The logic behind present perfect/infinitive + present perfect

May I ask what the logic is behind using present perfect/infinitive + present perfect in "present perfect + since + present perfect" sentences?     it has been a while since I have enjoyed a party this much.   and     It's been a long time since I have read an interesting book.   Why is it not present perfect + past simple? I understand the "it's been" part, since it's something that is still relevant or going on. But if I'm referring to a specific past event, why should present perfect even be considered?  2) Also, I've seen people replace infinitive forms with present perfects:  "You must be surprised to receive a letter from me" = "You must be surprised to have received a letter from me"  Is there such thing as an infinitive present perfect? How is this construction possible?   Please help me understand!


If we assume that the substance of time is slower in the presence of very high gravity( early years of the universe) then is it not reasonable to assume that as matter gets further apart, that time, due to less gravitational effect will speed up creating the illusion that the velocity of matter is accelerating.


I am able to use ripgrep to do things like this:   ps aux | rg 'process name'  I am able to search the output of the previous command. For some reason this doesn't work for me using regular grep. If I do:   ps aux | grep 'process name'  It ignores what I am trying to pipe into grep and searches the current working directory for the process I typed in.  This is the output of ps aux:   If I would grep firefox for example it would not show it.   ps aux | rg firefox gives me this:   EDIT: It seems to be because some sort of alias described here   This works: ps aux | \grep firefox


Suppose that $f$ is analytic on a domain $D$, which contains a simple closed curve $\gamma$ and the inside of $\gamma$. If $|f|$ is constant on $\gamma$, then I want to prove that either $f$ is constant or $f$ has a zero inside $\gamma$  if $f$ is not constant, then the max/min modulus principle applies ... meaning $|f|$ can not have any local max/min on D  I don't really know what to do next


It seems that the Group Policy Editor (gpedit) is missing for Windows 10 Home. If you do WindowsKey+R and enter "gpedit.msc" you get the following message:     Windows cannot find 'gpedit.msc'   What are the steps required to install gpedit on Windows 10 Home? Is there a Microsoft sanctioned download of gpedit from the Microsoft domain?


Trying to find the quotient and remainder of the problem below..but keep getting to wrong. Could someone demonstrate how to solve this correctly?


How do I expire a PHP session after 30 minutes?

I need to keep a session alive for 30 minutes and then destroy it.


What do you call a sick person who is lying in bed?

Some conditions require that a person lie in bed all the time until recovered. Is there a name for such conditions or people experiencing them at the moment?   For example,      I am currently <bed sick> and can't help you with your homework.   I tried looking for bed sick but hit a dead end.


User interaction with Python tool midway through script running?

I need to design a Python script that will take a CSV input, search for a matching polygon in our SDE data for each line, and then extract certain information about data that intersects with the polygon.  This is straightforward, except that about 5% of the input values will not be exact matches (e.g. a parcel number will have hyphens in the CSV, but the SDE value has no hyphens). I've got a few tests in there to handle these cases, but it will inevitably result in some situations where the script returns multiple possible candidate polygons and the user needs to be able to indicate which is correct. For example, the number may pull up Polygon A and Polygon B as possibilities, and it's up to the GIS analyst to visually examine to decide which is in the correct region.  If I was running the script in IDLE, then I could simply use raw_input to get that user input and proceed with the rest of the steps. Is there an equivalent mid-script method in ArcMap that accepts user input? I am only aware of the initial tool parameters, which wouldn't be useful for this issue.


What is an unbiased estimate of population R-square?

I am interested in getting an unbiased estimate of $R^2$ in a multiple linear regression.  On reflection, I can think of two different values that an unbiased estimate of $R^2$ might be trying to match.    Out of sample $R^2$: the r-square that would be obtained if the regression equation obtained from the sample (i.e., $\hat{\beta}$) were applied to an infinite amount of data external to the sample but from the same data generating process. Population $R^2$: The r-square that would be obtained if an infinite sample were obtained and the model fitted to that infinite sample (i.e., $\beta$) or alternatively just the R-square implied by the known data generating process.   I understand that  is designed to compensate for the overfitting observed in sample $R^2$. Nonetheless, it's not clear whether adjusted $R^2$ is actually an unbiased estimate of $R^2$, and if it is an unbiased estimate, which of the above two definitions of $R^2$ it is aiming to estimate.  Thus, my questions:   What is an unbiased estimate of what I call above out of sample $R^2$? What is an unbiased estimate of what I call above population $R^2$? Are there any references that provide simulation or other proof of the unbiasedness?


What tools are available to calculate the costs of tolls when planning a road trip in USA?

I am plotting a road trip using google maps.  On some routes it says "this routes has tolls"  Are there any means by which I can see where the tolls are and their prices?  EDIT: It has been determined that Via Michelin does not work with USA tolls.


How to make reading and writing the same file in the same pipeline always "fail"?

Say I have the following script:  #!/bin/bash for i in $(seq 1000) do     cp /etc/passwd tmp     cat tmp | head -1 | head -1 | head -1 > tmp  #this is the key line     cat tmp done   On the key line, I read and write the same file tmp which sometimes fails.  (I read it is because of race conditions because the processes in the pipeline are executed in parallel, which I do not understand why - each head needs to take the data from the previous one, doesn't it? This is NOT my main question, but you can answer it as well.)  When I run the script, it outputs about 200 lines. Is there any way I can force this script to output always 0 lines (so the I/O redirection to tmp is always prepared first and so the data is always destroyed)? To be clear, I mean changing the system settings, not this script.  Thanks for your ideas.


Ways to step through features without Browse Features from data reviewer extension or data driven pages?

I'm looking for ways to browse through a bunch of points that I have so that I can assign each of them a value. Ideally I would like to be able to use a button on the keyboard to step through each individual point (while keeping the same zoom level) so that I can keep my cursor over my attribute table in order to assign a value to the point. I have used Browse Features before and I know that is an obvious solution but I currently do not have the extension. Data driven pages does work, but it doesn't select the feature so it is easy to get lost where I am when I am in the table when I go to assign a point. I also have to move my cursor to click next page which is slow and clunky and I can't seem to assign a keyboard shortcut to it as well. It also doesn't seem to update the value in the drop down menu to what I have assigned to the name field so I can't keep track of where I am in the table with that either.   Does anyone have any ideas? Being able to stay zoomed in is also important since I need to be able to see the color of the pixel from my imagery that my point is sitting on top of.


Custom kernel: fails to load firmware when module built-in

I'd like to have all my modules built-in, but this fails with iwlagn:  iwlagn 0000:03:00.0: request for firmware file 'iwlwifi-6000-4.ucode' failed. iwlagn 0000:03:00.0: no suitable firmware found!   The microcode file exists in /lib/firmware and the whole thing works just fine if I compile iwlagn as module. I have no idea where it's looking for the file or what's wrong - any ideas?


Sum of "n" independent random variables.

Let $X_1,X_2,...,X_n \sim U_{[0,1]}$.  $X_1,..,X_n$ are independent. Let us define : $Y=X_1+X_2+...+X_n$ How to find the PDF of $Y$?


Matrix Representation of This Lie Algebra

Consider the three dimensional Lie algebra with basis $x,y,z$ and commutator relations $$[x,y]=y-z$$ $$[y,z]=0$$ $$[z,x]=y-z$$ I want to find a faithful matrix representation of this Lie algebra, by Ado's theorem one exists. The adjoint representation is not faithful so it needs to be some other set of matrices which give this.     I have tried to find a three $3\times3$ matrices which satisfy the above by brute force but the complexity and runtime of such a programme is extremely high. If anyone knows a solution or a practical way of finding one that would be great.


How to resolve "premature end of script headers" error with QGIS Server?

I attempted installing QGIS Server following .  Installation was successful with no errors reported.  However, when I try to use GetCapabilities I am getting this error:     Internal Server Error      The server encountered an internal error or   misconfiguration and was unable to complete your request.      Please contact the server administrator, admin@local.domain and inform   them of the time the error occurred, and anything you might have done   that may have caused the error.      More information about this error may be available in the server error   log   I looked for the error in Apache's logs and found this entry:  [Mon Oct 28 16:02:40 2013] [error] [client 127.0.0.1] Premature end of script headers: qgis_mapserv.fcgi.exe  Can anyone suggest how to troubleshoot this issue?


$$\lim\limits_{n \to \infty} g(t)=L $$  $g$ is monotonic strictly increasing, continuous in $ [0,\infty)$ and positive function.  I need to find :  $$\lim\limits_{n \to \infty} \int^2_1 g (nx) \,\mathrm{d}x  $$    I have started with:   $|g(t)-L|<\epsilon\>$  $L-\epsilon\>$$=<$$g(t)$$<=$$L+\epsilon\>$  $\int^2_1 (L-\epsilon\>) \,\mathrm{d}x$$=<$$\int^2_1 g (nx) \,\mathrm{d}x$$<=$$\int^2_1 (L+\epsilon\>) \,\mathrm{d}x$  I'm not sure if I'm in the right direction ...


asymptotics of $\sum_{n=0}^\infty x^{n^2}$ as $x\rightarrow 1$

This is an exercise in the book by Titchmarsh, 'the theory of functions', page 242.   The answer is $\frac{1}{2}\sqrt{\pi /(1-x )} $.   How to prove it?   It is a little bit surprising to me. The function $1/\sqrt{1-x} $ has a quite different Taylor expansion around $x= 0 $.


Can dark energy be converted into energy source?

Dark energy is an unexplained phenomena. But can it be used as a energy source?


Was Quirrell the Defense against the Dark Arts teacher for more than one year?

It's well seen throughout the series that there is a “curse” on the DADA teacher position, that no one can hold that post for more than a year. But it seems like Quirrell has been around for longer than a year. What's up with that?


I am editing my brother’s paper, and I realized I am unsure about the possessive form of Marine Corps, such as     The best kept secret of the Marine Corps   Is it     the Marine Corps’ best kept secret   or     the Marine Corp’s best kept secret   I am leaning towards the first because the s is part of the word corps.


What might cause my tyre to deflate to a certain point and then remain there?

This doesn't make sense to me. If I inflate my tyre to max I can cycle to work. Later on, the tyre is a bit deflated. Enough to be OK to ride on if I'm careful about potholes. However it never deflates any further. I left it all weekend and checked it and it's exactly the same level of deflatedness.  I'm about to switch out the inner tube but before I do I was hoping to discover why, in case I waste an inner tube.  I would expect a slow puncture to make it go completely flat.


What happened to the reputation information box design?

Here is a screenshot of my reputation information box.  The green +5 next to the 1,892 seems a bit too high. The numbers on the graph also look not quite right, and in fact, looking at the tooltip when moving over it, it is in the wrong place numerically.   It happens on both Firefox and Google Chrome.


What are differentials and how can we treat them?

