How can I possibly do this kind of noise effect in Photoshop?

Do you know how can I apply this kind of noise effect? (image attached) Seems like it somehow needs some gradients for that to have the effect, any help would be really appreciated, thank you! (Illustration is not mine)


So I was sorted into Horned Serpent in Ilvermony on Pottermore.   What are the other ones?


Red Dwarf, backwards: why is writing reversed?

In the Red Dwarf episode Backwards, the crew travels in time to a time after the end of the universe. It is established that universal expansion has reversed, and time with it. So they are on earth in the modern day, but everything takes place reversed in time.  However, writing is spelled backwards. If they're in the present, but time is reversed, why is the writing now backwards?  Edit: While some people feel the answer to this may be identical to an unrelated question about an unrelated episode. The question is not the same question.


\begin{align}f(x) &= \dfrac{e^{1/x}}{x^2}\\ x_{n+1} &= f\left( \dfrac{1}{x_n}\right)\end{align} Show that $x_n$ is convergent and that its limit is $0$.    It is very easy to find the limit from the recurrence relation. Just plugging $l$ instead of the terms of the sequence. But how do I show it is convergent?   I tried to evaluate the difference $x_{n+1}-x_n$ but its a messy calculation... Also I tried using the function monotony. But I don't see how it tells me something about the function


Balancing chemical equations using linear algebraic methods

I know there are already plenty of questions on this site regarding this topic but I am having difficulty with a particular chemical equation.  I am trying to balance the following:  $$ { C }_{ 2 }{ H }_{ 2 }{ Cl }_{ 4 }\quad +\quad { C }a{ { (OH }) }_{ 2 }\quad \xrightarrow [  ]{  } \quad { C }_{ 2 }{ H }{ Cl }_{ 3 }\quad +\quad Ca{ Cl }_{ 2 }\quad +\quad { H }_{ 2 }{ O } $$  The system of linear equations produces the following augmented matrix:  $$ \begin{pmatrix} 2 & 0 & -2 & 0 & 0 & 0 \\ 2 & 2 & -1 & 0 & -2 & 0 \\ 4 & 0 & -3 & -2 & 0 & 0 \\ 0 & 1 & 0 & 1 & 0 & 0 \\ 0 & 2 & 0 & 0 & -1 & 0 \end{pmatrix} $$  With the rows in the following order: Carbon Hydrogen Chlorine Calcium Oxygen  In row echelon form this reduces to:  $$ \begin{pmatrix} 1 & 0 & 0 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 & 0 & 0 \\ 0 & 0 & 1 & 0 & 0 & 0 \\ 0 & 0 & 0 & 1 & 0 & 0 \\ 0 & 0 & 0 & 0 & 1 & 0 \end{pmatrix} $$  Which would indicate that: x1 = 0; x2 = 0; x3 = 0; x4 = 0; x5 = 0 which is obviously not correct. What have I done wrong?


bibtex problem with year vs date in book entry

So I need to use a custom bibtex style for my thesis, and I have a bibtex entry like  @book{Grupen,     author={Grupen, Claus},     title={{Big Bang Nucleosynthesis}},     publisher={Astroparticle Physics, Springer},     date={2005}, }   which will compile, but gives a warning  Warning--empty year in Grupen   and, logically, does not display a year in the citation for this entry. If I try to change the entry to  @book{Grupen,     author={Grupen, Claus},     title={{Big Bang Nucleosynthesis}},     publisher={Astroparticle Physics, Springer},     year={2005}, }   substituting date with year, then I get an error:  You can't pop an empty literal stack for entry Grupen while executing---line 2529 of file mitthesis.bst    But mitthesis.bst is only ~1200 lines long, so I am totally baffled about where the problem is. The entry for book looks like this:  FUNCTION {book} { output.bibitem   author empty$     { format.editors "author and editor" output.check       add.blank     }     { format.authors output.nonnull       crossref missing$         { "author and editor" editor either.or.check }         'skip$       if$     }   if$   format.btitle "title" output.check   crossref missing$     { format.bvolume output       format.number.series output       format.publisher.address output     }     {       format.book.crossref output.nonnull       format.date "year" output.check        }   if$   format.edition output   format.note output   fin.entry }   Thanks in advance! ---------- Edit to add minimum test case:  main.bib:  @book{Grupen,     author={Grupen, Claus},     title={{Big Bang Nucleosynthesis}},     publisher={Astroparticle Physics, Springer},     year={2005} }   test.tex  \documentclass[12pt, twoside, singlespace]{article}                   \begin{document} asdf\cite{Grupen}  \bibliographystyle{mitthesis} \bibliography{main}  \cleardoublepage \thispagestyle{empty} \mbox{}  \end{document}     and mitthesis.bst is too big to paste here, but it is


What is the difference between Process builder and workflow?

I am learning process builder, I am getting confused then what is the difference between process builder and workflow. I mean when to use workflow and when to use process builder? If possible please explain me with examples.


Every undergraduate student knows that there are (exactly) two non-abelian groups of order 8: Dihedral ($D_8$) and Quaternion ($Q_8$). The group $Q_8$ has many interesting properties; simple of them are: it has unique element of order $2$, all subgroups are normal, etc. A property, which is strange and not obvious, the group $Q_8$ has, is that there is no group $G$ such that $G/Z(G)$ is isomorphic to $Q_8$. On the other hand, $D_8$ has no such property; there are (infinitely many) groups $G$ such that $G/Z(G)$ is isomorphic to $D_8$; example - $D_{16}$.   The question, I would like to ask, is related to a property of $D_8$, which is not shared by $Q_8$. There are (infinitely many) groups whose derived subgroup is $Q_8$; example- $SL_2(3)$. For groups $G$ of order <100, one can check on GAP that $D_8$ is not a derived subgroup of any group. The natural question is then:  Question 1: Does there exist a finite/infinite group whose derived subgroup is equal to $D_8$?  Question 2: Does there exist a finite/infinite group whose derived subgroup is equal to (general) dihedral group $D_{2n}$ of order $2n$ ($n>2$)?


Why is it "take something with you" and not "take something with yourself"?

Why are reflexive pronouns not used in the following examples? The sentences numbered 1 are what people say, but the sentences numbered 2 are what I understand should be be used, as the subjects of the sentences are doing some actions on themselves. Examples from the Oxford dictionary:   I forgot to take my bag with me when I got off the bus.  I forgot to take my bag with myself when I got off the bus.    and   Please don't forget to take your passport with you.  Please don't forget to take your passport with yourself.


What are integer solutions to $x^2+7=y^3$

Question: What are the integer solutions to$$x^2+7=y^3\tag1$$   Through Wolfram Alpha, there seems to be only two solutions. Namely, $$\begin{align*} & (x,y)=(1,2)\\ & (x,y)=(181,32)\end{align*}\tag2$$ So I'm wondering about how would you find those solutions. And is there a way to use some sort of transformation to make $(1)$ into a more recognizable form.  And furthermore, is there a formula to determine other type solutions similar to what you already have?


How to write complexity classes in LaTeX?

I would like to write the complexity classes P, NP, NP-complete and NP-hard in LaTex with the mathematical format as follows:


Presumably after an update, google chrome has very serious problems with page rendering. I want to downgrade it. (Switching to vmlinuz.old and initrd.img.old did not help).  $ apt-cache policy google-chrome-stable google-chrome-stable:   Installed: 35.0.1916.153-1   Candidate: 35.0.1916.153-1   Version table:  *** 35.0.1916.153-1 0         500 http://dl.google.com/linux/chrome/deb/ stable/main i386 Packages         100 /var/lib/dpkg/status   on a computer where google chrome works ok:  $ apt-cache policy google-chrome-stable google-chrome-stable:   Installed: 34.0.1847.132-1   Candidate: 35.0.1916.153-1   Version table:      35.0.1916.153-1 0         500 http://dl.google.com/linux/chrome/deb/ stable/main amd64 Packages  *** 34.0.1847.132-1 0         100 /var/lib/dpkg/status   (If I had the .deb on the 2nd computer, everything would be easier. But there's no .deb. And no old .deb's on the google site.)  So I try:  $ sudo aptitude install google-chrome-stable=34.0.1847.132-1 Unable to find a version "34.0.1847.132-1" for the package "google-chrome-stable" Unable to find a version "34.0.1847.132-1" for the package "google-chrome-stable" No packages will be installed, upgraded, or removed. 0 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B of archives. After unpacking 0 B will be used.   You see, it does not work. The Synaptic manager also shows no version that I could set.  So, how do I downgrade google-chrome-stable?  Probably someone knows an archive of old google-chrome .deb's?


I tried to watch a dvd and found that VLC was not installed. When I went to the Ubuntu software center I got this message when trying to install VLC. I do not know why. Here's the ouput:  "This error could be caused by required additional software packages which are missing or not installable. Furthermore there could be a conflict between software packages which are not allowed to be installed at the same time.  The following packages have unmet dependencies:  vlc: Depends: vlc-nox (= 2.1.4-0ubuntu14.04.1) but 2.1.4-0ubuntu14.04.1 is to be installed      Depends: libc6 (>= 2.15) but 2.19-0ubuntu6.4 is to be installed      Depends: libfreetype6 (>= 2.2.1) but 2.5.2-1ubuntu2.2 is to be installed      Depends: libgcc1 (>= 1:4.1.1) but 1:4.9.1-0ubuntu1 is to be installed      Depends: libqtcore4 (>= 4:4.8.0) but 4:4.8.5+git192-g085f851+dfsg-2ubuntu4 is to be installed      Depends: libqtgui4 (>= 4:4.8.0) but 4:4.8.5+git192-g085f851+dfsg-2ubuntu4 is to be installed      Depends: libstdc++6 (>= 4.6) but 4.8.2-19ubuntu1 is to be installed      Depends: zlib1g (>= 1:1.2.3.3) but 1:1.2.8.dfsg-1ubuntu1 is to be installed"   Thanks in advance for any help.


as all know this syntax will print file is empty   [ -s file.name ] || echo "file is empty"   but what in case file is with spaces or TAB or blank spaces ? , but without any real character as a-z 1-9 and so on  so I use this  [[ $(tr -d "\r\n" < file.name |wc -c) -eq 0 ]] && echo "File has no content"   but when we set that  echo "       " >file.name   then the follwing syntax will not print - File has no content   [[ $(tr -d "\r\n" < file.name |wc -c) -eq 0 ]] && echo "File has no content"    so we are in trouble here  how to verify file is empty but can include spaces / TABs / blank  or empty without anything  goal - verify file is empty but can include spaces / tab /blank lines , or empty without any spaces / blank lines / empty tab


Is there anything in real world (nature) which is uncountable ( i. e. infinite but not countably infinite)?

