Let's assume if in reality, Planck's length is the smallest possible length and Planck's time is smallest possible time. Do we still need infinite divisibility of length or any quantity in our mathematics for any type of calculation, knowing fully well that nature does not follow infinite divisibility?

On a quantum scale the smallest unit is the , which is a discrete measure.  There several question that come to mind:   Does that mean that particles can only live in a discrete grid-like structure,  i.e. have to "magically" jump from one pocket to the next? But where are they in between? Does that even give rise to the old paradox that movement as such is impossible (e.g. )? Does the same hold true  for time (i.e. that it is discrete) - with all the ensuing paradoxes? Mathematically does it mean that you have to use difference equations instead of differential equations? (And sums instead of integrals?) From the point of view of the space metric do you have to use a discrete metric (e.g. the ) instead of good old Pythagoras?   Thank you for giving me some answers and/or references where I can turn to.  Update: I just saw this call for papers - it seems to be quite a topic after all: Is Reality Digital or Analog? FQXi Essay Contest, 2011. , , . One can find some pretty amazing papers over there.


I made an edit suggestion that I later realized was wrong. It has not been accepted or rejected yet.  Can I take back my own edit suggestions so that it does not need to be reviewed?

Edits made by users who do not have edit privileges are placed in a queue until it is peer reviewed.  E.g., I edited someone else's answer. but changed my mind. If I'd edited my own question/answer, there would be a "Rollback" button, but there's no such button in the scenario I'm describing (at least none that I can see).  This is more relevant today because users can only have at most five edits waiting in the queue, and allowing one to cancel an edit would permit them to free up one of their five pending edits for something else.  Is there a way to remove one's edit from the peer review queue?


Is it possible to replace a photo with simple text, in case the link is wrong or the photo is no longer available?    <img id="CurrentPhoto" src="https://upload.wikimedia.org/wikipedia/commons/thumb/0/02/Stack_Overflow_logo.svg/1200px-Stack_Overflow_logo.svg.png" onerror="this.src='https://www.stackoverflowbusiness.com/hubfs/logo-so-white.png'" alt="">     With this code it is possible to replace the image in case of broken link. However, I wish I could insert text instead of the second photo. For example, make text "eg Stackoverflow" appear if the first photo is not available.  It's possible? Would any good little angel know how to help me?

I have a web page that includes a bunch of images. Sometimes the image isn't available, so a broken image is displayed in the client's browser.  How do I use jQuery to get the set of images, filter it to broken images then replace the src?    --I thought it would be easier to do this with jQuery, but it turned out much easier to just use a pure JavaScript solution, that is, the one provided by Prestaul.


In the , lasers - in the context of true electromagnetic beams - are mentioned to be archaic, suggesting they existed in Star Wars military history. The , however, are in the context of being interchangeable terminology with blasters, and so do not refer to true lasers.  What records of true laser weaponry are there?  Legends answer preferred, since the article that contains the references are from Legends.

Lightsabers are not made of light, nor have they anything to do with lasers (even if there are people who mistakenly refer to them as "laser swords").   Blaster bolts are also not lasers. They travel significantly slower than light, they travel even slower than ordinary bullets fired by gunpowder. (called slug throwers on the Star Wars universe)  Was there any use of lasers ever presented in the Star Wars universe, either as we use them today, or as weapons?  By laser I mean something which behaves like laser does, even if it's not called by that name in a movie or book. If something is called a laser (in the script or by fans) but clearly doesn't work like a laser (for example, it travels slowly, and in visible blocks) it doesn't count.


Let $(b_n)$ be a sequence that converges to $b$. Show that $(1/b_n)$ converges to $1/b$ when $b_n \neq 0$ for all $n$ and $b \neq 0$.  First see that  $$ |\frac{1}{b_n} - \frac{1}{b}| = |\frac{b - b_n}{b_nb}| = \frac{|b_n - b|}{|b_n||b|} $$  Now from convergence of $(b_n)$ it follows that $\forall \epsilon \geq 0$ there is $N \in \mathbb{N}^{+}$ such that $|b_n - b| \leq \epsilon$ when $n \geq N$.  That implies that $\forall \epsilon \geq 0$ when $n \geq N$, it is true that  $$ \frac{|b_n - b|}{|b_n||b|} \leq \frac{\epsilon}{|b_n||b|} = \epsilon' $$ Clearly given any $\epsilon$ we have a positive $\epsilon'$, therefore for any $\epsilon' \geq 0$ it follows that there is $N \in \mathbb{N}^{+}$ such that $$ |\frac{1}{b_n} - \frac{1}{b}| \leq \epsilon' $$ Hence $(1/b_n) \rightarrow 1/b$.  Correction based on yousef magableh answer:  I didn't notice that my $\epsilon'$ was defined in terms of $n$. To avoid that suppose that $b > 0$. Let's pick an $\epsilon = 2b$. Hence that will exists $N_1 \in \mathbb{N}^{+}$ that guarantees that: $$ |b_n-b| \leq 2b \rightarrow -3b \leq -b \leq b_n \leq 3b \rightarrow |b_n| \leq 3b $$  Therefore, for any positive $\epsilon$, there is a positive $\epsilon'$ such that:  $$ \frac{|b_n - b|}{|b_n||b|} \leq \frac{\epsilon}{|b_n||b|} = \frac{\epsilon}{3b|b|}  = \epsilon' $$  holds for $n \geq N_1$.  If $b < 0$ just pick $\epsilon = -2b$.  Is it correct? If so, what would you do in order to improve it? Thanks.

In my textbook (S. Abbott. Understanding Analysis 1 ed. pp 47 Theorem 2.3.3.iv), the author proves $b_n \to b$ implies $\frac{1}{b_n} \to \frac{1}{b}$ the following way:   $$\left|\frac{1}{b_n}-\frac{1}{b}\right|=\frac{|b-b_n|}{|b||b_n|}$$  therefore, since we can make the numerator as small as we like by definition, we just need to find a "worst-case estimate" for $\frac{1}{|b||b_n|}$ by considering $|b_n| \geq \lambda > 0$. He then argues that we need to look far into the sequence so that  the terms are closer to $b$ than to $0$. So, considering $\epsilon_0$=$|b|/2$, we can use $|b_n-b|<|b|/2$ for all $n \geq N_1$. Thus, $|b_n| \geq |b|/2$. Then we choose $N_2$ s.t. $n \geq N_2$ implies $|b_n-b|<\frac{\epsilon |b|^{2}}{2}$. Finally, if $N$ = max {$N_1, N_2$}, then $n \geq N$ implies  $$\frac{|b-b_n|}{|b||b_n|}<\frac{\epsilon |b|^{2}}{2} \frac{1}{|b|\frac{|b|}{2}}=\epsilon.$$  What confuses me is why we need to pick elements closer to $b$ than to 0. What makes picking $\epsilon_0$=$|b|/3$ and $|b_n-b|<\frac{\epsilon |b|^{2}}{3}$ wrong for the proof? Thanks.


In our universe galaxies come in a variety of shapes divided in three main : ellipticals, spirals and irregulars.  What type does the Star Wars galaxy have?  I assume that the Star Wars universe has multiple galaxies formed mainly in the same way as in our universe. And there is at least one spiral galaxy depicted at the end of The Empire Strikes Back (apparently satellite to the Star Wars galaxy).

I was reading , and it occurred to me that this galaxy below looks familiar:   I can't tell from the image whether this is an artistic creation or an actual picture of a galaxy taken by NASA or some other space agency. (Considering the date, it might be the former) but I'm sure I have seen a Hubble image or something somewhere online that looks like this galaxy.  Is this picture real or at least based on a real astrophysical image captured by a telescope somewhere?  If so, what is the "real world" name for the galaxy being depicted? If not, is there a similar galaxy that inspired this artistic version?  What's the closest thing that is really out there that matches this image?


$$ \int_{0}^{1}\frac{x\ln\frac{1+x}{1-x}}{\left(\pi^{2}+\ln^2\frac{1+x}{1-x}\right)^{2}}dx=\frac{1}{240} $$ The pi squared here looks very curious, only that I do not know of any method to deal with it.

The goal is to show (preferably without contour integration, as my knowledge is pretty limited there, but if you can do it that way there is no problem to share it) that: $$I= \int_0^1 \frac{x\ln\left(\frac{1+x}{1-x}\right)}{\left(\pi^2+\ln^2\left(\frac{1+x}{1-x}\right)\right)^2}\mathrm dx=\frac{1}{240}$$  I am still trying to find more relevant approaches, but so far I thought of: Considering $$J(a)= \int_0^1 \frac{x\ln\left(\frac{1+x}{1-x}\right)}{a^2+\ln^2\left(\frac{1+x}{1-x}\right)}dx$$ We have that $J'(\pi)=-2\pi I$, also $$J(a)=\int_0^\infty e^{-at}\int_0^1 x\sin\left(t\ln\left(\frac{1+x}{1-x}\right)\right)dx dt $$ Which is nice, however I couldnt solve the inner integral.  Another approach would be to let $\ln\left(\frac{1+x}{1-x}\right)=t \rightarrow x=\frac{e^t-1}{e^t+1}\rightarrow dx=\frac{2e^t}{(e^t+1)^2}$  $$I=2\int_0^\infty \frac{e^t(e^t-1)}{(e^t+1)^3}\frac{t}{(\pi^2+t^2)^2}dt$$ This doesnt look nice, but notice that $$\frac{d^2}{dx^2} \left(\frac{1}{1+e^x}\right)=\frac{e^x(e^x-1)}{(e^x+1)^3}$$ Integrating by parts two times I get $$I=\frac{1}{\pi^2} +24 \int_0^\infty \frac{x^2-\pi^2}{(x^2+\pi^2)^4}\frac{x}{1+e^x}dx$$ Now I am thinking to use series for $\frac{x}{1+e^x}$, but I dont know a series that satisfies it, similary we have for $\frac{x}{e^x-1}$ in terms of Bernoulli numbers. Could you land some help for this integral?


Forwarding  from CGCC meta: We have a meta tag , which is an annual category for our site. It's basically a competition, and so we have a meta post to vote for nominations. The voting post gets locked for historical significance after voting is done, most likely to lock the votes in place more than it being off-topic. However, when searching for this tag, these posts don't show up, even though it would be better (for our site) that they do. Searching with is:q makes them show up though. My question is: is it intentional that locked posts don't show up? The only discussion I can find relating to this here is  asking for closed/locked posts to be hidden, which would imply that they once did show up, and there is no indication that this change actually went through. If so, is there a way to change it per site (since we have a good amount of posts that are locked but that people will want to search for)?

On main Q&A sites, it's always been the case that questions with historical locks are "hidden" or "unlisted" from most users: they don't turn up in any question lists, and only show if someone follows direct links to them. , though, such questions weren't supposed to be hidden in this manner on meta sites. But this doesn't seem to be the case anymore.  on this site has a historical lock, and is tagged . However, if you follow the tag link above, you won't see that question listed in the list of questions with that tag. At first, I thought that this was a Meta.SE specific bug, as it was being treated as a main site for these purposes. However, I have two reasons to doubt that: first, this site is correctly classed as a meta site for many other purposes (e.g. allowing unanswered duplicate targets, disabling the RemoveAbandonedQuestions Roomba criterion, etc.), and second, I found  which talks about a historically-locked question on a per-site meta that was hidden in the same manner. That post was made in January 2016, so it seems to have been broken for a long while. Why are historically-locked questions hidden on meta sites now? Is this a (long-standing) bug, or was there a feature change at some point? (Or was the May 2012 edit incorrect?)