I'm currently reading through a textbook on Real Analysis, and the following is written:     "The great advantage of Leibnitz symbols is that, when they are properly   interpreted, we can treat the symbols d f, d y, dx, and so on, as if they represent members   of IR and carry out various algebraic operations, and the resulting formulas will have   meaning." - Patrick M Fitzgerald, Advanced Calculus, P114   In my physics courses, we very frequently say things like, "If you have a small amount of charge $dq$ in a small volume $dV$, we can define the charge density $\rho$ as $\frac{dq}{dV}$. However, I have been warned in the same classes that treatment of differentials in this manner is not mathematically rigorous and can lead to issues. What issues? I am not sure.  At the same time, in my Real Analysis course, we were told that $\frac{df(x)}{dx}$ should be treated as just notation, and not as a fraction.  And then I read the quoted text above, which appears to be merging the two concepts.  My question is this: How can differentials be treated? When is it rigorous to have a small amount of charge $dq$ be defined as $\rho dV$? My friends and I have grown skeptical of derivations of physics concepts when differentials were used, because we have been told to be skeptical. When is this warranted? When is it not? What do I watch for?


Say I want to have a beep at 13:00. I would use  speaker-test -t sine -f 1300 | at 13:00   I can find that something is going to be executed with atq but how to get the precise scheduled command? (that is   speaker-test -t sine -f 1300)


I've bought 2 ATtiny's from AliExpress and  I can't program them. I've read some feedback and people say that they might be fake but then I saw some activity on IO pins. So I've made a small oscilloscope program on my Arduino:  On pin 2 there was a square wave signal and on pin 7 there was a signal, fading in and out.  my question is that the microcontroller is original or not and also I want to know how can I unlock the MCU, if it's locked?  Sorry if my English is bad.  When I try to program it it says avrdude: Yikes! Invalid device signature. Double check connections and try again, or use -F to override this check. I used Arduino as IDE. The error shows up in ArduinoIDE.          – Schematic created using   There's a 10uF capacitor between Arduino's reset and Ground  Here's a photo of the chip (Sorry for low quality my phone didn't want to focus)


Why does connecting a battery's positive terminal to the negative terminal of another battery not create a short circuit?

This is a question regarding the physics behind the observation.  I have guessed the answer to the question, but I may be wrong, so I want to wait for the responses before posting it.  Some major considerations:   A battery's positive terminal does have a positive potential. ie, a test positive charge will repel it and a test negative charge will attract it. Vice versa for negative terminal. From the paper below (Section 1.2.1), it seems abundantly clear that the battery will have positive and negative potential on respective terminals. Given 'point 1', above, connecting the positive terminal of battery A to negative terminal of battery B will lead to current flow in the conductor. If the potential difference only comes into effect when the circuit is closed using the terminals of the same battery (due to cell chemistry), then does that mean that 'point 1' will not be valid after this experiment (connecting positive terminal of A to negative terminal of B)? If it is only a tiny quantity of current that flows, then will it ever stop? And what determines this quantity? (Equation would be nice)   Related paper:


Java object declaration beyond the common idiom

Generally, when a new object is created in Java it follows the idiom:  Object obj = new Object();   where the Object() constructor matches the object type Object.  But what if it doesn't? I understand from the Oracle Docs on  and  that the constructor must be in that object's class or one of its subclasses.  However, suppose we wanted to declare a new stack.  My first instinct would be:  Stack s1 = new Stack();   But I assume it's valid to do it this way, too:  Object s2 = new Stack(); //This   Is there a difference here?  What are we really saying about s2?  I'm guessing s2 is simply an empty stack, but only has access to the Object class methods?  I'm not sure why someone would ever do this, but I want to solidify my understanding of the Java hierarchy.  Are there really any circumstances where someone would use a subclass's constructor when creating a new object?  Any and all informative responses will be appreciated.  Thanks in advance!


My Printer is HP LaserJet 1020 Plus does not print

My printer is HP LaserJet 1020 Plus. I cannot print anything, I have noticed in the settings menu "Not calibrated".   What is the procedure to calibrate? Please explain with simple language.


Phrase to give a non-detailed answer/explanation

What expression could I use when giving non-detailed answers/explanations about how something works? Let's say I want to explain how a printer works without getting into too much detail, Would it be OK to say:   "At a very superficial level, a printer ...." "At a very high level, a printer ..."   I feel like there are more appropriate expressions to begin such type of sentence. Any help would be greatly appreciated.


How do I escape a backtick ` within in-line code in Markdown?

How do I escape a backtick ` within a code block?  This is probably a duplicate, since I'm sure it's a common concern, but I can't find a question that addresses this specifically.  How do I write List'1 with the "1" character still in the code-text format?


Make an external drive Ubuntu + Windows accessible

just wondering if there is a way to make an external hard drive ubuntu/linux only accessible. So if someone plugs it into windows or mac, it wouldn't show any files or even the drive or show they are locked out.   If not, is there any utility (free/paid) that allows the hard drive contents to be encrypted/locked and it works for at least Linux and windows?  Thanks!   EDIT: I am looking for some utility that works BOTH for Windows and Linux.


Hotkey to go DIRECTLY to vertex, edge, face edit mode?

As a long time user of other prominent 3d software, I'm used to being able to be in object mode and press 1 hotkey to go directly to vertex, edge, or face mode.    I'm using 2.8 and love it, but for the life of me, I can't get used to pressing "Tab" before I hit 1,2,or 3.  To make things worse, those keys (in object mode) hide and unhide collections.  It's driving me crazy.    I just want a smart hotkey that allows me to press 1,2,or 3 in object mode and automatically puts me in edit mode.  Pressing "Tab" would behave as it already does - toggling between object or edit mode.    Is there a way to do this?  Thanks, Chris


cannot connect to wifi on ubuntu 14.04.3

I installed Ubuntu 14.04.30 LTS using a USB stick. I didn't dual boot my pc, I deleted my old OS. I can't find Enable Wireless in the network menu. The output for rfkill   ---------------------------------- rfkill list all 0: hci0: Bluetooth          Soft blocked: no         Hard blocked: no -----------------------------------   The output for lshw -c network  *-network       description: Network controller       product: BCM4312 802.11b/g LP-PHY       vendor: Broadcom Corporation        physical id: 0       bus info: pci@0000:03:00.0       version: 01       width: 64 bits       clock: 33MHz       capabilities: bus_master cap_list       configuration: driver=b43-pci-bridge latency=0       resources: irq:18 memory:99700000-99703fff *- network        description: Ethernet interface        product: RTL1801E/RTL8102E PCI Express Fast Ethernet controller        vendor: Related Semiconductor Co., Ltd.       physical id: 0       bus info: pci@0000:04:00.0       logical name: eth0       version: 02       serial: 00:1e:ec:a1:73:dd       size: 10Mbit/s       capacity: 100Mbit/s       width: 64 bits       clock: 33MHz       capabilities: bus_master cap_list rom Ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation   I am new to Linux and have no idea what to do. I can see the WiFi symbol at the top right corner of the screen. But its blank. When I click on it I can see that Enable Networking is checked. The other options are Edit connections & VPN connections. I don't have access to internet. Can't use Ethernet as a WiFi network is all I can access. I have just downloaded Ubuntu 14.04.3 and haven't installed any drivers or packages


Show that $u(x)=\ln\left(\ln\left(1+\frac{1}{|x|}\right)\right)$ is in $W^{1,n}(U)$, where $U=B(0,1)\subset\mathbb{R}^n$.

The entire problem statement is:  Let $n>1$ and let $U=B(0,1)\subset\mathbb{R}^n$. Show that $u:U\to\mathbb{R}$ given by  $$u(x)=\ln\left(\ln\left(1+\frac{1}{|x|}\right)\right)$$ is in $W^{1,n}(U).$  My attempt at the proof is as follows:  To show that $u\in W^{1,n}(U)$ it suffices to show that $|Du|\in L^{n}(U)$. Consider $$u_{x_i}=\frac{1}{\ln\left(1+\frac{1}{|x|}\right)}\frac{1}{1+\frac{1}{|x|}}|x|^{-2}\frac{x_i}{|x|},$$ which simplifies to, $$u_{x_i}=\frac{1}{\ln\left(1+\frac{1}{|x|}\right)}\frac{1}{1+\frac{1}{|x|}}\frac{x_i}{|x|^3}.$$ Thus, $$|Du|=\frac{1}{\ln\left(1+\frac{1}{|x|}\right)}\frac{1}{1+\frac{1}{|x|}}\frac{1}{|x|^2}$$ which can be manipulated to, $$|Du|=\frac{1}{\ln\left(1+\frac{1}{|x|}\right)}\frac{1}{1+|x|}\frac{1}{|x|}.$$  Moreover, since $U=B(0,1)$ we can bound the second term from above which gives, $$|Du|\leq\frac{1}{\ln\left(1+\frac{1}{|x|}\right)}\frac{1}{|x|}$$  Thus, we can instead show that $$\int_U\left(\frac{1}{\ln\left(1+\frac{1}{|x|}\right)}\frac{1}{|x|}\right)^n<\infty.$$  Converting this into polar coordinates we have with $r=|x|$, $$\int_0^R\int_{\partial B(0,r)}\left(\frac{1}{\ln\left(1+\frac{1}{r}\right)}\frac{1}{r}\right)^n\,dSdr=\int_0^R\left(\frac{1}{\ln\left(1+\frac{1}{r}\right)}\frac{1}{r}\right)^n\int_{\partial B(0,r)}dSdr$$ Note that $\int_{\partial B(0,r)}\,dS=n\alpha(n)r^{n-1}$, which is the surface area of $B(0,r)$. Thus, we have then $$n\alpha(n)\int_0^R\left(\frac{1}{\ln\left(1+\frac{1}{r}\right)}\frac{1}{r}\right)^nr^{n-1}\,dr=n\alpha(n)\int_0^R\left(\frac{1}{\ln\left(1+\frac{1}{r}\right)}\right)^n\frac{1}{r}\,dr$$  And so this is where I get stuck in the problem, since I don't how I can evaluate that last integral to show it's finite.  Thank you for any help or feedback!


Is there a way go start google search from Ubuntu desktop?

I'm not talking about the Google Desktop Search, I'm looking for something more like an android-style widget, where I can enter the search term while on the desktop and it will launch the browser with the search results.


Distance between two points with covariance

I would like to find the distance between two points location 1 and location 2. In 2D, location 1 is represented by a Gaussian distribution with mean $\mu_1$ and co-variance matrix $\Sigma_1$. Similarly location 2 is represented by a Gaussian distribution with mean $\mu_2$ and co-variance matrix $\Sigma_2$.  \begin{align} \mu_1 &= \begin{bmatrix} \mu_{x_1}  \\ \mu_{y_1}\end{bmatrix} &{\rm and} &\qquad \Sigma_1 = \begin{bmatrix} \sigma_{x1} &\sigma_{x_1, y_1}  \\ \sigma_{y1, x1} &\sigma_{y_1}\end{bmatrix}  \\[10pt] \mu_2 &= \begin{bmatrix} \mu_{x_2}  \\ \mu_{y_2}\end{bmatrix} &{\rm and} &\qquad \Sigma_2 = \begin{bmatrix}\sigma_{x_2} &\sigma_{x_2, y_2}  \\ \sigma_{y_2, x_2} &\sigma_{y_2}\end{bmatrix} \end{align}  By looking at other questions, I believe the distance between these two locations will be a Gaussian distribution as well. In that case, distance would be a Gaussian would be:    \begin{align} \mu &= \mu_1-\mu_2  \\[5pt] \Sigma &= \Sigma_1 + \Sigma_2 \end{align}  But I am skeptical about this since $\mu_{x_1}$ and $\mu_{x_2}$ are correlated ($\sigma_{x_1y_1}$ is not equal to zero).  But location 1 and location 2 distributions are not correlated. So do I have to worry about the correlation of $\mu_{x_1}$ and $\mu_{x_2}$?


