we can find accounts for only about 4 percent of the universe. We know this by calculating how much mass would be needed to hold galaxies together and cause them to move about the way they do when they gather in large clusters. Another way to weigh the unseen matter is to look at how gravity bends the light from distant objects. Every measure tells astronomers that most of the universe is invisible.   I want to say that the universe must be full of dark clouds of dust or dead stars and be done with it, but there are persuasive arguments that this is not the case. First, although there are ways to spot even the darkest forms of matter, almost every attempt to find missing clouds and stars has failed. Second, and more convincing, cosmologists can make very precise calculations of the nuclear reactions that occurred right after the Big Bang and compare the expected results with the actual composition of the universe. Those calculations show that the total amount of ordinary matter, composed of familiar protons and neutrons, is much less than the total mass of the universe. Whatever the rest is, it isn't like the stuff of which we're made. But what actually is dark energy ? How should I connect dark energy with dark matter ?

Possible Duplicate:          I have recently read about  and , and why physicists think it must exist (dark matter: mass of galaxies are far bigger than expected, its gravitational effect on visible matter; dark energy: the force that causes the accelerated expansion of the universe).  I however don't find the case for dark matter or dark energy particularly strong, and I have a couple of questions regarding this:   Why do so many physicists accept the existence of dark matter and dark energy?  Are there any good alternative theories to explain these phenomena without the use of dark energy and/or matter?  Is the field of study regarding dark matter and dark energy (and possible alternative explanations) 'alive' or not so much? I still am young, but I find this interesting and if it has good prospects (like for example string theory does) I might like to work in it in the future.


I want to make a hole in the street using blender. I've tracked my footage and set up a scene. I could cut a hole in a plane and put a cylinder under that, but then the plane would be visible, and it would obscure part of the street. My question is: how do I make it so that the hole looks like it's in the street (without showing anything below the street) without having a plane obscure part of the street?

With my trial and error learning, I managed to track a video in Blender 2.67 and make a cube (the one which is there by default) appear on the "ground" (which is a table).  But how can I make a hole in the ground?    Edit:  I used the two buttons shown below:    The two functions seems to do a bunch of things to the scene, which seems to include setting the background and foreground layers, and adding a Ground object to the scene.  The problem is, what do I need to do to create a hole that appears to sink into the table?


I ran across the identity $$i{n \choose i} = n {n-1 \choose i-1}$$ which can be easily proved using the definition ${n \choose k} = \frac{n!}{(n-k)! k!}$ and a little bit of algebra. I was wondering if there was a simple combinatorial argument  to explain this identity. I'm not necessarily looking for a proof, but rather the heuristics behind why it is valid.

In the first course of probability by sheldon ross on page 155 at the bottom. It is the proof for the expectation of Binomial distribution. It uses the identity:  $$i{n \choose i } =n {n-1 \choose i - 1}$$  Since learning combinatorics, I have been trying to think of this intuitively. So is there an intuitive proof for this identity, rather than just using brute force?


I am trying to center all my columns in my table but I only get the first column to be centered, can anyone help me out?  This is the code i am using:  \begin{table}[H] \centering \caption{The four main criteria for conceptual model evaluation.} \label{concept_criteria} \begin{tabular}{|c|p{12cm}|}     \hline     \textbf{Criteria} &  \textbf{Description}\\      \hline     Validity  &  A modelers perception that the conceptual model can  be converted into an computer model accurate enough for the purpose at hand \\     \hline     Credability  &  The clients perception that the conceptual model can be converted into a computer model accurate enough for the purpose at hand  \\     \hline     Utility  & The conceptual model can be developed into a computer model that can be used as decision making in the specific context \\     \hline     Feasibility  & The conceptual model can be converted into a computer model with the time, resources and data available \\ \hline \end{tabular} \end{table}

I would like to create a table with some columns' width specified, while the text in those columns should be centered both horizontally and vertically. I found out that  \usepackage{array} \begin{tabular}{| c | c | m{5cm} |}   vertically centers the text in the last column, but justifies it horizontally (like text in normal paragraphs).  Update: With Jake's method, it seems both \\ and \hline cause an error. How to fix it?


