Recently restarted my computer after updates. I get pass grub and a login prompt with a black background came up to log in with a user name, password. After the login the prompt "name@name-GA990FXA-UD3:~$" this came up. I'm not sure where to go from here. I realize that GA990FXA-UD3 is my motherboard.   I attempted older version which gave me error due no detection of devices. Mouse and keyboard didn't work. Recovery mode and repair.


Re-enter Schengen after 6 months for 90 days

My mother has a multiple-entry visa issued for Belgium which is valid for one year, with maximum stay of 90 days.  Having entered the Schengen area June 25, her 90 days expires September 23 (she will exit September 20).  Since she has used up her 90 days, how would one go about restoring another 90 days when the 180 days are up (December 22)?  Does she need to reapply for a new visa (despite the fact that her current visa has not expired)?  Or does the 90 day limit reset automatically and she can re-enter with her existing visa?


Is an empty set reflexive? Symmetric? Transitive?

Suppose  $$A\neq\emptyset$$   Since, $$\emptyset\subseteq A * A$$  the set $$R=\emptyset$$ is a relation on A.  Is $R$ reflexive? symmetric? transitive?  I remember hearing something can be "vacuously" true. So the empty set would be reflexive, symmetric and transitive because it doesn't meet the definition?  So there is no $(x,x)$ that can exist in $R$ therefore vacuously reflexive.  There is no $(x,y)$ that can exist in $R$ therefore vacuously symmetric.  There is no $(x,y)$ that can exist in $R$ therefore vacuously transitive.  Is my reasoning correct here?


When executed. The code alerts an array full of undefined objects. I am trying to make a deck of cards by having each card be an array element that has 2 object attributes (suit and value). I think the issue is in the convergence of the 2 arrays.   Thanks for your help in advance!
Problem #1

Number of Players:
     <form id='form'>         <input type="radio" name="playerChoice" id="playerChoice-1" value="1" />         1         <input type="radio" name="playerChoice" id="playerChoice-2" value="2" />         2         <input type="radio" name="playerChoice" id="playerChoice-3" value="3" />         3         <input type="radio" name="playerChoice" id="playerChoice-4" value="4" checked="checked" />         4     </form>     Deal

Player 1:

Player 2:

Player 3:

Player 4:


I recently came across a funny picture with these questions:  Do you want som drugs?  No  Do you not want some drugs?  Presumably the answear is supposed to be "no" since you always say no to drugs, but does not both these questions result in him saying no to drugs?


I have one query related to name displayed on Air India website.  There is extra "MR" with my first name on website and "Title" field is empty.   Can you please suggest on this and whether it is fine? My name in passport is :  First Name: KAUSHAL  Last Name : KISHOR  Name on Air India website and ticket is displayed as KISHOR,KAUSHALMR. Will this be an issue??


How do you enable Hotspot Wifi Sharing on Nexus 5 Android M version on Sprint, Tmobile, and AT&T?

I just loaded the Android M preview version as of July 2015. I'm also on the Sprint network and my phone is rooted. How can I enable wifi hotspot ability on Android M?


Energy momentum tensor from Noether's theorem

in the book Quantum Field Theory by Itzykson and Zuber the following derivation for the stress-energy tensor is proposed (p.22):  Assume a Lagrangian density depending on the spacetime coordinates $x$ only through fields and their gradients. Under a translation we have $$\mathcal L (x+a)=\mathcal L[\phi_i(x+a),\partial_\mu\phi_i(x+a)].$$  Consider an infinitesimal $x$-dependent transformation $$\delta\phi_i=\delta a^\mu(x)\partial_\mu\phi_i(x),$$ $$\delta\partial_u\phi_i(x)=\delta a^\nu \partial_\nu\partial_\mu\phi_i(x)+\partial_\mu[\delta a^\nu (x)]\partial_\nu \phi_i(x).$$  The proof then proceeds with variation of the action and integration by parts. But why do we consider an $x$-dependent local transformation instead of a global transformation?


How can I quickly wipe everything and do a clean install

I have a Minidell with SSD from 2009. I'd like to do a quick wipe everything and clean install to give it away. What is the fastest way?


Weighting of the loss function for unbalanced data

I am trying to build logistic regression that will work with unbalanced data, i.e. I have about 0.33% of data parts that have to be classified as class 1 and others that have to be classified as 0.    The question is how should be standard binary crossentropy loss () changed in order to cope with such data?  I tried adding weight to the first part - 1 class, equal to inverted frequency of the 1 class; adding weights to both parts equal to percentage of 0 class for the first part and 1 class to the second class; but nothing seems to work


I don't want to use miss.   What are my other alternatives? I cannot go with Mrs because I don't want to have to use her name. Is it Madam then? It sounds so french and old-fashioned. "Bonjour madame".  Any other options?


why does function relates input to only one output?

I'm trying to understand the rationale behind definition of function. Why is function defined as a relation which relates input to only 1 output?  What would happen if we allow function to relate input to multiple output? Something like y^2 + x^2 = 4


Ubuntu 18.04 error on waking up from sleep : Read-error on swap device

After the laptop has been in sleep mode for a couple of hours,when I try and resume my session I get the following error:     Read-error on swap device    It takes about 30 seconds for the login screen to load post this happening. Once I log in, the screen blanks out once or twice for a second, and none of my programs are open anymore. I get a "System problem detected" prompt. When I click on "Send Report", another notification pops up saying:     Sorry the program "Xorg" closed unexpectedly. Your computeer does not have enough free memory to automatically analyze the problem and send a report to the developers.   What I have tried so far is to increase the swap space available. It was around 2 GB initially and I created another swap file of 9 GB. This hasn't helped. The occupied swap space ( as per the swapon command ) after the crash is always around 170MB.  The DMESG for when I resume my session, up to the read error on swap device is as follows:       [64046.474054] ACPI: Low-level resume complete [64046.474162] ACPI: EC: EC started [64046.474162] PM: Restoring platform NVS memory [64046.475139] Enabling non-boot CPUs ... [64046.475196] x86: Booting SMP configuration: [64046.475196] smpboot: Booting Node 0 Processor 1 APIC 0x2 [64046.475663]  cache: parent cpu1 should not be sleeping [64046.475859] CPU1 is up [64046.475910] smpboot: Booting Node 0 Processor 2 APIC 0x4 [64046.476330]  cache: parent cpu2 should not be sleeping [64046.476506] CPU2 is up [64046.476539] smpboot: Booting Node 0 Processor 3 APIC 0x6 [64046.477071]  cache: parent cpu3 should not be sleeping [64046.477255] CPU3 is up [64046.477274] smpboot: Booting Node 0 Processor 4 APIC 0x1 [64046.477721]  cache: parent cpu4 should not be sleeping [64046.477922] CPU4 is up [64046.477947] smpboot: Booting Node 0 Processor 5 APIC 0x3 [64046.478371]  cache: parent cpu5 should not be sleeping [64046.478571] CPU5 is up [64046.478591] smpboot: Booting Node 0 Processor 6 APIC 0x5 [64046.479018]  cache: parent cpu6 should not be sleeping [64046.479229] CPU6 is up [64046.479247] smpboot: Booting Node 0 Processor 7 APIC 0x7 [64046.479675]  cache: parent cpu7 should not be sleeping [64046.479899] CPU7 is up [64046.485913] ACPI: Waking up from system sleep state S3 [64046.639206] ACPI: EC: event unblocked [64046.639711] sd 2:0:0:0: [sda] Starting disk [64046.873289] usb 1-11: reset full-speed USB device number 2 using xhci_hcd [64046.976869] ata4: SATA link down (SStatus 4 SControl 300) [64046.976892] ata2: SATA link down (SStatus 4 SControl 300) [64047.149289] usb 1-6: reset high-speed USB device number 40 using xhci_hcd [64047.437370] psmouse serio1: synaptics: queried max coordinates: x [..5660], y [..4570] [64047.476302] psmouse serio1: synaptics: queried min coordinates: x [1364..], y [1284..] [64047.922603] OOM killer enabled. [64047.922605] Restarting tasks ... done. [64047.928727] thermal thermal_zone1: failed to read out thermal zone (-61) [64047.930036] Bluetooth: hci0: Bootloader revision 0.0 build 2 week 52 2014 [64047.935036] Bluetooth: hci0: Device revision is 5 [64047.935037] Bluetooth: hci0: Secure boot is enabled [64047.935038] Bluetooth: hci0: OTP lock is enabled [64047.935038] Bluetooth: hci0: API lock is enabled [64047.935039] Bluetooth: hci0: Debug lock is disabled [64047.935040] Bluetooth: hci0: Minimum firmware build 1 week 10 2014 [64047.935042] Bluetooth: hci0: Found device firmware: intel/ibt-11-5.sfi [64047.944372] PM: suspend exit [64048.050329] Read-error on swap-device (8:0:1543400288) [64048.460888] [drm] RC6 on   Please let me know if any other information is needed.


Lenovo X250 - Wifi Connection drops constantly - Ubuntu 14.04

I'm running Ubuntu 14.04 on my Lenovo X250 and I experience frequent drops of my WIFI connection. After the connection has gone down I can still see my network's name in the list of available networks. All other publicly visible networks are gone, however. If I try to reconnect nothing happens. Only a suspend or a restart solves the problem. Here is the output of lshw -C network:  *-network                       description: Ethernet interface        product: Ethernet Connection (3) I218-LM        vendor: Intel Corporation        physical id: 19        bus info: pci@0000:00:19.0        logical name: eth1        version: 03        serial: 68:f7:28:64:1b:9d        width: 32 bits        clock: 33MHz        capabilities: pm msi cap_list ethernet physical        configuration: broadcast=yes driver=e1000e latency=0 multicast=yes        resources: irq:20 memory:f1200000-f121ffff memory:f123e000-f123efff ioport:3080(size=32)   *-network        description: Wireless interface        product: Wireless 7265        vendor: Intel Corporation        physical id: 0        bus info: pci@0000:03:00.0        logical name: wlan1        version: 59        serial: 60:57:18:75:fe:c7        width: 64 bits        clock: 33MHz        capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless        configuration: broadcast=yes driver=iwlwifi driverversion=3.13.0-53-generic firmware=22.24.8.0 ip=192.168.178.30 latency=0 link=yes multicast=yes wireless=IEEE 802.11abgn        resources: irq:64 memory:f1000000-f1001fff   I'm running the kernel version: 3.13.0-53. I once updated to kernel 4.1 and I had the impression that wifi disconnects were less frequent or gone completely but I experienced very high CPU temps and the fan was running constantly.  Can anyone help, please?


Let $p\ge3$ be a prime number, $r$ be a natural number and $x$ be a primitive root modulo $p^r$. Show that $x$ is a primitive root modulo $p$.


