trouble converting data from string vector to floats and doubles
Can't convert string into float/double
Let $\mathbb S = \varnothing$.      Then from the definition: $ \bigcap \mathbb S = \left\{{x: \forall X \in \mathbb S: x \in X}\right\}$      Consider any $x \in \mathbb U$.      Then as $\mathbb S = \varnothing$, it follows that: $\forall X \in \mathbb S: x \in X$ from the definition of vacuous truth.      It follows directly that: $\bigcap \mathbb S = \left\{{x: x \in \mathbb U}\right\}$      That is: $\bigcap \mathbb S = \mathbb U$. ()   Proofwiki uses the above "proof" to "prove" that intersection of the empty set is the whole universe.   My question is, is the use of vacuous truth really allowed in axiomatic set theory, like ZFC? I don't see how the use of vacuous truth is justified.   The next problem I can think of is that we cannot really "define" the elements of empty set (to my knowledge, there is no element in empty set) so how can we then prove as the above proof did? This seems to contradict the use of vacuous truth.  And of course, there is issue of using the whole universe as a set, and I don't think this is allowed.... (Maybe proof above is using a different axiomatic set theory, as I am using ZF-minded thoughts...) How do I put big brackets under different parts of an equation to attach text labels? How do I put big brackets under different parts of an equation so that I can write, e.g., text specific to these parts? For example: f =  x^3 +  2     |___|  |__|        |     |    text 1  text 2 80's/90's movie: man and woman driving through a red desert planet I am trying to identify a sci-fi movie from the 80's or 90's, with the following parameters:  Setting:    Scenes of a red desert planet   Culture:    Either people roam fairly solo and try to acquire resources to survive, or you live in a weird society where if a stranger is captured he needs to play in a game of fight to the death.  Mobility:      One foil character has a giant battle-bot-looking tank as his form of transportation through the desert. Protagonist has a car that has a plastic half bubble on top to look out from.   Robot:      The protagonist runs around in the beginning of the film with a female robot/android whose face is melted off after it has acid touch its face.(This scene happens next to the protagonist's rover)  Love interest:      Somehow protagonist comes across female protagonist in desert. She smells really bad and is hungry. They sleep outside, and he tells her to sleep away from him. He uses a thermal blanket(the first I ever saw in my life). She wakes up next to him, smelling horrible. He bathes her in some water hole they find(as if water were not scarce and they could just waste water.)   Pupa monsters:      Scene where they are in a building and they are trying to get out. They come across a room that is white, in which multiple giant, white, snot, pupa are hanging securely from the ceiling. Through curiosity, they disturb them, and now they have to get out of that room fast.  Boss Antagonist:      Pervert bionic man, that is actually attached to a giant robotic arm, as only form of movement. He is in black and has a pale bald head as his most human looking part. Motion tracked Video doesn't show up in the render or in the compositing tab I tried to add a 3D object to a clip by following a youtube video. But clip doesn't show up in the render or in the compositing tab. It show up even in the camera view. I didn't change any settings. please help. Thank you.    And the  rendered images has only the cube in it like in the picture above. Reason of existense of the extra space in align environment and removal of it between two align environments This is a follow-up question regarding the extra vertical space in amsmath's align environment. Why when in use align uses so much vertical space in contrast with other environments like for example tabular or itemize?  \documentclass[12pt]{article} \usepackage[top=0.3in, bottom=1.2in, left=0.8in, right=0.8in]{geometry}   \usepackage[fleqn]{amsmath} \usepackage{unicode-math}  \setlength{\mathindent}{0cm} \newcommand{\3}{\vspace{0.3cm}}  \title{} \author{} \date{}  \begin{document}  70  \begin{align*} &amp;e^{jz}=\cos z+j\sin z\\ &amp;\cos z=(1/2)(2\cos z)=\\ &amp;=(1/2)(2\cos z+j\sin z-j\sin z)=\\ &amp;=(1/2)(\cos z+j\sin z+\cos z-j\sin z)=\\ &amp;=(1/2)(e^{jz}+e^{-jz}) \end{align*}  80  \begin{itemize} \item Item 1  \item Item 2  \end{itemize}  90  \begin{tabular}{c|c}  Entry 1&amp; Entry 2  \\  Entry 3&amp; Entry 4 \end{tabular}  \end{document}     Also another image of the huge space between two align environments. Even without the blank lines the space is a lot.    \begin{document}  \begin{multicols*}{2}   \begin{align*} &amp;\text{70}\\ &amp;e^{jz}=\cos z+j\sin z\\ &amp;\cos z=(1/2)(2\cos z)=\\ &amp;=(1/2)(2\cos z+j\sin z-j\sin z)=\\ &amp;=(1/2)(\cos z+j\sin z+\cos z-j\sin z)=\\ &amp;=(1/2)(e^{jz}+e^{-jz}) \end{align*}    \begin{align*} &amp;\text{207}\\ &amp;x(t)=A_{c}\cos \theta(t)\\ &amp;\theta(t)=2\pi f_{c}t+\phi(t)\\ &amp;\phi(t)=K_{p}m(t)\\ &amp;x(t)=A_{c}\cos[2\pi f_{c}t+K_{p}m(t)] \end{align*}   Edit I:  As I mention in a comment I have tried the following code and there is no difference between two align environments, only between text and an align environment. Why doesn't work in the case of the two environments and how can I fix it so to work? Also what is the reason that this space exists?  \setlength{\abovedisplayskip}{0pt} \setlength{\belowdisplayskip}{0pt} \setlength{\abovedisplayshortskip}{0pt} \setlength{\belowdisplayshortskip}{0pt} My  has failed me.  In Python, are the following two tests for equality equivalent?  n = 5 # Test one. if n == 5:     print 'Yay!'  # Test two. if n is 5:     print 'Yay!'   Does this hold true for objects where you would be comparing instances (a list say)?  Okay, so this kind of answers my question:  L = [] L.append(1) if L == [1]:     print 'Yay!' # Holds true, but...  if L is [1]:     print 'Yay!' # Doesn't.   So == tests value where is tests to see if they are the same object? In the construction of types of numbers, we have the following sequence:  $$\mathbb{R} \subset \mathbb{C} \subset \mathbb{H} \subset \mathbb{O} \subset \mathbb{S}$$  or:  $$2^0 \mathrm{-ions} \subset 2^1 \mathrm{-ions} \subset 2^2 \mathrm{-ions} \subset 2^3 \mathrm{-ions} \subset 2^4 \mathrm{-ions} $$  or:  "Reals" $\subset$ "Complex" $\subset$ "Quaternions" $\subset$ "Octonions" $\subset$ "Sedenions"  With the following "properties":   From $\mathbb{R}$ to $\mathbb{C}$ you gain "algebraic-closure"-ness (but you throw away ordering). From $\mathbb{C}$ to $\mathbb{H}$ we throw away commutativity. From $\mathbb{H}$ to $\mathbb{O}$ we throw away associativity. From $\mathbb{O}$ to $\mathbb{S}$ we throw away multiplicative normedness.   The question is, what lies on the right side of $\mathbb{S}$, and what do you lose when you go from $\mathbb{S}$ to one of these objects ? Embedding images explodes generated PDF size Make apt-get (or aptitude) run with -y but not prompt for replacement of configuration files? When running apt-get -y install &lt;packages ...&gt; on Ubuntu 10.04 I would like apt-get (or aptitude if that makes it easier) to not prompt me when installing additional dependencies (behavior of -y as I understand it) and but not prompt me about overwriting configuration files, instead assume to keep the existing ones always (which is usually the default). Unfortunately --trivial-only seems to be the inverse of -y and not affect the prompt that is shown, according to the man page.  In particular packages auch as samba, nullmailer, localepurge and lighttpd have forced me to interact with the terminal, even though the whole procedure was scripted and meant to be non-interactive. Are all algebraic integers with absolute value 1 roots of unity? How to reduce fireflies in Cycles? I often use Cycles' built in Glass BSDF shader to achieve realistic refraction effects, but in many cases, it seems that Cycles' glass caustics creates an unfortunately large number of fireflies (pixels that are abnormally bright relative to their surroundings). In some models of mine, even when I render for 3000 or more samples/pixel, my final image is still covered in fireflies. While I can improve this in many cases by increasing the total amount of light available in the scene, this loses a lot of the potency of the refractive effects I'm looking for, especially in scenes with low light levels.  So my question is, how can I reduce the amount of fireflies while using Cycles' caustics without sacrificing the quality of the refractive effects?  Note: I am aware that Cycles' caustics will perform much better once Cycles has full support for bidirectional path-tracing, but it looks unlikely that that will become , unfortunately. When I play Black Ops 2, it seems that my xbox controller is inverted. Example: if I press up, my character looks down and vice versa. It was not like this before. Does anyone know how to reset the controller back to its original settings? Alignment issue in 'Your Sites' section in the Android app How to EFI install Ubuntu? On trying to install Ubuntu 12.10 Desktop amd64 to a desktop pc using a ga a75 ud4h motherboard (which is using an AMD 3870k APU with a new 1TB HDD) following the advice in the  and  have now got to grub option screen for EFI install. Booting live dvd in EFI mode gives &quot;Secure Boot is not enabled&quot; just before grub kernel option list shows.  If the option to &quot;Install Ubuntu&quot; or &quot;Try Ubuntu without installing&quot; is selected gives &quot;can not read cd/0&quot; and &quot;the kernel must be loaded first&quot; errors. Using DVD or USB installation media gives same results and there has never been at any point an UEFI entry in bios/firmware settings or boot device list/s. It might be helpful to say that have had an alternative non-linux OS installing EFI mode on this hardware giving a GPT installation automagically using USB installation media when the hdd space was completely unallocated space. The USB device was listed under hard drives in bios/firmware one time boot list and did not have an UEFI entry. i.e. it installed EFI although no EFI or UEFI entry was assigned to the device like what is shown in many tutorials regarding UEFI installs. The only constructive information regarding this question is found at  and  but can not work out the answer. Checking md5sum and sha256 checksums on downloaded .iso and used &quot;Check disk for defects&quot; to check burned .iso when booting DVD in BIOS mode. No errors found. &quot;Check disk for defects&quot; will not run (or any other options) when DVD booted in EFI mode. Due to trying different distributions as well as older and newer flavours of Ubuntu all giving similar results in that no options from grub option screen in EFI mode are bootable (if getting that far) as well as spending time searching Ubuntu Forums have come to conclusion the firmware on this system is hardcoded to handle Microsoft EFI files only. After installing Windows EFI mode here is a  and here is a link to a thread i started at  which may be helpful to others building a dual boot system. Installing BIOS mode and using Boot-Repair to install grub-efi is not a complete solution due to the inability of using installation media EFI mode for recovery and maintenance due to the &quot;you need to load kernel first&quot; and &quot;can not read cd/files&quot; errors as described when trying to boot installation media using EFI. Secure Boot is not an issue. Using msinfo32 from windows confirms Secure Boot is not supported on this hardware. How to edit kernel or load kernel for EFI install? = How to EFI install Ubuntu? PLEASE CONSIDER: This is not a dupe!  The linked question that is indicated to having a working answer does not have a working answer to &quot;###How to edit kernel or load kernel for EFI install? = How to EFI install Ubuntu?&quot; therefor the workaround of installing using BIOS then manually install grub-efi without renaming bootloaders which works to get Ubuntu booting using EFI or using boot-repair to do this (and many unnecessary &quot;fixes&quot; if recommended repair is not changed in advanced settings) also works.  This goes some way to confirming hardcoding of firmware is not stopping grub the boot manager seeing the vmlinuz.efi files in /casper on DVD.  I would like an answer to this so would like this question to be reopened. Am I eligible for hats if I join a Stack Exchange site after the start of Winter-Bash? I read the definition of  as  $$W ~=~ \vec{F} \cdot \vec{d}$$  $$\text{ Work  =  (Force) $\cdot$ (Distance)}.$$ If a book is there on the table, no work is done as no distance is covered. If I hold up a book in my hand and my arm is stretched, if no work is being done, where is my energy going? I have tried some of the solutions posted elsewhere in the support forum, one seemed like it worked but after a steam update i found myself back at square one  I am a new Linux user and am already at a learning curve :)  Thanks for any help  Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  libgl1-mesa-glx:i386 : Depends: libglapi-mesa:i386 (= 10.1.3-0ubuntu0.3)  unity-control-center : Depends: libcheese-gtk23 (&gt;= 3.4.0) but it is not going to be installed                         Depends: libcheese7 (&gt;= 3.0.1) but it is not going to be installed E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages. Press return to continue: Determine the Galois group of $\mathbb{Q}(\sqrt{a+b\sqrt{d}})$ robots meta not blocking indexing We have a staging version of our website to test changes on at trailheadpaddleshack.ca/staging1. This never appeared in search before. Recently the staging site has appeared on Google and is affecting our search results.  I'm trying to figure out how the pages got there and how to remove them. The pages have always had &lt;meta name="robots" content="noindex, nofollow"&gt; in the head.  I am kinda new at this but was under the impression this should prevent Google from showing my site in results. I am pretty sure the results appeared in google after I accidently copy pasted some codes from the staging site to the live site that contained links to pages on the staging site. If anyone can point me in the right direction to figure out what happened and prevent it from happening again would be much appreciated.  robots.txt looks like this:  User-agent: * Disallow: /calendar-2/action~posterboard/ Disallow: /calendar-2/action~agenda/ Disallow: /calendar-2/action~oneday/ Disallow: /calendar-2/action~month/ Disallow: /calendar-2/action~week/ Disallow: /calendar-2/action~stream/ #Begin Attracta SEO Tools Sitemap. Do not remove sitemap: http://cdn.attracta.com/sitemap/4035112.xml.gz #End Attracta SEO Tools Sitemap. Do not remove   I also tried adding an X-Robots-Tag header and submited the site to be re-crawled. Did that a few days ago and I still see no changes. Here are the HTTP headers according to "Fetch as Google":  HTTP/1.1 200 OK X-Robots-Tag: noindex,nofollow Vary: Accept-Encoding Transfer-Encoding: chunked Date: Sun, 24 May 2015 16:26:49 GMT Server: LiteSpeed Connection: close X-Pingback: http://trailheadpaddleshack.ca/staging1/xmlrpc.php Content-Type: text/html; charset=UTF-8 Link: &lt;http://trailheadpaddleshack.ca/staging1/?p=170&gt;; rel=shortlink   I am now faced with a bunch of results I need to remove from Google asap as they contain out of date information and are affecting our search results. Webmaster Tools has something for removal of a single URL but I am looking to remove the entire /staging1/ subfolder. Any tips? Is there a way to get DateTime value from timestamp type column?