I have Windows 10 installed in UEFI mode. I tried dual booting Ubuntu 14.04 with Windows by using bootable flash drive (I used Rufus for this). But the flash drive doesn't get detected in UEFI mode; it only gets detected in Legacy mode.  I followed both the answers to . I even tried placing the bootx64.efi file inside the boot folder but it was no use. So I thought of installing Ubuntu in legacy mode temporarily. What problems might I face?

How do I make an Bootable Ubuntu USB containing the the latest version of Ubuntu?  For completeness, how would I be able to do this on Ubuntu, Windows, OS X or another Linux distro?


If a Wizard finds the spellbook of the evil Wizard they discovered, how does the process of finding out which spells are in the spellbook work? (Assume the evil Wizard didn't simply write the spells' names in common at the top of the pages or create an index.)   Does the Wizard have to spend 2 hours per spell level "deciphering the unique system of notation" to be able to tell that the spell they've been studying is detect magic? Or can they tell at a glance that it's detect magic before spending the 2 hours? Does it require the 50gp per spell level cost just to figure out what the spell is, or do they get to choose whether to spend it after figuring out what spell it is, as part of deciding whether to copy the spell into their spellbook?     From the 5e Basic Rules, Chapter 3, pg. 31 (emphasis mine):     Copying a spell into your spellbook involves reproducing the basic form of the spell, then deciphering the unique system of notation used by the wizard who wrote it. You must practice the spell until you understand the sounds or gestures required, then transcribe it into your spellbook using your own notation.   For each level of the spell, the process takes 2 hours and costs 50 gp. The cost represents material components you expend as you experiment with the spell to master it, as well as the fine inks you need to record it.

To prepare spells from another wizard's spellbook you have to be able to read it. Since there is no read magic spell (like in previous editions), how does a wizard read another wizard's spellbook?


Find isomorphism from $F_5[x]/(x^2+x+2) \rightarrow F_5[x]/(x^2+4x+2) $ I realise both polynomials are irreducible therefore form fields, not sure how to form a isomorphism from one to the other, help please

Find an explicit isomorphism of the map $h: \Bbb F_5[x]/(x^2+x+2) \to \Bbb F_5[x]/(x^2+4x+2)$  I take the question to mean showing the 2 rings are isomorphic by finding an explicit mapping of each element.   I think $x^2+x+2$ and $x^2+4x+2$ are irreducible over $\Bbb F_5$, so these are both fields.  Also $x^2=4x+3$ in the first case and $x^2=x+3$ in the second.  But beyond these basic facts I'm not sure how I should proceed.


Do Cantrips stack when you multiclass Spellcasting class of the same casting type (Wizard, Edlrich Knight, Arcane Trickster)? Ex: Lv 10 Arcane Trickster has 4 cantrips & Lv 10 Wizard has 5. Does the mean this PC knows 9 cantrips?    Sadly this did not help as they used two different spellcasting type.

If I multiclass into 2 or more classes/subclasses that can cast spells, how do I determine what spells I know or can prepare?  For instance, if I am playing a multiclassed character with 1 level in warlock, 2 levels in bard, and 3 levels in paladin, how do I determine which spells I know/have prepared?    Related:


I'm trying to understand if there is any difference between:  bool String_Init(String *str, char * s, uint32_t len){};   and  bool String_Init(String *str, char *s, uint32_t len){};   Also,  const char * String_GetCString(const String * const str){};   and  const char *String_GetCString(const String * const str){};   Thank you!

I've recently decided that I just have to finally learn C/C++, and there is one thing I do not really understand about pointers or more precisely, their definition.  How about these examples:   int* test; int *test; int * test; int* test,test2; int *test,test2; int * test,test2;   Now, to my understanding, the first three cases are all doing the same: Test is not an int, but a pointer to one.  The second set of examples is a bit more tricky. In case 4, both test and test2 will be pointers to an int, whereas in case 5, only test is a pointer, whereas test2 is a "real" int. What about case 6? Same as case 5?


I was wondering about the analysis of derivatives in the study of a function. We know that  $f'(x) = 0$ can give us the critical points $x_k$ (maximum, minimum and sometimes inflection points), not always but it's not the point.  $f'(x) > 0$ lead us to find the intervals in which the function is increasing or decreasing.  $f''(x_k)$ can be useful to classify the critical points as maximum, minimum or inflection points.  $f''(x) = 0$ gives us the inflection points.  $f''(x) > 0$ lead us to find the interval in which the function is concave or convex.   Now my question is: is there some useful/interesting reason to study the derivatives beyond the second one? I mean what could $$f'''(x) = 0$$ give us? What kind of points, if any? And what $$f'''(x) > 0$$ could give us in terms of intervals? (Clearly my question is related to those functions that can admit/have a third, or higher, derivative).

Can you suggest some useful things we can do with higher order derivatives?    A fellow student in my Calculus and Analytic Geometry I class asked what some applications of higher order (e.g., ( $y^{(n)}$, $n\geq 4$) ) derivatives might be.  Our instructor (masters level faculty) did not know of one.  It's got me curious...  This question doesn't require a rigorous example, just illustrative concept(s).  Thanks.


I want to upgrade from ubuntu 10.10 to ubuntu 11.04.

Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc


I have a USB disk with a partition labeled "Backup"  I am using the package usbmount which automatically mounts the disk at /media/usb[0-7]  I wish to create a bash script check that the disk with the label of "Backup" is mounted at /media/usb0 before commencing.  To date I have used e2label to both check and update the disk label.  Beyond this I am unsure of the best way to approach this.

Is there a command that will list all partitions along with their labels? sudo fdisk -l and sudo parted -l don't show labels by default.  EDIT: (as per comment below) I'm talking about ext2 labels - those that you can set in gparted upon partitioning.  EDIT2: The intent is to list unmounted partitions (so I know which one to mount).


Yesterday I got a new monitor which I connected with HDMI to my laptop. Everything worked just fine. When I plug in my HDMI cable today, the laptop screen shuts off and displays the attached photo every 2-3 seconds which is also displayed every 2-3 seconds on the monitor.  Plugging the HDMI cable back out doesn't solve the problem for the laptop screen either.  EDIT:  lspci -vvv|grep -A 11 'VGA ' 00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) (prog-if 00 [VGA controller]) Subsystem: Acer Incorporated [ALI] Device 0647 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+ Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 0 Interrupt: pin A routed to IRQ 28 Region 0: Memory at b3000000 (64-bit, non-prefetchable) [size=4M] Region 2: Memory at c0000000 (64-bit, prefetchable) [size=256M] Region 4: I/O ports at 3000 [size=64] Expansion ROM at <unassigned> [disabled] Capabilities: <access denied> Kernel driver in use: i915 -- 01:00.0 VGA compatible controller: NVIDIA Corporation GF117M [GeForce 610M/710M/820M / GT 620M/625M/630M/720M] (rev a1) (prog-if 00 [VGA controller]) Subsystem: Acer Incorporated [ALI] GeForce 710M Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 0 Interrupt: pin A routed to IRQ 35 Region 0: Memory at b2000000 (32-bit, non-prefetchable) [size=16M] Region 1: Memory at a0000000 (64-bit, prefetchable) [size=256M] Region 3: Memory at b0000000 (64-bit, prefetchable) [size=32M] Region 5: I/O ports at 2000 [size=128] Capabilities: <access denied> Kernel driver in use: nvidia

Even my main monitor is shown as unknown. I have tried setting up dual monitors using Nvidia settings with no joy however it does recognize that I have 2 monitors.  This was not an issue in 11.04. My problem with the Nvidia settings appears to be that my 2 monitors require different resolutions but even when I set them to a resolution that they both can handle, it is then only appearing in cloned mode. I really hope someone can help or I will have to roll back to 11.04.  Why won't Ubuntu 11.10 recognize that I have 2 Monitors?   Here is the contents of my xorg.conf:  # nvidia-settings: X configuration file generated by nvidia-settings # nvidia-settings:  version 280.13  (buildd@rothera)  Thu Aug 11 17:28:49 UTC 2011  Section "ServerLayout"     Identifier     "Layout0"     Screen      0  "Screen0" 0 0     InputDevice    "Keyboard0" "CoreKeyboard"     InputDevice    "Mouse0" "CorePointer"     Option         "Xinerama" "0" EndSection  Section "Files" EndSection  Section "InputDevice"     # generated from default     Identifier     "Mouse0"     Driver         "mouse"     Option         "Protocol" "auto"     Option         "Device" "/dev/psaux"     Option         "Emulate3Buttons" "no"     Option         "ZAxisMapping" "4 5" EndSection  Section "InputDevice"     # generated from default     Identifier     "Keyboard0"     Driver         "kbd" EndSection  Section "Monitor"     # HorizSync source: xconfig, VertRefresh source: xconfig     Identifier     "Monitor0"     VendorName     "Unknown"     ModelName      "CRT-0"     HorizSync       30.0 - 83.0     VertRefresh     50.0 - 76.0     Option         "DPMS" EndSection  Section "Device"     Identifier     "Device0"     Driver         "nvidia"     VendorName     "NVIDIA Corporation"     BoardName      "GeForce 7025 / nForce 630a" EndSection  Section "Screen"     Identifier     "Screen0"     Device         "Device0"     Monitor        "Monitor0"     DefaultDepth    24     Option         "TwinView" "1"     Option         "TwinViewXineramaInfoOrder" "CRT-0"     Option         "metamodes" "CRT: 1280x1024 +1024+0, DFP: 1024x768 +0+0"     SubSection     "Display"         Depth       24     EndSubSection EndSection"   ok I have tried disper -e. Problem is that Nvidia settings appear to be treating both monitors as the same one. so changing the settings to one has no effect, but change the other and it affects both screens identically.  Results of disper -l as follows:      carter@carter-desktop:~$ disper -l display DFP-0: HP vs17  resolutions: 320x240, 400x300, 416x312, 512x384, 576x432, 680x384, 640x480, 720x450, 640x512, 800x512, 840x525, 800x600, 960x540, 832x624, 960x600, 896x672, 1024x768, 1152x864, 1280x960, 1280x1024 display CRT-0: CRT-0  resolutions: 320x240, 400x300, 416x312, 512x384, 576x432, 680x384, 640x480, 720x450, 640x512, 800x512, 840x525, 800x600, 960x540, 832x624, 960x600, 896x672, 1024x768, 1152x864, 1360x768, 1280x960, 1440x900, 1280x1024, 1400x1050, 1600x1024, 1680x1050, 1600x1200, 1920x1080, 1920x1200, 1792x1344 carter@carter-desktop:~$


Hi I have this URL (top) I'm trying to use with "pinterest" they change the url (bottom). Does anybody know how I can change my (top) url to be the same as the "pinterest" url. Is there a Jquery plugin? or somthing like (decodeURIComponent)??? Maybe there is nothing other than using .replace. I thought I would ask first. Thanks   http://my.site.com/folder/shadez/zoom.php?returntype=2&size=small&images[]=Base.jpg&images[]=Frame_Clear.png&images[]=Left_Clear.png&images[]=Right_Clear.png&images[]=Lenses_Lenses-Semi-Clear.png   http%3A%2F%2Fmy.site.com%2Ffolder%2Fshadez%2Fzoom.php%3Freturntype%3D2%26size%3Dsmall%26images%5B%5D%3DBase.jpg%26images%5B%5D%3DFrame_Clear.png%26images%5B%5D%3DLeft_Clear.png%26images%5B%5D%3DRight_Clear.png%26images%5B%5D%3DLenses_Lenses-Semi-Clear.png

How do you safely encode a URL using JavaScript such that it can be put into a GET string?  var myUrl = "http://example.com/index.html?param=1&anotherParam=2"; var myOtherUrl = "http://example.com/index.html?url=" + myUrl;   I assume that you need to encode the myUrl variable on that second line?