In set theory I read that the sets are either finite or infinite. If they are infinite then there are also two categories countably infinite or uncountable. Natural numbers $\Bbb{N}$, integers $\Bbb{Z}$, rational numbers $\Bbb{Q}$ etc. are examples of countably infinite sets , whereas real numbers $\Bbb{R}$, irrational numbers are very well known examples of uncountable sets.  Today I was thinking about counting objects in our day to day life. That time I realize that we can count each and every object.   For example :   1) Suppose I decided to count number of sand particles on a beach, even though the number is huge but one can count them one by one. ( I also want to know that are they infinite or just finite ( a big natural number will be representing their quantity )).  2) Same thing when I think about number of leaves on big tree, they are definitely finite.  3) Stars in the sky ( I read on internet that there are approx $10^{24}$ stars in universe). etc.  Similarly many objects seems to be finite ( or countably infinite* ( * please correct me if I'm wrong)) .  So my question is do we have any object in real world which is uncountable.   Thanks in advance !


What is the difference between specialization and specialisation?

What is the difference between specialization  and specialisation ? where am i use   specialization   and specialisation  what does meaning of both.?


How do I prove that $\sum_{i=1}^m \cos^2\left(\frac{2\pi i}{m}\right) = \sum_{i=1}^m \sin^2\left(\frac{2\pi i}{m}\right) = \frac{m}{2}$?

I haven't had any good ideas nor found any helpful identities so far, so I'd appreciate some help.  Also, here $m > 2$.  Update: Thanks to the hints and to  previous post I managed to get to the conclusion I wanted. Thanks guys.


Since we have multicast delegates, why do we need events?

I was asked this question in an interview, and either I'm suffering from brain-lock or just plain dumb, but I didn't have an answer.


Resizing point on zoom out using OpenLayers

I need to resize a point on zoom.  When you deep zoom the point get larger and on zoom out the point is smaller.     seems to have exactly the answer.  @CaptDragon posted an image of exactly what I need and then a demo, HOWEVER the demo is now dead.  I've looked into the API that @Mapperz mentions but for whatever reason cannot get my point to resize larger when zooming in.  Can anyone provide a working example similar to that of @CaptDragon?


How do I compare a Range to a NamedRange?

I've defined a named range called Ticker that references 'Sheet 1!A1'. I'd like to know when this cell changes value, so that I can run trigger some functions to run. I know that onEdit seems to be the way to do this: function onEdit(e) {   var range = e.range;    if(range == NamedRange('Ticker')) {     // do something...   } }  I'd like to know the correct syntax for making the named range comparison:   if(range == NamedRange('Ticker')) {     // do something...   }


What are the dimensions of the stress energy tensor in relativity?

Can anyone tell me what the dimension of the stress energy tensor is? Also, if it represents energy density, will calling it kinetic or potential energy be appropriate?


Matrix and it's Transpose have the same eigenvalues?

I have the following question in my book for mathematics: "Show that $A\in M_{n\times n}$has the same eigenvalues as $A^\tau$.  I can see how to do this for a $1\times 1,\ 2\times 2$, etc.  I would just always calculate the characteristic polynomial $p(\lambda)$, where $p(\lambda) = \det (A - \lambda I)$ and than solve for $\lambda$.   Now I can't really wrap my head around how to do this for a general $n\times n$ matrix. I think this would probably involve induction over $n$, but I'm not really sure how and how to get even started.


I have hesitated putting this on here as I have so few details but here goes.  I was read this story in infant school in the mid 80's.     The story has children in it at least 1 boy and 1 girl these may be siblings.    They find a tree with a door in it not at the base but half way up.   The tree is in some woods near a house.    They manage to get through the door.....  and that's where my memory goes blank grrr.   The story had a very fantasy feel to it and I remember the book been large and thick so it might of been in a book with several stories. It was definitely hardback.  I don't remember the cover unfortunately.


What is LookDev/Material Preview mode for in 2.8?

I am struggling to understand what is LookDev/Material Preview mode for and how do I render an image which I see in this mode into a picture or video.  I tweaked my material to look how I want in LookDev mode, but rendering via F12 seems to be using the Rendered Mode and the material looks totally different.     What am I doing wrong and why this sudden bright pink glow in my material?


Sequence of fractions $c_n = a_n / b_n$ converges to irrational $x$, prove $a_n$ and $b_n$ diverges to infinity.

$a_n$ and $b_n$ are sequences of natural numbers, $\lim_{n->\infty}\frac{a_n}{b_n} = x$, where $x$ is irrational. Prove that $a_n$ and $b_n$ diverge to infinity.  I've proved that if a sequence of natural numbers converges to some number, then this sequence has to be constant for big $n$.


Find the limit of the following sequence:  $$\lim_{{n}\to {\infty}}\frac{1^p+2^p+\cdots+n^p}{n^{p+1}}=?$$  I've tried using the Stolz-Cesaro theorem. I've set $a_n=1^p+2^p+\cdots+n^p$, and $b_n=n^{p+1}$.  After some transformations I got $$\lim_{{n}\to{\infty}} \frac{(n+1)^p}{(n+1)^p-n^p},$$ but after expanding the binomials, I could not make any transformations that would give me a satisfactory result. Can you help me please? Thank you very much.


subtitle syncing with timings copy-paste?

I've got 2 subs in 2 different languages for a video. One is synced, the other has all the right lines but wrong timing [NOT fixed nor progressive delay]: the easiest thing would be changing the timings of the latter with the ones from the former, kind of copy paste time codes. Which subtitles editor for Ubuntu has the capabilities to accomplish/would be more suited for this task?  EDIT: Unfortunately there's no fixed delay, such that moving the subs by a certain amount of time could do it. They are simply wrongly synced (and that doesn't have to do with framerate either). I need an editor which can kind of copy and paste the "timing" column beside the "text" column  EDIT 2: please people be civilised and read before marking as a duplicate. I'm not looking for a general sub editor, I'm looking for one with a particular feature NOT even mentioned in the question you would like to redirect me to. If it was, would you be able to point that out? Sorry for any misunderstanding I might have created, I'm only looking for an answer, which unfortuntely is something I haven't got so far  FOR ANYONE WITH THE SAME ISSUE stumbling upon this question, the answer to what I was looking for is in the thread posted by smurfendrek123, containing nice programs that will help you (under Wine) to achieve copy-paste of timings:


I expected to find answers along the lines of quantum-computing insight into attacking AES; however, answers on this question aren't applicable because "Quantum computers give a quadratic speedup on a (sic) general search problems".  Let us suppose the very worst case: P=NP by constructive proof. Therefore, 3-SAT and direct polynomial attacks on AES and all other standard-model symmetric ciphers.  How do we construct something that takes a serious attack to break besides using ECB and sending one block per key? Do quantum-proof symmetric ciphers with properties other than those of the one-time pad actually exist?  I think I can prove that if you use any kind of MAC other than polynomial evaluation MAC (or something else with its characteristic deniability) your cipher must fail.  I can prove that ciphered random data is possible because you can't break ECB over random data, but that proof is useless.  I am aware of the implausibility of ending up in this world of P=NP. I am also aware of this old post describing very good reasons why P=?NP is a poor model for breakability. I am interested in this problem because I am reasonably certain that any solution must use an encryption method that is, of itself, deniable.  The one-time pad has this property; however, I'd rather have an answer that offers something less unwieldy, if possible.


What is the easiest way to grep the command output?

I a trying to grep for certain string after issuing the grpck -n ALL command so when trying grpck -n ALL | grep -i format, for example, I still see the whole output and not just the lines containing the format string.  I know I could direct the output to a file and use grep on that file but it has to be an easier way.  The grpck is just an example as I have noticed other commands that don't support grep.


Can I find the connected components of a graph using matrix operations on the graph's adjacency matrix?

If I have an adjacency matrix for a graph, can I do a series of matrix operations on the adjacency matrix to find the connected components of the graph?


Creating a point corresponding to the maximum elevation of a DEM

I am wondering how can I create a point corresponding to the maximum elevation value of a DEM. I mean, from the DEM I can easily get the maximum elevation. For the sake of a viewshed analysis, I would like to create a point feature corresponding to the spot with maximum elevation. I guess it is simple, but I am having difficulties in finding the right procedure.   I am using arcgis 10.1 (with advanced license).


Using ArcMap add x y data, points are in wrong location

According to ArcGIS  when I add a CSV with the "add XY" tool, * "The tool automatically adopts the data frame’s coordinate system"*.  Since I'm importing a csv with no defined coordinate system, I would expect that importing a csv with only lat/long values and a name, that it would produce a data set of points in the origional dataframe's coordinate system at the lat and long given in the table.  That is not what's happening.  I'm trying to add a CSV table or Excel file (tried both) of a list a radio sites around LA.  The project is NAD83, as I believe that's an FCC standard.  I'm trying to add the table using the ADD XY Data tool, placing the Longitude column in the X field and Latitude in the Y field ( Fig 1).  On the map the points end up half way to Hawaii however.  If you look at the identities window (Fig 2),  you'll see that my lat/longs in the identities table don't match the locations.  For example "Avalon" has a lat of 33.34101 in the table, but 27.196035, and the long is about 20 degrees off also (See green and orange circled values in Fig 2).  In my table below, there are only those values, where you can see where the lat and long values are coming from.  I've also tried a table where i removed the hyper link column, but the result is the same.  Also (fig 4), shows my layer properties for my point data feature. Does anyone have idea what's going on? Im thinking the CSV file I'm bringing in has no projection defined.  I would think the lat and long should just line up to the project coordinates. .     Fig 1   Fig 2   Fig 3   Fig 4


Is the tag info page not available on mobile theme?

I was surfing SO on my iPhone, and wanted to see the info (tag-wiki) page for a tag, but didn't find it. Clicking on the tag always leads to the list of question, and there is no other link to the tag wiki. Is it not available on the mobile site?


Can you save the current desktop background as an image?

I've deleted a photo by mistake. I have the photos as my desktop background. Is there any way that I can take it and save it?


The standard motherboard USB 3.0 connection looks like a standard 20 pin IDC male with 1 pin missing, however IDC pin pitch is 2.54 mm but  image shows it as a 2.0 mm pitch.  Is there a name for this connection?    Also, a bonus question, does anyone manufacture a lockable variant of this connection?  Thanks


Removing items from a javascript array - possibly using JavaScript's delete function?

I'm using Flot JS charts. I'm trying to remove one of the plot series from my data array completely with jquery or plain javascript.  This is what my data array looks like:  [  {   "label" : "Citrix PV Ethernet Adapter",   "data": [[1,0], [2,0.01], [3,0.02], [4,0.01], [5,0.01]]  },  {   "label" : "Virtual Adapter _1",   "data" : [[1,0], [2,0], [3,0], [4,0], [5,0]]  } ]   I want to be able to have the ability to completely remove one of the entries, preferably by using the "label" properties value, so it looks like this:  [  {   "label" : "Citrix PV Ethernet Adapter",   "data": [[1,0], [2,0.01], [3,0.02], [4,0.01], [5,0.01]]  } ]   Is this possible? I know it's possible to "toggle" the visibility of the series in Flot, but this doesn't suit in this case.  There could be many many entries in this array, I've just kept it to two for an example.  I've tried the playing around with javascripts delete function but I've had no luck so far.  How can this be done?


