I have a 2012 iMac running Catalina and I'd like to use it as a secondary display to my MacBook Pro. I connected the two computers via a USB cable and hit both ⌘ CommandF2 and then tried ⌘ CommandFnF2. It's not working. Do I need to use a Thunderbolt? Any input/advice would be most appreciated.
I have a Surface Pro 4 and an iMac (late 2019). I would like to connect my Surface Pro to the iMac to use the iMac screen as a second monitor.  Is that possible?  What are the requirements to use an iMac as a second screen?
Chrome: remove URL from autocomplete which doesn't show up in history? DES-X , computation load and storage Claim: if $f$ is differentiable at $x = x_0$ then $f$ is continuous at $x = x_0$.   Please, see if I made some mistake in the proof below. I mention some theorems in the proof:   The condition to $f(x)$ be continuous at $x=x_0$ is $\lim\limits_{x\to x_0} f(x)=f(x_0)$.  (1) If $f(x)$ is differentiable at $x-x_0$, then $f'(x)=\lim\limits_{x\to x_0} \dfrac{f(x)-f(x_0)}{x-x_0}$ exists and the function is defined at $x=x_0$.   (2) Therefore, by the Limit Linearity Theorem, $\lim\limits_{x\to x_0} f(x)$ exists and we'll show it is equals $f(x_0)$.   (3) We'll do this by the Precise Limit Definion: given $ \epsilon&gt;0, \exists\delta|0&lt;|x-x_0|&lt;\delta$, then $0&lt;|f(x)-f(x_0)|&lt;\epsilon$. As this limit exists by (2), we can make $f(x)$ as close to  $f(x_0)$ as one wishes, therefore $\lim\limits_{x\to x_0} f(x)=f(x_0)$, what satisfies the condition for $f(x)$ be differentiable at  $x=x_0$. The end. SF Short Story: alien apes invade during nuclear war Wrongly set chmod / 777. Problems? I was trying to run chmod -R 777 ./ but ended up typing chmod -R 777 / and set 777 on my entire machine. What can go wrong? How can I fix it? Why does sstatic.net serve cookies? According to :  This is a fast, cookieless domain intended for static content delivered to the   However, all responses from the server set a cookie anyway: $ http https://sstatic.net/ HTTP/1.1 200 OK CF-RAY: 162b88245bc406be-LHR Cache-Control: max-age=604800 Connection: keep-alive Content-Encoding: gzip Content-Type: text/html Date: Sun, 31 Aug 2014 19:11:04 GMT ETag: W/&quot;d5474fdfb5c3cf1:0&quot; Last-Modified: Fri, 29 Aug 2014 18:20:12 GMT Server: cloudflare-nginx Set-Cookie: __cfduid=db60cc6f3e7f6482e37f1f2b85c9dc5881409512264375; expires=Mon, 23-Dec-2019 23:50:00 GMT; path=/; domain=.sstatic.net; HttpOnly Transfer-Encoding: chunked Vary: Accept-Encoding [...]  Is this intentional, or just funny? Edited to add: I understand that the cookie is used to track visiting browsers so that cloudflare can distinguish them from misbehaving hosts using the same or a nearby IP address. However, if the policy is intentionally to serve cookies, then the self-documentation of sstatic.net as a &quot;cookieless domain&quot; is incorrect. Possible Duplicate:        When I click 'Unanswered' in the menubar, I get a list of questions, all of which have been answered. Does it just mean there's no accepted answer? If so, can we make that more obvious? Can we get some way of finding really unanswered questions? I have forgotten the password or username for my Google account, or I'm unable to access my account for other reasons.  How can I recover my account?  (This Q&amp;A is meant as a general description for all Google and Gmail username/password questions. See: ) I run processing.run(&quot;native:buffer&quot;) and from newly created vector I get all features and export them to string using QgsJsonExporter(). My problem is that newly created vector gives new IDs to all features and they aren't equal to attribute ID's values. And after exporting them to GeoJSON using QgsJsonExporter() I get GeoJSON features with identifiers. However I can solve this by declaring processing.run(&quot;native:buffer&quot;) algorithm OUTPUT to .geosjon file and opening it afterwards. Is there a way that I can get GeoJSON string without IDs without having to save OUTPUT to .geojson and reading it to string afterwards. vl = QgsVectorLayer(sys.argv[1],&quot;mygeojson&quot;,&quot;ogr&quot;)  def runProcessingNativeBuffer(inputGeoJson, distance):     processing.algorithmHelp(&quot;native:buffer&quot;)     return processing.run(&quot;native:buffer&quot;,                          {'INPUT': inputGeoJson,                           'DISTANCE': distance, 'SEGMENTS': 5,                           'END_CAP_STYLE': 0, 'JOIN_STYLE': 0,                           'MITER_LIMIT': 2, 'DISSOLVE': False,                           'OUTPUT': &quot;TEMPORARY_OUTPUT&quot;})  ats = runProcessingNativeBuffer(vl, sys.argv[2])  vl1=ats['OUTPUT']  features = vl1.getFeatures() exporter = QgsJsonExporter() print(&quot;GEOJSON&quot;,exporter.exportFeatures(features))  IDs in properties are fine I don't need additional IDs in &quot;features&quot; Any canon Shadowrun material related to NY/PA/NJ areas? I'm looking for specific, canon (i.e. official, published) references to material for the Shadowrun game-world setting. My game setting is based around the Philadelphia area; I've turned New Jersey into a radioactive swamp, then dropped a nuke in it; I've got some things established for the Philly area, and NYC.  What I want to know is whether anyone knows of specific references to published material dealing with this region. Any mention of the big apple in Shadowrun's history? Any famous names in the area, or megacorps that are mentioned? Anything at all that's part of the published SR work, that I can incorporate, or at least avoid contradicting.  