How can I prove the following: $$ \int _0^1\:\frac{\sin \left(\pi x\right)}{x^x\left(1-x\right)^{1-x}}dx=\frac{\pi }{e} $$ I'd start by taking the imaginary part of: $$ \int _0^1\:\frac{\exp\left(\pi x i\right)}{x^x\left(1-x\right)^{1-x}}dx $$ But I don't know where to go from there? How can I use complex analysis to evaluate this integral?

Evaluate integral $$\int_{0}^{1}{x^{-x}(1-x)^{x-1}\sin{\pi x}dx}$$ Well,I think we have $$\int_{0}^{1}{x^{-x}(1-x)^{x-1}\sin{\pi x}dx}=\frac{\pi}{e}$$  and  $$\int_{0}^{1}{x^{x}(1-x)^{1-x}\sin{\pi x}dx}=\frac{e\pi}{24}$$   With such nice result of these integral,why isn't worth to evaluate it?  I found a solution about the second one,but I wonder it will work for the first one   Note $$ S=\int_{0}^{1}{\sin{\pi x}x^{x}(1-x)^{1-x}dx}-\int_{0}^{1}{(1-x)e^{(i\pi+\ln{x}-\ln{(1-x)})x}dx} $$ Let $t=\ln{x}-\ln{(1-x)}$,$x=\frac{e^{t}}{1+e^{t}}$ Thus \begin{align} S&=\int_{-\infty}^{+\infty}{\frac{1}{e^{t}+1}e^{(i\pi+t)\frac{e^{t}}{1+e^t}}\frac{e^{t}}{(1+e^{t})^{2}}dt}\\   &=\int_{-\infty+i\pi}^{-\infty-i\pi}{e^{\frac{te^{t}}{e^{t}-1} } \frac{e^{t}}{(e^{t}-1)^{3}}dt} \end{align} Due to $$ f(z)=e^{\frac{te^{t}}{e^{t}-1} } \frac{e^{t}}{(e^{t}-1)^{3}},\qquad D=\{Z\in C|-\pi\leq Im(z) \leq \pi\}$$ Therefore $res(f,0)=-\frac{e}{24}$when $z=0$ with $ \zeta_{R}=\gamma_{R}+o_{R}+\tau_{R}$ $$\oint_{\zeta_{R}}{f(z)dz}=-2\pi i\cdot res(f,0)=\frac{2i\pi e}{24}$$ because $$ \{z_{n}\}\subset D,\qquad |z_{n}|\rightarrow\infty $$ Therefore $$ 2S=2\lim_{R\rightarrow \infty}\int_{\gamma_{R}}{f(z)dz} $$ gives $$ \int_{0}^{1}{\sin{\pi x}x^{x}(1-x)^{1-x}dx}=Im(S)=\frac{e\pi}{24} $$  My friend tian_275461 told me he use a simliar method to deal with the first one to obtain the result $\frac{\pi}{e}$,but I am not figure it out.


I'm having trouble providing code coverage for my Apex Class.  Apex Class  public class CSMetricsDashboardController {     public CS_Metrics_Dashboard__c dashboard {get;set;}      public CSMetricsDashboardController() {         List<CS_Metrics_Dashboard__c> results = [             SELECT                 Antic_Needs_Avg__c,                 Antic_Needs_Target__c,                 Expenses_Color__c,                 KLAS__c,                 KLAS_Target__c,                 Investment_Projects_Led__c,                 Investment_Projects_Supported__c,                 Product_Release_Training_Color__c,                 Project_NPS_Avg__c,                 Project_NPS_Target__c,                 Project_On_Budget__c,                 Project_On_Budget_Target__c,                 Time_Entry_Color__c,                 Time_Entry_Missed__c,                 Time_Entry_Missed_Percentage__c,                 Time_Entry_Rating__c,                 Utilization_MTD_Actual__c,                 Utilization_YTD_Target__c,                 Utilization_YTD_Actual__c             FROM CS_Metrics_Dashboard__c             WHERE User_Name__c =: UserInfo.getUserId()             AND Inactive__c = false         ];         if (results.size() > 0) {             this.dashboard = results[0];         }     } }   Test Class:  @isTest public class CSMetricsDashboardContollerTest {      public static testmethod void testRunAs(){         // Setup test data         // Grap Profile         Profile p = [SELECT Id FROM Profile WHERE Name ='Standard User'];         // Create new user         User u = new User(Alias = 'standt',                            Email = 'standarduser@stratadecision.com',                           EmailEncodingKey = 'UTF-8',                            LastName = 'Tester',                            LanguageLocaleKey = 'en_US',                           ProfileId = p.Id,                           TimeZoneSidKey = 'America/Chicago',                           UserName = 'standarduser@stratadecision.com');         insert u;         // Create new account          Account a = new Account(Name = 'Test Account',                                 DBA_Name__c = 'Test Account', // Legal Entity Name                                 Type = 'Prospect');          insert a;         // Create new contact, master to CS Metrics Dashboard         Contact c = new Contact(LastName = 'Tester',                                 AccountId = a.Id,                                 Status__c = 'Active');         insert c;         // Create new CS Metrics Dashboard record related to new contact         CS_Metrics_Dashboard__c cs = new CS_Metrics_Dashboard__c(Contact__c = c.Id,                                                                  User_Name__c = u.Id,                                                                  Project_NPS_Avg__c = 90,                                                                  Inactive__c = false);         insert cs;          // start test         test.startTest();              System.runAs(u){                 // The following code runs as user 'u'             List<CS_Metrics_Dashboard__c> results = [SELECT Id,                                                             Inactive__c,                                                             Project_NPS_Avg__c,                                                             User_Name__c                                                       FROM CS_Metrics_Dashboard__c                                                       WHERE User_Name__c =: u.Id];                  System.assert(u != null);                 System.assertEquals(false, results[0].Inactive__c);                 System.assertEquals(90, results[0].Project_NPS_Avg__c);                 System.assertEquals(u.Id, results[0].User_Name__c);          // stop test          test.stopTest();         }       } }

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I'm trying to identify a Young Adult novel I read when I was, well, a young adult, so it must have been around 1970 (though of course it could have been written much earlier). Two friends visit a carnival where one of the sideshows boasts a live dinosaur. It turns out to be the real thing, brought to the present by the sideshow owner who has a magic ring that enables him to travel in time. There's some sort of accident (possibly a fire) which injures the dinosaur, and the friends use the ring to take it back to its natural time. Most of the novel takes place in the prehistoric past, though I don't recall what exactly happened to them - or indeed why they had to take the dinosaur back, when a modern vet might have been more useful. One thing that sticks in my mind is that the dinosaur was a Cynognathus, whose pet name was 'Nog'.

I read this in English in the late 70s in primary school. What I remember:  Two boys are somehow caught up in a time travel scenario. I think their father may have been the inventor of the time machine. Their initial journey takes them back about 200 million years. They meet an animal they identify as a cynogasaurus. At least, that's what my memory told me. Google tells me my memory may be playing tricks and they met a  instead. It was definitely cynogsomething. They somehow jump forward to caveman times with the cynogasaurus/cynognathus in tow. They befriend a similarly-aged kid who's a member of a particular tribe, possibly the leopard tribe. The leopard tribe are enemies of the zebra tribe. It's possible I've got both animals wrong. Each tribe has a sacred animal. Disputes between the tribes are settled by their sacred animals fighting. Somehow the kids have caused the death of "their" tribe's sacred animal so they offer the cynogawhatsit, which the cave-people call Nog, in its place. Nog wins the fight and stays on as the sacred animal when the kids leave.  Edit: I thought it may have been Lester Del Rey's "Tunnel Through Time", the subject of a few queries here over the years. The cover looks familiar and some details match. However two comments have verified that it doesn't feature the cynog* creature, sacred animals or the fight, which are what I recall about the book.


In Blender 2.8, I have applied a Background image of a sky-scape to the camera view and have hit render. However, the rendered image shows the cube and gray world background, not the cube and the sky background image. I have fiddled about with the settings but to no avail.  Any thoughts?    Edit 1  I believe this question to be different than the question, "Why won't my 'background' render" (of which this question was closed as a duplicate) because the image I have is a Background image. The question mentioned by Ketchup boy 2002 relates to an image applied to an empty, which apparently is not renderable.

I'm having this problem in Blender that it is only loading the text, I am very new to this and don't know why it is cutting out what is even in the camera view and making it black. If you could help me, I would really appreciate it.   It's only rendering 'Kenny Miller" and not the green/black back:  [


What happens if a Muggle-born wizard/witch receives a Hogwarts acceptance letter but their family is very poor and doesn't have money to buy the school things on the shopping list? Would Hogwarts give them some kind of financial help?

We know that you can't transfigure food, so you have to grow it or buy it. Ditto money.  I'm sure that aside from some medicinal plants Herbology Professor had there were no farmlands at Hogwarts. So they must have bought food (as well as potions ingredients for Snape etc...). And they needed to pay the teacher salaries.  Where did all that money come from according to canon?  Ministry funding?  Tuition?  Patent money on Dumbledore's inventions?  Philanthropic donations by Malfoys and co?  Other?


For decades I’ve been struggling to remember the title of a science fiction short story I read in some anthology as I was younger: by tone and subject it could be from the 50s or 60s. It must have been written prior to the late Seventies or early Eighties, as it is when I read it. I have no idea about the author: I used to think it was Frederik Pohl but after reading everything I could find written by him I had to give up. It has to be someone else. And it isn’t «The Racer» by Ib Melchior either, as I’ve read it recently in the hope it was the story I’m looking for but it wasn’t.  The story is set in the near future, in a dystopian America where car drivers hunt for pedestrians on the streets: probably there’s an ongoing open war between pedestrians and drivers; both groups go by a nickname, which in the Italian translation that I read back then sounds like «the Dismounted» (or maybe «Ground Pounders») and «the Motorized».  The one scene I remember is the opening, when the protagonist’s armored car runs over an old lady who’s crossing a town’s street: instead of running away, she grabs her gun and shoots the car. Later the protagonist is shown fastening bolts on the car to patch the holes left by those bullets.  Could you help me find this story?