How to type the letter "i" with two dots (diaeresis) in math mode?

I would like to type the letter "i" in math mode, but with two (horizontally aligned) dots rather than with just one.  I know there is \ddot{i}, but that puts the two dots on top of the existing one, while \text{\"i} sets the letter in text form rather than in math mode. MWE:  \documentclass{article} \begin{document}  \begin{align*}   f(x) = \ddot i \\   f(x) = \text{\"i} \end{align*}  \end{document}   gives     How can I get the desired result? Thanks! (And I know that the two dots can lead to confusion with the second derivative.)


Prove that, for $x \in \mathbb R$ and $\delta_x > 0$, the open interval $(x-\delta_x, x+\delta_x)$ is itself an open set.   I am preparing for my exam and we will be asked to prove various theorems and I am struggling a lot with them. Frankly, I don’t have an idea of how to start. Can anyone please help with this proof?


Is it possible to make a solid rigid evacuated "balloon" out of Beryllium or other elements or alloys?  The critical buckling pressure at which an evacuated sphere is given as $$ P_1=\frac{2E\cdot\left(h/R\right)^2}{\sqrt{3\left(1-\nu^2\right)}} $$ where $E$ is , $h$ the shell's thickness, $R$ the radius to the midsurface shell, and $\nu$ is .  Of course this is theoretical and experimental and literature values for submersibles hover around 1/4 of the theoretical pressure.  Beryllium has the following properties:   Density=1.85 g/cm$^3$ Young's Modulus=287*10$^9$ Pa Poisson Ratio=0.032   Calculating the upward force, buoyancy at 101.3 kPa atmospheric pressure and Radius of 10m gives 4.24*10$^8$ N. The weight of this sphere with shell thickness 1mm has 2.32*10$^7$ N downward force of Beryllium material, so it will theoretically float at ground level.   Calculating the critical buckling stress of this beryllium sphere is 331.57 kPa, which is 3.27 times the atmospheric pressure of 101.3 kPa, so theoretically it won't buckle. But in experimentation done in earlier experiments as stated before, due to construction/material non-ideal situations, the critical buckling formula predicts about 4 times stronger than actual, so it would need about 400 kPa, not 331 kPa as Beryllium sphere with this specification would hold. Increasing the strength capability also increases weight and therefore lowers it's ability to float, but Beryllium is the closest element with this situation I have calculated that could work if ideal (I have only been using periodic table elements and household materials)  Is it possible with an alloy of elements? Using the equations for buckling and buoyancy, the following is needed. What alloys/materials come to your mind?  Material considerations:   Material with larger Poisson ratio Material with larger Young's Modulus Less dense material Construction (is it possible)   Material considerations affect on lift   Thickness can be larger, increases strength by the squared. But also increases weight. If a material with lower density with similar structural properties as Beryllium is used, it would help. Radius can be lower for same reason, but also lowers buoyancy (volume)   My other designs (don't worry about these just yet, just if you are curious is a vacuum sphere with a pressurized "outer tube" with spokes in tension (carbon fiber nanotubes maybe) to keep the 2 spheres in position. Another is a spherical truss out of carbon fiber nanotubes with a light membrane around. The truss prevents the outer membrane from collapsing due to the atmospheric pressure  The "point" of this if you ask, as to why not use a traditional balloon is it can be used as a boat by filling the sphere with air, and then used as a aircraft at will by evacuating the sphere. An alternative mode of transportation for sea vessels etc.


Installing Ubuntu 10.10 I get the GRUB2 boot manager. By default is does instant booting of the first entry, i.e. you have to hold the Shift key while booting when you want to enter the menu.   How can I disable this behavior? I mean, how can I configure GRUB2 such that it always displays its menu and uses perhaps a timeout of 5 seconds for the first entry?


Animation keys on IK target instead of underlying skeleton

I have animated a skeleton (that uses circles as the IK targets for the bones) and mesh with a walk cycle using the automatic keyframe insertion. However, the keys are ending up on the circles instead of the underlying skeleton. Is there anyway to animate the underlying bones using the targets?  edit:


Proof that Darboux upper/lower sums always converge to the Darboux upper/lower integral as the partition gets thinner

I'm going through my calculus lecture notes, and at some point the following claim is made: Let $f:\left[a,b\right]\to\mathbb{R}$ be a bound function. For any $\epsilon>0$ there exists some $\delta>0$ s.t. for any partition $P$ of $\left[a,b\right]$ for which $\Delta P<\delta$, it holds that   $$\left|U\left(f,P\right)-\bar{\int}f\left(x\right)dx\right|<\epsilon$$  Where $\Delta P$ is the size of the biggest segment in the partition (The text, which is not in English, refers to $\Delta P$ as the “partition parameter”, I don't think this is the correct translation into English since I did not find any reference to it). $U\left(f,P\right)$ is the upper Darboux sum for said partition and $\bar{\int}f\left(x\right)dx$ is the infimum for the upper Darboux sums of all possible partitions.   I have failed in proving this, and it seems important, could someone supply a source where this is proved?


Why are light fixture wires allowed to be lighter gauge than house wiring on the same circuit?

why do cables joining the wall sockets in a house need to be thicker than the cables joining the light fittings? I don't understand and I need to know before I buy it.


Preposition choice - Project [in/at/for] my company

Is this acceptable to say the following:     I am working on a project in my company   Will 'for' keep the same meaning?   How about 'at'?   Is there any rule of thumb to make such choices more easily?  I looked at   but I have a feeling that my case is slightly different. Because here we have an additional noun before "company". I understand that saying: "I work at XYZ" is preferred but what if we have something else coming before? If somebody is working on a project, is he working for or at company?


bash function doesnt not work the same as commandline

I have created this bash function to recursively find a file.  ff() {     find . -type f -name '$1' }   However, it returns no results.  When I execute the command directly on the commandline, I do get results.  I am not sure why it behaves differently, as shown below.  mattr@kiva-mattr:~/src/protocol$ ff *.so mattr@kiva-mattr:~/src/protocol$ find . -type f -name '*.so'  ./identity_wallet_service/resources/libindystrgpostgres.so   Why does my function not work as expected?  I am using MacOS and bash shell.  Thnx Matt


Explore contents of a ZIP/Archive from Finder?

I've lost count how many times I've double-clicked a .ZIP file on Mac to look inside it (like Windows) only for it to auto-extract in the current location, which is rarely my preference.  Does MacOS provide a way for me to explore (and ideally edit) the content of archive files like Windows?


Logistic regression model fit assessment

I have run logistic regression on data. The concordant percentage is coming out 45. That is too low. However, Hosmer–Lemeshow test is coming out insignificant. It means we cannot reject the null hypothesis stating model fits the data well. That's good! The ctable also shows 70% of the data correctly predicted.   How contradictory results of concordant and Hosmer-Lemeshow test should be considered? How should I interpret this model?


How do I prevent LaTeX-Suite from opening files automatically when there's an error?

I'm using Vim with LaTeX-Suite. Occasionally when I compile a file with errors using <Leader>ll, the error in my source is such that the LaTeX compiler registers an error in a file deep in the bowels of my TeX distribution, say pstricks-add.tex or something, so it automatically opens this irrelevant file in the window.  Since the actual error is in my source, I'd like to surpress this behavior, and only have it open the file when I press Enter after selecting it in the Quickfix window.    Notes:  The proper, erroneous line in my source is displayed in the .log file window below the Quickfix window  I have the following in my .vimrc:  " compile to pdf                               let g:Tex_DefaultTargetFormat = 'pdf'   " pdf compile and view settings                                 let g:Tex_ViewRule_pdf = 'open -a Preview' let g:Tex_CompileRule_pdf = 'latexmk -pdf'  " ignore all warnings below level 4 let g:TCLevel = 4  " one last thing for latex let g:tex_flavor = 'latex'


How can i Randomize Unique Numbers in Java

So i'm making a game where i have to randomize 52 numbers from 1 to 52 so the order has to change i use this       class Deck {     Random r = new Random();     int[] Card = new int[52]; }


Don't Remind Me to "Consider Accept Answers" on StackExchange

Being a veteran SO user and an active SE participator, it is quite-- erm, how to put it nicely--amusing to see me being reminded again and again to "not forget to mark an accepted answer" whenever I upvote one, especially at the time when I am joining a new SE site and casting my first upvote on that site.  Since somehow SO should have all the my data already, is it possible to distinguish between a real first time user, as opposed to a veteran SO user joining a new site, so that we won't have to be bothered by all the announcements, reminders that are normally reserved for the newbies?


How to create a dynamic macro to detect if display style is enabled

I don't really have much insight on how \displaystyle actually works, i just see the difference between in-line equation like $\frac{1}{2}$ which displays a small fraction and $\displaystyle \frac{1}{2}$ which produce a bigger fraction.  My question: is it possibile to build a single macros such that (on input a,b), in line equations produces $a/b$ and in display-style equation produces $\frac{a}{b}$?


Finding $E(X\mid X>Y)$ when $X,Y$ are i.i.d $U(0,1)$

I am unable to compute conditional probability(x|x>y) in the above question. Also, I am unable to determine the region of integration for calculation of the above expectation.


Why Ubuntu doesn't load settings from my .bashrc/.profile for apps not started from bash?

At other and previous distros it was common for me to have the environment setup in .bashrc/.profile applied globally, whether I started applications from bash or not (IIRC).  Now when I start applications from launcher icons or when clicking files with associated applications, they don't inherent my environment configuration.  Why of this now?  and  How can I get the desired behavior or what's the right way for this?  Disclaimer: I've already set some vars from my .bashrc by putting the exports at a .xsessionrc file, but I'd really like an approach where I put configurations in a single file without having duplicated setup.


I installed GDebi package installer.  I tried to configure it step by step but have not been successful.  I have used the command:  sudo apt-get install -f   with the output:  Reading package lists... Done Building dependency tree Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 24 not upgraded.    I also tried:  sudo dpkg --configure -a   And:  apt-get dist-upgrade   which gives the error:  Could not open lock file /var/lib/dpkg/lock-frontend - open (13: Permission denied) E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root?   What should I do?


How to protect against purge of bash history?

Following the :     When closing multiple bash instances at the same time, there is a   known race condition that may cause the history to be cleared. This   occurs because there is no locking used when the bash history file is   written.   How can I prevent against this cause of bash history purge?  I use i3wm and I think that it happens mostly when I shutdown the computer before I manually close urxvt terminals. The command used (via keybind) for shutdown is systemctl poweroff.