C++11 (gcc 4.9): error at template function (converting tuple vector to single component vector)

when compiling following code with C++11 (gcc 4.9), I get a compiler error:  //converts tuple vector to single component vector template<class In, class Out, int Idx> QVector<Out> tuple_vector_to_member_vector (const QVector<In>& in_vector) {     QVector<Out> out_vector;     for (In in : in_vector)         out_vector.push_back(in.get<Idx>());     return out_vector; }   The error is as following (and occurs as well when the template is not instantiated):   error: expected primary-expression before ')' token      out_vector.push_back(in.get<Idx>());   (Visual C++ 2013 accepts it on the other hand.)  I guess that one have to place   typename In::get<Idx>   or similar in any form, but I don't know where.  Has someone an idea?  Thank you.


Can one PlayStation Plus subscription be shared between multiple PSN accounts on the same machine?

I just purchased a new ps4 and found out that PlayStation Plus is required for online gameplay. My ps4 is shared with someone else at home so I want to ask if one PlayStation Plus subscription can be shared between multiple psn accounts on the same machine?


PC started having screen glitches after update

I'm not sure what's caused it. I haven't changed any system settings. The only thing I've done that may have broken something is updating my software. My update was: upgrade linux-generic-hwe-20.04:amd64 5.8.0.48.54~20.04.32 5.8.0.49.55~20.04.33 upgrade linux-image-generic-hwe-20.04:amd64 5.8.0.48.54~20.04.32  upgrade linux-headers-generic-hwe-20.04:amd64 5.8.0.48.54~20.04.32  upgrade linux-image-extra-virtual:amd64 5.4.0.70.73 5.4.0.71.74 upgrade linux-image-generic:amd64 5.4.0.70.73 5.4.0.71.74 upgrade linux-libc-dev:amd64 5.4.0-70.78 5.4.0-71.79 upgrade libseccomp2:amd64 2.4.3-1ubuntu3.20.04.3 2.5.1-1ubuntu1~20.04.1 upgrade nomachine:amd64 7.3.2-3 7.4.1-3```  Removing nomachine did not solve the problem. It was far worse before, I'm not sure how to describe exactly, but my entire screen's UI was glitching out. So I rebooted and that stopped, but now the terminal text looks like this:  I haven't changed any terminal settings. This seems to be occurring in the entire OS. Here is another example:  Not sure how to go about troubleshooting this? I don't have the time to reinstall the OS, nor do I think I should have to because this is just ridiculous and shouldn't happen. I'm not aware of anything I've done to make the system unstable. Edit Earlier I also tried booting the PC. It failed and got stuck on some command in a terminal (didn't manage to take a photo of what it said). So I rebooted into recovery mode with both available kernels. I was getting strange glitches like this:  That didn't work. So I rebooted the PC normally, and now I somehow logged in fine. Now I'm getting popups saying to report a system error. It says this:  Environment  Ubuntu 20.04.2 LTS GNOME 3.36.8  sudo lshw -class display   *-display        description: VGA compatible controller        product: Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller        vendor: Intel Corporation        physical id: 2        bus info: pci@0000:00:02.0        version: 06        width: 64 bits        clock: 33MHz        capabilities: msi pm vga_controller bus_master cap_list rom        configuration: driver=i915 latency=0        resources: irq:33 memory:f7800000-f7bfffff memory:e0000000-efffffff ioport:f000(size=64) memory:c0000-dffff  I also did , which passed with 0 errors. Let me know if more details are required.


Is a Mummy still inside its sarcophagus affected by a fireball hitting right over it?

My players found the mummy and decided to attack from a distance, which did not help much since the  has an area spell, , which is even worse than the ...  However, I'm now wondering whether the mummy should have been affected at all. The Fireball goes around corners, even in places that one cannot see, but would it enter a sarcophagus that was never opened before? (so one that's still well sealed)  If it does go inside the sarcophagus, would the Mummy at least get advantage on its saving throw roll?


I work with a legacy code and when I include some headers on linux I have to undef appropriate macros, for example: #pragma push_macro("align") #undef align  #include <memory>  #pragma pop_macro("align")  I would like to create a macro which expands to the above code and can be used this way: include_(memory, align)  I can use _Pragma instead of #pragma inside #definebut what about with #undef and #include ? Is it possible to create such macro ?


Showing the Irreducibility of a Polynomial and "Splitting" the Field

The following problem is part of my Algebra problem set:  Let $\alpha= \sqrt[3]{2}+\omega$ ,where $\omega=e ^{2\pi i /3} = -\frac{1}{2} + \frac{\sqrt{-3}}{2}$ is a primitive cube root of $1$.   $\alpha$ is a zero of $f(x) = 9 + 9x +3x^3 + 6x^4 + 3x^5 + x^6$.  Show that $f(x)$ is irreducible.  ** Eisenstein's Criterion fails here I realize that Gauss's Lemma is the best method of proving this although I am unclear as to whether proving the irreducibility of a polynomial in a subfield is sufficient to prove that it is irreducible. **  Please Also note that we have not had any Galois Theory.  Show that $\mathbb{Q}(\alpha)$ is the smallest field which contains all three zeros of $x^3 -2 $ (this is called the splitting field of $x^3 -2$).  Thank you in advance for your help!


$x^p-c$ has no root in a field $F$ if and only if $x^p-c$ is irreducible?

Hungerford's book of algebra has exercise $6$ chapter $3$ section $6$ [Probably impossible with the tools at hand.]:     Let $p \in \mathbb{Z}$ be a prime; let $F$ be a field  and let $c \in  F$. Then $x^p - c$ is irreducible in $F[x]$ if and only if $x^p - c$   has no root  in $F$. [Hint: consider two cases: char$(F) = p$ and   char$(F)$ different of $p$.]   I have attempted this a lot. Anyone has an answer?


I always thought gauntlet had 2 definitions: the hand piece of a suit of armour, and an obstacle course, like the kind filled with swinging traps and pits.  I've looked on the internet for a definition that fits my second definition, but I can't find one anywhere. All I find is an armour glove and something where 2 rows of people attack someone walking down the middle as a form of punishment.  Does anyone else know of this obstacle course definition I'm talking about? Can someone possibly link me to a definition if one is found?  A few examples are from the first 40 seconds of this video:   And also I thought the game 'Gauntlet' was in reference to the fact that the whole game is like a gauntlet, as in an obstacle course with traps and such.  Could someone confirm if this is a real definition or if I'm just losing my marbles? Thanks!


Can we call someone who teaches at a university a "teacher"?

For example, like someone who is teaching people at a university. Is he still called a "teacher" or not?


$\dfrac{pq}{r}+\dfrac{qr}{p}+\dfrac{pr}{q}\in\Bbb Z\,\Rightarrow\, \dfrac{pq}{r},\dfrac{qr}{p},\dfrac{pr}{q}\in\Bbb Z$

Let $p,q,r$ be integers such that the symmetric sum of fractions $\dfrac{pq}{r}+\dfrac{qr}{p}+\dfrac{pr}{q}$ is an integer. Prove that each of the numbers: $\dfrac{pq}{r},\dfrac{qr}{p},\dfrac{pr}{q}$ is an integer. How to do this? Someone posted but deleted soon.


Unable to compare lines read from txt file using Scanner in Java

I am trying write code which will read input from a txt file and stop after reaching a certain line.  This is my current code:  File data = new File("text.txt"); try {      Scanner load = new Scanner(data);      while (load.hasNextLine()) {         String line = load.nextLine();         if (line == "end") break;         System.out.println(line);     }      load.close();  } catch (FileNotFoundException e) {     System.out.println("File not found"); }   This is the text contained in text.txt:  line1 line2 line3 end line5 line6   I expected it to only output the lines before the line end, but instead, every line was printed. How can I fix this issue?


TikZ externalization with absolute path and MiKTeX distribution

This code:  \documentclass[11pt,openright]{book} \usepackage[T1]{fontenc} \usepackage[latin9]{inputenc} \usepackage[british]{babel}  \usepackage{tikz} \usetikzlibrary{external} \tikzexternalize[prefix={"C:/Users/MyName MySurname/Documents/LaTeX/Figures/"}]  %\tikzexternalize[prefix={Figures/}]   \begin{document} \begin{tikzpicture}     \draw (0,0) circle (1cm); \end{tikzpicture} \end{document}   gives me the error:     ! I can't write on file `"C:/Users/MyName   MySurname/Documents/LaTeX/Figures/MyMWE-figure0.md5"'.   I'm working with Windows 10, MiKTeX 2.9 distibution.  Following the advice Tarass gave me on a comment of this question:  and as indicated here:  I've registered a user-managed TEXMF directory but I still get the same error.  With \tikzexternalize[prefix={Figures/}] all works perfectly but, since I'm using LyX, the files are stored in a LyX temp dir, hence I loose them when I close the program (making externalization useless), so I need to use an absolute path.


I have tried installing Ubuntu on my computer. I used Rufus to burn the .iso and selected the boot device on bios. The problem is the dual boot option is not available. My PC is Windows 7 64-bit, 4 GB RAM; Dual core Pentium processor 2.5 GHz.


I thought they could be, but as I'm not putting my money where my mouth was (so to speak) setting the readonly attribute doesn't actually seem to do anything.  I'd rather not use Disabled, since I want the checked check boxes to be submitted with the rest of the form, I just don't want the client to be able to change them under certain circumstances.


How do I stop a second instance of my application from executing if one is already running in JAVA?

When I run my application using the .jar file, the GUI is displayed and javaw.exe shows up in System Processes in the task manager. But when I run the .jar file again without closing the first one, a second javaw.exe process starts and a second GUI is displayed. How do I stop this? I want there to be only one instance of my application at a time no matter how many times I run the .jar file.


Which one is correct? I am *even more happy* for you! or *even happier*?

Which one is correct? Even more happy or even happier?  P.S.: My question has more to do with the combination of the word "happy" with the word "even", on the context above.


The [title](url) is no longer formatted when the chat post is multi-lined Examples: ,


Difference in tone between Regards, Best regards, Kind regards and Sincerely in emails

I often end my emails just with "Regards, FirstName".  But I also often see "Best regards", "Kind regards" and "Sincerely".  What is the difference in tone and meaning? Is one more formal than the other? Is there a difference between US and UK?


I have a  to which I'd like to add JPEG and PNG images that I generate on the fly.  All the examples I've seen so far in the , specially in the  use ImageIcons.  I'm generating these images as byte arrays, and they are usually larger than the common icon they use in the examples, at 640x480.   Is there any (performance or other) problem in using the ImageIcon class to display an image that size in a JPanel? What's the usual way of doing it? How to add an image to a JPanel without using the ImageIcon class?   Edit: A more careful examination of the tutorials and the API shows that you cannot add an ImageIcon directly to a JPanel. Instead, they achieve the same effect by setting the image as an icon of a JLabel. This just doesn't feel right...