For the past 3 days, my WhatsApp group messages are not getting downloaded (when I switch on WiFi) in order of time. Rather, it looks like they are grouped as per contacts. I looked into this site, and as suggested, tried the following:   Change your phone to use "Automatic Date and Time": didn't help Reinstall WhatsApp: didn't help Checked the WiFi connection: no issue with the WiFi, web is running perfectly in the same phone Removed unnecessary apps which might delay things by totally resetting my phone to factory default, then reinstall WhatsApp: didn't help   What else should I do?

When in a group chat, if many messages are exchanged between other people in the group, when I check my Whatsapp, the messages are grouped according to sender and not chronologically. I know that my phone isn't the problem as I have recently changed my phone, however, I'm still experiencing the same problem.  I have tried uninstalling and re-installing WhatsApp on my phone, and the same problem still occurs.


i'm a bit confused by the smartdiagram package: I can't make any \newline, and it does not do it by itself (), as have seen in other cases of me using it before, or in . Now i am confused and hope someone here might help me. Thank you a lot in advance!

How can I insert a line break in a TikZ node? Simply putting \\ where I want the break doesn't work (see MWE).  Is there a way to make lines break automatically at some specified width?  And can I control the alignment of the text (left, right, centered, justified)?  \documentclass{article} \usepackage{tikz} \begin{document} \begin{tikzpicture} \node {First line\\second line}; \end{tikzpicture} \end{document}


It seems that a common way of running only one copy of a process is to  and then on start check whether a process with that pid exists. I imagine OS is trying not to reuse a pid quickly after a process has crashed, but since the number of pids is limited, sooner or later there is going to be another unrelated process using that pid. And the original one won't start. How can this situation be avoided?

I'm working on a GUI application in WxPython, and I am not sure how I can ensure that only one copy of my application is running at any given time on the machine. Due to the nature of the application, running more than once doesn't make any sense, and will fail quickly. Under Win32, I can simply make a named mutex and check that at startup. Unfortunately, I don't know of any facilities in Linux that can do this.   I'm looking for something that will automatically be released should the application crash unexpectedly. I don't want to have to burden my users with having to manually delete lock files because I crashed.


So I just rm -rf'ed a folder with a few files I need. Yes I know I should've had a backup, but it's just a Pi. It's designed to be played around with!  Is there anything I can do to recover that folder? Would the files be cached somewhere? Can you recommend any Linux file recovery programs?  I don't want to boot into the SD again as it might write over the data :(  Help!  EXT4 filesystem.

I accidentally deleted a file from my laptop. I'm using Fedora. Is it possible to recover the file?


In Natty, during boot I only see a dark aubergine screen, nothing on it. That is irritating, because I don't know whether the computer still runs or not.  So how can I display the normal "ubuntu" plymouth bootscreen? (I use the nvidia proprietary driver.)

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


If there is no difference between two Chromium options I see while installing, other than their developers, then why do their sizes differ? One is 212Mb and the other 224Kb. There's a similar case with VLC.

I have my Ubuntu Software Center set up to display available snaps. Some apps have both a snap version and an Ubuntu Software Center version available. However, I don't know what the difference is between them. I've seen rumors that snaps are self-updating, but I don't know if Ubuntu Software Center apps can do that, too. In general, I'm wondering what the differences and pros/cons are between the two.


I have to write \Leftrightarrow quite often, and i am currently using a macro for it, but it isn't working too well. Is it possible to make it so that when i type LRA in a math field, that it then outputs it as a \Leftrightarrow? Thanks a lot for any and all help!

I am very new to being able to use LaTeX to type up mathematical papers, and I just got my "system" set up. Currently I have installed TexWorks, and MikTex, and I have put together a 'hello world' article which seems to run well.   I have also used the syntax "\usepackage{amsmath}" and "\usepackage{amssymb}" in the beginning of my .tex file to write math symbols, only because some online tutorial said so.   My question is, firstly, are those the only packages I need to use for writing math, and secondly, I remember reading about some shortcuts(?) that can be used for writing math symbols, and/or user defined shortcuts that can be 'set' in the beginning so as to reduce the amount of LaTeX code needed to write mathematical symbols. However, I do not know if this is true, and if it is, how to go about 'installing' such a thing.   Does such a thing exist? Am I able to make my own shortcuts?  Thanks!


