Intel GPU Drivers
Installing AMD & Intel dual graphics
how can I show this question : function Let $f\colon\mathbb R\to\mathbb R$ defined by  $$f(x)=a_1\sin x+a_2\sin2x+a_3\sin3x+\cdots+a_n\sin nx,$$ for some values $a_1,a_2,a_3,\cdots,a_n\in\mathbb R.$ Prove that $$ |f(x)|\le|\sin x|\quad \forall x\in \mathbb{R}$$ implies: $$|a_1+2a_2+3a_3+\cdots+na_n|\le1$$ How to visualize the gradient as a one-form? I am reading Sean Carrol's book on General Relativity, and I just finished reading the proof that the gradient is a covariant vector or a one-form, but I am having a difficult time visualizing this. I usually visualize gradients as vector fields while I visualize one-forms with level sets. How to visualize the gradient as a one-form? When I read about , I see that they should appear as solution to prevent  and  but when I actually try to write a code which would use Lightning promises it still doesn't look like synchronous code, it still resembles both pyramid of doom and callback hell.  main: function(component, helper) {     helper.promise1(component, helper).then(         $A.getCallback(function(record) {             return helper.promise2(component, helper, record).then(                 $A.getCallback(function(){                     console.log("Success");                     helper.showToastMessage(component, "Great Success!!!!")                 }),                  $A.getCallback(function(errorMessage){                     console.log("Rejected by second promise2");                     helper.showToastMessage(component, "Failure " + errorMessage);                 })              )         }),          $A.getCallback(function(errors){             console.log("Rejected by first promise1");             let message = errors &amp;&amp; Array.isArray(errors) &amp;&amp; errors.length &gt; 0 ? errors[0].message :'Unknown error';             helper.showToastMessage(component, "Failure " + message);         })      ) }   Is that possible to refactor this code to look more like synchronous code and without callback hell or pyramid of doom? Bash script to remove the oldest file from from a folder I want to make a bash script to delete the older file form a folder. Every time when I run the script will be deleted only one file, the older one. Can you help me with this? Thanks Java string to date conversion How can I generate a sin wave with power law noise? How often should I remove the charger from my rMBP? I want my battery to remain healthy. I used to charge it full then remove the charger after it's done, then put it back on when it goes down to 10% .. However this is becoming hectic and I was wondering if I can keep it plugged in the whole day and probably remove just an hour or so before going to sleep.  What is the best way to charge and discharge my Retina Macbook Pro while keeping the battery healthy ? Random test data: How to do it right? Several months ago I started an experiment in test automation. Each test, before it starts, picks up random test data. For instance, when my test requires a user with administration privileges, I draw a random account and then I from a group of admin users for this account I draw a random admin user.  The reason for using random test data was two-fold:    First, when we were using static, i.e., hard-coded test data, sometimes tests started to fail, because test data no longer existed in DB, e.g., a user has been removed from the database (we're having production dump in our test DB, so I guess the user has been deleted in production). When we started to find such users at runtime, the problem disappeared.  Second problem was that it was not really clear why certain test data were used for a certain test. We have inherited tests from the other team and couldn't understand their intentions behind, for instance, using user "xyz@awesome.com". By writing queries to find data, we started to explicitly state what type of test data we want, e.g., that we want a user with administration privileges.   While my approach solved both problems, it introduced also some new issues:   Tests occasionally fail, because they pick up wrong test data. This is because queries are sometimes incorrect. For instance, once a test drawn a random account that had no administrators at all. Good thing about that is that this way I keep learning new things about the system under tests, e.g., that there must be business reasons to have accounts without administrators. Test setup becomes more and more complex, as queries start to grow and thus tests seems now a bit more complex to understand.   