I'm looking for the Author/Title of a dystopian short story I read in the 1970s, where traffickers claimed dead people's organs by stamping their foreheads. The beginning of the story describes an old lady getting run down by a car prowling the streets looking for victims and an organ trafficker stamping her forehead. The traffickers and the hit-and-run drivers worked together as I recall. I can't be sure but I believe the title had an X in it.  The story was written in English and I was living in Washington state within the USA when I read it. I'm pretty sure it was a short story but it's possible it was a book. Roughly forty years have passed since I read it and I don't recall much more than the opening and the general plot. I remember how creepy the beginning was when it described how unsuspecting pedestrians were stalked by cars and then run down when they tried to cross the street.


Can anyone help me change this script to use preg_split (recommended substitute by php.net) instead of split which is not used anymore. This function gets the file extension of any uploaded file in the variable $filename.  function findExtension ($filename) {    $filename = strtolower($filename) ;    $exts = split("[/\\.]", $filename) ; $n = count($exts)-1; $exts = $exts[$n]; return $exts; }

This is a question you can read everywhere on the web with various answers:  $ext = end(explode('.', $filename)); $ext = substr(strrchr($filename, '.'), 1); $ext = substr($filename, strrpos($filename, '.') + 1); $ext = preg_replace('/^.*\.([^.]+)$/D', '$1', $filename);  $exts = split("[/\\.]", $filename); $n    = count($exts)-1; $ext  = $exts[$n];   etc.  However, there is always "the best way" and it should be on Stack Overflow.


I know there are already questions which ask how to suppress chapter numbering:  and  In all examples, it's suggested to use chapter* instead of chapter in order to ignore chapter numbers. I want to be able to suppress chapter numbers from sections while still keeping the chapter numbers in order. Is this possible? MWE: \documentclass[12pt]{report}  \renewcommand\thesection{\arabic{section}}  \begin{document}  \chapter{Something} \section{First Section} \section{Second Section}  \chapter{Something Else} \section{Third Section} \section{Fourth Section}                                                                                \end{document}  This produces something like: Chapter 1: Something 1 First Section 2 Second Section  Chapter 2: Something Else 1 Third Section 2 Fourth Section  What I really want is for it to look like: Chapter 1: Something 1 First Section 2 Second Section  Chapter 2: Something Else 3 Third Section 4 Fourth Section  Since I need chapters to be numebered, I can't use chapter*. I can suppress the chapter number from showing up, but the section numbering restarts at the start of each chapter.  Note that there are a different number of sections for each chapter Yes, I could write these all by hand and do something like \chapter*{Chapter 1:\\ Something} in order to get what I want, but I'd prefer to do this programmatically if possible, hence why I'm asking on here.

Some document elements (e.g., figures in the book class) are numbered per chapter (figure 1.1, 1.2, 2.1, ...). How can I achieve continuous numbering (figure 1, 2, 3, ...)?  And vice versa: Some document elements (e.g., figures in the article class) are numbered continuously. How can I achieve per-section numbering?  \documentclass{book}% for "vice versa" variant, replace `book` with `article`  \begin{document}  \chapter{foo}% for "vice versa" variant, replace `\chapter` with `\section`  \begin{figure} \centering \rule{1cm}{1cm}% placeholder for graphic \caption{A figure} \end{figure}  \end{document}   Bonus question: Is it possible to adjust the numbering of the sectioning headings themselves? Can I, e.g., switch from per-chapter to continuous numbering of sections in the book class?


Every time I try to find the answer to this question I get redirected to different pages that ultimately do not end up answering my question. I have some understanding of Riemannian geometry but have no idea how to link it to the presence of a mass with .  Could someone provide an example, either linked or typed and submitted as answer, of a simple question with an object of defined mass?

I have have set my self a challenge to learn all the maths behind the Einstein field equation (EFE), and from reading it seems that the Metric tensor is the thing we are trying to find (from the 10 equations that forms the EFE). but since nearly all the terms in it are functions of this metric tensor, this seems very hard. What type of maths do we use to do this? (I have copied and pasted the EFE just for reference):  $$R_{\mu \nu}-\frac{1}{2}g_{\mu \nu}R+g_{\mu\nu}\Lambda=\frac{8 \pi G}{c^4}T_{\mu \nu}$$  Edit: Thanks for your comments. Just as I have no one else to ask, is this the equation that we try to solve:  $$\left(\frac{\partial}{\partial x^{\lambda}}\Gamma^{\lambda}_{\mu \nu}- \frac{\partial}{\partial x^{\nu}}\Gamma^{\lambda}_{\lambda \mu}+\Gamma^{\lambda}_{\lambda \rho}\Gamma^{\rho}_{\nu \mu}-\Gamma^{\lambda}_{\nu \rho}\Gamma^{\rho}_{\lambda \mu}\right)-\frac{1}{2}g_{\mu \nu}g^{ab}\left(\Gamma^c_{\enspace ab,c}-\Gamma^c_{\enspace ac,b}+\Gamma^d_{\enspace ab}\Gamma^c_{\enspace cd}-\Gamma^d_{\enspace ac}\Gamma^c_{\enspace bd} \right)+g_{\mu \nu}\Lambda=\frac{8 \pi G}{c^4}T_{\mu \nu}$$  with the $R_{μν}$ and $R$ terms expanded and where $g_{μν}$ and $T_{μν}$ are the μν th components from the related tensors? (a yes or no answer will be fine, thanks).


In this sentence     He went outside. He looked down the road.   What is meant by down? I don't think he's in higher place.

I am travelling geographically down the country from north of the city of London. Do I state "I am travelling down to London" or do I state "I am travelling up to London" in reference to its capital city status?


For $\int_{0}^{\infty}\frac{\sin^2(x)}{x^2}dx$. I considered using residue theorem. But since the function inside is holomorphic except for a removable singularity at the origin. So whatever contour I take, the integral would always be zero. Is there a way that we can get away with the situation and apply residue theorem to do the work?

I am trying to evaluate $$\int_{-\infty}^{\infty} \frac{\sin(x)^2}{x^2} dx $$ Would a contour work? I have tried using a contour but had no success. Thanks.  Edit: About 5 minutes after posting this question I suddenly realised how to solve it. Therefore, sorry about that. But thanks for all the answers anyways.


Can I update Ubuntu 15.04x32 to 15.04x64 or must it be a new/clean 64 bit install ?

I have a 32-bit system which runs on a 64-bit processor. How do I convert it to be all-64-bit, without re-installing? I have seen somewhere that it is doable as a result of .


Is the semicolon correct in this sentence?     Being taught and raised in a society; where art and design is an awful career option, I still manage myself pursuing my inner desire anyway.


Can someone explain how to use how V.S. whom? Please give an example for both, please!

I can never figure out whether I should use who and whom. Most people use who for both colloquially, but some people say this is not correct.  What’s the rule for using who and whom correctly?


I need to create something like the above in Ubuntu to connect my chromecast in my dorm room. It basically re-routes the wifi connection. This seems to be impossible in Ubuntu so far based on my research. Can you guide me regarding this topic:  Mobile hotspot wifi to wifi in Ubuntu...

I know how to create a hotspot when connected to a wired network, but when I am using internet from a WiFi connection, this disconnects the wireless connection the moment I activate the hotspot.  In Windows I can use , which enables me to share the internet connection from the same wireless adapter as I am creating an access point on. As you can read on the :     Access Point mode allows you to create a hotspot using the same Wi-Fi card that you are using to access the Internet.   How do I do this on Ubuntu?


I have asked this on CS subsite but since there was no reply yet and the question is also somewhat related to physics, I think it will be appropriate to post here as well.  Landauer's principle states the minimum possible amount of energy required to erase one bit of information is $k T \ln 2$   How is this formula found? In terms of energy and memory unit, what is the processing cost per bit for normal and reverse operations respectively?

Has anyone understood the ? What is the current status?  In specific, is there a theoretical derivation of the Landauer's Principle?(not the heuristic one based on Salizard's engine) How does one account for thermodynamic concepts applicable to situations involving measurement? What does it mean to reset the state of the apparatus why is free energy expended in the process?


In my Ubuntu 17.10 , Record My Desktop is not launching. How to launch and use?

After upgrading to Ubuntu 17.10 I noticed some of my screencasting applications are not working, for example screencasting tools like SimpleScreenRecorder and vokoscreen. ()  Also I noticed features like screenshot from GIMP is not working properly, producing blank screenshots (). Shutter too is producing glitchy screenshots ().  Screen-sharing option on Skype is also not working ().  The issue occurs sometimes on later Ubuntu releases too.  Why is this happening and how do I fix this?


My thesis compiles very well on my and others computers (no errors, no warnings, just some small badboxes around images).  On the other hand, when trying to compile it on arXiv, I get many errors. I was able to solve some of them by manually uploading  tikzlibrarycd.code.tex and tikzlibraryquotes.code.tex but now I do not understand how to get around this:  ! Package pgfkeys Error: I do not know the key '/handlers/first char syntax' an d I am going to ignore it. Perhaps you misspelled it.  See the pgfkeys package documentation for explanation. Type H <return> for immediate help. ...   l.38 \pgfkeys{/handlers/first char syntax=true}  ?  ! Emergency stop. ...   l.38 \pgfkeys{/handlers/first char syntax=true}  No pages of output. Transcript written on thesis.log.   (full report )  The only relevant discussion that I found while googling is , but obviously I cannot update anything on their server. So, I contacted them; they are aware of the many problems that they have by using an old distribution (2011), and they are trying to update it, but it takes a long time to maintain retro-compatibility. In the meanwhile, they said to         Include the complete tikz package for the version you're using locally within your source directory; or     Compile out your figures into images and embed them in your tex source using any figure inclusion command you choose (such as the \includegraphics directive from graphicx).       I would really like to avoid the second one unless there is an automated way to do it (I have a lot of tikz-cd figures, some of which are also inline). So, my question focus on the first "solution". What files do I need to upload exactly?

Since arXiv is still using outdated libraries, it doesn't have an up to date TikZ version, which is very inconvenient for me since I'm using TikZ 3.0. Consequently, I get lots of error messages when I submit my article like missing tikzlibraryquotes.code.tex or tikz-cd isn't working properly or doesn't accept certain arguments.  What do I do?


How is it that we can get two different answers for an integral depending on whether we apply an identity or not?   Typically, $$\int \sin x \cos x \ dx = \frac {\sin^2x}{2}+C~.$$  However if we apply the trigonometric identity $$\sin A \cos B = \frac12[\sin(A-B) + \sin(A+B)]~,$$ then the integral becomes $$\frac12 \int (\sin(0) + \sin(2x)) dx =\frac12 \int \sin(2x) dx = -\frac14 \cos(2x) $$  So we end up with a different answer. Have I made a mistake here, or is this just a property of integration/trigonometry?

$$ \int \sin \theta\cos \theta~d \theta= \int \frac {1} 2  \sin 2\theta~ d \theta=-\frac {1} 4  \cos 2\theta$$ But, if I let  $$ u=\sin \theta , \text{ then }du=\cos \theta~d\theta $$ Then $$ \int \sin \theta\cos \theta~d \theta= \int u ~ du =\frac { u^2 } 2 =\frac {1} 2 \sin^2 \theta $$ Since $$ \sin^2 \theta =\frac {1} 2 - \frac {1} 2 \cos 2\theta$$ The above can be written as $$ \int \sin \theta\cos \theta~d \theta= \frac {1} 2 \sin^2 \theta =\frac {1} 2 \left( \frac {1} 2 - \frac {1} 2 \cos 2\theta \right)=\frac {1} 4-\frac {1} 4 \cos 2\theta   $$ Why are the two results differ by the constant $1/4$? Thank you.