Difference between declaring methods within a class or using the class prototype in JavaScript

Is there any difference when we declare our methods within a class  class Foo {    ...    doSomething(){      ...    } }   or directly to the class prototype?  class Foo {     ... }  Foo.prototype.doSomething = function(){     ... }


Prove that: If $a,b,c \in \mathbb{N},$ then lcm (ca,cb) = c · lcm(a,b)

This is from an example in Chapter 4 of Book of Proof by Richard Hammack. The thing is that I do not quite understand why it is been solved in this way, in my understanding it seems redundant or I am misunderstanding somethings. My approach here is to quote the text directly from Hammack followed from comments of how I think it should be approached (I could be wrong). I would greatly appreaciate if you could point me where I got it wrong The text reads as:  If $a,b,c \in \mathbb{N},$ then lcm (ca,cb) = c · lcm(a,b)   Proof. Assume a,b,c ∈ N. Let m = lcm(ca,cb) and n = c·lcm(a,b). We will show m = n. By definition, lcm(a, b) is a positive multiple of both a and b, so lcm(a,b)=ax=by for some x,y ∈ N.  Why he writes that lcm(a,b) is only a positive multiple of a & b instead of the smallest one?  From this we see that n=c·lcm(a,b) = cax = cby is a positive multiple of both ca and cb.  Again, Why he assumes "n" is only positive? The definition of lcm states clearly that it must be the smallest number, not any number.  But m = lcm(ca, cb) is the smallest positive multiple of both ca and cb. Thus m ≤ n.  Why not state here that m=n, since we know from the defintion of lcm(a,b) that we are referring to the same value? I mean m = lcm (ca,cb) is the same as n= c * lcm (a,b) since we know lcm(a,b)=ax=by is the smallest integer multiplied by c  On the other hand, as m = lcm(ca, cb) is a multiple of both ca and cb, we have m = cax = cby for some x, y ∈ Z.  Why not consider "m" as the smallest multiple again?  Then $1(/c)m$ = ax = by is a multiple of both a and b. Therefore lcm(a, b) ≤ $1(/c)m$, so c · lcm(a, b) ≤ m, that is, n ≤ m.  Why not state that they are the same, again?  We’ve shown m≤n and n≤m, so m=n. The proof is complete.  Was it necessary to do it in both hands side? In my perspective it could have done considering only half of Hammack's answer


Can we describe all forces as a curvature in space-time?

If we have Einstein's field equation $$R_{\mu\nu} - \frac{1}{2}g_{\mu\nu}R=kT_{\mu\nu}$$ could we generalize it to $$R_{\mu\nu} - \frac{1}{2}m_{\mu\nu}R=kS_{\mu\nu}$$ where $S_{\mu\nu}$ is the source of the curvature and $m_{\mu\nu}=\eta_{\mu\nu}+f_{\mu\nu}$ where $f_{\mu\nu}$ is the perturbation caused by the force. Could we write one of these equations for each force, solve the equation for $f_{\mu\nu}$, sum up all of the $f_{\mu\nu}$ into one perturbation and add it to $\eta_{\mu\nu}$ to get one metric $g_{\mu\nu}$. For example, since the electromagnetic field is extremely similar to the gravitational field, we could solve for the acceleration and find Poisson's equation. Using Einstein's "derivation" of general relativity one could find that $$R_{\mu\nu} - \frac{1}{2}g_{\mu\nu}R=\frac{2q}{m\epsilon_0 c^2}Q_{\mu\nu}$$ Where $$g_{\mu\nu}=\eta_{\mu\nu}+A_{\mu\nu}$$ $A_{\mu\nu}$ is the electromagnetic pertubation and $$Q_{00}=\rho_Q$$ $$Q_{ij}=\frac{1}{c}v^i v^j\rho_Q$$ $$Q_{i0}=\frac{\vec{J}}{c}$$ and $\rho_Q$ is the charge density These are all the components since the tensor is symmetric. With this you can derive Maxwell's equations. But is this a valid approach, to describing how electromagnetism curves space-time? There is a related question  but this is about describing the forces using a Yang-Mills approach i.e. a curvature in the connection. In this question I am excluding gauge curvature and only talking about space time curvature.


How can I upgrade my R installation on Kubuntu 14.4 LTS from 3.0.2 to the current 3.2.4?  Something like  sudo su echo "deb http://www.stats.bris.ac.uk/R/bin/linux/ubuntu trusty/" >> /etc/apt/sources.list apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E084DAB9 apt-get update apt-get upgrade   or a variation of this won't work - R will stay at 3.0.2.


Outputting emission with transparency -what am i doing wrong?

im trying to render a laserbeam animation. (In EEVEE) The beams need to be on a transparent background, as they will be projected over an image/animation for a project. here is the problem: it looks correct in blender when rendering, the background is transparent, the beams glow. i added a glare node in composite and everything looks fine.  Now when i export the picture as a png or tiff or anything, it wont save the glow/emission , while it shows in the render window. In photoshop it turns up like this: (no glow! - black layer added to show)  Why doesnt it export the glow/emission ? what am i doing wrong? it drives me quite nuts at the moment ;|


Question about standardizing in ridge regression

Hey guys I found one or two papers which use ridge regression (for basketball data). I was always told to standardize my variables if I ran a ridge regression, but I was simply told to do this because ridge was scale variant (ridge regression wasn't really part of our course, so our lecturer skimmed through it).  These papers I read didn't standardize their variables, which I found a bit surprising. They also ended up with large values of lambda (around the 2000-4000 level) via cross-validation, and I was told that this is due to not standardizing the variables.  How exactly does leaving the variable(s) unstandardised lead to high lambda values and also, what are the consequences of not standardizing the variables in general? Is it really such a big deal?  Any help is much appreciated.


How to make background of EMF symbol transparent in ArcGIS?

I have been sent a collection of PNG and SVG images with which I should symbolize my points in ArcGIS 10.0. Unfortunately ArcGIS 10.0 doesn´t support PNG when symbolizing points, so I have converted them to EMF files. The background transparency of the images are now lost and are displayed black. How can I make the background of these emf images transparent in ArcGIS?


How many hours should a baby sleep in a day?

Recently, I noticed that my 2-month-old baby sleeps almost all day, including naps (maybe 3-5 hours awake). Should I do anything about this? Should I wake him up or, is it normal?


Alternatives for Monitoring and logging changes anywhere in file system [Ubuntu 14.04]

I would like to monitor and log following changes in file system:   Opening and closing of any file by any user. Creation/deletion of file by any user. Files downloaded by any user.   After some research I could find only 2 solutions:      (Disadvantage: lack of recursive support in directory)   Are there any other alternatives through which I can perform the above mentioned task or can I implement this somehow using some system calls?  What will be the best way to perform the above task?  OS details: Ubuntu 14.04, if it helps.


How can I put my pokemon in an allied gym in Pokemon Go?

Okay, I'm level 5, I have Pokemon that aren't currently defending a gym that are stronger than one of the Pokemon in a gym, but not another, do I have to defeat both for my Pokemon to be eligible to defend the gym? The gym is owned by my team.


parameterize both ORDER BY column and keyword variable in php/pdo

I need to parameterize both the ORDER BY column name and DESC or ASC keyword as a variable. I have it working already but the variables are in the query, which is not safe.  $fruitColumn='bananas' $sortbyORDER= 'DESC' $fruitSearch = $db->prepare(" SELECT * FROM fruits ORDER BY $fruitColumn $sortbyORDER"); $fruitSearch ->execute();   BUT - I need the variables bound in the execution for security.   $fruitSearch = $db->prepare(" SELECT * FROM fruits ORDER BY ? ?"); $fruitSearch ->execute([$fruitType,$sortbyORDER]);   This doesn't seem to work as the two ?s give me an error.   I have also tried combining the two variables into one eg. $order = ".$fruitColumn." ".$sortbyORDER;  Is this possible? Thanks in advance


Geometric interpretation of inner product of two matrices

Consider space $\mathcal{S}=\mathbb{R}^{n\times n}$. Let $\mathbf{X},\mathbf{Y}\in\mathcal{S}$. The inner product between $\mathbf{X},\mathbf{Y}$ is defined as ()  \begin{equation} <\mathbf{X},\mathbf{Y}> = trace(\mathbf{Y}^{T}\mathbf{X}^{})=\sum_{i=1}^{n}\sum_{j=1}^{n} \mathbf{X}_{i,j}\mathbf{Y}_{i,j}  \end{equation}  In $\mathbb{R}^2,\mathbb{R}^3$, "Inner Products" give us a notion of "angle" between the two vectors i-e  \begin{equation} <\mathbf{x},\mathbf{y}> = \|\mathbf{x}\|\|\mathbf{y}\| cos(\theta)  \end{equation}  I am wondering how to extend this geometric interpretation to matrices? What does it mean for two matrices to be "aligned". Does it mean their singular vectors are aligned?


jQuery .change() method does not work for dynamically created check-box

I have to create a cascade of elements dynamically.  Prix:
      <select  name="prix" id="prix">         <option value="0">Type de prix</option>         <option value="1">Gratuit</option>         <option value="2">Montant</option>         <option value="3">Echange</option>         <option value="4">Prix à discuter</option>         <option value="5">Prix n'est pas d'application</option>     </select>

   When I choose option value="2", a checkbox have to be inserted into div id="select_prix"  So I use jquery:  $('#prix').on('change', function() {     if ($(this).val() < 2) {         $("#select_prix").empty();     }        var stroffre  ='Offre ?                                  ';     stroffre +='
';     stroffre +='';     stroffre +='<input class="sr-only" id="chkoffre" type="checkbox" value="">';     stroffre +='Autoriser les  offres';     stroffre +='
';      if ($(this).val() == 2) {         $("#select_prix").append(stroffre);     } });   Ok. The checkbox appears and what I get is:     checkbox ' Autoriser les offres'   Now, when I select checkbox , I want to insert a new line input into div id="select_offre"  I made for that a new jQuery code:  $("#chkoffre").change(function () {     alert( 'CheckboxOffre' ); // or $(this).val()     if($(this).is(":checked")) {      }else{      } });   Unfortunately, I don't get the alert message.


Significant model but not the predictors? (Logistic regression)

I'm doing a binary regression, with two predictors one binary and one continuous. I'm using the enter method.   I want to know if my model can be significant when I compare it to the model with only the constant while at the same time all my predictors are not significant?   Or there something wrong about my model?


Clear explanation of dummy variable trap

I have a confusion in multiple regression about dummy variable trap, so far I had seen tutorials explaining about dummy variable trap and multicollinearity but I'm unable to understand it fully.


What are some good open source UI Testing tools for testing Windows GUI?

I need a list of some good tools which are open source and meant for automating the UI testing of Windows GUI. Any help will certainly be appreciated.


Is there a reason why this technique is invalid?

What is $ \lim_{x \rightarrow 0} \frac{1 - \cos x}{x}$? A simple way to evaluate this limit is to substitute $0$ for $x$ in the numerator to obtain   $ \displaystyle \lim_{x \rightarrow 0} \frac{1 - 1}{x} = \lim_{x \rightarrow 0} ( \frac{1}{x} - \frac{1}{x} ) = \lim_{x \rightarrow 0} (0) = 0 $   since $ \frac{1}{x} - \frac{1}{x} = 0$ since one quantity subtracted from the same quantity is 0. This technique circumvents the problem of division by zero while utilizing the fact that $\cos(0)$ is known.