Is Coulomb's law accurate for moving charges?

Can we use  to calculate the force between two charges which are not at rest? If not, what formula should be used to calculate the force? I searched it, but I couldn't find a clear answer.


Remove Win 10 password - not required but forgotten

My dad's laptop apparently has a password for Windows 10 but he doesn't need to enter it on start up - the password screen flashes by briefly with it already filled in. However, while trying to change the display settings recently, the desktop goes off for a moment, then comes back to the login screen, waiting for the password, which has long been forgotten, since it's never used. We can get past it by shutting down from the login screen and starting up again. How can we remove this password if we don't know it?


How do I draw a perfect/smooth circle using OpenGL 3.3 and GLSL? I can only find old OpenGL tutorials or ones that have a blocky circle. I would also like to be able to resize the circle to become an oval, but that is not my highest priority.


Convergence test: $\sum_{n=1}^\infty\frac{\cos(n) + i*\sin(n)}{n}$

How can I test if $\sum_{n=1}^\infty\frac{\cos(n) + i*\sin(n)}{n}$   ($i^2 := -1$)  is (absolute) convergent? I have tried to use the ratio test and the root test but I didn't succeed. Help appreciated!


When using principal components as predictors in linear regression, PC1 comes out not significant

I have a dataset with 37 independent variables and a dependent variable. In order to take care of multicollinearity among the independent variables, I conducted a PCA on them. My first principal component explains 53% of the variance in the data.  However, when I run a linear regression using top 10 PCs (explaining ~90% of the variance) as independent variables:  lm(dependent ~ PC1 + PC2 + ...))   the regression coefficient for PC1 comes to be statistically insignificant (all other 9 PCs are highly significant). I would have imagined that PC1 would have been highly significant.  Am I conceptually missing something?


How to lock Windows 7 computer automatically instead of sleeping?

After a set time period I'd like to have my computer lock. I do not want the computer to go into any kind of power saving mode, I'd just like it to lock the screen.  Which setting must I configure?


If you increase the pressure, the boiling temperature increases as well. In the other direction: if you decrease the pressure enough you could even make water boil at 18 dergees C.  However I met this strange thing in my wifes kitchen called "pressure cooker". I don't understand how you can cook things quicker with that. If you increase the pressure inside this tool, you are just increasing the cooking temperature. And thus nothing will even boil.  What did I misunderstand?


Cannot favorite or add to launcher (dock) in Ubuntu 18.04

I've literally spent 3 hours trying to add a favourite.  Some applications can be added, and some can't.  There's no error message anywhere to help you find out why it doesn't work.  The "Add to favorites" menu option is simply not offered.  I had no problems adding favorites in 16.04, but some of the same files and apps cannot be added after upgrading (or is it downgrading?) to 18.04.  Here's the "evil" desktop launcher that works fine but cannot be added as a favorite:  #!/usr/bin/env xdg-open [Desktop Entry] Version=1.0 Type=Application Terminal=false Exec=/home/russellr/bin/idea Name=Intellij-Idea Icon=/home/russellr/IDEA/bin/idea.png StartupNotify=true   Things I've tried that don't work:   dconf-editor as described  re-creating desktop files from scratch using an app to create the desktop files (gnome-desktop-item-edit --create-new) putting the files in Desktop folder putting the files in ~/.local/share/applications (and this means they don't appear on the desktop at all despite all the advice you can find on the web to say that's the right place!) writing a C program to launch the app creating a brand new account in 18.04 (on the assumption that my old account was somehow damaged after multiple upgrades)   The problem appears to be related to shell scripts, but that's not consistent.  Is there any wonder the ?


Historically our branch offices have had their own servers to do DNS, Active Directory and a few other services. But the number of people working out of our branch office has shrunk to about 4 people.  From head office we provide VPN access to all our remote users. I am proposing that instead of providing a server (and maintaining it) each user in this office instead uses VPN.  Email, File and Database access will be provided by head office in either configuration.  My question is how many users can work in the branch office before it becomes unworkable and I would need a server with site to site VPN?


Are the rules regarding absolute modifiers too absolute?

A common grammar lesson that was taught to me in the US and that I've had to teach abroad in EFL classrooms is that we're not to use adverbs of emphasis with absolute modifiers, just as we're not supposed to use them as comparatives or superlatives.  Classic egregious examples of this mistake include very unique and more perfect, which seem obviously flawed to me. Other instances of further modified absolute modifiers are similarly meaningless or contradictory in nature.  I wonder, though, if the rule that I learned isn't overly broad, and whether it's taught similarly in the UK and elsewhere. I find myself modifying absolute modifiers quite regularly, and in some circumstances I think it's not only logical and correct, but quite meaningful. Phrases like almost exactly or virtually all or practically infinite possess a specific meaning that can't really be replicated using nonabsolutes like very nearly or most or quite long.  In my own speech and writing, I use such phrases exactly as I see fit, so this isn't a request for permission, per se. I'm more curious about whether there's a more appropriate rule regarding absolutes that you rely on (and might be used in a classroom).


pgfplots import data from table with comma as decimal separator

I am trying to plot data from data files which are using the comma as decimal separator instead of a point (as is normal in SI style (French version):  ). However, even after excessive search I cannot find an option that would actually tell pgfplots to read the table with the comma as decimal separator. Minimal (not) working sample:  \documentclass[paper=a4,12pt,version=last,landscape]{scrartcl} \usepackage{tikz} \usepackage{pgfplots} \begin{document} \centering \begin{tikzpicture}     \begin{axis}[             width=0.9\textwidth,             height=0.5\textheight,             xlabel={Standardweg~[mm]},             ylabel={Standardkraft~[N]},             grid=major,             ]         \addplot table[x=Standardweg, y=Standardkraft] {Messwerte.TRA};     \end{axis} \end{tikzpicture} \end{document}   Messwerte.TRA:  Standardweg  Standardkraft 0,000000000000e+000  1,960904836655e+000 -2,349615044750e-004     3,081407308578e+000 -2,349615044750e-004     4,164415359497e+000 -2,349615044750e-004     5,441759109497e+000 -2,349615044750e-004     6,443712234497e+000 -2,349615044750e-004     7,598009109497e+000 -2,349615044750e-004     8,951524734497e+000 -6,029571522959e-001     1,002574348450e+001 -2,349615044750e-004     1,122496223450e+001 -2,349615044750e-004     1,252183723450e+001   On compilation, I get the error: ! Package PGF Math Error: Could not parse input '-2,349615044750e-004' as a floating point number, sorry. The unreadable part was near ',349615044750e-004'.. for every single number in the .TRA-file.  I know that I could find and replace every , with a . in the files, but that is not an option considering the amount of files I have to evaluate.  Also, I tried stuff like /pgf/number format/use comma, set decimal separator={{,}}, \pgfkeys{/pgf/number format/.cd,fixed,precision=2,use period} and use comma, but none of that helped and I am pretty much running out of options. The documentation for pgfplots did not give any other ideas, either.  So: How do I convince pgfplots to actually read the comma as decimal separator and to not search for the point?


How to tell whether a bash script has root privileges

I have a bash script that will only work with root privileges, so I want to test whether the user has them.  Other posts (see below) ask and answer how to know whether the user is actually running as root, but not whether the script has root privileges.  These posts say to test whether $EUID is 0.  To try this idea in the context of sudo, I wrote a bash script /tmp/a.sh:  #!/bin/bash echo $EUID   The following two commands were run as a non-root user with sudo privileges on Ubuntu 16.04. If the $EUID suggestion worked in the context of sudo, the second command would have printed 0 instead of a blank line.  $ /tmp/a.sh 1000 $ sudo /tmp/a.sh  $    FYI, an example of the related posts I am referencing is:


Recommended installation for Asus EEE 1015PEM Netbook

I just got my Asus EEE PC 1015PEM netbook with Windows 7 starter... obviously, I'd like to install Ubuntu (not sure yet if I'd like to dual boot or completely remove win7).  Anyway, I never had a netbook before. I know about unity but heard some bad stuff about it, so I wonder if I might be better sticking to the desktop edition. What do you think? any recommendations?  Also, should I use the 32 bit or 64 bit version?


why can't I see the frame number in beamer after my Mac update?

I have made a presentation with beamer and could see the frame number but i updated my MacBook to Mohave last week and I can't see the frame number after that? what should I do?I didn't change anything.  \documentclass[8pt,mathserif]{beamer} \mode<beamer> \mode<presentation> %--------------------------------- \usepackage{xcolor,colortbl}  \newcommand{\mc}[2]{\multicolumn{#1}{c}{#2}} \definecolor{Gray}{gray}{0.85} \definecolor{LightCyan}{rgb}{0.88,1,1} %------------------------------------------- \usepackage{hyperref} \usepackage{multimedia} \usepackage{amsmath} \usepackage{graphicx} \usepackage{tikz} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{fixltx2e} \usepackage{graphicx} \usepackage{longtable} \usepackage{float} \usepackage{wrapfig} \usepackage{soul} \usepackage{textcomp} \usepackage{marvosym} \usepackage{wasysym} \usepackage{latexsym} \usepackage{amssymb} \usepackage{hyperref} \usepackage{times} \usepackage{empheq} \usepackage[most]{tcolorbox} \usepackage{textpos} \usepackage{fancybox} \hypersetup{pdfpagemode=FullScreen} \newcommand{\comments}[1]{}  \logo{\includegraphics[scale=0.05]{logo1}} \usetheme{Luebeck}  \usefonttheme[onlylarge]{structuresmallcapsserif} \setbeamertemplate{navigation symbols}{} \setbeamercovered{dynamic}  \graphicspath{{./res/}} \usefonttheme[onlysmall]{structurebold} \setbeamerfont{title}{shape=\itshape,family=\rmfamily} \setbeamercolor{title}{fg=red!80!black,bg=red!20!white} \title{\bf{ Effective dynamics}} \author[SS]{ \textcolor{blue}{SS}}  \institute[ BB]{   Supervisor:\\ Dr. F} \beamertemplatenavigationsymbolsempty  \setbeamerfont{page number in head/foot}{size=\small} \setbeamertemplate{footline}[frame number]  \begin{document} \begin{frame}<handout:0> \titlepage \end{frame} \begin{frame} \frametitle{Outline} \tableofcontents[pausesections] \end{frame} \end{document}


How many Hamiltonian cycles are there in a complete graph $K_n$ ($n\geq 3$) Why?

It seems to me like the answer should be $n!$. Since you can first select the first vertex, then select each remaining vertex until you've got them all in a permutation.  My textbook, however, says that the answer is $(1/2)(n-1)!$  Unfortunately, it doesn't explain why this is. Why is it?