I've been using PB for quite a while now, but, Thrift has constantly been at the back of my mind.  The primary advantages of thrift, as I see it are:   Native collections (i.e, vector, set etc) vs PBs repeated providing functionality similar to, but not quite like (no iterators unless you dig into RepeatedField which the documentation states "shouldn't be required in most cases"). A decent RPC implementation provided, instead of just hooks to plug your own in. More officially supported languages (PB offers "official" support for Java, C++, Python)   The cons of Thrift:   The RPC implementation means I can't plug in my own (for example) encryption/authentication layer on top. Windows support doesn't seem to be great. PB definitely seems to have, if not better, more accessible documentation.   Neutral:   Unknown size of .lib/.dll on Windows (Thrift). Large size of .lib on Windows (PB, but it does offer a -lite which is significantly smaller). Speed wise, they both seem to be similar.   I'm not quite ready to take the plunge and switch to Thrift yet, can anyone offer me more pros/cons, or reasons to go one way or the other?  Thanks!

What are the biggest pros and cons of  vs ?


I got this error even thought I @Inject Message object in MyClass. I just try to learn it now how can I Inject an object.  Please help me, Thanks!  Here are my example.  Main:  public class Main {      public static void main(String [] arg){         new MyClass().print();     }  }   MyClass  import javax.inject.Inject;  public class MyClass {      @Inject private Message message;      public void print() {         System.out.println(message.getMessage());     }  }   Message  public class Message {      public String getMessage() {         return "Hello";     }  }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


How can I put the reference in alphabetical order, not in order of apparition in the text? I'm using  \documentclass[11pt,a4paper,openright,twoside]{book} \usepackage[square,authoryear,sort&compress,semicolon]{natbib}

I have read questions about this, and people say that it is just to include the natbib package and the plainnat style. For some reason my references will not sort alphabetically. Any help on this would be much appreciated! I am really new to LaTeX ...  My commands:  \documentclass[a4paper,norsk]{article} \usepackage{amstext} \usepackage{makeidx} \usepackage{graphicx} \usepackage[comma,authoryear]{natbib} \usepackage[norsk]{babel} \usepackage[hmargin=3cm,vmargin=3.5cm]{geometry} \pagestyle{plain}  \begin{document}  \begin{thebibliography}{56}  \end{thebibliography}  \printindex  \bibliographystyle{plainnat}  \end{document}


What happened to the su password, please?    No passwords, including blank, works.  Also, how do you log in as the administrator?

I want to login as root, but when I enter   sudo -s   and enter password, this message is shown: "you are not in sudoers file", and when I enter   su   and enter password, this is shown: "authentication failure".  My os has one account only. about past1 hours ago I log on as root and do some commands , when I logout , I can't login another time!


I just happen to see a show about air pressure host by Brian Cox. As the link: shows, he flipped a half-filled water cup upside down then the paper on cup doesn't drop:  It puzzled me, because the cup is half-filled, the pressure shouldn't balance since inside water pressure+atmosphere pressure should be bigger than outside atmosphere pressure only.   All the following answers seems not right, now I came the answer with myself: Treat the air inside as gas of a certain density. It's then obvious that the pressure of inside of the paper always equal to the outside unless the pressure exerted by gravity of {water+gas} system beyond the outside atmosphere pressure. The key is that inside is not {water pressure+atmosphere pressure} but {1: water pressure+ 2: small air pressure by inside air's own gravity+ 3: big atmosphere pressure-(1.+2.)}=atmosphere pressure. The third force came from the top inside of the flipped cup. So the paper wouldn't drop until (1.+2.)> atmosphere pressure, even when the paper is rigid body, in constrast to Steeven or others' result.

There is an experiment we learned from high school that demonstrated how atmosphere pressure worked.  Fill a cup of water and put a cardboard on top of it, then turn it upside-down, the water will not fall out. The explanation said this was because the atmosphere pressure was greater than the water pressure, which holds the water up.  I believed this explanation once, until I found some points that confused me:  1. Is the water pressure in the cup really smaller than the atmosphere pressure?  This is what we have been taught through our life. However, consider an object in the water under sea level, it experiences the pressure from water plus atmosphere pressure. So the water under sea level must be greater than the atmosphere pressure. Even it is contained in a cup, the pressure wouldn't change. Is this True?  I read . If the cup is fully filled, the compressibility of water is much greater than that of the air, also the surface tension of the water keeps the air out of the cup. So the water is held in the cup. This explains the problem. But I still want to ask if the water pressure smaller or greater than the atmosphere pressure in this situation.  2. When the cup is half filled with water, why it still holds?  I saw most of articles or opinions against this. They all agree that the water would not fall only if the cup is entirely filled. But I did the experiment myself, the water stayed still in the cup even it is not fully filled. Actually even with little amount of water, as long as it covers the open of the cup and the cardboard on it, the water stays in the cup.  Even the compressibility of water is much smaller, the air inside the cup provide enough compressibility, how come it still holds?