Commenting out a few words within a paragraph?

Is there anyway by which I can comment out a word within a sentence?


Given the 1st Postulate of SR, doesn't the 2nd Postulate go without saying?

i've been looking over possible duplicates of this question and haven't found one yet.  so, using Wikipedia as the textual source:   The Principle of Relativity – The laws by which the states of physical systems undergo change are not affected, whether these changes of state be referred to the one or the other of two systems in uniform translatory motion relative to each other. The Principle of Invariant Light Speed – "... light is always propagated in empty space with a definite velocity [speed] $c$ which is independent of the state of motion of the emitting body". That is, light in vacuum propagates with the speed $c$ (a fixed constant, independent of direction) in at least one system of inertial coordinates (the "stationary system"), regardless of the state of motion of the light source.   so, is it not the case that observers in "one or the other of two systems in uniform translatory motion relative to each other" have the very same $\epsilon_0$ and $\mu_0$?  if they don't, that contradicts the premise of the 1st Postulate.  i just cannot see how the 2nd Postulate is not redundant.  it comes about directly from the 1st and from the known laws of physics preceding SR.  you see, it's not just about light and $c$ and $\epsilon_0$ and $\mu_0$.  it's all the other laws of physics and the parameters that come with these laws.  i.e. every inertial frame of reference has the same Planck's constant, $\hbar$, same gravitational constant, $G$, and same elementary charge $e$.  if the frames of reference didn't have the same values, such would violate the 1st Postulate, but that wouldn't violate the 2nd Postulate since that's restricted to $c$.


How to use Redstone dust in Minecraft PE?

I have Minecraft Pocket Edition and I have collected a lot of redstone dust. For some reason, I couldn't use it for things such as iron doors. Why?


Will factory resetting my device remove the Android upgrade?

I have upgraded my phone to Android 2.1. I need to reset my phone but I don't want to lose the upgrade. Is it possible to do this? How?


How do you make Ubuntu Server accept files sent over bluetooth?

How do you configure Ubuntu Server to automatically receive files over Bluetooth and save them with no user interaction?  This question is almost identical to , but relates to Ubuntu Server, where no GUI is available.  Edit: To clarify, this question is not about pairing Bluetooth devices, but about making an Ubuntu Server machine automatically accept Bluetooth file transfers. This question is not a duplicate.


In a beamer presentation the title is long but ok for the first slide. The problem is that when the title appears below on each slide it is very long and I would like to use here some sort of running or shorter title, how can this be done?


I've heard from mathematicians, and not mathematicians, that the infinity is not a number. Is a concept, an idea.   Good! But we are in the world of mathematics, a world in where it's supposed to be able to define any mathematical object (I have doubts about this...) with precision and rigour.  I've been dealing with this concept in many areas but, SINCE THEN, I don't have the precise meaning. I don't like the idea of talking without definitions in math...  So I was wondering if the math definition of this concept exists? And where I can find it?


I have opened up  on launchpad too, but in the interest of getting a bigger response base I am posting it here, hoping someone will pick it up.  Natty doesn't behave very well with the Intel 82845GL chipset. I booted my old machine with Natty today to test drive it. The specs are:  Processor: Celeron 2.4GHz Video: Intel 845GL RAM: 1GB  The first problem is that the display is borked! What do I mean? Well, see for yourself:     If that gets fixed (and it did for a while but is back now), Unity is disabled.   I think these issues are owed to hardware acceleration being disabled...or in other words not the right driver for my hardware. A google search on 'intel 82845GL ubuntu' does return other users having similar problems in the past but I haven't been able to pick out a solution in the many many discussions on the subject- partly owed to my 'linux naivety' I guess...but maybe you can help?


UL height not expanding all the way down with floating LI

Hi,  I got this code:

some list

some list

some list

some list

some list

some list

   and my css:  ul { background-color: #EDEADF; height: 30px; }  li {float: left;}   on a PC screen this looks fine. The problem comes when you see it on a mobile because the LI elements go vertical instead of horizontal. Im okay with that, but what I dont like is that the UL stays at the same height and since it has a background it looks weird. It should expand automatically and reach the bottom to cover until the very last LI. How can i achieve that effect?  Thank you.


How to compile pdf in Overleaf not from scratch each time?

I am compiling a pdf in Overleaf but even if there is a minor change, the pdf will be compiled from scratch and that will take a while for a large document. How to avoid this? Is there an option to specify a setting so that only a part that was modified will be changed in the pdf?


The formula for covariance in terms of joint cdf

I want to show that  $$\newcommand{\cov}{\operatorname{cov}}\newcommand{\d}{\mathrm{d}}\cov(x,y) = \iint (F_{X,Y}(x,y) - F_X(x)F_Y(y))\,\d x\,\d y$$ However, I have no idea how to start. I know that  $$\cov(x,y) = \iint (x-\mu_X)(y-\mu_Y)f_{X,Y}(x,y)\,\d x\,\d y = \iint xyf_{X,Y}(x,y)\,\d x\,\d y - \mu_x \mu_y$$ where $\mu_x = \int x f_X(x)\,\d x$ and $\mu_y = \int y f_Y(y)\,\d y$.  However, I have no idea how to proceed. I would be very grateful for at least a small hint.


Cookie path and its accessibility to subfolder pages

Let say I have a website with domain: www.example.com  If I set a cookie with path '/' the cookie will be accessible via all pages in the domain, eg:   www.example.com/page1.html www.example.com/subfolder1/page1.html www.example.com/subfolder1/moresubfolder1/page1.html, etc.   What if we set the cookie to path '/subfolder1', will the cookie will be made available to any page or subfolder beneath the folder? Eg:   www.example.com/subfolder1/moresubfolder/page1.html   So, if not, I guess, I have no choice but to use path '/' for those cookies, right?


Differences in loss between offsetting and rollover futures?

For example, you are long/buy a crude oil futures contract in March at the spot price of $100 which expires in June. Then the day before they expire, the spot price of the June contract is $70.  If you offset the position, you will have to sell the contract which makes you lose $30. If you rollover, you will sell the June contract and buy a July contract. Does it mean that you also lose $30 when you rollover? If right, then what differences between these two options since they have the same loss?


I am writing an article using revtex4-1, and I am facing the following warning:  MnBi.bbl|1 warning| LaTeX Warning: A float is stuck (cannot be placed) on input line 1.   (As from vim's quickfix output, using latexmk)  My bib file is fine and it is compiled fine using bibtex. I tried to create a minimal example, but unable to reproduce the warning.  Also, while running pdflatex, I get same warning, but for different position, as:  Underfull \hbox (badness 10000) in paragraph at lines 322--323 []\OT1/cmr/m/n/10 This work is sup-ported by EP-SRC grant (./MnBi.bbl [2 <./images/cellE.png> <./images/Perfect_anisotropy.png> <./images /Mn_ExcessT.png>] LaTeX Warning: A float is stuck (cannot be placed) on input line 1. LaTeX Warning: A float is stuck (cannot be placed) on input line 1. Class revtex4-1 Warning: Deferred float stuck during \clearpage processing.   How can I get rid of this warning?  edit: This is said in the Revtex Manual:  Sometimes in L A TEX the float placement mechanism breaks down and a float can’t be placed. Such a “stuck” float may mean that it and all floats that follow are moved to the end of the job (and if there are too many of floats, the fatal error Too many unprocessed floats will oc- cur). REVTEX 4 provides the class option floatfix which attempts to invoke emergency float processing to avoid creating a “stuck” float. REVTEX 4 will provide a message suggesting the use of floatfix. If floatfix doesn’t work or if the resulting positioning of the float is poor, the float should be repositioned by hand.


Traveling to Canada with a Netherlands refugee passport

I would like to travel to Canada for holidays. I'm holding a refugee passport from the Netherlands, and I have already applied for eTA and received confirmation.   I am not a permanent resident of The Netherlands. I have temporary permission to stay for 5 years on my asylum ID.  Can I just book my ticket and go to Canada? Or do I need to request a visa beforehand?


How do I set WINE as default to run specific program

I am very new to ubuntu/linux. I have recently switched my laptop to Ubuntu 13.04 after I had an issue with Vista.   I have downloaded one of my favorite old games, Panzer General. I downloaded the zip file extracted it gotten the .exe file and am able to get it to run by right-clicking and using Open With...WINE windows program loader. However, if I go into properties(to make it the default), WINE does not appear in the list of applications to 'Open With' and the add button is un-clickable.   Any help would be great, thanks!


HP Compaq 8200 Elite SFF won't boot from USB drive. Solution

Can't get an HP 8200 Elite Small Form Factor to boot from USB. (MP8200 Elite SFF PC) BIOS version: J01 v02.15 ME Firmware version 7.1.3.1053 Tried on two different computers, with same BIOS version and the boot order list is not equal on the computers.   USB drive appears in BIOS "Device Configuration" list, but not in "Boot Order".  This is related to another thread, but I did not have enough reputation to answer on it.


How to force a login for an administrator when using Remote Desktop Connection?

Scenario:  I am at work. I want to remote desktop into my machine at home. Problem is, my 5-year-old daughter is playing games on Starfall.com (or something similar) on her (non-admin) account. When I attempt to connect I see this message:     Another user is currently logged on to this computer. If you continue, this user has to disconnect from this computer. Do you want to continue?   I click Yes and then see     Please wait for 'UserName' to respond   This presents my daughter with an Allow/Disallow dialog on whether to let me connect. She clicks Disallow (or No or whatever it says) and then I see     'UserName' has denied your request   Question:  How can I force my account to log in and disconnect her session?  Additional Info:  My account is an administrator account. My daughter's account is a non-administrator account. Home machine is Windows 7 Pro with fast user switching enabled.  Note In my case, turning off fast user switching is not an option. Kyle pointed out in his answer that turning it off would allow the admin to force another user off. I'm accepting his answer and it identifies the issue, even though it doesn't solve my exact problem. I need to keep fast user switching's ability to change accounts without closing the previous account's session over being able to force myself to connect.


Show that $n(n^2-1)$ is divisible by 24, if $n$ is an odd integer greater than $2$.

How can I show that $n(n^2-1)$ is divisible by 24, if $n$ is an odd integer greater than $2$?  I am thinking that since odd numbers have the form of $2n-1$ in which if it is to be more than $2$, it will be $2n-1+1 = 2n+1$. So would it be correct to use this and try solving through induction?


How Does One Remove Duplicate Text Lines From Files Larger Than 4GB?

I am looking for an open source (possibly 64 bit) windows text editor that will allow me to remove duplicate lines from an extremely large (4GB+) text file.  What do you use to remove duplicate lines from your large text files?