The word it’s seems to be a good substitute for it is. Yet it doesn’t sound correct to substitute it’s for it is in: “That’s just the way it is.” To make it: “That’s just the way it’s.”   Is it grammatically correct to make that substitute? And why doesn’t it sound correct? Is there any instance where the word it’s sounds correct and is grammatically correct at the end of a sentence?  The discussion in the answer to  does not seem to be on point because the premise of that answer is that "it is" at the end of the sentence has a stranded object, but it doesn't. Here the second "it is" has its distinct meaning precisely because there is no object. See first OED definition of "Be":  1 "Without required complement: to have or take place in the world of fact, to exist, occur, happen."


Shell script with a cron job to start a program if not running?

I am new to unix/linux and need a shell script to start a program if it is not running. The program's name is "literaail" and it has a log located "/local/publish/mtc_preprint/util/Literail.log"  on a server. This program is supposed to print this "Starting ftp check for Get_Job1." statement once every 30 seconds. If it doesn't, I need a shell script to start the process. Currently I am doing it manually using these commands:  ps -ef | grep ftp_util_mtc_pp.sh ps -ef | grep literail ( this command lists the jar file related to the literail program) kill "parentjobnumber" "childjobnumber" ./ftp_util_mtc_pp.sh & ( this command restarts the process ).   I have a "ftp_util_mtc_pp.sh" file, inside this file, i have the following commands:  #!/bin/bash  utildir="/local/publish/mtc_preprint/util"  cd $utildir  java -jar LiteRail_3.0.1.jar literail.properties > /dev/null 2>&1    exit   Can someone help me with the shell-script. Thank you.


Error Displaying last 10 minutes log with awk

I am using below command to display log data for last 10 mins. It works fine if the month stays same however when month is changed it doesn't show any data.  awk -v d1="$D1" -v d2="$D2" '$0 > d1 && $0 < d2 || $0 ~ d2' /home/user.log   Works fine if,  D1="Aug  1 12:00:00" D2="Aug  1 12:10:00"   But doesn't show any data if,  D1="Jul 31 11:55:00" D2="Aug  1 00:05:00"   P.S I am using AIX


How do I transfer programs from my old computer to my new Windows 7 computer?

I know about the Easy Transfer tool included in Windows 7 that will transfer all my files but I want to transfer my programs. Also, I don't want to buy any gimmicky program if I don't have to.


Hi Ive just downloaded the magic launcher, but when I enter my username and password (entering email address) it says incorrect details. But when I log into my mojang account, its right. Any ideas?


Lots of useful information for human beings, especially in academia. But, what is actually underlying the TeX engine? How does it really work? Does it parse everything and just put the stuff together? Or any special spec info?! Or even any good resources for further reading? How is it possible to write some modules and how to develop something more for the community?


What are the best tools for producing infographics - attractive displays that combine graphs, diagrams and text to convey a lot of information succinctly. I'm interested in both web-viewable content and posters for printing.  Specifically, I'm asking:   What combinations of tools are used (eg, one tool for making graphs, another for assembling graphs and text into the final infographic)? Are any vector graphic tools (eg, Illustrator) particularly more or less suited to the task than others? Are there any online tools which are useful in the assembly process?   (As an example of the kind of thing I'm interested in making [but on much more modest scale], )


Find the integral closure of an integral domain in its field of fractions

Let $k$ be a field and let $R = k[x,y]/(x^2-y^2+y^3)$. Note that $R$ is an integral domain. Let $F$ be the field of fractions of $R$. How to determine the integral closure of $R$ in $F$?   I have no idea how this integral closure looks like. But I find that $F = k(\overline{x}/\overline{y})$, because $\overline{y} = -(\overline{x}/\overline{y})^2 + 1$ and hence $\overline{x} = -(\overline{x}/\overline{y})^3 + (\overline{x}/\overline{y})$.  Also, a general method for find the integral closure of an integral domain in its field of fractions is strongly desirable. Many thanks.


How do I produce the .bbl file required for arXiv using JabRef for bibtex and Lyx?


paper on arXiv but not on Google scholar

My paper has been put on the arXiv very recently (approx. a week ago) and to the journal, and currently is under refereeing process.   I would like to ask how long it takes for Google Scholar to recognise the paper and associate it to my account. The paper does not even appear yet on Google scholar.


I need someone proficient enough in stats to help me clear up some confusion. The p-value is a conditional profitability. Given a null hypothesis to be true (mean difference in two groups to be 0), the p-value is the probability that chance alone caused the next observation to be outside of the statistical model. When the p-value is small, that is greater evidence against the null. Is up till that point correct?


Errors for using "style=apa" with biblatex

I am currently using biblatex version 3.4, Biber version 2.5, and biblatex-apa version 6.6, on a 2015 TeXLive distribution in Gentoo (x86-64).  I'm not sure what's happening, but just including the biblatex package (nothing else) causes a large stream of ! Illegal parameter number in definition of \blx@defformat@d errors.  For an example, let's take the following basic code:  \documentclass[12pt,letterpaper]{article} \usepackage[american]{babel} \usepackage[style=apa,backend=biber]{biblatex}  \begin{document}  Just a test  \end{document}   There's absolutely nothing else with the document, no special commands or altered settings, nothing other than just the basic lines, and the addition of biblatex.  No .bib files (yet), no citations, and no bibliography list has been added.  As long as style=apa is there, it will spit out a long list of errors, such as:  (/usr/share/texmf-site/tex/latex/biblatex/bbx/standard.bbx File: standard.bbx 2016/05/14 v3.4 biblatex bibliography style (PK/JW/AB) \c@bbx:relatedcount=\count219 \c@bbx:relatedtotal=\count220 ) ! Illegal parameter number in definition of \blx@defformat@d. <to be read again>  3 l.368 ...ts{\usebibmacro{name:apa:last-first}{#1}{#3                                               }{#4}{#5}{#7}?}} You meant to type ## instead of #, right? Or maybe a } was forgotten somewhere earlier, and things are all screwed up? I'm going to assume that you meant ##.   I can't use any other style, because the assignment I'm producing requires citations in APA format.  Am I doing something wrong?  Most of the searching I've done seem to result in questions relating to special circumstances, but as you can see, this is a vanilla document that just happens to have biblatex added to the usepackage list.


I am using a premium legit version of Minecraft that I purchased. I can log into minecraft.net as well as mojang.com but I am unable to login to Minecraft the game through the minecraft.exe or the Technic launcher. The Minecraft servers are up and running fine. My internet connection is also fine. I double checked my credentials and even tried changing my password. I tried using both my username and my email. I tried all of this on two separate accounts that I own. I tried deleting my login, launcher, launcher.pack.lzma, and launcher_profiles.json and then reopening Minecraft. I tried re-downloading minecraft.exe.   Nothing has worked and I seem to have run out of options. I sent a help request to Mojang but in the meantime I was hoping that maybe you guys could offer some advice.


Whether to use "is" or "are" in a question

Which of the following is correct?        Are any of your kids unwell?   Is any of your kids unwell?      The online grammar tool shows both as correct, so I am in a dilemma!


Voting to reopen a site proposal on Area 51

I recently went searching to see if there was a Stack Exchange site about relationships and found . Unfortunately, I have no way of pledging my support, as it was closed three years ago.  Is there a way to vote for a site to be reopened? I'd love to pledge my support and help give good site ideas a second chance.


Playing around with some integrals, I stumbled across a cute one: $$ \int_{0}^{\infty}\sin(x)\sin\left(\frac{1}{x}\right)\,dx $$ Substituting $z=\frac1x$ gives $$ \int_{0}^{\infty}\sin(x)\sin\left(\frac{1}x\right)\,dx = \int _0^{\infty} \frac{\sin(z)\sin\left(\frac{1}{z}\right)}{z^2}\,dz, $$which Mathematica gave as $\frac{\pi}{2}J_1(2)$, where $J_1$ is the . I'd be curious to see a derivation of this, as well as a rigorous proof the integral converges.


Which is better for a slow computer and a user who is only familiar with Windows, Ubuntu or Lubuntu?

I have Windows 7 and my computer has become very slow over the years. I am looking into switching over to Ubuntu or possibly Lubuntu. I was hoping to get some advice. I enjoy playing computer games and searching the web quickly, but right now my computer starts up incredibly slow and takes a while to open programs. I have never used a Linux OS as my main OS so I need a good transition between Windows and Linux. Which is better for this Lubuntu or Ubuntu?   Also, I want a way that I can switch over to Ubuntu/Lubuntu, but have the option to easily switch back if I decide that I do not like it. What is the best way to do this?  Thanks for your advice!  Edit: I also see that Xubuntu is an option for faster gaming performance. Could this be an even better option?


Should "Ladies" be marked with an apostrophe in the noun phrase "Ladies beer"?

What should it say on a label: Is it "ladies' beer" or "ladies beer?"


I was having an issue in which the time my ubuntu machine was showing is 5 hours ahead of my standard time. So I installed ntpd for that using  apt-get install ntp   after that I restarted ntp but still my time is 5 hours ahead of my standard time in India. Please Help.


which is correct:  Thank you for your and your team's time  or  Thank you for yours and your team's time  and should (or does it make a difference if) I place commas before and after "and your team's"  ... thanks!!


What are the differences between "go to school happily", "go happily to school" and "happily go to school"?

There are three similar phrases which I would like to know the differences between:        go to school happily   go happily to school   happily go to school       I have long been confused by the placement of adverbs. From my personal view, there are definitely tiny differences, but I'm not sure what exactly they are. Please explain in detail!


Why is the circumference of a circle the derivative of the area of the circle?

$${\frac{d}{dr}}(\pi r^2)=2\pi r$$  Why is that? And additionaly: Why doesn't hold this for the volume and area of a circle?


Allowing punctuation to be submitted to MySQL db

I have everything set up, and this works, but I can't add ' or any other punctuation without getting a MySQL syntax error when I hit submit. I want to know how I can add punctuation to the text row of my form. I have it set up to utf8_unicode_ci under Collation, but I still get a syntax error.   The textarea is where I want to be able to submit with any punctuation or character. Here's what I have.  This is the form I'm using  print "<form method=post action=reply.php>"; print "
Reply:
";  print "
<textarea name=reply_content textarea rows=4 cols=50></textarea>"; print "<input type=hidden name=reply_user value={$_SESSION['user_name']}>"; print "<input type=hidden name=topic_id value=$id>"; print "
<input type=submit></form>";   This is the SQL for reply.php  $reply_content=$_POST['reply_content']; $reply_time=date('Y-m-d H:i:s'); $reply_user=$_POST['reply_user']; $topic_id=$_POST['topic_id'];  mysql_query("INSERT INTO reply VALUES ('reply_id', '$reply_user', '$reply_content', '$reply_time', '$topic_id')") OR die(mysql_error());  print "
Reply Posted Successfully
";   I know there's a way to do this, I just don't know how. If anyone could help me out, I'd really appreciate it!