I realized my .git folder was taking up 1.3GB today and looked through the contents to see what the problem was. I found a .pack file taking up almost all of the space and searched around online, eventually running  git gc --aggressive.  This fixed the .pack files, which are now much smaller in the byte or kb range. However, I now have an object file that's 1.3GB.   I can cat the contents of the object and I know what's in it but I can't find that file in my repo history. I don't actually remember committing it but I think php storm may have added it to the repo when I put it in my project directory.  How can I remove this large object file without damaging the repo?  Edit: I checked out the duplicate answer and ran both shell and perl scripts in this link:  to try to find the commit but both returned nothing and no errors either.  Does this mean this object really references no commits?

I accidentally committed an unwanted file (filename.orig while resolving a merge) to my repository several commits ago, without me noticing it until now. I want to completely delete the file from the repository history.   Is it possible to rewrite the change history such that filename.orig was never added to the repository in the first place?


Good afternoon everyone! I am only 17 years old, and this may sound like a stupid question...     First way   Anyway, we currently calculate the "case fatality rate" by dividing the number of patients who have died from a specific disease by the total number of those who got infected.      Second way   However, why don't we calculate the CFR by dividing the number of patients who died by the number of patients who had been successfully healed plus the ones who have died?       Explanation   I understand that maybe the data we have isn't enough nor accurate to use that reason once a country could have only 100 cases, which out of them, 70 died, and only 30 recovered - giving a false CFR having in count time.   Besides that, I also have read this article:  , in which they explained why the second way of calculating CFR approaches the first one.  But that isn't necessarily true. Let's take, for example, the case of COVID-19 in Italy. Because of the older population, the mortality rate is expected to be a lot higher in Italy than in China (about 7.2% compared to 2.1%). Nevertheless, the statistics have been constant for a long time, remaining at almost 45% of death ratio (if calculated using the second way). This doesn't make any sense, but it also looks more accurate than 7.2%. If we take on mind that only 10,950 people recovered from the 20,084 closed cases, the numbers seem right.    I also have in mind that the second way of calculating the CFR doesn't apply to all ages and genders once a 40% mortality rate can't be applied to people <20 years the same way it is to people >60 years. The second way doesn't assume all of the population from a specific country. Although, neither does the first one. If we have to count the real consequences in a general way, isn't this the most appropriate way of calculating it?       Question   Why should we use the total number of cases (active cases + deaths + recoveries) to calculate CFR if the active cases didn't have an outcome yet?

According to the data on the , as of 3rd February 2020 there were 17491 confirmed cases of COVID-19 globally, 536 total recoveries and 362 deaths. From my non-expert calculation this implies a mortality rate of:  (Nd / (Nd + Nr)) * 100 = 41%  where:  Nd is the total number of deaths, Nr is the total number of full recoveries.  This leaves 16593 people still suffering from the disease who have neither recovered or died.  This is in stark contrast to the publicly disseminated value of ~2% mortality, so have I made a mistake in my calculation or assumptions, or is COVID-19 much more dangerous than commonly claimed?    [After a helpful discussion in the comments, 'mortality rate' is not the correct term to use here, instead I should say ''.]


I have an array of items.  var items = {'A', 'A', 'A', 'B', 'B', 'C'}   I want to output an array that counts how many of each item there is. So the output should look like:   {   'A': 3,   'B': 2,   'C': 1  }

I have a JavaScript object. Is there a built-in or accepted best practice way to get the length of this object? const myObject = new Object(); myObject["firstname"] = "Gareth"; myObject["lastname"] = "Simpson"; myObject["age"] = 21;


let promiseArr = [];     for (let i = 0; i < ISOarr.length; i++) {         options.body.start_time = ISOarr[i];         let newOptions = cloneOptions(options);         promiseArr.push(newOptions);     }     console.log(promiseArr);  Returns an array of the same object. Clone method: cloneOptions = options => {     let clone = {};     for( let key in options ) {         clone[key] = options[key]     }     return clone; }  So my question is how do I push an object that is not the same reference as the previous objects pushed, because even with it supposedly creating a new clone each loop it still somehow creates the same referenced object. In the loop if I console.log I get the proper output with the value of the key changed, but once it's pushed into the array and we console.log the array, all objects are the same. Any suggestions would be super helpful. Thank you in advance!