If you have any home-brewed material for that area, I would love to see a link in comments, but please don't put it as an answer. Thanks! =) I am studying the function and characteristic of an op-amp to build a line-following robot with the schematics below. However, in many tutorials, the way to differentiate an inverting and non-inverting op-amp is by looking at the connection to ground via the inverting or non-inverting terminal.  However, in the schematics, the op-amp is considered to have connections to ground, thus in this case, how do I differentiate it then?  I may have understood the whole concept wrongly. Pls help!    EDIT: Please ignore the switch as it may have been drawn wrongly by the supplier. How do I figure out the right size font / text for a given read distance? To avoid printing single letters at varying sizes and measuring how far away I can see it from a distance is there a formula for determining what size font for a particular read distance? Is it better to take the midpoint between the ascender line and x-height or to go purely off of the x-height (since going purely off the ascender line could leave lowercase letters difficult to read)? How does vertical height play into this? Would I need to then figure the hypotenuse distance instead of a straight distance?  For example if I'm shooting for a 20' read distance but the sign is to be placed about 30' up should I use a distance of  35' instead of 20'?  I'm shooting for a 20' read distance for the headline and then possibly a 10' read distance for additional content depending on how it all fits on the active area. How to verify iOS app integrity? If I write an app for iOS and it's accepted by the AppStore, how do I know if the app is actually the app I compiled and has not being substituted/altered by, say, a "Man in the middle" style interception/attack? Is there a way to do a checksum either after the fact or from inside the app itself? Why is glass transparent? Once I asked this question from my teacher and he replied "Because it passes light.". "And why does it pass light?" I asked and he said, "Because it is transparent.".  The same question again, Why glass is transparent? Why does light pass through it, while for opaque objects, it does not? Formula for the $n$th term of $1, 2, 2, 3, 3, 3, 4, 4 ,4, 4, 5, ...$ There exists a formula for the $n$th term of this sequence  from the OEIS ("$n$ appears $n$ times") $$1, 2, 2, 3, 3, 3, 4, 4 ,4, 4, 5...$$ which is $$\left \lfloor \frac {1+\sqrt{1+8n}}{2} \right \rfloor.$$  Is there a better formula for the $n$th term? A formula that isn't a 'magic' one that just happens to work but one that comes from a well-founded observation. Preferably one not using the floor function. I also have suspicions about the sustainability of the above formula as I feel with very $n$ it may not function properly. How to flatten a non-planar face to a targeted plane? Let's take a non-planar quad here for a simple example, how to only move one vertex on it, to finally make it planar while keeping the other three vertices still? Series rearrangement and Riemann's theorem I think understand that when I have a conditionally convergent series, it consists of series of positive and negative values which are divergent and thus one can find such permutation of indices $\phi : \mathbb{N}\rightarrow\mathbb{N}$ so the rearranged series sums up to an arbitrary value, diverges or oscillates.   This is how I understand what Riemann's rearrangement theorem says, but how do I use it practically? For example, when I have the conditionally convergent series:  $$\sum_{n=1}^{\infty}\frac{(-1)^n}{\sqrt{n}}$$  and I want to rearrange it to be divergent or to sum up to certain value M? How do I define such bijections $\phi$ ?  I appreciate all help. Does the review queue page show only reviews requiring your action? Does it differ, and when does it? This confusion came up in comments .  On the site I use most actively (RPG.SE), I've noticed that the counts for each review queue appear to only indicate the reviews available to me requiring my action. Just to be clear, I'm talking about this number here:        Since I'm a 10k user, that's pretty easy to tell: even after doing all my reviews, and the review page saying there's 0 items in each queue, I might still have that 10k notice in my top bar saying there's [5] reviews pending, or some other number. So they must still be there, just waiting on other users to finish them, and it just doesn't show them to me. This is fine, I like this behaviour.  However, on Meta SE about an hour ago, there was 1 item in the close vote review queue. I reviewed that item. The count stayed at 1 on the review page. When I clicked to re-enter the queue in case there were new items, I was presented with this:        Another user in that meta question I linked claims this is normal behaviour for them on their own site (Christianity.SE I think?).  What's going on here? Are the review queues supposed to be customised just to what I personally can actually review at the time? Is there a bug, are sites customised differently, or is there just some kind of caching thing leading to a time delay on the review count getting updated? (As they say, it is always caching, but is caching really the culprit here too?) Do flight attendants prefer I press the button or walk to the back? (Long-haul flights) What happens if I buy a game I already own through Steam a second time? I am debating whether or not to get the Potato Sack (yes, I realize I've been debating for several weeks now) bundle through steam.  I already own: Defense Grid: The Awakening, Super Meat Boy, and Audiosurf, all of which are part of the sack pack. What happens if I buy the Potato Sack?  Do I get 2nd copies of the three above mentioned games to gift elsewhere?  Is the price of the bundle reduced by the games I already have?  Do I get nothing special for already owning those 3 games?