An uniformly charged infinite surface plane

The electric field of an uniformly charged infinite surface plane is totally independent of how far away the test charge is. But isn't electric field depends upon distance by the relation $1/r^2$? I understand that if the plane is truly infinite then it does'nt matter how far away you are. But there is no such thing as infinite plane. So, is the independency of distance works in real or practical life?


Is it possible to start windows with NUM Lock on?

A password is always combination of characters & numbers. I am so much used to num pad that every time windows start I end up entering wrong password just because NUM lock isn't ON by default. Since it's network login, it takes a bit long time to reset & prompt for right password. Is there a way to enable NUM Lock on when Windows loads?


/testfor @p[score_state=1,score_state_min=1]   doesn't work! Why?  It returns this:     The entity UUID provided is in an invalid format   How can I fix this?


My computer is playing some strange joke at me, and I'm at a loss.  Everybody knows that hot temperatures causes many components to become unstable and even cause damage. When I built this machine, I was careful to do a bunch of experiments with different airflow configurations, with CPU-and-GPU intensive benchmarks running, and measuring the temperature at different points to find the best configuration.  Generally, the internal temperature of this machine is very close to ambient temperature (with 2 exceptions: the GPU always runs ~10°C above ambient, and the CPU goes to at most ~12°C above ambient when running CPU-intensive applications).  Now comes the problem: at really cold mornings. At cold mornings (~10°C (50°F) or below), the system shows really strange general instability. Beeps from the BIOS, the operating system displays strange messages about memory corruption and PCI devices that failed to initialize, and then, everything hangs. The computer hangs to the point that all USB devices turn of. Hitting the Reset button blanks the screen but the mainboard fails to proceed to the boot.  I never thought that low temperatures could cause computer instability. And 10°C is not that cold, it is still within operating temperatures of all components as far as I checked.  I'm quite sure it is related with the temperature. There were too many cold and warm mornings that demonstrated that the problem only showed in the cold ones. I'm working around this problem by letting the computer sit at the GRUB menu for some 5-10 minutes before letting the OS start, or blowing hot air inside the case if I'm in a hurry.  I don't know what should I approach next to find the source of this problem. Since it is difficult to reproduce (I need a cold morning, and the computer must be cooled down (powered off for many hours)), I need to plan ahead the experiment, since it stabilizes after a few minutes on.  Machine is an ASUS P5VDC-X equipped with Intel P4 64-bit 3GHz, 2GB of DDR2 RAM, a 500W PSU and an nVidia GeForce 9600GT. Everything else was already disconnected/removed before and the problem persisted, so the problem should be in one of these remaining parts.  Any help is appreciated!


Why can't we post a question within 40 minutes of our other question?

Today I have a bunch of questions about Blender. I have asked 2 questions about layouts and stuff but now I have a question about sculpting. The problem is that I am unable to post it because of the forty minutes between questions rule. So what should I do?


What do people who are using a pensieve look like?

As far as I remember from the books, there's no description of what a person using a Pensieve looks like. When Harry is using the Pensieve, he describes it as if he were falling into it, but it's never stated whether his body really enters the Pensieve, because the experience is just told from his point of view.   Now let's say Dumbledore enters his office while Harry was using the Pensieve -- what would Dumbledore see? Is there an answer in the books/canon?


Prove that there exists $n_0 \in \mathbb{Z}$ such that $I = \{kn_0 | k \in \mathbb{Z}\}$ given that $I$ satisfies the following properties

Assume that the set $I \subseteq \mathbb{Z}$ satisfies the following properties:  (a) There exists $n \in I$ such that $n \not = 0$  (b) If $m, n \in I$, then $m + n \in I$  (c) If $m \in  I$ and $a \in \mathbb{Z}$, then $am \in I$  Prove that there exists $n_0 \in \mathbb{Z}$ such that $I = \{kn_0 | k \in \mathbb{Z}\}$  Not too sure if I am correct but I am thinking if $n_0$ is actually $gcd(m, n)$, then $I$ would be the set of all integer combinations of $m$ and $n$. So essentially this question is to relate the set of all integer linear combinations to the set of all integer multiples of the $gcd(m, n)$.


Is there an unsubdivide function in Blender?

I am wondering if there is a modifier or tool that will essentially undo a subsurf or subdivide command.


Angular velocity is the rate of angular displacement about an axis. Its direction is determined by right hand rule.  According to right hand rule, if you hold the axis with your right hand and rotate the fingers in the direction of motion of the rotating body then thumb will point the direction of the angular velocity.  The direction of angular velocity is above or below the plane. But what does it mean? I mean in linear velocity the direction of velocity is in the direction of motion of body but what does it mean that body is moving in one direction while the direction of its angular velocity is in another direction?


Can I apply for a US visa in another country?

I am a citizen of Cameroon living in Cameroon. Can I apply for a US visa in a neighboring country?


extract only a specific folder Contents from a zipped archive to a given directory

This is very close to the SO   I need something close but I always get the folder with the contents, not it's contents only  This is what was suggested:   #note $2 is passed in and would be == "magefoler"  unzip /srv/file.zip "$2-master/*" -d /srv/www/mage/   What I need to do it to take a zip that has this structure in it  file.zip  |-magefoler-master/  |-magefoler-master/app/*tons of files  |-magefoler-master/skin/*tons of files   and I need to move it to another folder but, I can't move the magefoler, I only want the app and skin folders.  This doesn't mean that it'll always be those two folders, just that any child content, files or folders, in the magefoler is what I need to get out.  What is trying to be avoided is to export all to a folder and then just move it from there.  The end result I'm looking for is from the zip file I output to the /mage folder like this:  /srv/www/mage/      |--/mage/app/*tons of files      |--/mage/skin/*tons of files


i noticed one cpu core using 100% resources so running htop shows, xmrig is running which i never installed. and i can see it is running from path /tmp/xmrig-... and i am running a wordpress site here on openlitespeed. so i doubt someone uploaded xmrig into /tmp folder using wordpress hack  (this is my doubt ofcourse) and i killed process and deleted folder from /tmp now after few hours, i see folder back and process running too. how can i find from where the process is started? like from cron or a service? Just for Fun: if it running from a process, i would like to change hacker wallet address with mine and it mines to my wallet. in serious note: how can i find more info about hacker and just blocking mining port is enough? any help is appreciated. thanks.


Interpreting the 'metric' column in routing table

I'm a little confused about the output I'm seeing in my routing table, particularly the 'metric' column:  $ route -n Kernel IP routing table Destination     Gateway         Genmask         Flags Metric Ref    Use Iface 0.0.0.0         192.168.0.1     0.0.0.0         UG    0      0        0 wlan0 172.16.35.0     0.0.0.0         255.255.255.0   U     0      0        0 vmnet1 192.168.0.0     0.0.0.0         255.255.255.0   U     9      0        0 wlan0 192.168.82.0    0.0.0.0         255.255.255.0   U     0      0        0 vmnet8   According to the man page, metric indicates the 'distance' to the target. I was a little confused about what exactly "target" was. I assumed it was my router (it goes to gateway 0.0.0.0, which then goes to my router at 192.168.0.1). Thus, I expected the metric to be a single hop to my router. However, it's 9! Why is this so number high?


Did I code this problem correctly? here is my outcome   In the searchRecursive method. in the searchRecusrsive method I am trying to check the element in the middle position , if the target is greater than the element in the middle position,recursively search for the second half of the array. if the target is less than the element in the middle position, recursively search the first half.   The first base case returns false if the low index exceeds the high index. the second base case returns true if the target is in the middle position.  class SearchSortedArray {   public static void main(String[] args)   {     int[] sorted = {10, 20, 30, 40};      System.out.println("***Iterative***");     for (int i = 0; i < sorted.length; i++)     {       System.out.println(sorted[i] + " found? " +                          searchIterative(sorted[i], sorted));       System.out.println((sorted[i] + 1) + " found? " +                          searchIterative(sorted[i] + 1, sorted));     }      System.out.println("***Recursive***");     for (int i = 0; i < sorted.length; i++)     {       System.out.println(sorted[i] + " found? " +                          searchRecursive(sorted[i], sorted, 0, sorted.length - 1));       System.out.println((sorted[i] + 1) + " found? " +                          searchRecursive(sorted[i] + 1, sorted, 0, sorted.length - 1));     }   }    private static boolean searchIterative(int target, int[] a)   {     int low    = 0,         high   = a.length - 1,         middle;      while (low <= high)     {       middle = (low + high) / 2;       if (target == a[middle])         return true;       if (target > a[middle])         low = middle + 1;       else         high = middle - 1;     }     return false;   }    private static boolean searchRecursive(int target, int[] a, int low, int high)   {       if (low > high) return false;        int middle;              middle = (low + high) / 2;         if (target == a[middle])          return true;         if (target <  a[middle])                  {         return searchRecursive(target, a, low, middle -1);           }         if (target >  a[middle])          {          return searchRecursive(target, a, middle+1, high);           }        return false;   } }


As Windows 7 support end soon, I am planning to have all PCs to have clean install of Windows 10. But installing them one by one on every PC is very time consuming and I am thinking to take this opportunity to have clean refresh for all PC.   So, I am thinking to have clean install of Windows 10 with some commonly use application on one PC (license not activated). Then, clone that drive to all the other PC (Every PC has different kind of hardware & setup). Only then, I will install proper driver for each PC and put in license to activate the software.  Is it possible and OK to do that? Will there be any side effect (such as cloned version will run much slowly or random error) with this method?


How to change the color and format of the static host/path/user string in the Terminal or iTerm?

Example:  cookie:~ j$ date Sun Aug  5 02:14:29 CEST 2012 cookie:~ j$   Just as it's pasted here, all three lines are of the same color. I would like to have "cookie:~ j$" or at least part of the string be of a different color than the rest.  I know that I can specifically enable color coding for specific applications like ls or git, but I haven't found anything like this.  Is there a way to change the coloring and format of the static host/path/user string in the Terminal or iTerm?


Disable hot questions to prevent distraction

I come to stack overflow to ask specific questions and read the answers for specific questions. Sometimes I also answer a few questions. However, I noticed that since the "hot questions" drop down was implemented, when I check my inbox I sometimes spot an interesting question, click on it and get distracted. Before I know, I spend 20 minutes answering an unrelated question and another 20 minutes reading though existing answers and I have long forgotten the original question I googled. This means I spend way more time on stack overflow, than I would spend otherwise. Unfortunately, this also has a negative effect on the amount of work done.  When I work, I usually block facebook and reddit to prevent myself from being distracted. Since I started doing this, my productivity has increased a great deal. I always considered stackoverflow a work related website that didn't have this problem. Until "hot questions" came along.  I understand that "hot questions" is a nice feature to have when someone is browsing for interesting topics. It also drives traffic to the website by extending the time the average user spends on the site. However, as an end user who uses stackoverflow for work, I want to stay focused and minimize distraction.  Therefore, is it possible to disable the hot question button or make the inbox the default view? If not, is there any third party extension that I could use to hide it?  Edit: Wow, I didn't expect that this question would invoke such hostility. I think hot questions is a great feature when you're in "looking for interesting stuff" mode. But when you're in "getting things done" mode, it's a distraction. At least to me. I know that everyone on this site is perfect and never has looked at a youtube funny cat video during their work hours, but I must admit that I have. And it actually resulted in less work done. And to me it does help that youtube is blocked when I work, because I'm not perfect, and there's a chance that I would still end up there somehow in some way as it happened to me in the past a few times... and please don't get me started about facebook and reddit...