What is the most efficient way to clone a JavaScript object? I've seen obj = eval(uneval(o)); being used, but . I've done things like obj = JSON.parse(JSON.stringify(o)); but question the efficiency.  I've also seen recursive copying functions with various flaws.  I'm surprised no canonical solution exists.


I want to create a temporary file and pipe some text into it using a makefile. In bash, I can create a temp file and pipe text into it like so: temp_file=$(mktemp) echo "text goes into file" > ${temp_file} cat ${temp_file} rm ${temp_file}  Output when running it (as expected):     text goes into file  When using the same code in a makefile, I get the following output: makefile: test:     temp_file=$(mktemp)     echo "text goes into file" > ${temp_file}     cat ${temp_file}     rm ${temp_file}  $make test     echo "text goes into file" >  /bin/sh: -c: line 1: syntax error near     unexpected token `newline' /bin/sh: -c: line 1: `echo "text goes into     file" > ' make: *** [makefile:18: test] Error 2  Any idea what I'm doing wrong here or if I'm missing any special makefile syntax rules?

I'm trying to run a simple script- clone a git repository into a certain directory, then cd to this directory in order to execute an installation script.  This script is in a Makefile.  But the cd seems not to be working. It doesn't find my installation script.  I added a pwd after the cd in the script, and it shows me the directory from where I'm executing the script, not the directory where I cd into.  What's the problem?  git clone http://somerepo ~/some_dir cd ~/some_dir/ pwd python myscript.py install   =>   pwd: /hereIsPathToDirectoryFromWhichIRunTheScript     python: can't open file 'setup.py': [Errno 2] No such file or directory   It also doesn't work with ./setup.py.  If I enter the absolute path ~/some_dir/setup.py the script fails later because it's trying to access resources in the same folder.


I have a controller that does simple queries of data for a visualforce email template.  Not setting or computations, simple queries for list lines.  How do I test this?  public class QuoteLineEmailController {  public id QuoteID {get;set;}  public SBQQ__Quote__c getQuotee() { return QuoteId == null? null:     [Select Name, ID, Subtotal_Before_Trade_In__c, Trade_In__c, Total_After_Trade_In__c, Opportunity_ID_Number__c,                 Special_Incentive_Total__c, SBQQ__NetAmount__c, Net_Amount_Internal__c,                 Internal_External_Difference__c, Approved__c, CurrencyIsoCode      FROM SBQQ__Quote__c       WHERE ID = :QuoteID];   }      public list<SBQQ__QuoteLine__c> getQuoteLines() {      list<SBQQ__QuoteLine__c> QLI = [SELECT  Name, SBQQ__ProductCode__c, SBQQ__Quantity__c, SBQQ__ListPrice__c,                                        Discounts__c, SBQQ__NetPrice__c, SBQQ__NetTotal__c, Internal_Discounts__c, Internal_Discount_Type__c, CurrencyIsoCode,                                        Net_Unit_Price_Internal__c, SBQQ__Optional__c, Net_Total_Internal__c, Internal_External_Difference__c, Tier__c,                                       Trade_In_Discount_Grouping__c, Order_Admin_Description__c, Product_Name_and_Description__c                                     FROM SBQQ__QuoteLine__c                                      WHERE SBQQ__Quote__c = :QuoteID ORDER by Name];      return QLI;                          List<SBQQ__QuoteLine__c> result = [SELECT   Name, SBQQ__Optional__c, Trade_In_Discount_Grouping__c                                     FROM SBQQ__QuoteLine__c                                      WHERE SBQQ__Quote__c = :QuoteID ORDER by Name];     return result;     }  public Boolean showTradeInSection { get {   List<SBQQ__QuoteLine__c> all_qli = getQuoteLines();   Boolean result = false;   for (SBQQ__QuoteLine__c qli : all_qli) {     if (qli.Trade_In_Discount_Grouping__c == 'Additional Discounts') {       result = true;       break;     }   }   return result; } private set; }  public Boolean showOptionalSection {     get {   List<SBQQ__QuoteLine__c> all_qli = getQuoteLines();   Boolean result = false;   for (SBQQ__QuoteLine__c qli : all_qli) {     if (qli.SBQQ__Optional__c == TRUE) {       result = true;       break;     }   }   return result; } private set; }     public list<SBQQ__QuoteLine__c> getCSVQuoteLines() {      list<SBQQ__QuoteLine__c> CSVQLI = [SELECT   Name, SBQQ__ProductCode__c, SBQQ__Quantity__c, SBQQ__ListPrice__c, Order_Number__c,                                      Price_List_Name__c, PRICE_MODF_NAME2__c, PRICE_MODF_NUMBER2__c,                                      User_Description__c, Internal_Discount__c                                     FROM SBQQ__QuoteLine__c                                      WHERE (NOT SBQQ__ProductCode__c LIKE '%Bundle')                                         AND SBQQ__Quote__c = :QuoteID ORDER by Name];      return CSVQLI;                      }  }