Disk full error while installing linux-image-4.10.0-33-generic

I'm a new in the  ubuntu community. I am having trouble with 17.04: even after running most of the recommended scripts, I still cannot solve the below error. What can I do?  linux-signed-image-4.10.0-33-generic : Depends: linux-image-4.10.0-33-generic (= 4.10.0-33.37) but it is not going to be installed E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution). dingi3@dingi3-HP-Pavilion-15-Notebook-PC:~$ sudo apt --fix-broken install Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following additional packages will be installed:     linux-image-4.10.0-33-generic Suggested packages:     fdutils linux-doc-4.10.0 | linux-source-4.10.0 linux-tools The following NEW packages will be installed:     linux-image-4.10.0-33-generic 0 to upgrade, 1 to newly install, 0 to remove and 57 not to upgrade. 14 not fully installed or removed. Need to get 0 B/20.3 MB of archives. After this operation, 70.5 MB of additional disk space will be used. Do you want to continue? [Y/n] Y (Reading database ... 472330 files and directories currently installed.) Preparing to unpack .../linux-image-4.10.0-33-generic_4.10.0-33.37_amd64.deb ... Examining /etc/kernel/preinst.d/ run-parts: executing /etc/kernel/preinst.d/intel-microcode 4.10.0-33-generic /boot/vmlinuz-4.10.0-33-generic Done. Unpacking linux-image-4.10.0-33-generic (4.10.0-33.37) ... dpkg: error processing archive /var/cache/apt/archives/linux-image-4.10.0-33-generic_4.10.0-33.37_amd64.deb (--unpack): cannot copy extracted data for './boot/vmlinuz-4.10.0-33-generic' to '/boot/vmlinuz-4.10.0-33-generic.dpkg-new': failed to write (No space left on device) No apport report written because the error message indicates a disk full error dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.10.0-33-generic /boot/vmlinuz-4.10.0-33-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.10.0-33-generic /boot/vmlinuz-4.10.0-33-generic Errors were encountered while processing:  /var/cache/apt/archives/linux-image-4.10.0-33-generic_4.10.0-33.37_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)


Are countable topological spaces second-countable?

Are countable spaces (i.e. $\mathbb{N}$ with any topology) second-countable? A countable space can have at most $2^\omega$ open subsets which suggests that a counterexample may exist. On the other hand both discrete and anti-discrete (or more generally with countable topology) spaces are second-countable. Also note that obviously a countable space is separable. So if it is additionally metrizable then it is second-countable.  But I couldn't prove that in general. Or is there a counterexample?


I am stuck with this exercise:     Show that $\forall s >0 \quad \exists N >0$ such that $$x^2 \equiv 1\pmod N$$ has more than $s$ solutions.   I think I cannot use the theory if quadratic residues, because the modulus is not prime, so maybe I must prove it with square roots or roots of unity, but I don't know how to approach it at all.  Thanks for any help.


Are there rules for falling in water vs. diving vs. just jumping in for various depths of water?

Just realized that in DMing 5e I have unconsciously used a falling-in-water rule-of-thumb that I inherited from somewhere (maybe 2e or AD&D or maybe even Pathfinder). The ruling I've been using is as follows:   No damage for 20 feet of falling. Half-damage next 20 feet. Normal damage beyond that.   Realizing there should be a Strength (Athletics) for "swimming" (in context, "diving") to take even less damage with a proper dive in sufficiently deep water, I started to look for specifics on that. Am I just missing it somewhere? (Also didn't find it searching this stack.)  Are there clear 5e rules for both jumping and diving in water of various depths?


Any Chance for me to install ubuntu on laptop Asus n61 JQ-X1?

I bought this laptop (ASUS N61JQ -X1) 2 years ago,till now i'm using window 7 64bit i wanna change OS for my laptop and Ubuntu is an advice that "google" gave me, but im not sure that Ubuntu has all drivers for my laptop or not because there are no Linux/Ubuntu driver for my model from ASUS   please help me, tell me if i have any chance on this


Bibliography not showing up in Table of Contents with tocbibind package

I'm trying to get the Bibliography inside my Table of Contents by using the tocbibind package, but only the List of Figures shows. I used the package like this: \usepackage[nottoc]{tocbibind}, and everything compiles without any errors, but the Bibliography is not in there. I saw in several forum discussions that people write the \bibliography{bib} command within the document class, after \tableofcontents, but if I try that, I get an error saying that the bibliography command can only be used in the preamble. I've also never seen how people using this package print the bibliography. I do it in the appendix like this: \begin{appendix}     \newpage     \printbibliography     \newpage     \listoffigures \end{appendix}  The bibliography itself looks perfectly fine, it's just not listed in the contents. Does anyone have an idea what might be causing this? This is what it looks like, the Bibliography should be on page 50:


I came to a situation, where while I was suggesting an edit, the OP already improved it (better than my version). As this was only 1-2 minutes after the question was posed, OP's edit isn't even listed in the edit history. Am I able to retract my own edit, as it makes no longer sence, and would just look like an degradation? Should I just write a short comment, explaining the issue?


The dihedral group $D_8$ isn't Hamiltonian

Let $D_8=\{a^ib^j:i\in\{0,1\},j\in\{0,...,3\}\} $ be a dihedral group, where $$a=\begin{pmatrix} -1 &0 \\  0 & 1 \end{pmatrix}\qquad\text{ and }\qquad b=\begin{pmatrix} cos\theta  & -sin\theta \\  sin\theta & cos\theta \end{pmatrix},$$ with $\theta=\frac{2\pi}{4}$. Prove that $D_8$ is not a Hamiltonian group.


Why is the option very low quality  sometimes hidden in the flag menu?  About a moment ago, I saw a post of very low quality on Stack Overflow, and I wanted to flag it as very low quality but this option was not in the flag menu.   Why?


Extracting IP address from a text and store it in a variable

I have a text file named abd shown below.   48878 128.206.6.136 34782 128.206.6.137 12817 23.234.22.106   I want to extract only IP address from the text and store it in a variable and use for other purpose.  I have tried this.  for line in `cat abd` do  ip=`grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}' $line`  echo $ip  done   I am getting an error as follows  grep: 34782: No such file or directory  grep: 128.206.6.137: No such file or directory  grep: 12817: No such file or directory  grep: 23.234.22.106: No such file or directory   I don't know what is going wrong here.  Any help would be appreciated.


I am interested in setting up a Ruby on Rails environment on my 10.10 laptop.   Is there anything special I need to keep in mind for installation (i.e. that could be new or unique to 10.10)?   Are there any suggested walkthroughs that I could follow along with?  Thanks in advance.


Can a cleric prepare spells later in the day?

Do clerics absolutely need to choose your spells right after the long rest, or can they choose some of them later in the day?  For example, I can take 8 spells. After my long rest I choose 6 of them — can I keep 2 slots empty for later in the day (so if I need a specific spell I can prepare it later that day)?


I am running Ubuntu 19.10. The gcc binary installed is  > ls -laht /usr/bin | grep gcc ... lrwxrwxrwx  1 root root       12 Apr  8 17:38 x86_64-linux-gnu-gcc-ranlib -> gcc-ranlib-9 lrwxrwxrwx  1 root root        8 Apr  8 17:38 x86_64-linux-gnu-gcc-ar -> gcc-ar-9 lrwxrwxrwx  1 root root        8 Apr  8 17:38 x86_64-linux-gnu-gcc-nm -> gcc-nm-9 lrwxrwxrwx  1 root root        5 Apr  8 17:38 x86_64-linux-gnu-gcc -> gcc-9 lrwxrwxrwx  1 root root        5 Apr  8 17:38 gcc -> gcc-9 lrwxrwxrwx  1 root root       22 Apr  8 17:38 gcc-9 -> x86_64-linux-gnu-gcc-9 lrwxrwxrwx  1 root root        8 Apr  8 17:38 gcc-ar -> gcc-ar-9 lrwxrwxrwx  1 root root       25 Apr  8 17:38 gcc-ar-9 -> x86_64-linux-gnu-gcc-ar-9 lrwxrwxrwx  1 root root        8 Apr  8 17:38 gcc-nm -> gcc-nm-9 lrwxrwxrwx  1 root root       25 Apr  8 17:38 gcc-nm-9 -> x86_64-linux-gnu-gcc-nm-9 lrwxrwxrwx  1 root root       12 Apr  8 17:38 gcc-ranlib -> gcc-ranlib-9 lrwxrwxrwx  1 root root       29 Apr  8 17:38 gcc-ranlib-9 -> x86_64-linux-gnu-gcc-ranlib-9 -rwxr-xr-x  1 root root     1.2M Oct 10  2019 x86_64-linux-gnu-gcc-9 -rwxr-xr-x  1 root root      35K Oct 10  2019 x86_64-linux-gnu-gcc-ar-9 -rwxr-xr-x  1 root root      35K Oct 10  2019 x86_64-linux-gnu-gcc-nm-9 -rwxr-xr-x  1 root root      35K Oct 10  2019 x86_64-linux-gnu-gcc-ranlib-9 -rwxr-xr-x  1 root root      454 Apr 11  2011 c99-gcc -rwxr-xr-x  1 root root      428 May  7  2006 c89-gcc ...   I want to install gcc-8 for some specific uses only. I can install gcc by running  sudo apt update && sudo apt install gcc-8   but I am worried that it will mess up everything in my /usr/bin directory, as well as other dependencies on gcc-9.  What is the safest way to install gcc-8 without having to build it myself?


I'm traveling with KLM from Chicago via Amsterdam to Frankfurt. I decided spontaneously to stay a few days in Amsterdam. Therefore I wanted to cancel my connection flight, but the KLM website says I'll have to pay a fee in order to do that. I don't see the point as I'm not using a service I payed for anyway.   So is it possible for me to tell the people at the check in to book my luggage for Amsterdam, not Frankfurt? And just get off over there?   As I am German, there should be no problem with border controls I assume.


How is the contradiction in this NPC's backstory in Curse of Strahd resolved?

This question includes NPC lore spoilers for Curse of Strahd, proceed at your own risk.  While running Curse of Strahd and prepping ahead, I have happened upon a rather glaring contradiction in the backstories of two of the important NPCs. I'm wondering if anything has been said by the developers regarding this...  This contradiction centers around       Ezmerelda d'Avenir and "Rictavio" (Rudolph van Richten)   In the former's backstory, we have this little snippet regarding their first encounter with the latter.      When Ezmerelda was a little girl, her family kidnapped van Richten’s teenage son, Erasmus, and delivered him into the clutches of a vampire. Even today, years later, she can still hear Erasmus’s pleas for mercy. That event haunted her childhood. Van Richten tracked down Ezmerelda’s family soon after the kidnapping, but not before the Vistani had sold the boy. Though van Richten could have done them harm, he instead interrogated Ezmerelda’s mother and father on the whereabouts of his missing son. Satisfied with their answers, he spared their lives before departing with the information they had given him. Ezmerelda witnessed van Richten’s act of mercy and was deeply moved by it.      However, in  (Handouts) we have the...      Journal of Rudolph van Richten   In which we find this entirely contradicting statement...      When I found the caravan [that had kidnapped Erasmus], I threatened to set the zombies on the Vistani unless they returned my dear boy. They replied that he had been sold to the vampire, Baron Metus. Something inside me snapped. I released the zombies, and the entire tribe was eaten alive.   After this, it goes on to explain      That this is where van Richten got is "monsters kill everyone you love" curse.   I know that if you go back to the AD&D2E Ravenloft books, the story from the Handout is how things actually went down, and the character who is the subject of the first story is a new character that was invented for the 5E Module.  Has anything been said about this backstory contradiction? It's kind of a big deal if these two characters turn out to be important to the plot (which they will in the game I'm running).  If the first story is true then...      Ezmerelda's family was not killed by van Richten, but the event that should have caused van Richten to get cursed never happened.   If the second story is true then...      Ezmerelda's origin and relationship with van Richten doesn't make sense, as she should have died with the rest of her family...and there was no 'act of mercy' for her to witness that made her want to seek out van Richten.