When the comments are listed to either a question or answer, sometimes there are rather long comments, pushing the length limits. Other times there are loads upon loads of comments. I know there's settings to only show a few, and then click to load the rest. But I consider that a crutch when I think about my idea.  This is just like when you're browsing any list of posts which show the first little bit, only enough to fill 2 lines of text. When comments are listed, if it's more than 2-3 lines for example, cut it down. This way, you can do a bit less scrolling on those posts that have a lot of long comments. Because after expanding all the comments of some of these posts, it takes sometimes 20 mouse wheel turns to get past all the comments. (Well, not for me, more like "wireless mouse touch-sensitive scroll" or whatever they call it).  Obviously there would have to be some sort of indication on each comment if it has been shortened. To the right, there should be a "..." at the end of the text, as well as some sort of indicator such as an arrow pointing down. When clicking on that comment (or tapping your finger), it expands to the full text. If you click again after it's expanded, it will condense it again.  A very similar method is at play on . When you're browsing news headlines, if you click on one, it expands and shows more info and related stories. Click on it again, and it shrinks back to its small box. This is exactly how I imagine the comments to work on Stack Overflow, and why not all Stack Exchange sites?  PS - I originally thought that 2 lines of text would do the trick, but now I'm debating with myself whether it should be 1 or 2 lines. I figured I'd leave that decision up for higher authority.    UPDATE  Yeah, I'm thinking 2-3 line limits would be more adequate.


Fake Links Showing up in Google Webmaster Tools

Google Webmaster tools is reporting a large increase in 'not found errors' on my site, and I see approximately 1700 'Not Found Errors over the past 2 months. All of them are for a url that is formatted like:  http://mydomain.com/click.php?c%3EdHm7fnGkc3Smdz6kc31%3E'dmjdlgsbve%3E2'lfzxpset%3EQfbs'sbol%3E2'f%3Evt%3Cvt%3C79%3C2%3C2%3C54528243%3Cgmbnjohpspbe%3C2%3C6224'vsm%3Eiuuq%264B%263G%263Gxxx%2Fopdmjdlz%2Fdpn%263G'gffe%3Eopqbz'qsjdf%3E'tbq%3E%3A84%3A9g54e662db639%3A28eeb2cc8bb8e9'zbsht%3Exxx%2Fopdmjdlz%2Fdpn   Google says these are linked from:  http://mydomain.com/index.php?Keywords=Pear&search_type=related2&cat2=Lemon+Cake&r=c%3EdHm7fnGkc3Smdz6kc31%3E'f%3Evt%3Cvt%3C79%3C2%3C2%3C27748763%3Ctuzmf2%60dvtupn/dtt%3C3%3Cjoufsdptnpt%60bggjmjbuf%603%60e3s%60efsq%3Cgmbnjohpspbe%3Cgmbnjohpspbe%3C656178%3C6224%3Cdmfbo%3Cmjtujoht%3Czbipp%3C'jqvb%60je%3E:84:9g54e662db639:28eeb2cc8bb8e9'enybsht%3Eg4dc139e6673d:812b:b::d8e34:9fe9&rd=1   When I browse to the url Google says these are linked from (both using my browser, and the fetch by Google tool), I don't see any links on the page to click.php. These links are supposedly coming from MY domain / server, but click.php does not even exist on my server. When I look through my server logs, I do not see any of the index.php? urls this says they are accessed from.  What am I missing here? Is the link getting encoded in the url or something? How can I fix this? I would REALLY appreciate some help in figuring this out.  Update:  I had purchased a domain (that was previously parked), and moved my site to it a few months ago. Apparently these links existed on the parked domain, and Google has gone through and crawled all ~1700 of the links twice now. Once a few months ago, and once 2 days ago. Is this something that will affect my ranking in Google? Is there any way to notify Google that all of these links are gone / incorrect? Should I use the 'remove urls' tool in webmaster tools?


I want to print [entityInfo:protected] present in below image.   I am able to print all element except [entityInfo:protected] and [entityType:protected]


What are the advantages and disadvantages of doing a postdoc in Singapore and UK?

I am end of my PhD. I would like to do a postdoc. In UK the average postdoc salary is around 30K (per year). But in UK the tax is very high, after taxes I may get around 1800 pounds (per month). I heard in Singapore the salaries for postdoc are a bit high and the taxes are also very low.   I have my wife and two children, In that case I would like to know the advantages and disadvantages of doing a postdoc in UK or Singapore.


Is sky a countable noun or an uncountable noun?

Is "sky" a countable noun or an uncountable noun? We can count the sky as it is only one, but it's that people refer to as it being uncountable.


I've just downloaded a file called "Yousician.tar.gz". I understand it's a compacted file and it contains other files and folders. I can extract the contents with no problems. I wonder, though, how I can run the software. I really have no experience with Ubuntu 14.04 LTS (which is the one installed in my PC) or any other version of it.  Can anyone help, please?


Using Varnish (only) for DDoS mitigation

My VPS is suffering from a (D)DoS doing a SYN flood with spoofed IPs. I'm right now searching from ways how to be able to defend (at least a bit) against it.  It's running a DirectAdmin apache2 webserver. Mainly used for serving PHP and MySQL.  We are using CloudFlare, which are saying that they are able to mitigate (D)DoS at some level, now the attacker knows our real IP address, so CloudFlare isn't helping a bit.  I've done some searching on the net and found out about enabling SYN cookies, to defend against it. I've checked my settings and it seems it was enabled all along.  I've also read about that Varnish is able to defend against SYN flooding and Slowloris attacks, now I'm pretty interested in using that.   The thing is that CloudFlare is already caching a lot from us, and I don't wish to spend too much resources on Varnish. Is it possible and smart to set up Varnish only for the better handling of requests? Are there perhaps better ways which I've missed?  Thanks in advance, Martin


I am trying to read an excel file using the Apache P.O.I library, but when I try to read the cell type I get a null pointer excep

I am reading an excel file:   For now, all I want to do is print to the console each entry in this excel file in the format of: zip code - city - state. For now, all I am trying to do is get zip codes. Here is my approach:          FileInputStream inputStream = new FileInputStream("C:/Users/student/eclipse-workspace/Weather2/bin/resources/uszips.xlsx");         Workbook workbook = new XSSFWorkbook(inputStream);         Sheet firstSheet = workbook.getSheetAt(0);         Iterator<Row> iterator = firstSheet.iterator();         int i = 0;         while(iterator.hasNext()) {             Row nextRow = iterator.next();             if(nextRow.getCell(i+1).getCellType().equals("NUMERIC") && nextRow.getCell(i).toString().length()==5) //this if statement is where the error occurs {                 System.out.println(nextRow.getCell(i).getNumericCellValue());             }             Iterator<Cell> cellIterator = nextRow.cellIterator();             while(cellIterator.hasNext()) {                 Cell cell = cellIterator.next();             }             i++;         }         workbook.close();         inputStream.close();     } }   I get the following error when I run this method:      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)     at java.lang.reflect.Method.invoke(Unknown Source)     at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)     at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)     at java.lang.reflect.Method.invoke(Unknown Source)     at sun.launcher.LauncherHelper$FXHelper.main(Unknown Source) Caused by: java.lang.NullPointerException     at Forecast.search_Zipcodes(Weather2.java:41)     at Weather2.main(Weather2.java:94)     ... 11 more Exception running application Weather2   I don't understand why I receive a null pointer exception. I know for sure that a value for the cell exists, or is the null pointer exception for something else? Any help would be appreciated, thanks.


How do I download a torrent file from PirateBay?

When I try to download a torrent file I don't get prompted by Ubuntu 12.04 to select the location where to save the file, instead I get asked to select an application (which I'm not able to select for whatever reason). If anyone could help out with this it would be greatly appreciated. Please note that I've installed Ubuntu two days ago and I'm completely new to the thing. Explain as if you were talking to a 5 years old kid. Or a golden retriever.  Thanks in advance


What should I use to protect and cover my floors during construction?

We are building a new house and I'm installing the laminate wood flooring.  The builder suggested I cover the flooring after I'm done to protect it during the last few weeks of construction and with moving in.  What would you suggest I use?  Rosin paper, Kraft paper, or something more?


did Anakin bring "balance to the force" by killing all jedi?

In the later trilogy, it is stated various times that Anakin could be the choosen one that "bring balance to the force" At the end of the episode 3, there is only left 2 jedi and 2 siths...  Could it be that the prophecy was misinterpreted and that Anakin did bring the balance by killing nearly all jedi?


How do I migrate a question to a more appropriate SE site?

on SO and someone has pointed out (via a close vote) that it would be better suited to Super User.  I agree.  Let's move the question.  How do I do that?  A minute or two of looking through the UI and meta doesn't seem to have the answer.


Understanding arr[::-1] in numpy. Is this a special case?

I realize that arr[::-1] returns a reversed view for arr. Further arr[st_index:end_index:increment] is a compact syntax for indexing while creating view. (BTW what is this way of indexing called?) So if I have code like: arr = np.array(range(10)) print(arr)  #prints: [0 1 2 3 4 5 6 7 8 9]  Now, if I want to see the arr as reversed I can try (I don’t need to subtract 1 from len(arr)): arr[len(arr)-1: 0: -1] #This gives o/p as: array([9, 8, 7, 6, 5, 4, 3, 2, 1])  The first element was not selected, which was expected. And if I change 0 to -1, i.e, if I try: arr[len(arr)-1: -1: -1] OR even arr[:-1:-1], I get an empty array. Apparently I get the reversed array view by: arr[::-1] Q: How is this working? If I do not specify the first two arguments how does it infer that it needs to continue till 0? In fact it is just interpreting that it needs to go till the boundary as arr[::1] gives normal array. Is this just coded as a special case or is there something more going on? And is there a way to get reversed array view by explicitly specifying the three expressions in indexing. i.e., are there any values for expr1, expr2, expr3 which can reverse arr in arr[expr1:expr2:expr3]?


How long will homemade salad dressing stay good in the fridge?

How long can I keep salad dressings that I made?  Since this is probably affected by what it's made up of, let's say we're talking about different salad dressings made from a combination of the following ingredients: mayonnaise, ketchup, mustard, vinegar, sugar, garlic, oil, salt, pepper, lemon juice...  And are there any other ingredients that I should watch out for that could affect salad dressing shelf life? Any rules of thumb regarding storing salad dressings...?