How do I write a unit-test / test class for a trigger?  What are my options?   Inline with the trigger?  New Class?


While studying, I came upon  this problem: "What is the largest possible volume a right circular cylinder can have if it is inscribed in a sphere of radius 5?" The answer was shown as (500*pi)/(3*sqrt(3)). The explanation simply told me to find and substitute a volume equation, then use derivatives. I did not fully understand this problem with this short explanation. Could someone offer a detailed explanation to this problem?

Find the height of a cylinder of maximum volume inscribed in a sphere of radius R.   How do I solve this? I found something online but I don't get why R is the red line in their drawing.


In working on an Euler problem as a new Java programmer, I have encountered something peculiar related to printing an array.  I do not understand why this is happening - the individual values appear to be correct, when printed individually, but the toString() is clearly creating a string which is not what I expect.  I would have expected either a compile error, or the array to be put into a concatenated list. Neither of these happened.  Note: I am not interested in "how to print an array?" but rather understanding why the toString() does NOT print the array. There are plenty of resources online available to find how to do so.  public class example {      public static void main(String[] args) {          /* Setup a string/int array converion*/         int i=0;         String nums = "123456";         char[] splitNums = nums.toCharArray();         int[] ints = new int[nums.length()];          for (char c : splitNums) {             ints[i++] = Character.digit(c,10);         }          //Print using the string/char[]         System.out.println(nums);         System.out.println(splitNums);          //Values are clearly there         for (int j : ints){             System.out.println(j);         }          //What is toString() doing?          System.out.println(ints.toString());      }  }   Output:  123456 123456 1 2 3 4 5 6 [I@4b71bbc9

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


Make a conjecture about a formula for the product: $\left(1−\frac14\right)\cdot\left(1−\frac19\right)\cdot\cdots\cdot\left(1−\frac1{n^2}\right)$ for all natural numbers $n$ with $n \ge 2$. Then, state a theorem about the formula and use mathematical induction to prove your theorem. Any help appreciated!  I don't know what the conjecture is, thats what I need help with. All I found was the result is always between 0 and 1. I don't know if there should be something more to that or not.

So I have to prove the following using induction.  ${\displaystyle \prod_{i=2}^{i=n} \left(1-\frac{1}{i^2}\right)} = \frac{n+1}{2n}$  I showed the basis step that if $n=i=2$, then the two functions are equal $\frac{3}{4}$, and I know that the induction step involves simplifying the function where $n=n+1$. But I'm not sure how to do it with the following algorithm. I am quite confused. Can someone show me how I can prove this in the induction step?


People can take a risk by engaging the autopilot of alien spaceships discovered in an alien space station. Sometimes they strike it rich. Sometimes they die a horrible death. Probably written in the eighties or earlier. I think its an entire series instead of just one novel. Pretty sure its by a big name in sci-fi, too.