I was also hoping to increase coverage and find more bugs by using random test data just like it is done in fuzz testing. Instead, I mostly found bugs in my test and learned how little I know about the system under test. Finally, ROI doesn't seem big. Before the change there was a cost of maintaining static test data (updating test data if they were outdates). Now I have to maintain complex queries when the test takes "wrong" test data and this tends to occur more often than outdating of static test data previously.  I wonder whether using random test data really makes sense and how to do it right? What can I do to increase passive HF RFID read range? I am working on a prototype, one function of which is to detect whether an object is "in range" by a few cm. Right now I'm just using an Arduino and a cheap  that operates at 13.56 MHz:    I've successfully gotten it to detect the tag, but only at a distance of about 3-4 cm when the tag is oriented parallel to the antenna.  According to my  , the HF band allows read ranges of between 10 cm and 1 m for passive tags, depending on factors like antenna size, tag size and orientation, and transceiver power.  I realize this inexpensive reader is not up to task as-is, but I'm interested in building something that achieves read ranges of 15-20 cm.  Some criteria:   No need to read multiple tags; only whether one tag is in range or not. No need to write to the tag. Cannot use an active tag.   I'm not experienced with RFID reader construction (yet) but am interested in knowing what I should pursue.  Here are some things I've considered:   Ditch the embedded antenna on the cheap RFID reader and construct my own, larger antenna. I'd need to see if the onboard  is up to the task of providing additional power. Look for a different IC around which to build a reader from scratch. Find a ready-made solution instead of trying to build one (more cost-effective?). Use something other than RFID for simple proximity detection.   I am experienced with microcontrollers and basic electronics, and have made audio and lighting projects, but this is a first with RFID. Since I don't need to read multiple tags, which RFID is suitable for, I've considered maybe some sort of magnet and hall-effect sensor, but the range does not seem adequate. I considered using an ultrasonic proximity detector, but the application calls for detecting the tagged object while ignoring untagged ones (ultrasonic would produce false positives on untagged objects). I've considered some sort of reflective surface placed on the object, and detecting reflected light, but the object orientation is not reliable enough to maintain alignment.  So, in a nutshell, What modifications can I make to my existing reader, or what alternate technology should I pursue to achieve 15-20 cm detection of a passively tagged object?  I plan on connecting whatever proximity detector is used to a microcontroller using SPI. Find all rings $R$ satisfying $\mathbb Z \subset R \subset \mathbb Z[\frac {1}{2}]$ WSOD after migrating to another site? Troubleshooting a site migration If I have a PATH variable that (when exploded onto multiple lines) contains something like this (with a few notes added by me):  /Users/brandon/.rvm/gems/ruby-2.0.0-p353/bin /Users/brandon/.rvm/gems/ruby-2.0.0-p353@global/bin /Users/brandon/.rvm/rubies/ruby-2.0.0-p353/bin /opt/local/bin /opt/local/sbin /usr/local/sbin /usr/local/bin   # &lt;&lt;--- notice this path appears again later /usr/bin         # &lt;&lt;--- notice this comes AFTER /usr/local/bin /bin /usr/sbin /sbin /usr/local/bin   # &lt;&lt;--- here it is again! /usr/local/git/bin /Users/brandon/bin /Users/brandon/.homebrew/bin /usr/local/mysql/bin /usr/local/share/npm/bin /Applications/Postgres93.app/Contents/MacOS/bin /Users/brandon/.rvm/bin   is it possible for the presence of the second /usr/local/bin/ to cause the /usr/bin to take precedence over /usr/local/bin?  This seems crazy (to me: I've never heard of such a thing) but that's exactly the behavior I'm seeing.  