I tried extracting text from .doc files. Text were extracted, but the problem is it always outputs with these:  ��ࡱ�>�� ln  characters.  Here is my code:      doc=open(input_file,'r')     read_text_file = doc.readline()     doc_text = ""     for line in read_text_file:         doc_text+=str(line)      return doc_text   Is there a way to remove or re-encode it to utf-8?


I was wondering if it is possible to modify what values show up in the Chrome omnibox when typing certain phrases.  For example, when I start typing "basecamp" it goes to basecamp.com/#####/projects/#####-old-project-im-not-on. I'd like it to either not have this one show up at all or instead prefer basecamp.com/#####/projects/#####-brand-spakin-new-project-yay.


I'd like to write GML using Geotools. Unfortunately, I can't find documentation on a GML Writer (except for this one from 2006: ).  Could you point me at documentation/examples?


I have a UITextField with the following restrictions - characters can only be numbers, as in the method below.  I want to also limit the number of max characters to 3 digits.  How can I modify my method to do that?  - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string { NSCharacterSet *aCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"]; for (int i = 0; i < [string length]; i++) {     unichar aCharacter = [string characterAtIndex:i];     if ([aCharacterSet characterIsMember:aCharacter]) {         return YES;     } }  NSUInteger newLength = self.textField.text.length + string.length - range.length; return (newLength > 3) ? NO : YES; }


Compiling C++ code to .EXE which returns double

I am working with a MATLAB optimization platform for black-box cost functions (BBCF).  To make the user free-handed, the utilized BBCF can be any executable file which inputs the input parameters of BBF and must output (return) the cost value of BBCF, so that the MATLAB BBCF optimizer finds the best (least cost) input parameter.  Considering that, from the one hand, my BBCF is implemented in C++, and from the other hand the cost value is a double (real number), I need to compile my code to an EXE file that outputs (returns) double.  But, to the best of my knowledge, when I compile a C++ code to EXE, it "mainly" compiles the main() function and its output is the output of main() function (i.e. 0 if running successful!).  An idea could be using a main function that returns double, and then, compiling such main() to EXE but, unfortunately, it is not possible in C++ (as explained in  or as claimed in the 3rd answer of  to be a bug of C++ neither of which are business of this question).  Can anyone provide an idea by which the EXE compiled form of a C++ code, outputs (returns) a double value?


I bought myself a new Android phone since my last one died (overheated). So I've lost all the applications.  Is there some kind of download history to find what you've downloaded via your Google Account or something? I'm aware of something similar in Market > My Apps,  but that contains only what you have on the current device.


MiKTeX: [...] does not seem to be a local package repository

I used MiKTeX 2.9 on windows. I have downloaded a package I want to install from the internet (manually, not through MiKTeX). The archive (*.lmza) containing the package was saved to a directory on my C:\ drive. Through MikTeX -> Maintenance -> Settings -> Packages -> Change... I can select the directory in which I have saved the archive containing the package. However, if I choose Packages shall be installed from a directory and choose the location of the package, I get this error message: C:\my\package\is\here does not seem to be a local package repository. What does it take for a directory/folder to become a local package repository?


Inequality with choose function: $1\sqrt{\binom n1} + 2\sqrt{\binom n2}+3\sqrt{\binom n3}+\cdots+n\sqrt{\binom nn} < \sqrt{{2^{n-1}}{n^3}}$

From the 1987 Spanish Mathematical Olympiad: Prove, for all natural numbers $n$ with $n > 1$, that $1\sqrt{n\choose1} + 2\sqrt{n\choose2}+3\sqrt{n\choose3}+\cdots+n\sqrt{n\choose{n}} < \sqrt{{2^{n-1}}{n^3}}$.  I tried using some estimates on the size of $n\choose k$, like ${n \choose k} \leq \frac{n^k}{k!}$, but nothing seemed to work, mainly due to all the choose functions being enclosed within square-roots.


When hearing about the two-daughter problem, I first thought it to be quite clear (after, of course, at first falling into the trap like many of us), but on the second glance, I encountered some serious problems with my understanding.  The original problem seems to be quite easy: Assume that the only thing you know about a man with two kids is that at least one of the kids is a daughter. What is the probability that the other kid is a daughter as well? (Boys and girls are assumed to be born equally often.)  After the first impulse ("1/2 of course!"), it becomes clear that it is only 1/3. The problem can be mapped to a situation where from the multitude of families with two children, only those with M/M are ruled out, while the equally often cases F/F, F/M and M/F remain, making F/F only one third of all remaining cases.  But now, meet Mr. Smith. I don't know much about him (except that he has two children), but when he approached me, he told me: "I am so happy! Victoria just got the scholarship she wanted!"  Now what is the probability that Victoria has a sister?  Since I only know that Mr. Smith has two children, and one is obviously a girl, I am tempted to map this onto the two-daughter-problem, leading to the answer "1/3".  But wait! What if I ask Mr. Smith first, if Victoria is his elder daughter? Assume his answer is yes (and ignore any problems with twins - even then one is typically a few seconds "older" than the other). So now I know that from the cases (F/F, F/M, M/F), M/F also drops out. And now, the probability for F/F just rose to 1/2.  Okay, but what if his answer is no? Then Victoria is the younger one, and F/M drops out. Again, the probability rises to 1/2.  So I'm going to just ask him: "Well, Mr. Smith, is Victoria your elder daughter? Wait - don't answer, because whatever you may answer, it doesn't matter. The probability just rose from 1/3 to 1/2."  Or, even better, I do not even have to ask him, just thinking about the question will shift probabilities to 1/2, which means that the original probability for Victoria having a sister must already have been 1/2. But then the mapping to the two-daughter-problem is obviously false.  Where is my error?  Making things worse, I could also create a setup where Mr. Smith just tells me: "I have two kids, and at least one of them is a girl." I then ask him: "Oh, can you give me a name of a daughter of yours?" and he answers: "Sure. Victoria."  (Side note: I have a gut feeling that this has something to do with how to assume probability distributions behind situations, similar to the , but I can't figure this out completely yet.)  -------- UPDATE --------  It seems that my error is that the question "Is Victoria the older child?" does not change the probabilities. If I know for sure that Mr. Smith was picked from an equally distributed (M/F, F/M, F/F) sample, then the knowledge that Victoria is the older child does not change anything, as was pointed out  here, and the probability for her having a sister is 1/3.  But it is very interesting that solely from the sentence "Victoria just got the scholarship she wanted!" I can NOT infer that Mr. Smith is indeed chosen from this uniform distribution.  Imagine that all kids have the same chance to get a scholarship, and the happy father will tell us if it is the case. Then it is actually twice as probable that Mr. Smith will tell us about his daughter's success if he has two girls, so the weighting of the four possibilities (M/M, F/M, M/F, F/F) is (0, 1, 1, 2). And in this case, the probability of Victoria having a sister is 1/2.  So another problem in my reasoning is the mapping of Mr. Smith's statement to the two-daughter-problem. Simply put, without knowing more about the circumstances that led to Mr. Smith telling me about Victoria, I simply can't say if the probability is 1/3 or 1/2.  Now I've got a headache...


I'm trying to install the minimal Ubuntu installation on a USB drive (complete install, not a live boot).  After installation, however, when I try to boot from the USB, I get "Missing operating system". I think there might be a problem with grub, but I don't know how to fix it.  I've done an install to an USB before which messed up the main grub file, so I don't want to do that. This is the output of fdisk -l pertaining to the USB drive: Disk /dev/sdc: 4027 MB, 4027580416 bytes 124 heads, 62 sectors/track, 1023 cylinders, total 7866368 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x73a571aa  Device Boot      Start         End      Blocks   Id  System /dev/sdc1            2048     7616511     3807232   83  Linux /dev/sdc2         7618558     7864319      122881    5  Extended /dev/sdc5         7618560     7864319      122880   82  Linux swap / Solaris  Also, my boot partition may not be labeled as bootable, based on this output.  Please help! Update I followed Terrance's suggestion, so /dev/sdc1 is now labeled as a boot partition.  However, the drive still won't boot. I am not asking for how to install Ubuntu to a USB drive, I'm asking for help fixing a USB which I've already installed Ubuntu to. Update Terrance's updated answer solved it for me.  Just a note, to get it working on my USB I had to create a /boot/extlinux/syslinux.cfg file containing: PROMPT 0 TIMEOUT 50 DEFAULT arch  LABEL arch         LINUX ../vmlinuz-4.4.0-45-generic         APPEND root=UUID=[The USB UUID]         INITRD ../initrd.img-4.4.0-45-generic


My teacher said "Red apple is red because it absorb all light and reflect only red while our eyes can detect all light"  I know that all object/thing made of atoms so different atoms are the source of different color.   My main question is: "How can atoms reflect different colors? Is it because electron excitation and de-excitation?"


I have the following line in my .bashrc: #!/usr/bin/env bash alias see='nano --view $1'  But now shellcheck is producing a high priority warning:  Aliases can't use positional parameters, use a function instead.  Reasonable except for one thing: it works fine! What's going on?


transit visa for UK required? layover time-14 hrs/ travel - india to vancouver/ valid canadian visa/ arriving in london on 20 aug and leaving 21

im going to travel from Hyderabad to Vancouver on 20th august, and will be passing through heathrow. My layover time being 14hrs, will I require a transit visa? I have a valid canadian study permit, but will be arriving at heathrow on 20th and leaving on 21st. I do not have any intention to go out for a visit and also don't need to go through immigration. please help, i dont have much time!


I am trying to make this simple function:  private void getID(){     for(int i=0;i<crops.size();i++){         ID.add(i);     } }   where cropps.size() is the size of a bitmaparraylist which i've made. People told me that these function fail because you can get the argument null. But how can i get null if i don't fill in any arguments...  I've also tried to make the input of the function an Arraylist of integers but this failed as wel. On my Oncreate method i use getID() after i made the crops so that isn't the error as well. So i'm kind of confused here and help would be much appreciated.  Kees


I have a function      $$f(x)=\frac{x^2-4}{x-2}$$   while solving this simply I get $f(1)=3,f(2)=\frac00,f(3)=5,\cdots$ the problem is when I solve this simply I get $$f(x)=x+2$$ and then I found except $f(2)$ all the values were same. Can someone help me where I did the mistake?


When a recipe calls for sugar and oil or butter which one can applesauce be substituted for and what is the ratio?


Two string reference are referring to same string but when comparing, result return false.

The value of s2 and s3 is "ab" and this string is stored in string pool. As per doc s2==s3 should return true but it is returning false. Why?   public class Sample {       public static void main(String[] args) {       String s="a";       String s1="b";       String s2=s+s1;       String s3="ab";       System.out.println(s2==s3);    } }