As a starting point I have started to use the fact, that every subset of $\mathbb{N}$ countable is. A $\subset \mathbb{N}$ is also a subset of $ \mathbb{N}$ and at this point I can't go forward. Or can I eventually use somehow Hilbert's Hotel theorem? I appreciate any help a lot.

Is there any way to solve this problem using the diagonalization method? I know there's the proof that uses $\mathcal{P}(\mathbb{N})$ = set of all finite subsets $\cup$ set of all infinite subsets, but I'm trying to solve it using the diagonalization method specifically. I was thinking that we can assume the two have the same cardinality and arrive at a contradiction, but I don't know how to get there. How can we show there has to be some infinite set in the set of all infinite subsets that cannot match 1-1 with a natural number?


This is a silly bug, but I am reporting it anyway.   Steps to reproduce: Click edit on your profile. Then, without changing any fields, click Update.  Result:     Oops! There was a problem updating your profile:         temporary error updating your profile -- please try again!      The error message is deceiving, I guess it is thrown because the Update command returned zero affected rows and the result of the update turned out false; just a guess.

At the moment, you get an error message when you try to update your profile fast.  Steps to reproduce   Go to your profile page in StackOverflow (or another SE site) Press "edit" to edit the profile  Immediately press "Save and Copy Profile To All Stack Exchange Accounts"     How this happened to me:  I wanted to push my SO info to other SE sites.  Possible fix:   Wait for the page to be ready before showing the button Display an appropriate message


Short question: Poor eyesight might have been a major impediment to survival and reproduction in early man (say, 100,000 years ago), but, with the advent of agriculture, major cultural changes, and modern medicine, one might imagine that genes for poor eyesight would persist more easily. Is that true? Has selection on eyesight been relaxed, or changed significantly, in modern humans? If so, when? Do we know what might explain relaxed selection? If there are any genes associated with, for example, myopia, has their population frequency increased through human history, or has it remained constant? This  discusses genetic changes 8 to 4 thousand years ago related to skin color, amino acid absorption, and eventually milk digestion, but it does not mention eyesight. Background on why I find the question interesting: A friend of mine speculated that human eyesight is worse today than it was only a few centuries ago, due to the invention and widespread adoption of glasses: a person with poor eyesight genes will now survive and have children, whereas in 1600 they might have died without reproducing. I'm skeptical: first, glasses became widespread only a few generations ago; second, blurry vision plausibly has little effect on evolutionary fitness. I see no reason why someone with slight myopia would on average have significantly fewer offspring than someone with 20/20 vision, even in a tribe of hunter-gatherers. A short-sighted person could specialize in making hand-axes, for example, and trade them for food -- so I find it plausible that eyesight-related allele frequencies have not changed much over time. However, I recently heard someone on the radio speculate that eyesight might have worsened significantly a few thousand years ago with the invention of agriculture; the story is that above-average eyesight is a major fitness advantage for a hunter, but not for a farmer.  What does the evidence say? Side note: I realize that eyesight is affected by more than just genes -- for example, age as well as time spent reading books probably both affect eyesight. That's not what this question is about -- I'm interested in genetic selection. Edit:  this question is indeed similar to , but it isn't identical.  That question asks why poor eyesight can persist at all, while mine asks whether evolutionary pressures have changed over time.  In particular, do we know of any genes associated with, say, myopia?  Do we know whether their allele frequencies have changed over human history?

Why do many humans have bad eyesight, such as near-sightedness, which hampers performance in a wide variety of tasks? Shouldn't there be evolutionary pressure towards better eyesight?


Is there a way to get the brackets of the matrices to ignore the spacing that I set up for the paper? There is just a little too much space at the top of each matrix when using \doublespacing. I would like to keep the double spacing everywhere else as it makes the text nice and readable.

I am having some difficulty getting this to display properly.      \begin{equation} {\bf H} = -{\bf \mu} \cdot {\bf B} = - \gamma B_o {\bf S}_z = -\frac{\gamma B_o\hbar}{2}  \begin{bmatrix} 1&0\\0&-1 \end{bmatrix}. \end{equation}   Which appears as,    I would like the matrix height to be consistant with the rest of the equation.


I am trying a script to get the no. of days between now and a future date. I intend to run this script on AIX and linux from a common location. Now, I am using modules DateTime for linux and Date::Calc for AIX. For some reason, each doesn't work in the other OS. So, I am writing an if statement and checking for OS. If it's AIX, I am using Date::Calc or I am using DateTime. Here's my code  #!/usr/bin/perl use strict; use warnings; my $OS = `uname`; if ( $OS=~/AIX/i ) { use Date::Calc qw(Delta_Days); my @today = (localtime)[5,4,3]; $today[0] += 1900; $today[1]++; my @end = (2015, 11, 12); my $expiry = Delta_Days(@today, @end); print "$expiry\n"; } else { require DateTime; my $exp = DateTime->new( year => 2015, month => 11, day => 12 ); my $now = DateTime->now; my $diff = $now->delta_days($exp); my $expiry = $diff->delta_days; print $expiry,"\n";}   This scripts appears to be working fine in AIX when i use use Date::Calc in the if loop. But when i run this script in linux, it gives me an error saying can't locate Date/Calc pm in @INC. When i change it to require Date::Calc in the if loop, it gives me an error can't locate Date::Calc pm in @INC on the AIX server. And it's vice versa with the else loop for Linux OS too.  How can i achieve common ground? For some reason, i can't install these modules in one server or the other.

I get this error:  Can't locate Foo.pm in @INC  Is there an easier way to install it than downloading, untarring, making, etc?


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

Given the following code (that doesn't work):  while True:     #snip: print out current state     while True:         ok = get_input("Is this ok? (y/n)")         if ok.lower() == "y": break 2 #this doesn't work :(         if ok.lower() == "n": break     #do more processing with menus and stuff   Is there a way to make this work? Or do I have do one check to break out of the input loop, then another, more limited, check in the outside loop to break out all together if the user is satisfied?


Is there a way to call an Apex method with input parameters from Visual Force?  For example, if I have this Apex method:  public static String formatAddress(String city, String state, String country){     String formatted = city;     if(!String.isEmpty(city)){         formatted += ", " + city;     }      if(country != "US"){         formatted += ", " + country;     }      return formatted; }   And I have this VF page:  <apex:repeat value="{!fooList}" var="foo">     <apex:outputText value="{!formatAddress(foo.city, foo.state, foo.country)}" /> </apex:repeat>   I know I can put the city/state/country values up as page params, and pull them in Apex from the page params map, or put them in member variables on the controller, but I was looking for a way to do this without having to do any temporary storing of the data.  Thanks    edit -  sorry I couldn't reply to the comments below, but to provide more clarification:  @Rao - I've never used js remoting before, but quick glance at your link it looked like it will do ajax calls and update the dom later on.  I don't think this will work in my situation since the info I'm trying to print is not dynamic and will not need to be updated via ajax.  also, since I'm looping through a list, I don't think it would be a good idea to do ajax calls within a loop  @IllusiveBrian - I can definitely store the formatted addresses in a map, but I'm trying to keep my view state low.  this is definitely a viable solution though  @sfdcfox - I was going to do this but I thought I'd end up storing the data in memory twice, one for the actual "foo", and another for the "fooWrapper", which isn't bad but I was just looking for a leaner solution

I have this Visualforce code snippet in a page:  <apex:outputLink value="javascript:if (window.confirm('Are you sure?')) DeleteQuoteLineItem('{!LineItem.QuoteLineItem.Id}');">     Del </apex:outputLink>  <apex:actionFunction action="{!DeleteQuoteLineItem}" name="DeleteQuoteLineItem" reRender="content">     <apex:param value="test"/> </apex:actionFunction>   The two methods I'm using for testing are:  public void DeleteQuoteLineItem(String RecordID) {     System.debug('method with a paramater');     System.debug(RecordID); }  public void DeleteQuoteLineItem() {     System.debug('method without a parameter'); }   Everytime I click on the link to execute the apex:actionFunction, it's calling the DeleteQuoteLineItem() method without any parameter. I looked online and it seems like I need to create a class attribute and use assignTo= in my apex:param to populate it accordingly.  Is it possible to prevent this behavior and use standard method parameters, so I don't have to create class attributes? I want to work on a clean and optimized codebase, preventing unnecessary variable scope (so no class attribute when it's not required) and improve code re-usability by staying context agnostic.  Thanks


Suppose you had a rigid steel beam of steel one light year in length. Would it not be a simple matter to rotate the beam only a few rad/s to make the end of the beam faster than light? Disregarding the enormous torque you would need (although if the beam was a single rigid carbon nanotube, that might make the job easier), if you rotated the beam at 1 rad/s, then the end would move at 9.46*10^15 m/s, well over the speed of light. Is there some complicated quantum effect or relativistic thing going on to prevent this?

Imagine a bar   spinning like a helicopter propeller,  At $\omega$ rad/s because the extremes of the bar goes at speed  $$V = \omega * r$$  then we can reach near $c$ (speed of light) applying some finite amount of energy just doing   $$\omega = V / r$$  The bar should be long, low density, strong to minimize the amount of energy needed  For example a $2000\,\mathrm{m}$ bar  $$\omega = 300 000 \frac{\mathrm{rad}}{\mathrm{s}} = 2864789\,\mathrm{rpm}$$  (a dental drill can commonly rotate at $400000\,\mathrm{rpm}$)  $V$ (with dental drill) = 14% of speed of light.  Then I say this experiment can be really made and bar extremes could approach $c$.  What do you say?   EDIT:  Our planet is orbiting at sun and it's orbiting milky way, and who knows what else, then any Earth point have a speed of 500 km/s or more agains CMB.  I wonder if we are orbiting something at that speed then there would be detectable relativist effect in different direction of measurements, simply extending a long bar or any directional mass in different galactic directions we should measure mass change due to relativity, simply because $V = \omega * r$  What do you think?


Ubuntu behave sometimes different in Virtualbox client then standalone. I want, in terminal, to detect if Ubuntu is running in Virtualbox client. Even if Virtualbox Guest additions are not installed. Which happens sometimes. Is that possible? If so how?  My search direction was something similar as VBox guest addition. Guest additional does communicate with Virtualbox host. So maybe a signal can be capture. But this direction gets to complicated. I presume there must be a difference between Ubuntu running standalone, and Ubuntu in VM client what can be captured.  title seems to cover the topic, but the content, in my view, not. But I have no idea what and even how to search.