I've just installed PHP with Homebrew, and yet the system PHP (from /usr/bin) is taking precedence:  $ which php /usr/bin/php   BUT, after manually altering the PATH (rather than digging through all the files sourced by my .zshrc to try to figure out why &amp; where the duplication is coming from) to remove the second instance of /usr/local/bin, I find that /usr/local/bin is taking precedence over /usr/bin as I would have expected it to in the first place:  $ which php /usr/local/bin/php   What would cause this?  Is this normal? PHP class: Global variable as property in class , Laser Interferometer Gravitational-Wave Observatory, is a large-scale physics experiment aiming to directly detect gravitational waves. The device measures the phase shift laser beams.  If I understand this well, the measurement assumes that a suitable gravitational wave reduces and prolongs one of the tubes and the extension will take effect in the phase-shifting laser beams.  But I think if there's a gravitational wave that passes through it, it will affect everything, even the laser beam. This means that when the wave lengthens or shortens the tube, it also lengthens or shortens the wavelength of the laser beam.  In my opinion, therefore, this device does not work. Or am I wrong? Why can't I connect to Ubuntu One? I have purchase new laptop from Dell with ubuntu 12.04 preinstalled. while connecting to Ubuntu One following occurs and I am not able to sync with Ubuntu One.   WebClientErr u'Error downloading https://one.ubuntu.com/api/account/ - server replied:Not       Found' u'&lt;!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"&gt;\n&lt;html&gt; &lt;head&gt;\n&lt;title&gt;404 Not Found&lt;/title&gt;\n&lt;/head&gt;&lt;body&gt;\n&lt;h1&gt; Not Found&lt;/h1&gt;\n&lt;p&gt;The requested URL /api/account/ was not found on this server. &lt;/p&gt;\n&lt;hr&gt;\n&lt;address&gt;Apache/2.2.22 (Ubuntu) Server at one.ubuntu.com Port 443 &lt;/address&gt;\n&lt;/body&gt;&lt;/html&gt;\n' Without using Axiom of Choice, prove that $$\forall\alpha\geq\omega,~~|L_\alpha|=|\alpha|,$$  in which $\alpha$ is an ordinals, $\omega$ is the set of natural numbers, $L_\alpha$ is the $\alpha$-th constructiable set, $|x|$ is the cardinals of $x$.  I am learning a set theory, and I have read a proof by using AC. The AC is used only when $\alpha$ is a limit ordinals during the transfinite inductive method for $\alpha$ . I wonder if there is a proof without AC. 　THANKS! What is this lock screen with ads and how do I remove it? I think my device got a malware. A lock screen with ads sometimes appear, and I must swipe an area at the bottom of the screen to open the phone. I am in Eastern Europe, some ads are in Slavic languages, and they are seemingly related to travel.    Image resized. Click to view the full image  I have seen ads for Lot Air (Polish carrier). I recently went to their site.  Considering my recent surfing activity and the nature of the ads, I guess the malware is connected to airlines active in Eastern Europe.  The lock screen also promotes the app "DU Quick Charger" by claiming it has recharged the phone extra fast during screen off. (!?) It also shows battery level. I have never installed DU Quick Charger. I doubt DU Quick Charger is installed on the phone.  The problem started after installing Ryanair app. The problem is maybe, but not surely, related to this. Uninstalling Ryanair and restarting the phone doesn't remove the occasional appearance of this lock screen. After a while the situation has changed for the worse, now this lock screen appears after EVERY screen off.  I have always used Avast. I am not rooted and only install via Google Play.  What is this? And how do I remove it? "strlen(s1) - strlen(s2)" is never less than zero Rough Smart objects problem in Photoshop I am using Adobe CC(2015) latest version and the behaviour of the smart objects isn't normal. When I paste a vector from Illustrator to Photoshop, the vector looks low quality or rough.   ORIGINAL  IN PHOTOSHOP   However, if I click over the smart object layer(in Photoshop)and this is opened in Illustrator, the vectors looks as the original one.   VECTOR OPENED IN ILLUSTRATOR FROM PHOTOSHOP SMART OBJECT   How can I solve this? How to show that $\det(AB) =\det(A) \det(B)$? Given two square matrices $A$ and $B$, how do you show that $$\det(AB) = \det(A)\det(B)$$ where $\det(\cdot)$ is the determinant of the matrix?