How to get rid of a character you no longer are interested in playing?

So I have been playing this character for a couple of months, and truth be told its just not working for me. He's playing his role in the group fine and has plenty to do, but the character turns out to be hard to motivate and the motivations he has are starting to run perpendicular to the rest of the group.  Short of going kamikaze and getting a new character that way, what would be the right way to go about getting this character replaced?


In RSA encryption, can I calculate d given only m,n,c and e?

Newbie here. Not familiar with cryptography; just interested and reading up about it from time to time.   We know that the RSA problem (let's say $c=m^e \bmod N, c^d= m \bmod N$) is about recovering $m$ given $N, c$ and $e$. However, if given $N, m, C$ and $e$ - can I recover $d$?


I know that C uses "%x" for hexadecimal and "%d" for decimal and I already tried using "%b".   How can I write an integer in binary in C?


Is there a stamp for crossing from one Schengen country to another?

Driving from Lithuania to Latvia on a bus, there was no stamp on crossing a border. Is it just a coincidence or stamps are set only on entering and exiting the Schengen zone?


Forgotten iPad passcode - How to reset it with no access to old email address and without using iTunes?

At first we forgot the passcode for our iPad, so we tried to change the passcode but it was connected to an old email address we no longer use.   The iPad is now disabled.  How do we reset it totally without using iTunes?


Unable to access window controls on maximized windows

I installed Ubuntu 13.04 but an annoying error has been bothering me. I formatted my PC to get rid of it, but about 2 hours after the fresh install, it came back.  The thing is that the title bar of any window, at the upper-left side, where the "close, minimize and maximize" buttons are, disappears when the mouse cursor is set over them. This disables the possibility of using them when the windows is maximized (full screen) but not when it's not. But it is very annoying.  The second screenshot may help show what I'm trying to say (notice the cursor and what happens when I try to click the close button on any window)    This is the problem:      I'm aware that there is a , but the thing is that the solution in that post involves using Unity2D, which was removed in Ubuntu 13.04  I hope there's a way to fix it.


Prove $\sin(x)\tan(x) > x^2$ for $x \in ( \,0, \frac{\pi}{2}) \,$  So I did the following: Let $f(x) = \sin(x)\tan(x) - x^2$.  Then of course $f(0) = 0$ and I want to show that for $x \in ( \,0, \frac{\pi}{2}) \,$ $f'(x) > 0$ but I don't really know where to go from here as I can't get anything reasonable done with the derivative.  I was thinking of approximating it using the following inequality $\sin(x) < x < \tan(x)$.   Is that a good direction?


Hi,  I want to contact a Stack Overflow user - is there anyway to send them a message or request access to there contact details?  The reason is a particular user has a lot of experience in a field in which we are looking to hire someone so we would like to contact them initially to see if they would be interested.


Is it safe to show user IDs in the profile URL?

In my website, there's a user's profile page. What I have currently doing is just pass the user ID via a GET request and use it to query the user's details.   So, the user profile URL is like this...  http://www.example.com/user.php?id=345   So, my problem is that, is it safe to show this user's ID (Primary key of the user table) in the URL so, that anyone can see it... ?


I have this assignment for a class- a postfix evaluator using stacks and queues.  The elements are in a queue entering the evaluation method, and a stack should be used to store elements; however, for some reason I cannot push the final value onto the stack.  The method is below:  private String processPostfix(MyQueue postfix) {     postfix.viewQueue();     MyQueue temp=postfix;     MyStack nums=new MyStack();     String t="";     String final_value="";     int a2;     int a1 = 0;      while(!temp.isEmpty()){         t=(String)postfix.dequeue();         if(t.equals("+") || t.equals("*") || t.equals("-")){             a2=Integer.parseInt(nums.pop().data);             a1=Integer.parseInt(nums.pop().data);             if(t.equals("+")){                 t=Integer.toString(a1+a2);             }             else if(t.equals("*")){                 t=Integer.toString(a1*a2);             }             else if(t.equals("-")){                 t=Integer.toString(a1-a2);             }         }         nums.push(new StackNode(t));     }     final_value=nums.pop().data;     return final_value; }   I can get the right answer to appear if I use  final_value=t;   But the problem is is that continuing to use the calculator, since the final value is not on the stack, any further input cannot be processed against it.  I therefore get a NullPointerException error.  The test temporary solution for this has been to ignore the empty stack error using this code:  if(!nums.isEmpty()){     a1=Integer.parseInt(nums.pop().data); }   I would really appreciate any explanation of this error.


Is this definition for a private access modifier accurate?:  private: Any thing declared as private can’t be seen outside of its class.   What about a private nested class?  This class can be seen "outside of its own class" by the class that is nesting it.  Maybe you could say that this nested class is actually a private member of the class nesting it and therefore can't be seen outside of the nesting class which would make the definition provided above true.  If a private nested class is NOT considered a member of the nesting class then I think the definition provided above is not accurate.


Why do employers require you to spread your 401(k) contributions throughout the year to get the maximum match?

I think the title says it all. I can't see any reason employers have to incentivize employees to contribute to their 401(k) evenly throughout the year. Instead couldn't they use a relatively simple formula that is based on how much of their income the employee has contributed to their 401(k) thus far for the year? If that or their current contribution is over the threshold, they get the match this pay period, even if they didn't contribute anything.  EDIT: To clarify, my employer matches 100% of the first 3% of my contribution and 50% of the next 2%. The match is added every pay period along with my contribution. I am pretty sure there is no "true-up" feature, so if I were to hit the $17.5K limit early, and not be able to contribute at least 5% of my salary, I would not get the full match. So I have to be careful to make my contributions evenly throughout the year to get the maximum match. Just trying to figure out my employer's motivation for requiring this.


Was wondering if there is an automated way to re-position shapes to minimize the space between them. Besides manually trying to guess the optimal configuration.  I am trying to achieve some layouts like the following


Will upgrading to a newer version delete my files, apps, or settings?

I am planning to upgrade from 13.04 to 13.10?  Does upgrading delete my files, documents and third party apps. Or does it keep my files and documents but deletes third party apps??


How do I fill an area with faces lined up in a grid over a not flat surface?

Hello to everyone again,  I'm looking for an addon or a short cut to fill fast and simmetrically a NOT FLAT surface that needs to be closed with vertices. Doing it manually it takes a lot of time. I tried to do CTRL F and then Grid fill,but it didn't work. Neither F key works. Check the attached screenshot. thanks.


Change the '.,' in to ',' between authors and eliminate the '.' between surname and first name

The traditional reference format can be set by the following command  \documentclass[12pt,openright]{book} \usepackage[backend = bibtex8, defernumbers = true,  sorting=none, style = numeric]{biblatex} \usepackage{filecontents} \begin{filecontents}{bib1.bib} @ARTICLE{dunbar2006distributed, author = {Dunbar, William B and Dunbar, William B and Murray, Richard M}, title = {Distributed receding horizon control for multi-vehicle formation stabilization}, journal = {Automatica},  year = {2006},  volume = {42}, pages = {549--558}, number = {4}, publisher = {Elsevier}, } \end{filecontents}  \addbibresource{bib1.bib} \renewbibmacro*{name:last-first}[4]{% \setcounter{liststop}{10}%                             % 列出所有的作者 \ifuseprefix {\usebibmacro{name:delim}{#3#1}%  \usebibmacro{name:hook}{#3#1}%  \ifblank{#3}{}{%    \ifcapital      {\mkbibnameprefix{\MakeCapital{#3}}\isdot}  {\mkbibnameprefix{#3}\isdot}%    \ifpunctmark{'}{}{\bibnamedelimc}}%  \mkbibnamelast{#1}\isdot  \ifblank{#4}{}{\bibnamedelimd\mkbibnameaffix{#4}\isdot}%  \ifblank{#2}{}{\addcomma\bibnamedelimd\mkbibnamefirst{#2}\isdot}} {\usebibmacro{name:delim}{#1}%  \usebibmacro{name:hook}{#1}%  \mkbibnamelast{#1}\isdot  \ifblank{#4}{}{\bibnamedelimd\mkbibnameaffix{#4}\isdot}%  %     \ifblank{#2#3}{}{\addcomma}%  \ifblank{#2}{}{\bibnamedelimd\mkbibnamefirst{#2}\isdot}%  \ifblank{#3}{}{\bibnamedelimd\mkbibnameprefix{#3}\isdot} }}  \DeclareNameFormat{default}{% \usebibmacro{name:last-first}{#1}{#4}{#5}{#7}% \usebibmacro{name:andothers}% } \renewrobustcmd*{\bibinitperiod}{} \renewrobustcmd*{\bibinithyphendelim}{} \begin{document} some text \cite{dunbar2006distributed}. \printbibliography \end{document}   and the corresponding output shown as:   Here is the desired output:   How can I modify the command to change the '.,' into ',' between authors and eliminate the '.' between surname and first name? Thanks!


Why doesn't the UK ask for travel bookings for a tourist visitor visa?

I am planning to visit London for 6 days from the US. I have given my biometrics and when I was preparing to mail my documents to the UK visa processing center in the US, I used this link from the UK government website to cross-check the documents to be sent to the processing center.     (Guide to supporting documents).  Something that really surprised me was in Section 4 (documents that should NOT be sent along with the package) was hotel bookings and flights bookings.     Section 4: documents you should not send unless specifically requested      This page provides guidance on the types of documents that are not required to consider your application.         hotel bookings   flight bookings      Typically I have always been asked to provide my travel plans, accommodation plans and proof of them. This is the first time that travel plans and accommodation plans are not asked to be sent. What might be the reason behind it? This really confuses me. Any help in clearing my confusion would be greatly welcome.


Chi-square test or Z-test for comparing two proportions?

On  the appropriate statistical test for comparing two independent proportions is described as a $Z$-test (a normal distribution is used to obtain a $p$-value).  However, in R prop.test, a Chi-square distribution is invoked to obtain the $p$-value comparing two independent proportions.  An R example is:  prop.test(x = c(474, 376), n = c(750, 750))   I was wondering how a Chi-square based approach comparing two independent proportions works (e.g., is the test a chi-square test or a different test that produces a statistic that follows a Chi-square distribution) and how it compares with the Z-test approach (e.g., in terms of accuracy and power) discussed ?