Is there a command or tool that can be used to determine whether Ubuntu is running as a guest within a virtualization program such as VirtualBox or Qemu or whether it is running on the bare metal?


I have a time series data and I want to calculate p90 percentile.  Because there's a huge amount of data I need to split my calculations somehow.  I was thinking that maybe could calculate the percentile of every day data and then , using that, calculate every month, and then using months, the whole year but  ¿Is this calculation method correct? I think is not, in fact to solve the problem exactly I should use all the data to calculate the year percentile, and every time I get a new data I should recalculate  ¿Do you know how to solve/approximate this problem?  This problem is different from continuous P2 approach because I'm not only interested in the final percentile I want the daily, the monthly, trimestral an anual. For example, if I use P2, when I get the January percentile and continue the calculation with February it is not possible to get the isolated February data isn't? I will get the January-February. It will be great to work somehow with monthly percentiles (for example) to get the annual one.

I want to estimate the quantile of some data. The data are so huge that they can not be accommodated in the memory. And data are not static, new data keep coming. Does anyone know any algorithm to monitor the quantiles of the data observed so far with very limited memory and computation? I find  useful, but it does not work very well for my data, which are extremely heavy-tailed distributed.


Every time I've had the opportunity to meet a moviestar/rockstar who I idolize and imitate in every way (and call it influence), I always flub it up. Without fail. This is because I get so nervous and I want so badly to strike up a rivetting conversation that I lose my ability to talk, or even think. But still, somehow, I muster up the courage to approach my personal epitome of awesomeness, trusting my social instincts will kick in by the time I actually try talking to him. But the closer I appproach, the blanker my mind grows. Eventually I reach a proximity that forces him to acknowledge my intention to speak to him; and so he makes eye contact with me, waiting. I can't just tell him how much I love his music, being just like every other annoying fan. But still... that'd be better than what I was actually being like: some weirdo who walks up and stares with mouth agape and eyes wide, as if staring into the ark of the covenant, manifested in the form of Cedric Bixler the vocalist of 2 revolutionary post-punk/screamo bands as well as half the reason why hipsters wear skinny jeans. It was the most painfully awkward 30 seconds of my life and it took years of psycho therapy to finally heal from the trauma caused by my Oscar winning portrayal of Captain Awkward. But what I'm really needing to know ASAP would be the perfect word and/or phrase to describe that feeling that left me speechless? It was kind of like an amalgamation of being nervous and feeling privileged to be in the presence of such an amazing human being. It's similar to words like intimidated, overhelmed, daunting, honored, umworthy, nerve wracking, mind-blowing, formidable, impressed, flustered, veneration, revery, dazed, bewildered, dumb-struck, and of course, nervous or privileged.  But I feel like there's yet another pseudosynonym that embodies the precise meaning of this word that is lodged within my subconscious state of awareness, beyond the reach of my self-awareness. Whatever that perfectly descriptive adjective is, I'll know immediately upon hearing it. It will possess all the expected connotations, implications, and inspirations that are conjured when I unsuccessfully attempt to recall this ellusive adjective (presumably. It may turn out to be any variety probably combination of words, but used in such a way to describe a complex emotional state) The reason I'm asking is because I have, by a stroke of luck, become engaged in an online conversation with a member of the royal family of a very rich nation. (it is a long term convo: days or weeks btwn replies) noooo it is not the Prince of Nigeria. I was skeptical at first but he seems to only be interested in the human connection and has said nothing suspicious. But I was trying to be appropriately humble as I suspect civilians are expected to be towards royalty in his culture, and I was trying to say that it made me nervous but immensely grateful at the same time to be in conversation with such a person as his lordship. But I juSt could not find the exact right word. Help me to ingratiate this genuinely regal fellow who may possibly become another one of my many friends in high places. Thank you The exact wording of the sentence that I am planning to use this yet to be determined adjective is as follows: "I must admit it is rather  __________ to be conversing with royalty." I might say "a bit" instead of "rather." If I can not find my perfect descriptor, I will just be forced to describe the 2 juxtaposed emotions separately. I've already written a rough draft as a back up just in case the unimaginable happens and it turns out I'm hunting a word that doesn't exist. Here it is: "I must admi it is a bit intimidating to be conversing with royalty. However, it is also a great honor. I feel very fortunate that..." I think using "a bit" makes it less formal. And I don't wAnt to address him as MY prince, but rather A Prince that I happen to be friends with. So I am trying to maintain a careful balance between formal and casual types of parlance

Suppose you met a famous person, and you were shy and anxious and almost overwhelmed by them.   Is there a word for describing that? Similar to getting stage fright, or "choking", except in this case for a person?     When he said hello to me, I couldn't respond. I (was) __________.


I live in Asia which means I am surrounded by a lot of myths and superstitions. I have heard in here that if a man eats food that women eat while they have cravings during pregnancy (Sour/Acidic Food), the man can get himself something that is called ED or Erectile Dysfunction. Is it true by any means? is it even near to the truth? I like to eat sour food such as Tamarind, Pani Puri etc, so it would be very helpful for a person like me to get the answer to this questions.

Erection problems happen mostly with men.  What causes it and what is happening in the body?


I need to read a single row from SQL Server with a stored procedure as a standalone call. Let's say there is a BL.GetRecord(int id) for it. I need to call this method from inside another method. Do I need a transaction scope for reading it? Here are possible GetRecord(int id) bodies: using(var ts = new TransactionScope()) {     return prov.GetRecord(id); }  or using(var ts = new TransactionScope()) {     var record = prov.GetRecord(id);     ts.Complete();     return record; }  OR just return prov.GetRecord(id);  Method for 2. will have its own TransactionScope with Complete(). The purpose is to read 'clean' records. Do I need to Complete() (is it = COMMIT?) on reading as we aren't saving anything? All these operate on a single table. I need something like, 1 user updates a record (which also does a reading first). I think it's better if second user should read updated value by waiting rather than reading whatever is currently if the first is going to update it in few milliseconds anyway.

I've been reading that some devs/dbas recommend using transactions in all database calls, even read-only calls. While I understand inserting/updating within a transaction what is the benefit of reading within a transaction?


Of the set $A=${$1,2,...,100$}, we will choose $51$ numbers. Prove that, among the $51$ chosen numbers, there are two such that one is multiple of the other  My notes:  1) There are $25$ prime numbers between $1$ and $100$ ;  2) There are $26$ odd and non-prime numbers between $1$ and $100$  3) There are $49$ even and non-prime numbers between $1$ and $100$  4) $B=${$51,52,...,100$} do not have multiples on the set $A$, but if we choose a number in $A-B$ we can find a multiple of this number in $B$  I couldn't find a good way to organize the problem. Sometimes I think I am just getting a particular solution, I mean, I am choosing particular numbers to form my set of $51$ numbers. I thought the better situation is to choose all the primes and apply the pigeon hole principle to the rest of the chosen numbers.  Thanks for your help!

Given $51$ integers $a_1, a_2, \ldots, a_{51}$ satisfying $1 \leq a_i \leq 100$. Prove that there exist $i$ and $j$ such that $a_i \mid a_j$.   I'm a little unsure how to approach this problem. Thanks for any help.


I was studying and I saw a sentence that went like this: "Have I done something wrong?"  I was wondering, instead of writing "something", shouldn´t I write "anything", since the sentence is a question?  Thank you people.

Is there any difference between "Is there something wrong?" and "Is there anything wrong?"? Also, you would say "He would like something to drink" but "Would you like anything to drink?", right? I'd appreciate if any one could explain the usage of "something" and "anything".


import java.util.Scanner;  public class NewClass {     public static void main(String[] args){          Scanner scanner = new Scanner(System.in);          System.out.println("Enter your name");         String name = scanner.nextLine();         System.out.println("Is "+ name + " really your name?");         String answer1 = scanner.nextLine();         if (answer1 == "yes"){         System.out.println("Alright ");         }else  {System.out.println("Liar!");     }     } }   It outputs Liar! even though I typed yes, so that answer1 equals yes. Why?

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I am an undergraduate studying mathematics.  I am currently in the process of writing my first paper for submission to an academic journal.    While learning about the process of submitting a paper it has become apparent to me that most journals require the paper to be formatted using LaTeX.  So... I am now trying to learn how to use it.    I do have a little experience with LaTeX because I have used Math Stack Exchange.    That being said, I just feel very overwhelmed.    So I am hoping you guys could give me a little direction and answer a few questions.  I downloaded the ProText distribution yesterday and installed Texstudio and MiKTeX, and then it also came with Sumatra.    So Textstudio is what you would call a LaTex editor right?  Then what exactly is MiKTeX and Sumatra?  I don't see an .exe file for MiKTeX, is it an application?  One of the journals I am thinking of submitting my paper to is the Fibonacci Quarterly.  They provide a style file that gives you a template for how the paper should look.  So I guess that should make it much easier for me.  I should be able to just copy and paste the code right into TeXstudio correct?  And then just insert my text and equations in the appropriate areas.  So is the ProText distribution a good distribution to be using along with TeXstudio, MiKTeX, and Sumatra?  Am I on the right track?    Is there anything else I should know?  Thanks in advance for the help.

I am a noob when it comes to TeX, however, I do use LaTeX for typing mathematical and engineering formulas, etc.   Recently I have taken it upon myself to try and write some technical papers to try and get published, however I do not know what... 'type'(?) of TeX software to use best, so that I can hit the ground running with it.   If you look , this can give you context as to the forums that I would be publishing to, (IEEE), and they even have some templates there. However I cam getting easily confused between BibTex, TeX, etc, and how they all 'fit' together, in my goal of writing a paper. I would like guidance on this.   What might be the easiest 'headache less' software to start writing a paper in TeX for a noob such as myself? Am I on the right track?  Thanks!


From The Two Towers, Book 3, Chapter 2, The Riders of Rohan:  Suddenly Gimli looked up, and there just on the edge of the firelight stood an old bent man, leaning on a staff, and wrapped in a great cloak; his wide-brimmed hat was pulled over his eyes...[Aragorn] strode forward, but the old man was gone. There was no trace of him to be found near at hand, and they did not dare to wander far.  Later on we have (Chapter 5, The White Rider):  'Wait a minute!' cried Gimli. 'There is another thing that I should like to know first. Was it you, Gandalf, or Saruman that we saw last night?' 'You certainly did not see me,' answered Gandalf, 'therefore I must guess that you saw Saruman. Evidently we look so much alike that your desire to make an incurable dent in my hat must be excused.'  But if it was indeed Saruman, why did he simply observe the three companions and then disappear? Gandalf says to Gimli in Chapter 10, The Voice of Saruman:  'I will come,' said Gimli. 'I wish to see him and learn if he really looks like you.' 'And how will you learn that, Master Dwarf?' said Gandalf. 'Saruman could look like me in your eyes, if it suited his purpose with you.'  So why did not Saruman question the three if it really was him? At that point in the story he was surely in need of knowledge of the orc host and their captives. Throughout the book Frodo has visions of things happening (or about to, or have done), so could this have instead been a vision of Gandalf they saw, as a premonition of his return? Is there anything explaining or shedding more light on this?