Book series - towns separated by energy storm

Towns/cities are surrounded by a kind of swirling & confusing energy storm or field.  In my mind's eye it was blue/purple in color.  The towns/inhabited regions are in bubbles of normal environment.  This fantasy (or perhaps SF) world has special guides able to lead caravans between the towns/cities, without which the caravans would become hopelessly lost.  In one of the books, I think it's revealed that the energy fields between cities can charge people up with (magical?) power.  I think only the guides are able to use this power.  I vaguely associate this story with Roger Zelazny but I can't find anything in his bibliography that looks like this trilogy(?).  These books would have been published no later than the late '80s.


How do I choose secondary branding colors?

How can I make my branding color palette from primary colors?  This is the url with the logo and the primary colors:   How can I make other colors?


Dual national traveling to Indonesia, can I use my Albanian to leave my country and my South African passport to enter Indonesia?

I am traveling to Indonesia with 2 stops, one in Germany and another in Singapore. Can I use my Albanian passport to leave Albania and pass through Germany and my South African passport to pass through Singapore and enter Indonesia, since South African passport grants me visa on arrival in Indonesia.   Also what documents should I provide at the airport besides ticket and passport?


What are the limits for passing through mass with the Etherealness spell?

The  spell states:  You ignore all objects and effects that aren't on the Ethereal Plane, allowing you to move through objects you perceive on the plane you originated from. When the spell ends, you immediately return to the plane you originated from in the spot you currently occupy. If you occupy the same spot as a solid object or creature when this happens, you are immediately shunted to the nearest unoccupied space that you can occupy and take force damage equal to twice the number of feet you are moved.  This is pretty straightforward for smaller objects, like weapons and items, and is discussed in  In this post, the bounty-winning answer cites :  For the purpose of these rules, an object is a discrete, inanimate item like a window, door, sword, book, table, chair, or stone, not a building or a vehicle that is composed of many other objects.  I assumed that Etherealness allowed travel through walls, as they are composed of multiple objects; however, this answer implies a composition of objects is not an object. Additionally, if a wall or large object like a vehicle is not an object, what is the point of the damage/ejection clause in the spell? I'd like to know what the limits are for passing through things on the Ethereal Plane. In particular, please answer the following questions with as much RAW support as possible:  Is it possible to pass through a building? Is it possible to pass through the ground? Is there anything that has mass and is neither a creature nor an object? If so, please provide examples and indicate whether it falls into an explicit class of its own, analogous to objects and creatures.  If the answer to either of the above is no, I am interested in a lore-based reason why this isn't possible.


Contradiction in my Lagrangian mechanics problem

The Lagrangian for a particle of mass $m$ in a potential well $V(r)$ is given by $$ L = \frac{1}{2}m(\dot{r}^2 +r^2\dot{\theta}^2) - V(r).  $$  Working though the Euler-Lagrange equation I get  $$\frac{\partial L}{\partial r}=mr\dot{\theta}^2-\frac{\mathrm{d}V(r)}{\mathrm{d}r} $$ $$\frac{\mathrm{d}}{\mathrm{d}t}\frac{\partial L}{\partial \dot{r}} = m\ddot{r} $$  so the equation of motion for the $r$ coordinate is:  $$ m\ddot{r} = mr\dot{\theta}^2-\frac{\mathrm{d}V(r)}{\mathrm{d}r}. $$  Now the above Lagrangian tells me that there is a conserved quantity $ \frac{\partial L}{\partial \theta} = mr^2\dot{\theta} = l$ so I can express the equation of motion as   $$ m\ddot{r} = \frac{l^2}{mr^3}-\frac{\mathrm{d}V(r)}{\mathrm{d}r}.\tag{1} $$  Well if I was to substitute $l$ directly into the Lagrangian before solving for the equations of motion I get  $$ L = \frac{1}{2}m\bigg(\dot{r}^2 + \frac{l^2}{m^2 r^2}\bigg) - V(r). $$  This Lagrangian gives me   $$\frac{\partial L}{\partial r} = -\frac{l^2}{mr^3} - \frac{\mathrm{d}V(r)}{\mathrm{d}r} $$  and the equation of motion  $$ m\ddot{r} = -\frac{l^2}{mr^3}-\frac{\mathrm{d}V(r)}{\mathrm{d}r}. \tag{2}$$  I have a minus sign on the first term on the RHS and I have a contradiction between $(1)$ and $(2)$. What is going on?


Say an object in space collides with another object at 100mph. Say the same thing happens on Earth. Would the impact in space exert more force on the receiving object than on Earth because some energy on Earth would be lost to sound/shockwave being generated due to air being present?


Looking for a book about a crystal like prison planet

I'm looking for a book in which the main character was sent to a prison type planet made of crystal. He wakes up with a symbiotic creature plugged into his ear. The creature is able to communicate through plug in. The creature manufactures new crystal parts for the main character to survive, but does it when he's sleeping; such as changing out his eyes and later internal organs.  Read it in the mid 80's, but I think it was written earlier. Any help on this title would be appreciated. Thanks


If a.b.c,d are rationals and x is irrational number, then prove that $\frac{ax+b}{cx+d}$ is usually a irrational number. When do exceptions occur?  This is a homework Question. i did this by assuming that given fraction is rational say $\frac{p}{q}$. Now i write $$\frac{ax+b}{cx+d} = \frac{p}{q}$$. After cross multiplying i get   $$\frac{qb-pd}{pc-qa}=x$$  So this contradiction as right hand side is rational and left hand side is irrational. Now the question asks where does exceptions occur. I see that exceptions can occur when $a=c=0$ and $a=b=c=d$. But what are other exceptions and is my working method correct?  Thanks


What is the correct term to use, or what is the difference between the two?  For instance, if you describe yourself as a founder in a resume it sounds like you founded something alone. In plural form (founders), it suddenly seems more like co-founders - that you didn't do it alone. But I don't know if co-founder alone maybe sounds as if you didn't have a leading role in the founding part.   Hope anyone can clear up my confusion here! Thanks  CC (From Denmark - if the grammar isn't perfect I apologize in advance ;)


What live-action 80s show had a metal pterodactyl?

I’m looking for a live-action TV show I saw in the USA on Sundays back in the 80's. It might have been on PBS, so possibly it was British.  It had a (CG?) metal pterodactyl or dragon-looking thing, kinda like  (one of the cassette tapes that comes out of Soundwave in Transformers).


I installed Ubuntu as a dual os on my pc and I have seperated disks such as system(c), personal(d) and sth like that. I can see the files in the other disks but I can not do anything changing, editing, adding somethings I mean for example, word files, txt files.  How can I figure this problem out?


Ploting images in different windows in MATLAB

I want to plot 2 images. When I plot first image, I can see that in figure1. But as I plot another image it is again displayed in the same window figure1.  What I want is to plot 2 different images in two different window. Please don't suggest me to use subplot or hold on, becuase my requirement are different than those.


IE11 Developer Tools is blank white/gray

When I run F12 Developer Tools in my Windows Server 2012 R2's install of IE 11.0.9600.17498 (Update 11.0.15), I get a blank white area with grayed out buttons:    (That white rectangle at the bottom of the image is F12 devtools)  I've discovered a number of other people with similar issues (e.g. ), but they're a bit different in that they have the "black stripe" above the tools and an error message.  I've tried running filesystem checks and updating all Windows Updates to no avail.  EDIT: I don't think this is a dupe, as I've installed the specified updates, and the issues persist.


Report high-Google-ranking Stack Exchange content copiers here

NB The following is a community-generated list of web pages that display Stack Exchange content and rank higher in search results than the original SE posts they copy. It is no longer being maintained, because the procedure for reporting such sites has changed; see the duplicate for more information.  For the original instructions, see this question's . You may also be looking for  (that is, without following attribution guidelines).


The only proper subfield of $\mathbb C$ , which is path connected as a subset of $\mathbb C$ , must be $\mathbb R$?

Is it true that the only proper subfield of $\mathbb C$ , which is path connected as a subset of $\mathbb C$ , must be $\mathbb R$ ?   NOTE : The answer to this   indicates the claim stated is true . But the answer there only gives a reference and no proof ( or outline of proof) of the result , and the paper cited is highly technical . I would like to see if there is any elementary ( at least more elementary than the cited paper if possible ) proof .


Floating a ping pong ball in the air just using a pen!

Caution: Apparently this problem is harder than it seems!    There is a well known phenomena, which I first learnt about when I was a 10 years old kid. You can levitate a ping pong(or whatever not-so-heavy) ball in the air by blowing throw an empty pen body or using a hair dryer. An interesting demonstration can be seen .    While this demonstration is usually  (for instance look at  or other citation links from ), it seems that it is explained using the . The Coandă effect is the tendency of a fluid jet to be attracted to a nearby surface.    I am looking for a simple(and humbly realistic) model which is capable of answering the following questions quantitatively: Assume the ball's mass is $m$ and its radius is $r$, the diameter of our pen is $d$, the  of air through the pen body is $Q$ and the gravitational constant is $g$   What is the minimum of $Q$ which makes this demonstration possible? Perhaps using this minimum rate $Q$ and , how can I estimate the longest time that a normal person can levitate a ping pong ball in the air using his breath? I have noticed that the smaller $d$ is the longer I can levitate the ball. For a normal pen body, my personal experience is about 3 seconds. An estimation of the maximum angle that the pen can make with vertical direction? If we deflect the ball by a tiny amount, what will be the frequencies of motion along the vertical and horizontal direction?


Unable to upgrade Trusty 14.04.1 to the 14.04.2 HWE

I issued the command string found at  and got this result:  Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  account-plugin-facebook : Depends: libaccount-plugin-generic-oauth but it is not going to be installed or                                     ubuntu-system-settings-online-accounts but it is not going to be installed  account-plugin-google : Depends: libaccount-plugin-google but it is not going to be installed or                                   ubuntu-system-settings-online-accounts but it is not going to be installed  libcheese-gtk23 : Depends: libcheese7 (>= 3.4.0) but it is not going to be installed                    Depends: libclutter-1.0-0 (>= 1.13.2) but it is not going to be installed                    Depends: libclutter-gtk-1.0-0 (>= 0.91.8) but it is not going to be installed                    Depends: libcogl15 (>= 1.15.8) but it is not going to be installed  libqt5gui5 : Depends: libgbm1 (>= 8.1~0) but it is not going to be installed E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.


How do you generate a random number with equal probability using Math.random() in Java

I'm currently working through an exercise where I am required to generate a random number which can be one of 4 values. (note I'm only allowed to use Math.random())  0 1 2 or 3  Currently I am using this: randno = (int) (Math.random()*4); // range 0-3   However, the outcome MUST have equal probability. My tests so far (although the method is lacking) shows that 3 occurs far less than the other numbers.   Is this coincidence? Or does my generator not have equal probability.  Thanks!


Why when I save a value of say 40.54 in SQL Server to a column of type Real does it return to me a value that is more like 40.53999878999 instead of 40.54?  I've seen this a few times but have never figured out quite why it happens.  Has anyone else experienced this issue and if so causes it?


How important were the roles of the Blue Wizards?

The Blue Wizards were sent to aid the peoples of Middle-Earth in the fight against the growing threat of Sauron. I read somewhere that stated that the Blue Wizards went into the East to create cults of some kind.   How important was their roles against Sauron (if they had succeeded)?


Will the flash light accelerate in space?

As we know from school physics course light has pressure. So my question is will flash light accelerate in space in the direction opposite to light emission? If not, then will flash light with attached mirror accelerate is the direction opposite to light emission?


Can we use magnetic energy to convert electrical energy by replacing mechanical work by a fan for concern watch the video

Can we use a computer fan with magnets attached to its blades, and another magnet, to generate electricity, as shown in this video?


Always boot into Ubuntu, but with Windows option on restart

I'm not sure if this is possible - I've tried searching, but can't seem to find anything. I run a dual boot system, Trusty & Win 7 - being in the former about 98% of the time.  Here's what I'd like: always boot into Ubuntu, but have the option from within Ubuntu of rebooting into Win 7 - with subsequent boots going back to Ubuntu.  Thoughts?


In the Windows 7 Power Options, under "PCI Express", I can adjust "Link State Power Management".  The options are:   Off Moderate power savings Maximum power savings   What do these settings do?  Is there any reason to enable it when my laptop is plugged in?


So I've got a file with loads of simple objects. This will later be used to cut out these shapes out of plastic. So, using the material optimally is of outmost importance. I was wondering if there is any script or plugin that could automaticly arrange the objects within the artboard so they could fit best.


I was using ubuntu 13.10 alongside w-7. there was some broken packages on ubuntu so I decided to freshly install ubuntu. while installation I selected "erase ubuntu 13.10 and reinstall" . ubuntu reinstalled but my windows and whole partition got deleted annd entire disk is assigned to ubuntu only. there was some IMP data in that partition partition and I want to recover that data . so guys , can I recover that data and how  . please  help its urgent


Ok, my understanding of physics is still limited, hoping to change that in the following years, but I have a question.  Dark energy is what provokes the expansion of the universe, so, in theory, it must be exerting some kind of "anti-gravity", definitely an energy as I see it.  Would it be possible to turn dark energy into usable, electric energy? For example, using a piezoelectric sensor?  I think if we found a way to do that, we would provide the world with infinite, free energy. Forever.


android hiding ui and showing ui code not working

package com.example.eiraj.listviewseefrgmentsfiirst;  import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.TextView;  public class MainActivity extends AppCompatActivity {      TextView textView= (TextView) findViewById(R.id.textView);      public void show(View view){         textView.setVisibility(View.VISIBLE);     }      public void hide(View view){        textView.setVisibility(View.INVISIBLE);     }      @Override     protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    } }   here two buttons are being used to show data and hide data but whenever I try to run it emulator shows the message unfortunately uihide stopped also I downloaded the apk to run it on my phone but same message came there


How do I transfer minecraft worlds to sandisk flash drive?

I've managed to download Minecraft onto my SandDisk USB thumbdrive. But how do I copy all my worlds to it?


How can I prevent URLDownloadToFile from writing in the cache

I am using URLDownloadToFile to download the files from URL.  while downloading URLDownloadToFile API creates cache files in INETCache if "Temporary Internet files and website files" is unchecked in Internet Explorer "Delete browser history settings".  can we prevent creating these cached files ?  Your help will be appreciated :)


What is this "Comprehensive LaTeX Artifact Novelty" thing?

Today, looking for a package on the CTAN, this window popped up:    Is this for real? Or is it something else?


Problem after upgrading Ubuntu 13.10 to 14.04

I just upgraded my Ubuntu to 14.04, after I got a notification about it. All the installation went well but after restart now, when I go to the Ubuntu option from grub, it shows only a purple screen and nothing happens after that. I also have Windows 8 installed in my laptop, but hope that should not be a problem, as it worked well with ubuntu 13.10.   Please help me to fix this problem, or at least to get back to my previous ubuntu I had.  Thanks.


Unfortunately, $(x^2)$ is not a prime ideal, so I can't use the trick of "quotient of a PID by a prime ideal is a field". However, I do know that $\mathbb{R}[x]$ is itself a PID, and the Lattice Isomorphism Theorem says that ideals of $\mathbb{R}[x]/(x^2)$ correspond to ideals of $\mathbb{R}[x]$ containing $(x^2)$ via the map $J\mapsto J+(x^2)$. Can I use this to show every ideal of $\mathbb{R}[x]/(x^2)$ is principal?


Resizing a table by textheight reduces the width

I have a large table (height does not fit in page) and I use this code in order to fit it in height.  \begin{table}[] \resizebox{!}{0.65\textheight}{ \begin{tabular}{lllll}  ...  \end{tabular}} \end{table}   The problem is that the table shrinks also in width. Is it possible to keep the original width of the table but shrink in height in order to fit in page?  I do not want to use some special packages here.


Dual-boot Ubuntu 12.10 on UEFI along Windows 8 (GRUB - error: can't find command drivemap)

Hello after a successfull installation of Ubuntu 12.10 amd64, I am now unable to boot Windows 8.  Here are my actions:   Made room (15 GB) for Ubuntu from Windows 8 Computer Managment Boot Ubuntu 12.10 amd64 LiveUSB with EFI and with Secure Boot enabled Created 2 new partitions at the end (13 GB Ext4 Root amd 2 GB Swap) Selected Windows 8 EFI System Partition to install bootloader   Grub gives me at boot:   Ubuntu (works without problems) Windows Recovery Environment (lots of errors) Windows 8 (2 error messages describe just below)   The 2 error messages  are:   error: can't find command drivemap. error: invalid EFI file path


macOS partition startup Volume type FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF

I have encountered a nearly identical issue to the one  (and this too: ), but my hard drive's main partition is formatted in APFS. When I tried correcting the GUID error as shown in the answer, after reaching the step in which the following command: gpt add -i 2 -b 409640 -s 372637568 -t APFS /disk0 had to be entered, it returned an error: usage: gpt add [-b lba] [-i index] [-s lba] [-t uuid] device ....     I cannot boot into macOS, my computer is in internet recovery environment. What's the uuid of the new APFS format? I cannot seem to find it anywhere in the web, and my computer isn't detecting the type of the main macOS partition. My computer's model: MacBook Pro late 2013. My data is not backed up and I would really love to recover it. Update:  gpt -r show disk0:    Update: I created a MacOS High Sierra Installation disk, and rebooted to it. The new disk utility does not recognize the disk0s2 partition at all, and diskutil list included the size of the main osx partition in GUID_partition_scheme part of the disk. Would it be possible (and how) to recover the data of the deleted partition (s2) if I reinstalled macOS on an existing unused partition (the Linux partition disk0s4)?


I ran these commands:  sudo rmmod iwlwif sudo modprobe iwlwifi 11n_disable=1 sudo su echo "options iwlwifi 11n_disable=1" >> /etc/modprobe.d/iwlwifi.conf   Now, my WiFi connection is lost and there is no WiFi option in the network manager. How can I restore it?


How to install complete, easily updatable LaTeX system with text editor front-end?

I'm new to Xubuntu, having used Windows XP for many years.  On Windows I ran MiKTeX, with editors/front-ends WinEdt and TeXworks.  I found the MiKTeX Package Manager and Update tools to be especially useful.  I'm now running Xubuntu 12.04 LTS.  How should I install a complete, easily updatable LaTeX system with text editor/front end?


If $f:[0,\infty)\to [0,\infty)$ and $f(x+y)=f(x)+f(y)$ then prove that $f(x)=ax$

Let $\,f:[0,\infty)\to [0,\infty)$ be a function such that $\,f(x+y)=f(x)+f(y),\,$ for all $\,x,y\ge 0$. Prove that $\,f(x)=ax,\,$ for some constant $a$.   My proof :  We have , $\,f(0)=0$. Then ,  $$\displaystyle f'(x)=\lim_{h\to 0}\frac{f(x+h)-f(x)}{h}=\lim_{h\to 0}\frac{f(h)}{h}=\lim_{h\to 0}\frac{f(h)-f(0)}{h}=f'(0)=a\text{(constant)}.$$  Then, $\,f(x)=ax+b$. As, $\,f(0)=0$ so $b=0$ and $f(x)=ax.$  Is my proof correct?


os.environ not setting environment variables

I'm trying to set a Windows environment variable using Python.  It seems that, contrary to the docs,  can get environment variables but cannot set them. Try running these in a Windows Command Prompt:  This works:  python -c "import os; print(os.environ['PATH'])"   This does not:  python -c "import os; os.environ['FOO'] = 'BAR'"   Try typing set in the Command Prompt. The environment variable FOO does not exist.  How can I set a permanent Windows environment variable from Python?


How can I find the source code for linux commands?

I often come across interesting Linux commands that make me wonder; what are these commands actually doing?  Yes, they might be 'force-removing dependencies', 'installing programs' and doing lots of other stuff, but I'd like to know how they're doing it.  Looking into the source code seems the right thing to do then, but where am I supposed to get it from?  I suppose they'll be written in C?  EDIT: I'm not talking about packages installed using apt-get. I'm looking for the source code of linux/unix commands.


How to animate a cube pivoting more than once without affecting it's original position

Hi I'm in desperate need of help, I'm creating an animation for a Magic Cube.     This video shows what I need to create  So far I have been able to move the pivot of a cube one way and then again another by using an armature and an empty, however because these are now linked up I cannot figure out how to move the cube another turn     here demonstrates the point i'm at, I have place empty cubes to show where I need the actual cubes to be, however if I attempt to link them the original position has changed. Is there anyway I can animate these cubes rotating with the one above them?  I'm new to Blender and have had to learn after using 3Ds max for a while I'm struggling a lot would really appreciate the help please! Also I hope this makes sense...


Let the Convention badge be tracked as "next badge"

The  badge seems like a great candidate for a trackable badge: it requires doing a thing multiple times, there aren't any other requirements to get it, and it is (seems?) quite easy to determine how many times the thing has been done.  But Convention does not appear in the list of badges that can be tracked. I would like to be able to see a quick count of my well-received meta posts without going to my meta user activity page and poking around.


Missing values are very common in large time series data. How should the missing values of a time series be estimated? Is interpolation useful or I need to forecast them from the past values?


How can I check if device is 4 or 4s?  Is there a way for me to do this?  I want to check because I am using a UINavigationBar blur, and it for my situation it doesn't look good without the blur, so I will change it if it is an iPhone 4.


Why my highlights getting lost when re-importing a rendering into the compositor?

I noticed that I'm loosing colour information in the highlights after exporting and importing pngs from Blender. I know that the compositor works with linear space but something gets lost when saving to png. Here is what I do:  Render my image and look at it in compositor, all highlights preserved Save the image as png and look at the png with an image viewer, all highlights preserved Use an Image node in compositor and look at png, highlights lost Safe the image from the node to png, highlights still lost  So there is something going on while importing/reading the file. I have checked "View as Render" in the image nodes properties. I use Blender 2.90.0 Any ideas?


Where to ask question about database normalization

I'm looking to ask a question about the creation and population of a database using C#. For example:     I have a table for RangedItems, Charms, Necklaces, and WristItems. Now, there's an item that can go into any of those slots. What table do you add that item to?   What site is the best to ask these types of questions? This would probably also translate into a class creation question, as I would have a class for each table.


How to select all from table except one column using MySQL query?

I want to select all columns from a table except one column using MySQL. I know we can select all columns using this  <?php $query = SELECT * FROM posts; ?>   But how can I leave one specific column from the table?


How to get the child name of class in PHP

I want to get the child class name, in parent class constructor. The classes are namespaced so if I use get_class(); function, it will retrieve the entire namespace and I need only the class name of a child.  The parent class is a abstract class if that's matter.


I spend my days hopping between VPN connections in Ubuntu 10.10 and this is becoming severely annoying. What happens is that every once in a while - typically several times a day - when I click on the networking icon in the top bar, the nm-applet's VPN Connections flyout menu is gone. (Said menu item is still there, it just doesn't have a submenu or do anything when clicked.) Every time I killall nm-applet and start it again, which usually brings the menu back.   Has anybody here experienced this and been able to fix it?


In Python3, how do you test exception handling within a unit test?

I have several unit tests that I'm working on for an api. The tests use @patch to mock the api calls. Some of the tests I wish to create should trigger exceptions. How do I handle that in a unit test?  Here's what I have so far. Pylint complains about the assertTrue() statements. I'm sure there's a better way to handle exceptions.  @patch('myapi.myapi.requests.request') def test_auth_failure(self, mock_request):     # Configure the request mock to return an auth failure     # Auth/login (/session) failures return status 200, but without a token!     mock_request.return_value.status_code = 200     mock_request.return_value.content = json.dumps(self.mock_auth_failure)     try:         # Call auth()         self.api.auth()         # Exception should have been raised         self.assertTrue(False)     except exceptions.HTTPUnauthorized:         # Exception caught         self.assertTrue(True)   Additional Information: This is in a class extending from unittest.TestCase. Example:   class MyApiTests(unittest.TestCase):


Blender 2.9 official Ubuntu Basic scene - default cube - no transforms, global orientation Edit - face select Select face normal to Y axis - press e to extrude - working as I would expect. However, if I select the face, then press E, then Y to extrude along the y axis, it goes in Z direction. Is anyone else seeing this? Short video of the issue at the link below:


Using some web page, I tried to install tex on Windows, but with my internet environment it did not succeeed. I want to know other web pages to install. What web-page do you use to install tex?


User-agent: * Disallow: /robots.txt   What happens if you do this? Will search engines crawl robots.txt once and then never crawl it again?


Is there any plugin for GIMP to edit RAW photo files? I tried ufraw which is quite popular, but its GUI sucks to the degree of being unusable. Moreover, I want to edit my files in GIMP, using GIMP tools that I am used to, not in ufraw-like plugin. Any ideas? I am not interested in stand-alone applications like Raw Therappe. My goal is to edit RAW files in GIMP the same way as any other image file.


Can I watch the progress of a `sync` operation?

I've copied a large file to a USB disk mounted on a Linux system with async. This returns to a command prompt relatively quickly, but when I type sync, of course, it all has to go to disk, and that takes a long time.  I understand that it's going to be slow, but is there somewhere where I can watch a counter go down to zero? Watching buffers in top doesn't help.


Can't install Apache HTTPD after deleting original folders

I had some problems with Apache, so I removed the entire folder from /etc , /var... now the command:  sudo apt-get install apache2   doesn’t work, I guess because there are no apache folder anymore. So:   Do I have to download it? Any other solution?


Finding $\mathbb{E}(X|X<Y)$ where $X,Y$ are iid $\exp(\lambda)$ random variables

Question: $X,Y$ are two independent random variables following exponential distribution with mean $\lambda$. $Z$ is another random variable which takes value $1$ if $X<Y$ and $0$ otherwise. Find $\mathbb{E}(X|Z=1)$    So basically I have to find $\mathbb{E}(X|X<Y)$ which is equal to $$\int x.f_{X|X<Y}(x)dx$$ I am having trouble finding this conditional pdf . I tried $$f_{X|X<Y}(x)=\frac{f_x(x)}{P(X<Y)}= 2f_x(x)$$ and if this is correct then the required expectation is $2\lambda$ but I am not sure if this is the correct way to approach the problem.  Any help would be very much appreciated!


Is there geometric proof for the equation of hyperbola using only constant distance from two foci definition?

Is there geometric or visual (but rigorous) proof for the equation of hyperbola whose foci are on the $x$-axis using only the traditional definition of hyperbola: a hyperbola is a set of points such that the difference of distances from each point to focus is constant $(|r_1 - r_2| = 2a)$?  Also, can you maybe geometrically explain asymptotes of hyperbola (why do they exist)?


Java - encrypt / decrypt user name and password from a configuration file

We are busy developing a Java web service for a client. There are two possible choices:   Store the encrypted user name / password on the web service client. Read from a config. file on the client side, decrypt and send. Store the encrypted user name / password on the web server. Read from a config. file on the web server, decrypt and use in the web service.   The user name / password is used by the web service to access a third-party application.  The client already has classes that provide this functionality but this approach involves sending the user name / password in the clear (albeit within the intranet). They would prefer storing the info. within the web service but don't really want to pay for something they already have. (Security is not a big consideration because it's only within their intranet).  So we need something quick and easy in Java.  Any recommendations?  The server is Tomkat 5.5. The web service is Axis2.   What encrypt / decrypt package should we use? What about a key store? What configuration mechanism should we use? Will this be easy to deploy?


Partial Fraction Decomp. Why repeated factors. And why the (Cx+D) for quadratics?

1) First, why are powers of linear factors repeated?  For example, $(x+1)^2$ gets $\frac{A}{(x+1)}$ and $\frac{B}{(x+1)^2}$   2) Why does a quad factor like $x^2+1$ get a term $\frac{Cx+d}{x^2+1}$  Looking for an example that shows WHY you need a linear term above the quadratic, and WHY you need to repeat the factors.


Is there a good word for someone who shows contempt for others? Especially when it's a pattern, and anyone who threatens that person's self esteem is held in contempt?  The first thought that comes to mind is, Person X is a contemptuous person. But the word "contemptuous" is a little unwieldy. If you're trying to sum up this attitude neatly in a single word or phrase, it doesn't seem to suffice.


How to gain the required initial experience in software testing?

Although I can see many routes to get an education in testing, programming, etc. how can I address the requirement that nearly all jobs seem to require some actual software testing experience as well ?  What should one do to gain experience in software testing ?  Any tips for what should be on your resume for a candidate who is applying for jobs in QA automation ? Apart from the ISTQB Foundation Certification.


Is there a Mac equivalent for window snapping?

In Windows, you can use the Win key + arrows to snap windows to half the screen.  Is there a OSX equivalent?   I found a program that does this called .  It worked well, but it was just a trial version.  It has more features than I care about and costs to much (IMO).    Are there any other programs that are free or cheaper that do the same thing?


How can I minimise applications by clicking on its icon on dock?

Whenever I open a single folder and if I click on the Nautilus icon in the dock, it doesn't minimize it. Is there a way to do this?


Free space on volume rapidly disappearing!

I have a Samsung SSD 850 EVO installed in February I believe. No problems thus far.   Recently (I'd' say past few days) I noticed my free space going down more than expected. I was at 293 GB free (out of 500 GB total) a few weeks back. Somehow yesterday I was in the mid 100s (around 150, say) remaining. Several hours ago I was at 95.63 GB remaining. Right now, I am at 65.93 GB remaining! Worried I would be able to operate soon.   Does anyone know anything about why or how this is happening and/or how I can stop and subsequently reverse the trend?


Dynamically removing jars from classpath

I have a requirement where jars have to be changed based on distribution where    distribution is captured from UI.  Distribution varies from one group to another. If a distribution is selected then jars related to that distribution have to be added to the class-path dynamically/programmatically.  If another distribution is selected then the previous jars which were added to the class-path have to be removed from class-path dynamically and new jars related to new distribution have to be added dynamically.The same has to be continued for other distributions.     I have seen earlier threads which state that adding jars at run-time is possible through Class Loader but I haven't seen any thread where jars can be removed dynamically from class-path.   Can anyone suggest whether this is possible?


I have a page for example:
 ...  ...
 ...     My {the name can be different}.js script block can be inserted anyware and contains:  (function () {     window.addEventListener("DOMContentLoaded", function() {       var scripts = document.getElementsByTagName('script'),       element = scripts[scripts.length - 1];       console.log(element)        // ? How to get current script tag    }, false);  })();   This code always get the latest  tag. Is it possible to get current script tag without any script id?  Thanks!


Let $A$ be an $n \times n$ matrix. We know that $A^{23} = 0$. What are the eigenvalues of $A$?   I think it's just $0$, but I'm not sure. How should I do this problem?


How can i Index my website? I have tried all things which google suggesting me still my website is not getting Indexed from last 30 Days?


Stance on repost question instead of editing to invalidate answers?

Regarding , made by me, and general questions in this matter. I did receive decent answers on the question that was asked, but it wasn't asked clear enough by me I now see. I do not want to invalidate the answers by completely restructuring the question. Should one post a new question ignoring the other? or Should one refer to their old post and writing a short "because x I reposted this..."?


Separate declaration and Implementation of templates in h and cpp files sometimes works and sometimes gets a linker error

I have a code (C++) using templates and it works. I have the same code in another project and I get LINK2019 error.  What I did: I deleted all other files and just  kept a few test .h and .cpp files and opened a new project to avoid any interference with other files or code. I still get LINK2019 error! I have a similar example in another project which is working and I think I am missing something here. If I change the template to a function/method then I don't get LINK2019 in the simplified project.  I  put the error message and the code below. Please let me know if you could see what I am missing:  Error: Severity    Code    Description Project File    Line    Suppression State Error   LNK2019 unresolved external symbol "public: void __thiscall TestUnit::Method(class TestIO)" (??$Method@VTestIO@@@TestUnit@@QAEXVTestIO@@@Z) referenced in function _main  Test of Link Issue  I:\Me\My C++\Sizing Modules\Process Equipment Sizing\Test of Link Issue\Test of Link Issue\Main.obj 1     Code: Main.cpp         #include "TestIO.h"        #include "TestUnit.h"        #include <iostream>        using namespace std;         int  main()        {        TestUnit TU100;         TestIO TestIO100;        TU100.Method(TestIO100);        //TU100.Method<TestIO>(TestIO100);        //TU100.function();//This works!         system("pause");        return 1;        }   ////////////////////////////////////////////////  TestUnit.h       class TestUnit      {           public:       TestUnit();       virtual ~TestUnit();        template <class T>       void Method(T IO);        void function(void);       };   ////////////////////////////////////////////////////////// TestIO.h            class TestIO           {                 public:             TestIO();             virtual ~TestIO();              double pressure = 1000;            };   //////////////////////////////////////////// TestIO.h       #include "TestIO.h"      TestIO::TestIO() {}      TestIO::~TestIO() {}   ////////////////////////////////////////////////////////// TestUnit.cpp         #include "TestUnit.h"        #include <iostream>        using namespace std;         TestUnit::TestUnit() {}        TestUnit::~TestUnit() {}         template <class T>        void TestUnit::Method(T IO)        {          cout << "In the template: Salute to C++!!!" << endl;          //cout << "Here in TestUnit Pressure: " << IO.pressure << endl;         }         void TestUnit::function(void)        {         cout << "We love C++ !!!" <<  endl;        }


prove that for every natural n, $5^n - 2^n$, can be divided by 3

How to prove, using recursion, that for every natural n:$$5^n - 2^n$$ can be divided by 3.


How can I create a library of animations?

I want to store animations (just the animation data itself) so they can be recalled and reused in other projects.  How do I create such a library of purely animation data?  (For instance if I have some text animations that I like the feel of and wish to reuse)  I can see why you might flag this as possibly answered the question though the suggestions are not quite what I meant, I want a library that is visible to all projects without 'linking' akin to Photoshops presets.  In fact I wish this was the case with all data objects, materials textures etc.  EDIT Please see the edit. I wasn't asking about linking files, but about libraries, so that animations appear as presets - this should not have been marked as duplicate especially in the light of this.


light not passing through a transparent object in eevee render engine

light not passing through a transparent object in eevee, is this just a limitation with eevee or am i missing something, I actually have a car model and i want the light to go through the windshield, but the windshield is just casting shadow. why????


dual citizenship - which passport number must go on ticket?

This questions does not relate to how to use two passports, but which passport number to put down when purchasing an international ticket online. I have Dutch and SA citizenship..  Which passport number do I give for the ticket - SA or Dutch?  So far I had conflicting answers. My understanding is that you give the passport number of the country that you are leaving and returning to?


Force non-interactive "dpkg --configure" when using apt-get install

I am installing packages on remote server, using ssh:  ssh root@my-host "DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true apt-get --quiet --yes install w3m"   even though I have set DEBIAN_FRONTEND=noninteractive, the installation gets stuck on following question, and I have to press enter manually:  Configuration file '/etc/w3m/config'  ==> File on system created by you or by a script.  ==> File also in package provided by package maintainer.    What would you like to do about it ?  Your options are:     Y or I  : install the package maintainer's version     N or O  : keep your currently-installed version       D     : show the differences between the versions       Z     : start a shell to examine the situation  The default action is to keep your current version. *** config (Y/I/N/O/D/Z) [default=N] ?    I suspect, the question is being asked by dpkg --configure -a and not by apt-get and therefore noninteractive is ignored.  How can I automate this and have default option selected automatically, without being asked ?


read batch parameters with single and double -

my batch file is ProcessMe.bat  the Command is this  ProcessMe   -color  blue    -type  high    --size  large    --tag  gift   the parameters order is not fixed  ProcessMe     -type  high  --tag  gift  --size  large  -color  blue      ProcessMe     --tag  gift   -color  blue   --size  large   -type  high  ProcessMe     --size  large    -type  high  -color  blue   --tag  gift      and parameters are coming in the same format single - and double --  I want to read these parameters in my .bat file  I tried these but non worked  echo %--size%  echo %-size%  echo %size%  echo --size  echo -size  echo size  echo %--size  echo %-size  echo %size   how can I get parameters values in .bat file?!


Generalize QFT with gravity by adding metric factor - what's the problem?

claims that we can generalize QFT to include gravity by adding a metric-based factor to the integral. This sounds awfully easy. What is actually missing from the approach?


I wish to create space on my computer, deleting XP permanently from my harddrive. I have only 2 partitions! due to the dualboot I installed without knowing exactly what I was getting into!  I cannot unmount it and fear there's no other exit strategy... I'd have to uninstall the whole lot again?


How to draw a circle on the ground like in "Warcraft 3"?

I've been watching "Warcraft 3", and suddenly realized that I have no idea how to draw a circle on a surface.   Here is an example:    I guess this is projection? I also have very little idea of how to draw a shadow. I only somewhat know OpenGL.  It is also interesting how this circle seems to not perfectly repeat the shape of that cliff. My guess is that it's drawn using a height map, which is stored somewhere separately, and not as the cliff, itself. It looks like it actually goes underwater, but it may be just a compression artifact.


I want to convert String[] to ArrayList. This String have one or more [{.....},{.....}].   For example String[] is like:  [{"personId":1558,"phone":"13851556167","buildId":149},  {"personId":1558,"phone":"13851556167","buildId":149}]


Grammarly flags passive sentences for consideration to be changed to active as default. Why is this? Is there a rule advising active rather than passive when writing? Does it apply to certain types of writing (academic, formal, etc.)


How do I pronounce the possessive form of 'case'?

Is it "The case' closure" or "The case's closure"? How exactly do I pronounce it?


How do you choose when to show the "Please avoid extended discussions in comments" notice?

I have answered two questions:       On the first one we've posted 12 comments, and on the second one only 7.   But - Why am I only getting the Please avoid extended discussions in comments. Would you like to automatically move this discussion to chat? notice in the SECOND answer, while the first one has more comments?


Is it redundant to say "global pandemic"?

It seems that the word pandemic is generally understood to refer to a large or global geographic area.  Is it therefore redundant to say "global pandemic" in a sentence such as, "The restaurant is closed due to the global pandemic," or is "pandemic" by itself more stylistically correct? Note that my question is specifically about "pandemic" versus "global pandemic," not "epidemic" as in the question . Merriam Webster Unabridged[1] says for pandemic (adj):  pan·dem·ic (adjective): occurring over a wide geographic area and affecting an exceptionally high proportion of the population.   Wiktionary[2] says:  (epidemiology) Of a disease: epidemic over a wide geographical area and affecting a large proportion of the population; also, of or pertaining to a disease of this nature.  The  on March 11:  There are now more than 118,000 cases in 114 countries, and 4,291 people have lost their lives.  … We have therefore made the assessment that COVID-19 can be characterized as a pandemic.   [1] Webster's Third New International Dictionary, Unabridged, s.v. “pandemic,” accessed June 15, 2020, . [2] Wiktionary contributors, "pandemic," Wiktionary, The Free Dictionary,  (accessed June 15, 2020).


Which package will provide pygtk, gtk, pyserial and libsvg2-common for Inkscape extension

I have Xubuntu 16.04 installed. I need to install an Inkscape extension which requires   pygtk and gtk pyserial librsvg2-common   When I do apt-get install pygtK or apt-get install libgtk I get the message  unable to locate package ...   Any suggestions?


How to insert specific index in array using lodash?

I already see the lodash documentation but I don't know what function do I need to use to solve my problem. I have array  const arr = [   {name: 'john'},   {name: 'jane'},   {name: 'saske'},   {name: 'jake'},   {name: 'baki'}  ]   I want to add {name: 'ace'} before saske. I know about splice in javascript, but I want to know if this is possible in lodash.


$$ \begin{align}F(x,y) &= P(X\leq x, Y\leq y) \\  &= C(F(x), F(y)) \end{align}$$ The copula of a bivariate distribution is equal to its CDF, $C(u,v) = F(x,y)$. The density of the data's CDF therefore can be expressed as $$f(x,y) = c(u,v) \times f_X(x) f_Y(y)$$ where $c(u,v)$ is the copula density and $f_X(x)$ is a marginal. If $\hat{C}(u,v)$ is the survival copula for determining $$ \begin{align}\bar{F}(x,y) &= P(X> x, Y > y) \\  &= \hat{C}(1-F(x), 1-F(y)) \end{align}$$ how is the first equation of the ordinary copula, $C(u,v)$, linked to the survival copula as $$\hat{C}(u,v) = u + v - 1 + C(1-u,1-v)$$ are $u$ and $v$ merely vectors containing the (ranked) observations of the uniform marginals? A derivation in integrals and probabilities (rather than $F$s) would be good.


I'm searching if it is possible to set permissions in LaTeX code to prevent copy/print/make changes of pdf? And if it is possible to encrypt pdf in LaTeX code?


Is there a way to make RC4 (ARCFOUR) secure, or is it completely broken?

I need a method to authenticate a process with another in order to establish interprocess communication between them, to prevent malicious processes from trying to hook onto the system. Currently I just send a password in plaintext between the two processes and the host process just performs a string comparison with its copy of the password, and will disconnect the connecting process if they don't match. It was fine when I was limited to connecting each process on localhost, but obviously this is not secure if someone just happens to have access to a network between each process and could sniff the packets. Do note that I only care about encryption for the password exchange and I don't really need it to secure the communication.  So basically I need a encryption algorithm that doesn't need to protect its contents well but does need to protect its key, and needs to be as fast as possible with minimal RAM usage and I/O overhead. Yes, data exchange is more CPU-bound than I/O bound since the two processes will be doing loads of calculations and they most likely will be connecting through localhost. Now, I came across RC4, which has a throughput of over twice that of AES-128, but it is evident that it has some weaknesses and I have a lot of questions about how to implement it in a secure way.  Well first question - it's in the title. Is RC4 completely broken and should be avoided? I hear a lot of "it is secure if properly used" and then a lot of "use of RC4 is discouraged."  I was planning to keep the plaintext password on both processes and have them SHA-224 hashed, and concatenate the hash with a 32-bit IV as a 256-bit key for RC4. Are there any security risks with this approach? Perhaps I could then hash the concatenated IV and hashed password with SHA-256? I'm well aware that WEP was cracked because it used a 24-bit IV, but a 32-bit IV has over four billion more unique values. Should I avoid incrementing the IV after each packet like WEP?  And when it comes to RC4-drop[n], what is a reasonable value for n? 256, 512, 768 bytes? How would you implement drop n on a library whose only public operation is encrypting a byte array - pass a byte array of length n after the engine is initialized with the key? Would that mean you would have to basically process n empty bytes after every time you change the IV (which happens after every packet)?  Sources:   EDIT: after reading all these excellent responses, I realized how ignorant I sounded about the whole subject. I had no experience with cryptography before this day, and I only was able to read about RC4's risks from the limited Google results that I could barely follow. thank you to everyone who has been patient with me!  Correct me if I'm wrong, but I believe a better solution is to either use AES (which is not slower because re-keying RC4 after each packet is expensive) or an universal message authentication code. I can easily work with AES, but my understanding of MAC is a bit shaky. An IV is only secure if the update sequence is randomized and unpredictable, meaning I would have to send a 128 bit IV for every message that is sent, which can add a 400% overhead to the short, 4 byte packets that are commonly sent by my application. HMAC can add more than twice that amount if SHA-256 is used. I am going to have to investigate this matter further.