I am looking for a novel that I'd love to re-read it with my wife (my 13-year old self must be proud of me I guess). Key Plot points The plot was about humanity finding an alien station on an orbit of Earth. (I'm not sure if it wasn't Moon itself). On this station there were thousands of ships ready to travel so there rose a company that paid people to get on those ships and explore the galaxy. The problem was humans didn't understand how to steer those ships so they had to rely on preset targets. Of course there was no telling where particular ship was to go and fair amount of them never returned. Chronology and other relevant information I read it as an early teenager back in early 2000s. It was Polish translation of a foreign (possibly English) story. I think (not sure) that the book wasn't new at the time. It was just one of those books you dig out in a library and take to see if it's good. I don't recall cover either and even if I did it'd be of the Polish version. Additional information could be that the narration was led along the psychoanalytics of the main protagonists where he relives his memories from inside the station and his journeys.


cost = [[-1]*2]*2   matrix = [[2,3],[4,5]]   for i in range(2):       for j in range(2):            if i == 0:                cost[i][j] = matrix[i][j]           print(cost)   I am expecting output  [[2,3],[-1, -1]], but the actual output is [[2, 3],[2,3]]. I am not understanding that why are second-row elements are getting changed along with the first row?

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I have jQuery code which is never executed. When I'm trying the same code in the browser console it works, so I don't understand why my code is never executed.  HTML CODE :
      {$valeur}
          {foreach $reponse as $ligne}              <input type="radio" name="answers" id="answer_{$ligne@iteration}" value="{$ligne@iteration}"/>$ligne
          {/foreach}

   Update :   document.addEventListener("DOMContentLoaded", function() {   setTimeout(function(){     $.post(ajax_path+"bla.php", {} , function(response) {           $('#quest').html(response);           $('#quest').collapse("show");     })     .fail(function(jqXHR, textStatus, errorThrown) {         {/literal}         toastr.error(__['Error'], __['Error']);         {literal}     });   }, 50);    $('input[name=answers]').on('change', function () {       $(this).closest("form").submit();     }); });

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Just got to China. (Got my game from the American app store.)  Maps are barren. No pokémon. No gyms. No pokéstops.  Forbes says:      For the hit mobile game Pokémon GO to come to China, it would require nothing short of a total game redesign.   How to play Pokémon Go in China?

I'm from the United States and I'll be visiting Canada soon. Since Pokémon GO is not out for Canada yet, would I still be able to play and catch Pokémon in Canada seeing as my phone/game/account all originate from the United States?  For that matter, will I be able to play Pokémon GO in Canada once it is released in Canada? Or am I restricted to playing in the United States only?


The hydrogen is one proton and the helium is two protons and two neutrons. Neutron is a little heavier than the proton. But there is something strange. Where is the mass defection? As a result, the helium should be heavier than the sum of four protons, but it is not. So I guess the reason for binding energy. But I can't understand. In the picture, the helium's binding energy is bigger than hydrogen's. And particle's mass ( 4 protons < 2 protons and 2 neutrons) and binding energy (hydrogen < helium) Through the E=mc^2, isn't right the helium's mass bigger than the sum of 4 hydrogens?

I think I am confused between the mass defect of just splitting up a nucleus into its component nucleons and the mass defect involved between the two sides of a nuclear transmutation reaction. I assume the problem refers to the second, and the answer is B by just plugging in the numbers of the table. However can somehow please explain why the mass of the left side of the reaction is less than the right? I thought when you SPLIT up an atom (as in the Lithium to 2 Heliums) you have to put in energy therefore the mass-energy should be higher in the product side?   Thanks in advance!


I tried to do install yandex browser. Something went wrong and now i get this message:  N: Ignoring file 'yandex-browser.list.save.1' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension N: Ignoring file 'yandex-browser.list.save.2' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension E: Type 'andex.ru/yandex-browser/deb' is not known on line 1 in source list /etc/apt/sources.list.d/yandex-browser.list E: The list of sources could not be read. N: Ignoring file 'yandex-browser.list.save.1' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension N: Ignoring file 'yandex-browser.list.save.2' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension E: Type 'andex.ru/yandex-browser/deb' is not known on line 1 in source list /etc/apt/sources.list.d/yandex-browser.list E: The list of sources could not be read.   Can somebody help me? Im new to linux.When i tried to remove file from directory,it said i dont have permission to do that,i think. Thanks

N: Ignoring file 'yandex-browser.list.save.1' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension N: Ignoring file 'yandex-browser.list.save.2' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension E: Type 'andex.ru/yandex-browser/deb' is not known on line 1 in source list /etc/apt/sources.list.d/yandex-browser.list E: The list of sources could not be read.   How can I fix this?