When Aragorn, Gimli and Legolas find the dead bodies of the orcs that they had pursued to the edge of Fangorn, they see an old man robed in white:     Suddenly Gimli looked up, and there just on the edge of the fire-light   stood an old bent man, leaning on a staff, and wrapped in a great   cloak; his wide-brimmed hat was pulled down over his eyes. Gimli   sprang up, too amazed for the moment to cry out, thought at once the   thought flashed into his mind that Saruman had caught them   It is implied in the book (though never verified AFAIK) that this was Saruman, particularly since Gandalf confirms that it was not him     "You certainly did not see me," answered Gandalf, "therefore I must   guess that you saw Saruman."   So if it was indeed Saruman, why would he travel all the way to Fangorn alone? Orthanc to Fangorn is not a short journey and he also had the Palantir at his disposal so what is the purpose of his being there (assuming that it is indeed Saruman).


Help plz with this problem Let a $3 × 3$ matrix $A$ be such that for any column vector $v ∈ \Bbb R^3$ the vectors $Av$ and $v$ are orthogonal. Prove that $A^t + A = 0$, where $A^t$ is the transpose matrix. I've read all about orthogonal matrices but not have yet results.

Let A be $3\times3$ matrix such that $Au$ and $u$ are orthogonal for each column vector $u\in\Bbb R^3$. Prove that $A^T=-A$. I thought  $(A+A^T)u\cdot u=0$ but it doesn't imply $A^T=-A$, so I'm stuck... Edit : Does this property also hold when we replace 3 by an arbitrary $n$?


I am trying to understand what it means to have an extension that is an algebraic closure of the base field. I'm looking for someone who can help conceptually.  I understand how $C/R$ looks. The basis of the extension is $\{1,i\}$, so the degree must be $2$. Moreover, the extension is Galois, and $\mathrm{Gal}(C/R)$ is isomorphic to C2.   However, I am unclear about how this works when we are working with finite fields. If we let $K$ be the algebraic closure of $F_p$, then I know $K$ as equivalent to $F_p$ adjoin every single root of every single polynomial in $F_p[X]$. I know, given $\alpha \in K$ implies $\alpha$ is the root of some polynomial, $p(x)$ of deg $n$ in $F_p[X] \Rightarrow [F_p(\alpha):F_p]=n$, and $[K/F_p] = |N|$, as was kindly pointed out below.  This extension is Galois (finite fields are always separable, and $K$ is clearly the splitting field of each xˆ(p)ˆn - 1, for every $n \in N$). So $\mathrm{Gal} (K/F_p) = |N|$. I want to clarify: what does $\mathrm{Gal} (K/F_p)$ actually look like? Am I correct to write $\mathrm{Gal} (K/F_p) = \{\sigma: a \mapsto aˆpˆn | n \in N\}$ ?

$F$ is an extension field of a field $K$. Let $F$  be an algebraic closure of $\mathbb{Z}_p $ ($p$ prime). Show that $(i)$ $F$ is algebraic Galois over $\mathbb{Z}_p$ $(ii)$  The map $\alpha:F\rightarrow F$ given by $u\mapsto u^p$ is a nonidentiy $\mathbb{Z}_p$-automorphism of $F$. $(iii)$  The subgroup $H=\langle \alpha \rangle$ is a proper subgroup of Aut$(F/\mathbb{Z}_p)$ where the fixed field is $\mathbb{Z}_p$, which is also the fixed field of Aut$(F/\mathbb{Z}_p)$ by $(i).$    So, here is my attempt for (i). Let  $S \subset \mathbb{Z}_p[x])$ of monic polynomials of the form $x^{p^n}-x$.  Then for all $f\in S$, gcd$(f,f^{\prime})=1$(i.e, the polynomials are separble) and $F=\mathbb{Z}_p(a\in F:f(a)=0)$. So $(F/\mathbb{Z}_p)$ is Galois. I'd be glad if I could get assistance for (ii) and (iii) as well.  Thanks.  ADDED:  Attempt at (iii).   but I know that since $F/\mathbb{Z}_p$ is a finite Galois extension, its fixed field is $\mathbb{Z}_p$ hints...  The field $\mathbb{Z}_p$ must be contained in $F$. For $a\in \mathbb{Z}_p$, $\alpha(a)=a^p=a$. Thus the polynomial $x^p-x$ has $p$ zeros in $F$, namely, the elements of $\mathbb{Z}_p$. But the elements fixed under $\alpha$ are precisely the zeros in $F$ of $x^p-x$. Hence the fixed field of $\alpha$ is $\mathbb{Z}_p$ which is also the fixed field of Aut$(F/\mathbb{Z}_p)$. Left to show that $H$ is a proper subgroup... If it helps I know that the order of $\langle \alpha \rangle $ is $n$...


Today I came accross to . And after some study, I have derived the following solution. Request to the experts, kindly let me know if I have made any mistakes.  The question is: if $M, N$ be $n$ square matrices such that tr$(M^k)=$ tr$(N^k)$ for all $k=1, 2, \cdots, n$ then prove that $M$ and $N$ will have same eigenvalues. What about this one?  We know that if $\psi_A(x)=x^n+c_{n-1}x^{n-1}+c_{n-2}x^{n-2}+\cdots+c_1x+(-1)^n|A|I_n$ be characteristic polynomial of $A$, then the coefficients are given by  $$c_{n-m}=\frac{(-1)^m}{m}\left|                               \begin{array}{ccccc}                                 t_1 & m-1 & 0 & \cdots &  0 \\                                 t_2 & t_1 & m-2 & \cdots &  0  \\                                 \vdots  & \vdots &   &   &  \vdots \\                                 t_{m-1} & t_{m-2} & t_2 & t_1 & 1 \\                                 t_m & t_{m-1} & t_3 & t_2 & t_1 \\                               \end{array}                             \right|$$  where $t_r:=$ tr$(A^r)$.  Assume that $\psi_{M}(x)=x^n+a_{n-1}x^{n-1}+a_{n-2}x^{n-2}+\cdots+a_1x+(-1)^n|M|I_n$ and $\psi_N(x)=x^n+b_{n-1}x^{n-1}+b_{n-2}x^{n-2}+\cdots+b_1x+(-1)^n|N|I_n$. Then $$a_r=b_r$$ (by using tr$(M^k)=$ tr$(N^k)$ and the above determinant).   Hence $\psi_M(x)=\psi_N(x)$ which means $M$ and $N$ will have same eigenvalues.

Let $M,N$ be $n \times n$ square matrices over an algebraically closed field with the properties that the trace of both matrices coincides along with all powers of the matrix. More specifically, suppose that $\mathrm{Tr}(M^k) = \mathrm{Tr}(N^k)$ for all $1\leq k \leq n$. The following questions about eigenvalues is then natural and I was thinking it would be an application of Cayley-Hamilton but I am having trouble writing out a proof.  How do we show that $M$ and $N$ have the same eigenvalues?  Added (because this question is now target of many duplicates, it should state its hypotheses properly). Assume that all the mentioned values of $k$ are nonzero in the field considered; in other words either the field is of characteristic $0$, or else its prime characteristic $p$ satisfies $p>n$.


This is exactly what it says  For Realtek RTL8101E/8102E PCI-E Ethernet cable controller v1.08 (080408)  PXE-E61: Media test failure, check cable  PXE-M0F: Exiting PXE ROM.  No bootable device -- insert boot disk and press any key  Here is another message i get  Windows has encountered a problem communicating with a device connected to your computer.  This error can be caused by unplugging a removable storage device such as an external USB drive while the device is in use or by faulty hardware such as a hard drive or CD-ROM drive that is failing. Make sure any removable storage is properly connected and then restart your computer.  Status: OxcOOOOe9 Info: An unexpected I/O error has occured.  I dont understand what happened. I was on the internet and then my computer was turned on(This makes me lose wifi) and i tried going to a different URL then my laptop went to this error screen.  If you have any advice please tell me. Many thanks, Joseph Milo

My computer no longer boots Windows or the installed operating system. Instead, I may get this error:  PXE-E61: Media test failure, check cable -or- Check cable connection!  PXE-M0F: Exiting PXE ROM.   and/or one of the following messages or similar:  Operating System not found  No boot device available- No bootable devices--strike F1 to retry boot, F2 for setup utility  No bootable device -- insert boot disk and press any key  No Boot Device Found. Press any key to reboot the machine  Default Boot Device Missing or Boot Failed  Reboot and Select proper Boot device or Insert Boot Media in selected Boot device   What does this mean and what can I do?     This question comes up often and the answers are usually the same. This post is meant to provide a definitive, canonical answer for this problem. Feel free to edit the answer to add additional details.


I made a superflat world and typed /tp ~ ~ ~-10000 or something similar a few times to have a separate area to build a house on, but i accidentally died and lost my house. What can I do to find it?  I have McEdit if that helps.

I wandered too far to go look for sheep and now I'm on a completely different island.  How do I find my way back to my house?


I have the following java code to read a CSV file and store the values in an ArrayList().          try {         File file =new File("Data.csv");         BufferedReader br=new BufferedReader(new FileReader(file));         while(br.readLine() != null){             String input=br.readLine();             input=input.replace('"', '\0');             datam.add(input.split(",|\\s|;"));         }     } catch (FileNotFoundException e) {         // TODO Auto-generated catch block         System.out.println("Exception");         e.printStackTrace();     }   But i am getting the exception at the following lines  String input=br.readLine();             input=input.replace('"', '\0');             datam.add(input.split(",|\\s|;"));   I am finding no error in the code. I am using the Arraylist for populating a JTable. The exception message is the following:  java.lang.NullPointerException at com.cs319.MyTable.<init>(Lab2Swing.java:366) at com.cs319.Lab2Swing.createPanel3(Lab2Swing.java:190) at com.cs319.Lab2Swing.<init>(Lab2Swing.java:103) at com.cs319.Lab2Swing$1.run(Lab2Swing.java:75) at java.awt.event.InvocationEvent.dispatch(Unknown Source) at java.awt.EventQueue.dispatchEventImpl(Unknown Source) at java.awt.EventQueue.access$400(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source)

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


Why does running the script not show the file in the output folder correctly? The script was run in PyQGIS 3.10. Below find the script used  import processing import os  path ='DESCUELAJORNADA_CIENT_ALLclip_L8' output = DESCUELAJORNADA_CIENT_ALLOUTPUT  bandList = [band for band in os.listdir(path) if band[-4:]=='.TIF']  input = [os.path.join(path,band)for band in bandList]  def pca_grass(input,output)     processing.runAndLoadResults(grass7i.pca,     {'-f': False,      'n': False,      'GRASS_REGION_CELLSIZE_PARAMETER':0,      'GRASS_REGION_PARAMETER':None,      'input': input,      'output':output,      'percent':99,      'rescale':[0,400]})     outList=[band for band in os.listdir(output) if band[-4:]=='.TIF']     new_output = [ os.path.join(output,band) for band in outList ]     for band in new_output         iface.addRasterLayer(band,band) pca_grass(input,output)