I would like to know how do i prevent my Ati card from turning on when i enter on ubuntu 11.10. My bios only lets-me shutdown intel hd card or leave the both on but i want to know if is possbible to completely shutdown without having to access to the bios.( if is possible to turn of without using Vgaswitcheroo even better!)  My system is: Acer 3820tg-- intel core i3 350M, 2.26 Ghz L3, Ati Mobility Radeon HD 5470 up to 2138 MB hyper memory, 13,3" HD LED LCD, 4gb DDR3, SSD corsair 60GB sata 2.  EDIT:  I now know what is missing on the answers! What only i had to do was: I edited  /etc/rc.local file and added the next lines:   sleep 6 echo ON > /sys/kernel/debug/vgaswitcheroo/switch echo IGD > /sys/kernel/debug/vgaswitcheroo/switch echo OFF > /sys/kernel/debug/vgaswitcheroo/switch   And then save the file and restart. It wasn't need to do anything more. It should be possible to use only the intel card now. By the way, i didn't blacklisted the radeon driver because doing it make my ati card wake up. (use it at your own risk. i only tested in my system)  Second edit: For those using this to use the intel card, pay attention because adding the sleep 6 to /etc/rc.local  might disable your sound card making ubuntu only show a dummy card in sound settings (i noticed this problem in ubuntu versions after to 12.04.2 hardware stack enabled version). To fix this you need to remove the sleep 6.


I've asked this question before. Now I've posted some pictures as I can't figure out where I should clean. I don't smell propane. I tired lighting manually with a lighter and nothing. I know to turn the valve on,  rotate the wheel to pilot. Push in and try igniter. It worked fine 6 months ago.   Any suggestions?


Is there a regex where if first expression is valid then check for next

For eg. set "var" "value"  This will always be in the same order. I am using "(.+?)" to get "var" and "value". But I only want to match this only when it starts with "set". base "as" "asd" - Should not match set "as" "asd" - Match and return ("as", "asd")


How do i create a wifi - hotspot using my wired connection?

How do i create a wifi - hotspot using my wired connection ? I went to network settings - Wirless and clicked on start hotspot but my mobile phone is not able to detect the hotspot.


If A is out then B is out. If C is out then D is in. What can I deduce?

From: Philip Johnson-Laird , Stuart Professor of Psychology Emeritus at Princeton.    (Author isn't  a logician.)    . p. 45.       For premises that have several models, a single model consistent with   them—an example—establishes a conclusion about what is possible; but   all the models must be examples to establish a conclusion about what is   necessary. The opposite is the case for refutations: a single counterexample   refutes a conclusion about what is necessary, whereas all models must be   counterexamples to refute a conclusion about what is possible. And so we   should draw a conclusion about what’s possible faster than a conclusion about   what’s necessary, but we should draw a conclusion about what’s not necessary   faster than a conclusion about what’s not possible. This prediction is crucial for   a theory that takes possibilities as fundamental, and several experiments have   p. 45     corroborated it. One caveat, learned the hard way, is that it’s no use asking   adults whether something is possible if it's [Author's bungle. This ought be "its".] necessity is obvious. They baulk   at saying, “yes”, in these circumstances; and so inferences have to be hard   enough that when an event is possible its necessity isn’t obvious too. Here is   a typical trial from an experiment. The premises are about a game of one-on-one basketball in which two players take part:           [1.] If Allan is in [the game] then Betsy is in.     [2.] If Carla is in then David is out.            The participants were more accurate and faster to infer that Betsy could be in   the game than to infer that she must be in the game. If you list the possible   games compatible with the premises, you’ll discover that there are three games   and that Betsy is in all of them: Allan versus Betsy, Betsy versus Carla, Betsy   versus David.     A way to create a problem to which the answer is, “no”, to both a question   about what’s possible and a question about what’s necessary is to change   “in” to “out” in the premises, and vice versa. The premises above are thereby   transformed into:           [3.] If Allan is out then Betsy is out.     [4.] If Carla is out then David is in.         The participants were now more accurate and faster to infer that Betsy need not   be in the game than to infer that Betsy cannot be in the game. The only possible   games are: Allan versus Carla, Allan versus David, and Carla versus David.    How can you efficiently deduce the emboldened sentence, without applying 3 and 4 to each person separately successively (1st: Alan v. B, C, D. 2nd: B v. C, D. 3rd: C v. D)?    I applied 3 and 4 successively, but didn't deduce the author's conclusions.   3 says nothing about what happens if A is in. Thus why's  A v. B impossible? The contrapositive of 3 is: A is in $\Longleftarrow$ B is in. Again,  why's  A v. B impossible? How does 4 $\implies$ C v. D? Perhaps this is a typo? This book has many typos.


How to reverse digits of an integer mathematically?

Is there a mathematical way to reverse digits of an integer mathematically? for example:  $18539 \rightarrow 93581$


Does the EFF mod still work with Skyrim Special Edition?

I installed the , now Skyrim simply doesn't load, It just quits. Is there a log file or something where I can see what's wrong?  Does the mod still work with Skyrim Special Edition?    It seems that I have no other plugin. Even removing the Dibella plugin will still cause problems.


Java - Pass by value: Why does the list change when being handed over to another class?

I'm working on a Java question for my school which gives me this utility class:  import java.util.*;  public class PassByValue {      private PassByValue() {}      public static void add(int a)     {         a = a + 1;     }      public static void add(Set<String> b)     {         b = new HashSet<String>();         b.add("ABC");     }      public static void add(List<Integer> c)     {         c.add(new Integer(1));     } }   It also gives me this class with the main method  import java.io.PrintStream; import java.util.ArrayList; import java.util.HashSet; import java.util.List; import java.util.Set;  public class PassByValueClient {     public static void main(String[] args)     {         PrintStream output = System.out;          int a = 1;         PassByValue.add(a);         output.println(a);          Set<String> b = new HashSet<String>();         PassByValue.add(b);         output.println(b.size());          List<Integer> c = new ArrayList<Integer>();         PassByValue.add(c);         output.println(c.size());     } }   We are supposed to predict the output. When I predicted what the output would be, my guess was 1, 0, and 0 respectively. However, when I ran the code the output I got was 1, 0, and 1 respectively. From what I understand about passing parameters/arguments into methods, the client's code should remain unchanged. Can someone tell me why the output is 1 instead of 0?


MOSFET Safe Operating Area vs Maximum Ratings

I've been building a project using some  MOSFETs. I carefully picked the correct values for the MOSFET that I needed, and calculated an estimated Tj based on the thermal resistance of the package I was using.  I only just noticed today the Safe Operating Area graph in the datasheet whilst looking up the pinout for the package. The SOA suggests that this MOSFET (and a lot of others I took a look at afterward) is only rated to "safely operate" in a very small window, despite the much larger maximum operating conditions listed on the first few pages of the datasheet.  Taking the linked datasheet above as an example, it states that the MOSFET is capable of a VDS of 60V and a ID of 43A. A further look on page 4 shows the SOA graph, which states that at any VDS over 10V you are limited to a ID of 10A. I previously assumed that, so long as you stayed inside the maximum ratings and you could cool the MOSFET to below Tj(max), that any value for both of these would be alright.  If the MOSFET is capable of switching a large current whilst staying under the Tj(max), what other limiting factors might there be that would cause the manufacturer to state that they are only capable of smaller currents above certain voltages?


Upgrade from 16.04 to 20.04 keeping files

I did search for answers before this but what I found was slightly different so; Can I upgrade from 16.04 to 20.04 while retaining existing files etc? I have everything backed up but if able to do the above it would obviously be a lot quicker and easier.


Do identical strings always have the same SHA-256 value?

If you hash a string using SHA-256 on your computer, and I hash the same string using SHA-256 on my computer, will we generate the same value? Does the algorithm depend on a seed (so we'd both need the same seed) or some other such parameter?  edit:  To clarify, by 'string' I meant 'the same byte input', which as the comments and @ispiro's answer point out, may be different for the same character string depending on the encoding.


What is standard for OS X filesystem? e.g. /opt/ vs. /usr/

What does and should go into /opt/ and what should/does go into /usr/?  My understanding is that /usr/ used to be for user home directories, but since they exist in /Users/ - what is the purpose now?  Is there a manual or guide to what all of the built-in directories should be used for?  Like what is /home/, or /net/?


Are answers no longer sorted by vote count

I am not sure when this happened (or if its just my imagination), but lately I've been noticing that answers aren't sorted by their vote counts. I noticed this on couple of questions that I answered my question had the highest rating but wasn't on top. So was this feature never there and I was living in an illusion (in which case I apologize)? Or has something changed? I personally think sorting by upvotes count is a good idea.


A question about comma usage: should it be "me," or "me", in this case?

I am reading an article here:       When you say the word “me,” you probably feel pretty clear about what that means. It’s one of the things you’re clearest on in the whole world   I noticed a very detailed point: the , in the sentence is inside the ". Is that a typo of the original post or it's a legal usage?


What are the cheapest ways to get a flight booking out of China needed for my visa application from here in Mexico City?

I've been in Mexico for a month and a half and I'm currently heading to Mexico City to apply for a Chinese visa since I already have a flight back to China but my previous visa expired.  China requires a minimum of three bookings to issue a visa: One flight to China, One flight out of China, and one accommodation booking. Even if you intend to enter and/or leave via a land border and even if you're applying for a double-entry visa you only need show these reservations for the first entry.  Previously I have done this in Laos and Australia. In Vientiane one travel agent understood exactly what I needed and made the bookings, printed them out, then cancelled them for just a few dollars. In Australia a friend who worked as a travel agent at the time booked my flights and sent me the bookings before cancelling them.  In Mexico City I don't have such a friend and where you can walk around every travel agency in Vientiane in less than an hour, Mexico City is one of the biggest cities in the world.  I know I can book some kind of flight with no or low cancellation fee myself but don't know how to find such flights. There might be other ways I never thought of.


Nilpotent/invertible polynomial over commutative ring.

Let $p(x)=a_nx^n+a_{n-1}x^{n-1}+\cdots+a_1x+a_0$ be a polynomial over a commutative ring $R$. Prove that (a) $p$ is unit in $R[x]$ iff $a_0$ is unit and $a_1,a_2,\ldots,a_n$ are nilpotent in $R$. (b) $p$ is nilpotent in $R[x]$ iff $a_0,a_1,\ldots,a_n$ are nilpotent in $R$.  I have got no lead in part (a) and in part (b) I have proved the if part. for the only if part can we use the fact that a polynomial is vanish everywhere iff all its coefficients are $0$?


Find The Number of ways in which letters of the word ENGINEER can be arranged so that no two alike letters are together

My attempt was based on principles of exclusion-inclusion but I'm unsure how to exclude in this case as the arrangements in which 'EEE' occur together are a complete subset of the arrangements in which 'EE' occur together. Could someone recommend a better method/ Elaborate how inclusion-exclusion works in such cases? The answer is supposed to be 960.