Remove() method in HashTable failing tests

I've been writing a HashTable for an assignment and I've been given tests to run and pass. As of now I'm passing all the tests apart from 3. But as far as I can tell from my own tests all the methods work fine. Apart from my Exception on the remove() method.  public void remove(String key) throws MapException{     int i = this.linearProbing(key);     if(hashTable[i].getKey() == key){    //line 76         numberOfEntries--;         numberOfRemovals++;         hashTable[i] = this.DEFUNCT;     }     else{                String e = "No entry of this key found";         throw new MapException(e);     } }   When I run this test I get an error and I'm not sure what it is.  //Remove a non-existent entry. Should throw an Exception     private static boolean test4() throws MapException {     StringHashCode sHC = new StringHashCode();     float maxLF = (float) 0.5;     HashTableMap h = new HashTableMap(sHC,maxLF);     try {         h.insert("R3C1");     } catch (MapException e1) {         return false;     }     try {         h.remove("R6C8");              //line 117         return false;     } catch (MapException e) {         return true;        } }   I'll also link my MapException Class here:  import java.lang.Exception;  public class MapException extends Exception {      public MapException(){      }      public MapException(String exception){         super(exception);     }      public MapException(String exception, Throwable throwable) {         super(exception, throwable);     }      public MapException(Throwable throwable) {         super(throwable);      }  }   The error is:     Exception in thread "main" ***Test 1 failed Test 2 succeeded Test 3 succeeded java.lang.NullPointerException at HashTableMap.remove(HashTableMap.java:73) at TestHashTableMap.test4(TestHashTableMap.java:117) at TestHashTableMap.main(TestHashTableMap.java:24)


Jquery Change ID functions only one way works?

I've got a label in view with the ID filterOff and this jquery:  $(document).ready(function () { $('#filterOn').click(function () {     $('#filters').hide();     $(this).attr('id', 'filterOff'); }); });  $(document).ready(function () { $('#filterOff').click(function () {     $('#filters').show();     $(this).attr('id', 'filterOn'); }); });   It works on the first instance either way around though doesn't work for the 2nd click. I can't work out what's wrong with it? The ID is changing i've checked select element in developer view, though it doesn't work.


Uniform continuity of $x \sin{\frac{1}{x}}$

$f(x) = x \sin{\frac{1}{x}}$ for $x > 0$, $0$ otherwise. Prove $f$ is uniformly continuous. I know similar questions have appeard asking for uniform continuity on $(0, 1)$, but here is uniform continuity on $\mathbb{R}$ and such problems are sensitive to the domain. I am wondering how to prove it formally.


Unable to Restore iPhone 4 and ERROR -50

I'm using Windows XP SP3. I installed iOS 5 on my iPhone 4. The installation process went OK, but, when trying to restore my contents, it gives me ERROR -50. I tried all the different things assosiated with this error.  Question: The only things that I miss are photos and, of course, my text messages. Is it possible to get the photos from my backup files manually?  iTunes does not show that it actually backed up the data on that date. The backup before that was a month earlier, which is did allow me to restore, so I'm stuck with the loss of a month.


What is the difference between MAC and HMAC?

In reference to , what are the "stronger security properties" that HMAC provides over MAC. I got that MAC requires an IV whereas HMAC doesn't. I also understood that MAC may reveal information about plaintext in contrast to HMAC. Is my understanding right?  What are other security properties of MAC and HMAC?


what are the eigenvalues in orthgonal matrix, How to explain?

what are the possible eigenvalues of an orthogonal matrix?  I got the answer key which says its 1 and -1 but it doesn't explain well


Averaging averages without losing standard deviation information

I've got a computerized procedure which runs a test and takes a few hundred samples during testing.  When finished, it spits back out the average and standard deviation of the samples.  Now, I've run this test several times on test subjects that should be identical, but of course I get back slightly different average and standard deviation data each time.  I only have a record of the average and standard deviation returned at the end of the test, not of each individual sample point.  A typical data set will look something like the following:  SUBJECT   AVG     STD       1   129.2   31.0       2   125.0   37.3       3   123.6   34.7       4   130.1   31.3      ...   ...    ...   Now, if I just average together the averages I get 127.0, but the standard deviation is only 3.2, when in fact the standard deviation between any actual samples is likely to be closer to 30.  Is there a way I can combine my summary statistics that preserves the information I have about the standard deviation between samples?  Unfortunately, I don't have access to the size of the data sets which generated the outputs above (it's somewhere around a hundred points, but is different each time and not something I have access to records of).


Has anyone else noticed that Chrome refuses to quit instantly when using CmdQ?  Happens with one or several tabs open...  All the other apps I run can be ended by typing / tapping briefly CmdQ, but Chrome insists that I have to hold for an appreciable period of time.  This is becoming annoying, any ideas?


What is the energy of a single charge system?

I will try to limit the question in the case of the electric fields, but is something that applies also to the magnetic ones. There are two ways to express the energy in a capacitor:    By Voltage : $U = 1/2 CV^2 $ And by Field : $U = 1/2 \varepsilon E^2Ad$, With Energy Density: $u = 1/2 \varepsilon E^2 $    Unless i understood everything wrong and these two are NOT the same quantity, i have the following question. When we have two charges placed at points A and B, then in order to calculate the energy of the system, we will take the first charge, place it at point A WITHOUT doing any work, and then we will calculate the work needed to place the second charge at point B.  The weird thing to me here, is that while we have placed the first charge, without generating any work the system will still have the energy held in the field of the charge!   There is obviously something that i miss, but what?


What is difference between INNER join and OUTER join

Difference between inner and outer join. i am using two table and want to fetch data from both table so which type join we should use owning of that we can solve our problem


I was reading  on the axiom of choice (AC) and it mentions that a growing number of people are moving into school of thought that considers AC unacceptable due to its lack of constructive proofs. A discussion with Mariano Suárez-Alvarez clarified that this rejection of AC only occurs when it makes sense.   This got me thinking. What are some examples of theorems in number theory that require the axiom of choice or its equivalents (ie Zorn's lemma) for its proof?  Note: Someone mentioned to me that Fermat's Last Theorem requires AC. Can someone verify this?


Is there a way to get Decisive Strike with a non-Monk weapon?

I'm working on a Darth Vader build for a competition. To represent the light saber, I would really like to use mind blade (from the 3.0 Soulknife prestige class, which is actually pretty cool, especially compared to the 3.5 base class). However, the Monk ACF Decisive Strike would make a fantastic addition to the build, and this ACF replaces Flurry of Blows.  Problem is, Unorthodox Flurry and Whirling Steel Strike - either of which would make the mind blade a special monk weapon - both have "flurry of blows class feature" as a prerequisite, so I can't use them. My second thought was Shou Disciple, but it only lets you flurry with other weapons; it doesn't make them special monk weapons, and thus it wouldn't let you decisive strike with mind blade either. The Eberron Monk substitution levels give you Whirling Steel Strike as a bonus feat, which would normally obviate the need for the prerequisites... but explicitly still requires all prerequisites. There are also numerous classes that give you a "flurry" of some flavor, but none I've found so far are specifically a "flurry of blows" that would work as a monk-independent way of qualifying for one of the feats.  So how about it? Is there a way to make a mind blade, short sword, or longsword* count as a monk special weapon that doesn't also require you to have Flurry of Blows?   Or a way to count as having the "Flurry of Blows class feature" to qualify for a feat?   Or for that matter, a way to get Decisive Strike without trading away Flurry of Blows?    *The Soulknife prestige class (Psionics Handbook pg 113) says the mind blade is "identical to" a short sword until level 8, at which point it's "identical to" a longsword. As far as I'm concerned, that means any method that works for one of those also works for the mind blade. It also means longsword is the least preferable of the three.


Greater than lesser than comparison in floating points in C

Consider the following code:  float x = 0.1; if ( x> 0.1){     printf("if"); }   Now when I check equality, it is explained that x is being converted to double by padding 0s at the end, but 0.1 on RHS is stored in double, hence the inequality. But if I go through this logic, the "if" in the above code should have given false, but istead it is true. Why?


Lewis Carroll's Pillow Problem via Bayes' Theorem

In Pillow Problems and a Tangled Tale Lewis Carroll presents the following problem:     A bag contains a counter, known to be either white or black. A white counter is put in, the bag is shaken, and a counter is drawn out, which proves to be white. What is now the chance of drawing a white counter?   One can easily reason that in the end, the bag must be in one of three states:   Black remains, new white taken New white remains, original white taken Original white remains, new white taken   In two of those states, a white counter remains to be drawn. Therefore, the chance is 2/3.  How can one arrive to this answer using Bayes' theorem?


Soundness of a rule of a proof system with respect to the truth tables?

I have the following question: "Explain the concept of the soundness of a rule of a proof system with respect to the truth tables"  Would it be correct to state the following:  "A rule of a proof system is sound with respect to the truth tables iff the conditions of the rules (requirements of the rule) ensure that the final formula will behave according to it's intended truth table."?  This is a question in a practice exam, and I can not find a specific mentioning so far, by scanning Google and Proof Wiki.  What would the correct answer be?  Thank you.


Pause cronjobs for an account (WHM/cpanel)

Is it possible to stop all cronjobs for a particular cpanel user? The cronjobs should be resumable when required later.  There are several hundred cronjobs running under this user. Only this user's cronjobs should be paused/suspended.


Why i am getting NullPointerException when accessing a member of Array of objects?

This is where i am getting error  Student[] student = new Student[10];  System.out.println(" Test : " + student[2].RollNo);   But i do not get error when  Student student = new Student();  System.out.println(" Test : " + student.RollNo);   Error only shows up when i am creating array of objects.


Why does Ubuntu have a disabled root account?

Ubuntu disables root login for "security reasons". However it seems to me that it doesn't help with security at all.  If an intruder manages to get your login password for Ubuntu, then he also has the super-user password, since it's the same as the login password.  However if the root password is required, then just having the login won't help the intruder much - that's right isn't it?  So basically, what I want to know is: Why did Ubuntu choose to disable the root password? What are the security reasons?  Please don't answer according to what you "think" was the reason - I'm looking for an answer from official sources, or linked to them.


Group of all $2\times2$ matrices where $a$, $b$, $c$, and $d$ are integers modulo $p$, Herstein Q$26$ Page $37$

Let $G$ be group of all square matrices of order $2$ $$\begin{bmatrix} a & b\\ c & d \end{bmatrix}$$  such that $a$, $b$, $c$, and $d$ are integers modulo a prime number $p$, such that $ad-bc\ne0$. $G$ forms a group relative to matrix multiplication. What is order of $G$?  I have tried for smaller values of $p$ by explicitly writing matrices. But how do I do this for general $p$.  Thanks


Do positive semidefinite matrices have to be symmetric? Can you have a non-symmetric matrix that is positive definite? I can't seem to figure out why you wouldn't be able to have such a matrix, but all my notes specify positive definite matrices as "symmetric $n \times n$ matrices."  Can anyone help me with an example of a non-symmetric positive definite matrix, or some insight into a proof for why it would need to be symmetric should that be the case? Thanks!


NullPointerException while parsing through a HashMap

I am trying to parse through a HashMap stored into an ArrayList (Not good at it). I did as I have been told however, I am getting an NullPointerException  Here is my code:  private void populateList() {     list = new ArrayList<HashMap>();      HashMap temp = new HashMap();     temp.put(CODE,"128");     temp.put(SERVICE_CODE, "NRS");     temp.put(SERVICE_GROUP, "Medical Treatment Loan");     temp.put(SERVICE, "Number of referral slip");     list.add(temp);      HashMap temp1 = new HashMap();     temp1.put(CODE,"128");     temp1.put(SERVICE_CODE, "NL");     temp1.put(SERVICE_GROUP, "Medical Treatment Loan");     temp1.put(SERVICE, "Number of Loan");     list.add(temp1);       HashMap temp3 = new HashMap();     temp3.put(CODE,"128");     temp3.put(SERVICE_CODE, "AD");     temp3.put(SERVICE_GROUP, "Medical Treatment Loan");     temp3.put(SERVICE, "Amount disbursed");     list.add(temp3); }   and here is how I was trying to Iterate through my list:   for (int a =0; a < list.size();a++)                 {                     HashMap<String, Integer> tmpData = (HashMap<String, Integer>) list.get(a);                     Set<String> key = tmpData.keySet();                     Iterator it = key.iterator();                      while (it.hasNext()) {                          String code = ""+tmpData.get(CODE);                          String service, service_group;                          if(code.equalsIgnoreCase("128"))                         {                              if(tmpData.get("SERVICE_CODE").toString().equalsIgnoreCase("AD"))                             {                                 service = tmpData.get("SERVICE").toString();                                 service_group = tmpData.get("SERVICE_GROUP").toString();                                 tv.setText("code >> "+code + "\nService Code >> "+tmpData.get("SERVICE_CODE").toString()                                 +"\nservice >> "+service+"\nservice_group >> "+service_group);                             }                         }                         it.remove(); // avoids a ConcurrentModificationException                     }                  }   My Error:    12-04 19:30:22.887 24861-24861/com.example.monkey.mysql_dump E/AndroidRuntime: java.lang.NullPointerException  12-04 19:30:22.887 24861-24861/com.example.monkey.mysql_dump E/AndroidRuntime:     at com.example.monkey.mysql_dump.input_taking$2.onClick(input_taking.java:74)   Basically I am trying to get the last value here, just to see if I can actually go through the whole arrayList.  Thank you.


Uninstalling Ubuntu from dual boot / changing bootloader

I have a Win/Ubuntu 11.10 dual-boot setup, where I am running the OSes on separate partitions of my laptop HDD. I assume the best method of uninstalling is 'simply' a matter of deleting the Ubuntu partitions -once I've made sure control is given to the Windows bootloader instead of grub after POST.  The question is: How do I do that?  Stuff I've tried:  I tried the boot-repair CD (), but that was a bit beyond my abilities to figure out if I could do it with that tool :/.  I also tried EasyBCD (). It couldn't identify my ext3 partitions, let alone change the bootloader.  Lastly, I tried installing startup-manager in Ubuntu, and using that to set the Win7 bootloader as default. But upon restart, it still loads grub.


Package biblatex Warning: citation '' was not found at all in the .bbl, bibliography labels cannot be generated

This is the package I am using to cite in my master thesis and the error that's occurring is the one displayed in the title. I don't understand where this error is coming from. If you need to see any more of the code for a solution just let me know. I'm happy for any help! Thanks a lot for trying to solve my problem.  \usepackage[backend=biber,style=numeric,natbib=true]{biblatex}  \addbibresource{Literaturliste.bib}  \ExecuteBibliographyOptions{sorting=nyt,maxbibnames=999,  maxcitenames=1,  backref=false,  bibencoding=utf8,  defernumbers=true}


How do you pronounce the word "married"? Why do most people pronounce it like "mɛrid" or "mɛərid" even though IPA for it is "mærid"?


Exception in Sending Mail from Zimbra to Gmail

The project I am working on need to send mail to Zimbra as well as Gmail IDs. The mail server used here is Zimbra Client Server and Port used is 25. But while sending mail to Gmail ID,Exception occurs as follows. Exception : Transaction failed. The server response was: 5.7.1 somegmail_Id@gmail.com: Relay access denied Code section             int port = 25;             oSmtpClient.UseDefaultCredentials = false;             oSmtpClient.Credentials = new NetworkCredential(sUserName, sPassword);             oSmtpClient.Host = sServer;             oSmtpClient.Port = port;             oSmtpClient.EnableSsl = true;             oSmtpClient.UseDefaultCredentials = false;             MailMessage oMailMessage = new MailMessage(); ;             oMailMessage.From = new MailAddress(sFrom);             oMailMessage.To.Add(new MailAddress(MailId));             oMailMessage.Subject = "Subject";             oMailMessage.Body = sBody;             oMailMessage.IsBodyHtml = true;             oSmtpClient.Send(oMailMessage);


I have an older Rails 3 app that use SQLite3 database. I need to switch it to MySQL - that's kind of easy-peasy.  The problem is that in the SQLite3 database is a scheme of categories - about 500. I need to export these categories from SQLite3 database and import them into the newly create MySQL one.  Now the thing is (as I haven't done it before) - how to make this kind of migration in its simplest way?


How find this limit $\lim\limits_{x\to 0^{+}}\frac{\sin{(\tan{x})}-\tan{(\sin{x})}}{x^7}$

Find the limit $$\lim_{x\to 0^{+}}\dfrac{\sin{(\tan{x})}-\tan{(\sin{x})}}{x^7}$$  My attempt: Since $$\sin{x}=x-\dfrac{1}{3!}x^3+\dfrac{1}{5!}x^5-\dfrac{1}{7!}x^7+o(x^7)$$ $$\tan{x}=x+\dfrac{1}{3}x^3+\dfrac{2}{15}x^5+\dfrac{1}{63}x^7+o(x^3)$$ So $$\sin{(\tan{x})}=\tan{x}-\dfrac{1}{3!}(\tan{x})^3+\dfrac{1}{5!}(\tan{x})^5-\dfrac{1}{7!}(\tan{x})^7+o(x^7)$$ Though this method might solve, I think this problem has nicer methods. Thanks.


Whats the difference between SUDO and Changing to root

If I issue a   sudo /bin/bash`   [sudo] password for mark: cmp -bl /dev/blah1 /dev/blah2   and using   sudo cmp -bl /dev/blah1 /dev/blah2   then logging in as root?  I don't see whats different, if issuing multiple command lines then rooting IMHO seems the logical option over typing sudo prefix to command lines.  I have seen sudo -i being used to log in to root, that used to work but the last week its issuing an error.  ** EDIT **  I logged in as root, issued the command  mark@mark-zotac:~$ sudo cmp -bl /dev/sda "/media/mark/Seagate Expansion Drive/SSD/ssd.img" [sudo] password for mark:  mark@mark-zotac:~$   It ran, took about 30 minutes to run but produced zero as in nothing output. I am left with no indication of failure or success... So how do I know if the compare result was a success?


In my country, we are told when we mention musical instruments such the guitar, or the piano, we have to attach the definite article, "the" before that. , Nick, insists, "We say 'I play guitar'" (the video is partly in English and partly in Japanese), which is correct grammatically?


To prove in a Group Left identity and left inverse implies right identity and right inverse

Let $G$ be a nonempty set closed under an associative product, which in addition satisfies :      A. There exists an $e$ in $G$ such that $a \cdot e=a$ for all $a \in G$.      B. Given $a \in G$, there exists an element $y(a) \in G$ such that $a \cdot y(a) =e$.      Prove that $G$ must be a group under this product.   Attempt -Since Associativity is given and Closure also, also the right identity and right inverse is given .So i just have to prove left identity and left inverse.  Now as $ae=a$ post multiplying by a, $aea=aa$. Now pre multiply by a^{-1} I get hence $ea=a$. And doing same process for inverse Is this Right?


Why is the net angular momentum of Solar system not zero?

Title says it all. When we take the angular momentum of the solar system into account, we know that it is a net positive value. From where, how and why did our solar system acquire such a huge angular momentum?


A and B are real, symmetric and positive semi-definite matrices of the same order; is AB diagonalizable?

I've already proved this with B positive definite using the fact that $B^{-\frac{1}{2}}$ does exist and AB is similar to $A^{\frac{1}{2}}BA^{\frac{1}{2}}$, but since B is positive semi-definite I don't know if that is true. I also know that $A^{\frac{1}{2}}$ and $B^{\frac{1}{2}}$ are defined.  I´m trying to see that $A^{\frac{1}{2}}BA^{\frac{1}{2}}$ is similar to $A^{\frac{1}{2}}A^{\frac{1}{2}}B$, but i'm having problems with that.  Any hint would help, thanks!


What mistake am I making in plotting this graph of effective potential for the Earth-Moon system?

I am trying to create a graph of effective potential for the Earth-Moon system in Excel. It should result in a graph that looks like this:   But this is not what I end up with. (I've made a Google Docs version of my spreadsheet .)   I start by calculating the gravitational potential at r: $V(r)=-\frac{GM_E}{r}$. Then multiply by the mass of the Moon to get the gravitational term (i.e. $U(r)=-\frac{GM_EM_M}{r}$). Then calculate the gravitational force with $F=G\frac{M_E M_M}{r^2}$ and calculate the orbital velocity with $v=\sqrt{\frac{Fr}{M_M}}$. Calculate angular momentum with $L = M_Mvr$. Calculate the value of $\frac{L^2}{2\mu r^2}$ where $\mu$ is the reduced mass $\mu = \frac{M_M M_E}{M_M+M_E}$. Find the resultant $\frac{L^2}{2\mu r^2} - \frac{GM_E}{r}$.   I'm making an obvious mistake somewhere, as I end up with a negative effective potential at all radii. I can't post an image because I don't have enough reputation for more than two links, but it's in the Google Docs spreadsheet linked above.


Given that $$\lim_{n\to \infty}a_n=a,\lim_{n\to \infty}b_n=b,$$ prove that $$\lim_{n\to \infty}\frac{a_1b_n+a_2b_{n-1}+···+a_nb_1}{n}=ab.$$


Decrypting a password protected LibreOffice Calc .ods file (forgotten password)

Sometime ago I created an .ods file with Libreoffice Calc which I password protected. I have now forgotten the password and as a result I am unable to access the file. Is there any way of bypassing or recovering the password, e.g. as root using the terminal?


How can a body travel at an instant and what does instantaneous speed tells us? What really is meant by speed of an object at an instant if an object does not travel at an instant? I would like a mathematical explanation.


I trained an SVM to classify images based on some extracted features (using the ISIC dataset). The resulting ROC curve produced by sklearn looks like this:   I have don't quite understand the line for class 0 and 1 (orange and green). I have never seen a ROC curve under the diagonal. What does this tell me now and is this even a valid curve? The other computed evaluation metrices are the following if that helps my question.


Install applications on a second hard drive

I have a laptop with a 128GB SSD in it and a 1,5TB HDD. I want to, when I install applications, that the apps get installed on my secondary hard drive. Is this possible in apt? What do I have to do?


Get high I/O rate alert from linode.com,how to location problem?

Today I get an  alert mail from linode.com "Your Linode, Randy, has exceeded the notification threshold (1000) for disk io rate by averaging 1571.81 for the last 2 hours.".   Last time I get alert like that is several month ago, I keeping get alerts, but at the same time my website network traffic never grow. I try everything, but can not location the problem. Finally, I guess the growing log file size is the problem. I use cronolog cut log file, and problem resolved.  Now,I/O rate chart shows I/O rate is keeping growing too, how to I  location problem? Is there anything can help me?  My server is Ubuntu 8.04.4 LTS/apache/php/mysql at linode.com.


break command for nested loops inside conditional statement

I want to break main while loop using break statement inside if condition a = 0 b = True while b:     print(a)     while a < 10:         if a == 8:             b = False             break       # want to break both while loops using this command         else:             print(a)             a += 1  result should be 0 0 1 2 3 4 5 6 7


Java Generate Random Number Between Two Given Values

I would like to know how to generate a random number between two given values.  I am able to generate a random number with the following:  Random r = new Random();  for(int i = 0; i < a.length; i++){     for(int j = 0; j < a[i].length; j++){         a[i][j] = r.nextInt();     }  }   However, how can I generate a random number between 0 and 100 (inclusive)?


Can't understand behaviour of sed command

I have a file test with some data and I am using sed command to modify some word in the file and then redirect the output to the same file but after the command is executed the file contains no data. I don't get the reason behind that behavior?  $ cat test foo bar 123 bar foo foo $ sed 's/foo/bar/' test > test $ cat test $


Sometimes, someone edits my posts. The edits were very helpful, so I want to thank them.   How do I thank someone for a helpful edit to my post? Adding a comment, or something else?


Do you add your modifiers to attack rolls when you fight with two weapons?

I plan on making a dual wielding barbarian/fighter, and in fighter's fighting style it says that this style allows me to add modifiers to damage rolls for second weapon. But do I get a bonus for the second attack itself, or does everyone already have it? If not, is there something that allows me to add it? P.s. apologies for bad english.


Unable to add unicode flag to regex for email check


Cross domain cookie for same Drupal installation

The English translation of my Drupal installation runs on MYSITE.com and my German translation runs on MYSITE.de. Of course, I want my users to be able to switch languages without having to log in again.  I read that there is no way to set cross domain cookies for domain1.com and domain2.com if they point to different websites, only for subdomains 1.domain.com and 2.domain.com. Is there any way to set a cross domain cookie in my case, where both domains point to the same installation?


I have the exact problem in 13.10 as this user .  Here are some screenshots:      Here are some screenshots from another user:     ifconfig and iwconfig outputs  $ ifconfig lo        Link encap:Local Loopback             inet addr:XXXXXX  Mask:XXXXXXX           inet6 addr: ::1/128 Scope:Host           UP LOOPBACK RUNNING  MTU:65536  Metric:1           RX packets:2243 errors:0 dropped:0 overruns:0 frame:0           TX packets:2243 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:0            RX bytes:209889 (209.8 KB)  TX bytes:209889 (209.8 KB)  wlan0     Link encap:Ethernet  HWaddr XXXXXXXXX             inet addr:XXXXXX  Bcast:XXXXXXXX  Mask:XXXXXXX           inet6 addr: XXXXXXX Scope:Link           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           RX packets:5925 errors:0 dropped:0 overruns:0 frame:0           TX packets:3361 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000            RX bytes:2951818 (2.9 MB)  TX bytes:630579 (630.5 KB)  $ iwconfig lo        no wireless extensions.  wlan0     IEEE 802.11abgn  ESSID:"XXXXX"             Mode:Managed  Frequency:2.437 GHz  Access Point: XXXXXXXX           Bit Rate=72.2 Mb/s   Tx-Power=15 dBm              Retry  long limit:7   RTS thr:off   Fragment thr:off           Power Management:on           Link Quality=49/70  Signal level=-61 dBm             Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0           Tx excessive retries:153  Invalid misc:472   Missed beacon:0


Array.Sort() not preserving element order with case-insensitive comparer

I am using Array.Sort() with the parameters shown in the code. I'm unable to get the required order for the following array  jONeS jones joNes jones aDaMs adams adaMS ADAMs   The program shown prints the following  adams aDaMs adaMS ADAMs jONeS jones joNes jones   Where as according to me the following order should be printed  aDaMs adams adaMS ADAMs jONeS jones joNes jones   Note the first two elements displayed wrongly. Where am I going wrong?  int N = Convert.ToInt32(Console.ReadLine()); string[] arr=new string[N]; for (int i = 0; i < N; ++i)     arr[i] = Console.ReadLine(); Array.Sort(arr, StringComparer.Create(new CultureInfo("en-US"),true)); Console.WriteLine(); for (int i = 0; i < N; ++i)     Console.WriteLine(arr[i]);


how to set default login asking for password again?

I want to set my login screen (greeting screen or GUI) to the default setting, which asks for password befor let me login, I dont know how did I messed it out, now running saucy, it just can show me the list of desktop environments, but after I chose the environment I want, I just click and login directly, then after I login to the descktop another message pop out asking me to type my keyring password.     I wounder if me inserted (PGP) key from previous system did that!, any how, I just want the normal default login back, any help please? step by step for a newbie  I tried System Settings --> User Accounts GUI tool, or use the passwd command  sudo passwd username   pressing "Unlock" but is not responding as all other "Unlock"s in this laptop right now nor the terminal commands change anything, they change the password in terminal but still the same exat above mentioned drama


Having a bit of a problem with a question. There is a 4m ladder leaving against a wall. There is a box in between The ladder and wall. The box is a cubic metre.  I have found a quartic to find the length up the wall the ladder will reach. But its proving difficult for me to solve.   $$x^4 +2x^3 -14x^2 +2x +1=0$$


When I try to render my scene, there are no Lights at Final Render.    But if I use Shift+Z shortcut to see a preview, all works fine.    I really don't understand what is going on... Can you guys help this newbie? I installed Filmic Renderer that BlenderGuru recommended. Other than that, everyting are default, I think.


Apply Krull's principal ideal theorem to an affine cone

This is Exercise 11.3.C from Vakil's notes.   Suppose $X$ is a closed subset of $\mathbb{P}_k^n$ of dimension at least $1$, and $H$ is a nonempty hypersurface in $\mathbb{P}_k^n$. Show that $H$ meets $X$.  (Hint: note that the affine cone over $H$ contains the origin in $\mathbb{A}_k^{n+1}$. Apply Krull's Principal Ideal Theorem to the cone over $X$.)  My attempt: Let $A=k[x_0,\dots,x_n]$,  $X=\operatorname{Proj}A/I$ and $H=\operatorname{Proj}A/(f)$. I suppose the hint suggests to consider $V(f)$ in $\operatorname{Spec}A/I$. Suppose $f$ is not a zero divisor of $A/I$, then every irreducible component of $\operatorname{Spec}A/I\cap \operatorname{Spec}A/(f)$ has codimension precisely $1$. There is an injection $\operatorname{Spec}A/I\setminus \{0\}\hookrightarrow \operatorname{Proj}A/I$, similiarly  $\operatorname{Spec}A/(f)\setminus \{0\}\hookrightarrow \operatorname{Proj}A/(f)$. If I can show that $\operatorname{Spec}A/I\cap \operatorname{Spec}A/(f)$ is not the maximal ideal corresponding to the origin. Then  I can conclude $X\cap H\neq \emptyset$.   Is this correct? Can any suggest how to proceed?


I used the prcomp() function to perform a PCA (principal component analysis) in R. However, there's a bug in that function such that the na.action parameter does not work. ; two users there offered two different ways of dealing with NA values. However, the problem with both solutions is that when there is an NA value, that row is dropped and not considered in the PCA analysis. My real data set is a matrix of 100 x 100 and I do not want to lose a whole row just because it contains a single NA value.  The following example shows that the prcomp() function does not return any principal components for row 5 as it contains a NA value.  d       <- data.frame(V1 = sample(1:100, 10), V2 = sample(1:100, 10),                        V3 = sample(1:100, 10)) result  <- prcomp(d, center = TRUE, scale = TRUE, na.action = na.omit) result$x                                # $ d$V1[5] <- NA                           # $ result  <- prcomp(~V1+V2, data=d, center = TRUE, scale = TRUE, na.action = na.omit) result$x   I was wondering if I can set the NA values to a specific numerical value when center and scale are set to TRUE so that the prcomp() function works and does not remove rows containing NA's, but also does not influence the outcome of the PCA analysis.  I thought about replacing NA values with the median value across a single column, or with a value very close to 0. However, I am not sure how that influences the PCA analysis.  Can anybody think of a good way of solving that problem?


I have a server "A" that has an NFS mount /FOO.   I setup an NFS server on server "A" to export the NFS mount /FOO.   I have other server: "B". But I cannot mount the /FOO from server "A" - probably because it was already an NFS mount.   I can export local dir on server "A", but not an NFS mount.   OS is SLES 11.   The question: how can I export an NFS mount via NFS to other servers? :)


I want to make a register form which will be connected with database. I have a problem because after filling in the form i get exception      java.lang.NullPointerException Database.Person.getName(Person.java:18)   Database.Register.doPost(Register.java:25)   I was looking for an answer, but there are only solution in easy way ( i mean everything in one class). There is my code  Person.java  package Database;   import javax.servlet.http.HttpServletRequest;  public class Person {     private String name;     private String surname;     private String email;     private String employer;     private String getKnow;     private String hobbies;      HttpServletRequest request;       public String getName() {         return request.getParameter("name");     }      public void setName(String name) {         this.name = name;     }      public String getSurname() {         return request.getParameter("surname");     }      public void setSurname(String surname) {         this.surname = surname;     }      public String getEmail() {          return request.getParameter("email");     }      public void setEmail(String email) {         this.email = email;     }      public String getEmployer() {         return request.getParameter("pracodawca");  }      public void setEmployer(String employer) {         this.employer = employer;     }      public String getGetKnow() {         return request.getParameter("getKnow"); }      public void setGetKnow(String getKnow) {         this.getKnow = getKnow;     }      public String getHobbies() {         return request.getParameter("hobbies"); }      public void setHobbies(String hobbies) {         this.hobbies = hobbies;     }   Register.java  package Database;  import java.io.IOException; import java.io.PrintWriter; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.Statement;  import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;  @WebServlet(urlPatterns = "/Register") public class Register extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response)             throws ServletException, IOException {     response.setContentType("text/html");     PrintWriter out = response.getWriter();      Person person = new Person();     String name = person.getName();     String surname = person.getSurname();     String email = person.getEmail();     String nameC = person.getEmployer();     String getKnow = person.getGetKnow();     String hobbies = person.getHobbies();           try {             Class.forName("org.postgresql.Driver");             Connection connection = DriverManager.getConnection(                     "jdbc:postgresql://localhost:5432/formularz", "postgres",                     "qwerty");             PreparedStatement ps = connection.prepareStatement(                     "INSERT INTO zgloszenia(name,surname, email,pracodawca, getknow, hobbies) values(?,?,?,?,?,?)");             ps.setString(1, name);             ps.setString(2, surname);             ps.setString(3, email);             ps.setString(4, nameC);             ps.setString(5, getKnow);             ps.setString(6, hobbies);              int i = ps.executeUpdate();             if (i > 0) {                 out.print("Registered successfully...");                 connection.close();             }           } catch (Exception e) {             e.printStackTrace();         }     }      }