It runs without problem but I don't get the expected pca bands, my output folder is empty, I don't know what to test. path ='C/Users/Manuel/Documents/INPUT' output='C/Users/Manuel/Documents/OUTPUT'  bandList = [band for band in              os.listdir(path) if              band[-4:]=='.TIF'] input = [os.path.join(path,band)for band in bandList]  def PCA_GRASS(input,output):     processing.runAndLoadResults("grass7:i.pca",\     {'-f': False,'n':False,\     'GRASS_REGION_CELLSIZE_PARAMETER' : 0,\     'GRASS_REGION_PARAMETER' : None,\     'input': input,\     'output': output,\     'percent': 99,\     'rescale':[0,400]})   outList=[band for band in os.listdir(output) if                        band[-4]=='.tif']   new_output = [ os.path.join(output,band) for band in                                 outList ]   for band in new_output:            iface.addRasterLayer(band,band)  PCA_GRASS(input,output)  When I run the script I open log message and an ogr error appears (can't open _ address of input files_) I don't understand why () I am working with Landsat 8 band and I have tried other images to see if the code works.  Using processing whit grass I have performed other tasks satisfactorily but this one is causing me many problems.  The images are not the problem when I perform the operation (i.pca) from the processing toolbox, it is done without problem. I have also changed the syntax with which I enter the input data but nothing.


file WAV or MP3,  i need to create a SET value to calculation how long a sound file.  like:  echo %VideoTime% Minutes. Pause > nul   OUTPUT:  2.32 Minutes.  i know it is a hard one to make this.  or not idk but i know; this is very objectionable request.  where i need to use this?  i am trying to make a Music Video Player program with CMD.  crazy? yep it is. all script done. but one think is not.  when the music end, this is not refreshing music or not playing next music.  help here please*

How can I get video duration in seconds?   What I've tried:  ffmpeg -i file.flv 2>&1 | grep "Duration"   Duration: 00:39:43.08, start: 0.040000, bitrate: 386 kb/s   mediainfo file.flv | grep Duration Duration : 39mn 43s   This what close, but it's not so accurate, 2383 is 39.71 minutes   ffmpeg -i file.flv 2>&1 | grep "Duration"| cut -d ' ' -f 4 | sed s/,// | sed 's@\..*@@g' | awk '{ split($1, A, ":"); split(A[3], B, "."); print 3600*A[1] + 60*A[2] + B[1] }' 2383


I was able to mark questions as favourite in Stack Exchange app for android, but now could not find how to get list of it to revisit them.

I haven't been able to find my favorite questions in the official Stack Exchange Android app.  Looking at my accounts page gives nothing on them.


I'm trying to run Firefox in Headless mode in a CentOS Linux release 7.0.1406 (Core)  I have already have firefox-45.3.0-1.el7.centos.x86_64 installed.  I have run the following commands for the configurations:  // install Xvfb package yum install xorg-x11-server-Xvfb // add screen resolution Xvfb :99 -screen 0 1024x768x24 & // add Display export DISPLAY=:99 // run firefox firefox   After running the firefox,  have encountered this error: "Xlib: extension "RANDR" missing on display ":99"."  I have tried to add this extension using:  Xvfb :99 -screen 0 1024x768x24 +extension RANDR &    But stil, the same error persist when I attempt to run the firefox again.  How can I add RANDR in Xvfb when running in firefox?  Thanks for the response in advance.

My system:  $lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 14.04.3 LTS Release:        14.04 Codename:       trusty   Xvfb:  $ dpkg -s xvfb Package: xvfb Status: install ok installed Priority: optional Section: x11 Installed-Size: 2140 Maintainer: Ubuntu X-SWAT <ubuntu-x@lists.ubuntu.com> Architecture: amd64 Multi-Arch: foreign Source: xorg-server Version: 2:1.15.1-0ubuntu2.7 Provides: xserver   Current problem:  Xvfb do not support RANDR extension, even if I add the flag:  +extension RANDR   If I run xdpyinfo, RANDR is not on the list. It's a missing feature or a bug. I found a reference here with a patch:   And looks like that in other distros like debian, there is already a testing build of Xvfb with support:   I am trying to run a program throught Xvfb, and it returns the following error:  Xlib:  extension "RANDR" missing on display ":99".   The program works if I run it via ssh/command line. The problem appears to be the the lack of support for "RANDR" in xvfb.  My question is: what is the easiest way to get xvfb with "RANDR" support in my system?


I tried Pinta image editor but I can't make cut to images or copy small peices, I want a program like Paint program on windows

I want something similar to "preview" in macs.  For example: I want an image editor that ONLY does simple adjustments like increase/decrease contrast, saturation, exposure, color tinting.... rotate, flip vertically, flip horizontally, make black and white, change size or format, crop.  THATS IT.  I know gimp can do all those things but its a bit overkill.  I just want to right click an image, open it with this magical program i just described, do a few quick adjustments, and then save and exit.  Nothing really fancy.  Anyone know of anything like this?  Btw I am using ubuntu 12.04 :) It rocks and I am glad I switched from mac, i just need to replace this one piece of software.


I have looked all around but couldn't find the answer to a very simply question:  I would like to log into machine C from machine A, passing through machine B. However, B is slow, so I would also like my connection to C to be compressed/decompressed at C, tunneled through B, and decompressed/compressed at A.   What ssh command should I execute (in machine A) to get a prompt at machine C when:   I am physically at machine A.  I can use ssh to log directly...  2.1. ... into machine B from A  2.2. ... into machine C from B I cannot log into machine C from A directly     [EDIT]  This is not a duplicate because:   I am not asking how to forward traffic in general, only an ssh connection, so there could be a different answer for the particular case of ssh forwarding through ssh I am asking for compression at the ends (as even the title mentions)

I want to be able to route a portion of my traffic through another machine over SSH. For example, is it possible to browse the web through the ssh tunnel and also browse the web through your LAN connection without much effort? (i.e. I want a seamless transition from using tunnel to using LAN)   Thus it is not a simple how do I tunnel ALL web traffic through ssh tunnel, but moreso how can I setup a tunnel that I can use at my discretion but not impeded my normal traffic flow. (Kind of on an as-needed basis)    I would like the filtered traffic to be encrypted when leaving the LAN and it could be ftp, ssh, web, mail whatever traffic.    Some questions I think I need to answer/address:   Does this require multiple nics?  Does this require setting up a proxy?  Can I even do this the way I want it to function?    Are there other options aside from a tunnel to achieve the result of having some traffic (user decides) encrypted through another machine (outside the LAN) and have other traffic use the normal flow through the LAN and out into the internet world?   Edit: If some of the answers depend on specific traffic types I can be more specific and say that web traffic is a primary focus of this. However, other traffic such as IM/Email traffic would be desirable.


Basically I want to protect myself from SQL injections. I have tried searching online and watching videos but cannot understand exactly what I have to change because as far as I can tell, everyone does it a little bit differently. Any help is appreciated!  ?php // Create connection $con = mysqli_connect("IPAddress","User","Password","DBName"); // Check connection if ($con->connect_error) {     die("Connection failed: " . $con->connect_error); }  $sql = "INSERT INTO Email_Subs (email) VALUES ('$_POST[email]')";  if ($con->query($sql) === TRUE) {     echo "You have successfully subscribed!"; } else {     echo "Error: " . $sql . "<br>" . $con->error; }  $con->close(); ?>

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I am trying to write a formula, which includes operators Re{}, F(\omega) and e(). Anyways, it doesn't work, I know I must be missing some parantheses, but I can't figure out where or what else might be wrong:   \documentclass[11pt,a4paper, oneside]{article} \usepackage[utf8]{inputenc} \usepackage[ngerman,english]{babel} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{graphicx} \usepackage[free-standing-units]{siunitx}  \begin{document}  \begin{equation} \mathcal{Re}\left{\frac{1}{2\pi} \int_{0}{\inf} 2F(\omega) \operatorname{e}^{i\omega t} d\omega \right} \end{equation}  \end{document}

I am stuck with a LaTeX glitch! I am making an exercise on sequences and series. I have to write down an expression for the general form of a sequence for which I need large delimiters. I tried various ways but it did not work.   Here is a minimal example.  \documentclass[a4, 14pt]{extarticle}  \begin{document}  \begin{align}  \[ \left{        \frac{(-1)^{n}}{n}     \right}_{n=1}^{\infty}  \]  \end{align}  \end{document}   I tried $$ .... $$, \[ ... \], and \begin{align} ... \end{align} but all returned errors on compiling. I don't know how to fix this!


I'm filling out my Tier 4 UK visa application for postgraduate studies and will be travelling with my parents to the UK a week before my program starts for a little vacation. My parents will only be with me for a week, but do I still need to list them on the "travelling with another person" section in the application?

I am filling in the UK online visa application on visa4uk.gov.uk. They ask if I am travelling "with" anyone. My plans have been made in conjunction with someone else, we arrive at the same time and leave at the same time and some of our tickets have both our names on them although our movements will differ some of the time, and we are doing separate interviews. I would like to give them every detail possible to as not to be accused of withholding information.   However there is this question about "does this person have a valid visa for the UK?". The answer is "not yet", he will not have a visa until his own application process is complete (just like me). However the options are "yes" and "no". So the correct answer is (currently) "no". Will this cause my own application hassles?


In 3 (and 2 for that matter) dimensions, there is a "canonical" (independent of arbitrary choices) rotation that takes a given unit vector $u$ to another unit vector $v$ (edit: when $u,v$ are in general position): just rotate around the direction orthogonal to both vectors.  However, is there such a canonical rotation in higher dimensions?

There is a 2d rotation matrix around point $(0, 0)$ with angle $\theta$.  $$ \left[ \begin{array}{ccc} \cos(\theta) & -\sin(\theta) \\ \sin(\theta) & \cos(\theta) \end{array} \right] $$  Next, there is a 3d rotation matrix around point $(0, 0, 0)$ and unit axis $(u_x, u_y, u_z)$ with angle $\theta$ ().  \begin{bmatrix} \cos \theta +u_x^2 \left(1-\cos \theta\right) & u_x u_y \left(1-\cos \theta\right) - u_z \sin \theta & u_x u_z \left(1-\cos \theta\right) + u_y \sin \theta \\ u_y u_x \left(1-\cos \theta\right) + u_z \sin \theta & \cos \theta + u_y^2\left(1-\cos \theta\right) & u_y u_z \left(1-\cos \theta\right) - u_x \sin \theta \\ u_z u_x \left(1-\cos \theta\right) - u_y \sin \theta & u_z u_y \left(1-\cos \theta\right) + u_x \sin \theta & \cos \theta + u_z^2\left(1-\cos \theta\right)  \end{bmatrix}  How it is possible to generalize rotation matrix on $N$ dimension around zero point and $N-2$ dimensional unit axis with angle $\theta$?


I need a help to deal with the serie $\sum_{1\leq l \lt m\lt n} \dfrac{1}{5^l3^m2^n}$ (OBM level university, 2018). Some ideia? Thanks very much.

How to solve this summation ? Also, I'm not sure what does $1\leq l< m <n$ supposed to imply in the development of summation form.  $$\sum_{1\leq l< m <n}^{} \frac{1}{5^l3^m2^n}$$  This one is from the Galois-Noether Contest in 2018: