What is the difference between != null and !== null? Sorry for what I'm sure had have been asked in the past, but it's very hard to search for a question like this. "!=" and "!==" are not exactly search friendly. If anyone knows a duplicate question you can point me to it.  What is the difference between doing myVar != null and myVar !== null? I know that != is not equal and !== is not equal value or not equal type, but when comparing to null is there ever a case where they would return different results? Is one better to use than the other?
Difference between == and === in JavaScript What is the difference between == and === in JavaScript?  I have also seen != and !== operators.  Are there more such operators?
Right so seeing as the new Deadpool movie shows the origins of Deadpool: specifically, he got cancer... blah blah had to get him the healing factor from Wolverine.  But that makes no sense — they used the same actor, so I'm assuming there must be some connection, right... right? Proofs of Determinants of Block matrices Does anyone know how to remove this dead bolt that has no screw heads to use a screw driver? Here's a picture below. Arduino Negative Voltage Reading with Positive Ground I am trying to measure voltage &amp; current off a solar charge controller from panel, battery &amp; load simultaneously with my arduino. I have managed to achieve this by tying all the negatives together and using it as GND, however, when I do that the charge controller doesn't function properly and when I switch to off-mode the loads still run. After checking the instruction manual further, I found out that the positives are shared common between Pan, Bat, Load. This was confirmed with a multimeter.   So now what I am thinking of doing is using the positive from the battery as the GND reference and then measuring all other voltages (through voltage dividers with respect to the GND). The voltages should then range between -17V to 0V.   However, I have read that the analog input pins are not able to read negative voltages, and with respect to the positive GND, the Analog inputs will all be negative.   EDIT: I was thinking of using an amplifier to invert positive ground to a negative ground, meaning I could measure all the positive sides of the voltages. But after getting answers from you guys it seems I may not have to use an amplifier and a voltage divider may suffice. I have currently included a 2 resistor voltage divider between each analog input, +5V source, Vmeasure which you can see in the diagram below.  According to my calculations, if this works, @-17V I should see 0.6V @ analog input. @0V I should see 4V at analog input.   I'd appreciate feedback on this circuit, and below in the second image I've also included a piece of another method suggested by @jonk (thanks), and would be interested in knowing what the benefits are of method B) over method A)  Thanks!  Ps. the ameters are there in place of ACS712 current sensors which also go into analog input pins.   Method A)        &ndash; Schematic created using   Method B (EDIT: This method has worked, I am still yet to test method A) thanks @Jonk)) Is ¬¬(¬¬P → P) provable in intuitionistic logic? Grub not showing on startup for Windows 8.1 Ubuntu 13.10 Dual boot Ok, so I'm such a newbie to Ubuntu and I bought a Windows 8 pre-installed laptop last month.  I updated to Windows 8.1 and then I thought about installing Ubuntu as a dual boot so I could mess around and learn more about it.   So I followed a Youtube tutorial (  ) and I got my stuff working fine.   The first few times I booted I got the GRUB menu instead of my default HP Boot OS Manager, and I was able to select my OS.   So I went to sleep and the next day I turned on my computer and the GRUB menu did not show up. I tried several times and it didn't automatically show up.  In order for me to see the GRUB menu I had to turn on my PC and on start had to press ESC to pause startup and press F9 to get boot options. Then from there I had to pick from OS Boot, Ubuntu, Ubuntu (Yes there were two Ubuntus available) and a default EFI file thingy.   When I click the first Ubuntu I get the GRUB Menu (I was too scared to try the second in case I screwed my laptop up) and I can safely load Ubuntu from there and use it (although I do have to increase my brightness every time I load Ubuntu because it somehow reduces my brightness to complete darkness on boot)  So my problem here is why isn't my GRUB showing on boot, after it worked on the first day?   My laptop is a HP TouchSmart j-078CA.  EDIT 1: FYI I just switched to Ubuntu LiveCD to check my Installation and found out that one of my partition is flagged as msftres. Here is a screenshot of my GParted on a LiveCD: Intel Corporation Device [8086:0d4f] is not supported on Ubuntu 18.04.3 I am currently unable to install ubuntu server 18.04.03 LTS on the latest intel NUC10i7FNH.  Ubuntu always states both network adapters as unclaimed. The previous version (NUC8i7BEH) has the same network controller I219-V and worked like a charm.  *-network:0 UNCLAIMED      description:  Network controller      product: Intel Corporation      vendor: Intel Corporation      physical id: 14.3      ...   Without network it is not even possible to follow most suggestions how to get it enabled, because it is impossible to fetch new packages from internet.  Here are some more information as requested:  The output from: modprobe -v e1000e &amp;&amp; dmesg | grep e10   [ 3447.889394] e1000e: Intel(R) PRO/1000 Network Driver - 3.2.6-k [ 3447.889395] e1000e: Copyright(c) 1999 - 2015 Intel Corporation.   The output from: sudo lspci -knn  00:1f.6 Ethernet controller [0200]: Intel Corporation Device [8086:0d4f]     Subsystem: Intel Corporation Device [8086:2081] 01:00.0 PCI bridge [0604]: Intel Corporation JHL7540 Thunderbolt 3 Bridge [Titan Ridge 2C 2018] [8086:15e7] (rev 06)    For me this looks somehow, as the kernal driver would not be in use :-/  Here are a few more information i got from playiung around with 19.10 desktop version.  [    0.000000] Linux version 5.3.0-29-generic (buildd@lcy01-amd64-024) (gcc version 9.2.1 20191008 (Ubuntu 9.2.1-9ubuntu2)) #31-Ubuntu SMP Fri Jan 17 17:27:26 UTC 2020 (Ubuntu 5.3.0-29.31-generic 5.3.13)   output from lshw:    *-network:0        Beschreibung: Kabellose Verbindung        Produkt: Intel Corporation        Hersteller: Intel Corporation        Physische ID: 14.3        Bus-Informationen: pci@0000:00:14.3        Logischer Name: wlp0s20f3        Version: 00        Seriennummer: c8:09:a8:9c:cd:e0        Breite: 64 bits        Takt: 33MHz        Fähigkeiten: pm msi pciexpress msix bus_master cap_list ethernet physical wireless        Konfiguration: broadcast=yes driver=iwlwifi driverversion=5.3.0-29-generic firmware=48.4fa0041f.0 ip=192.168.178.109 latency=0 link=yes multicast=yes wireless=IEEE 802.11        Ressourcen: iomemory:600-5ff irq:16 memory:6023114000-6023117fff   The output from: modprobe -v e1000e &amp;&amp; dmesg | grep e10  [    2.357430] e1000e: Intel(R) PRO/1000 Network Driver - 3.2.6-k [    2.357430] e1000e: Copyright(c) 1999 - 2015 Intel Corporation. [    2.357616] e1000e 0000:00:1f.6: Interrupt Throttling Rate (ints/sec) set to dynamic conservative mode [    2.562796] e1000e 0000:00:1f.6 0000:00:1f.6 (uninitialized): registered PHC clock [    2.634139] e1000e 0000:00:1f.6 eth0: (PCI Express:2.5GT/s:Width x1) 1c:69:7a:60:44:f0 [    2.634140] e1000e 0000:00:1f.6 eth0: Intel(R) PRO/1000 Network Connection [    2.634258] e1000e 0000:00:1f.6 eth0: MAC: 13, PHY: 12, PBA No: FFFFFF-0FF [    2.634991] e1000e 0000:00:1f.6 eno1: renamed from eth0 [    5.103285] checking generic (4000000000 e10000) vs hw (4000000000 10000000) [   15.806697] e1000e: eno1 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None    output from lspci:  00:1f.6 Ethernet controller [0200]: Intel Corporation Ethernet Connection (10) I219-V [8086:0d4f]     DeviceName:  LAN     Subsystem: Intel Corporation Ethernet Connection (10) I219-V [8086:2081]     Kernel driver in use: e1000e     Kernel modules: e1000e I'm trying to compute the difference between the output of two awk commands but my simple attempts at it seem to be failing. Here is what I'm trying:  diff $(awk '{print $3}' f1.txt | sort -u) $(awk '{print $2}' f2.txt | sort -u)   This doesn't work for reasons unknown to me. I was under the assumption that $() construct was used to capture the output of another command but my "diff" invocation fails to recognize the two inputs given to it. Is there any way I can make this work.  By the way, I can't use the obvious solution of writing the output of those two commands to separate files given that I'm logged on to a production box with no 'write' privileges. Getting Started to Xetex for Devangari? I have a file with ANSI colors.  test.txt: \e[0;31mExample\e[0m  I would like to display the content of this file in a terminal, like cat does, but I would like to display the colors as well. How to automate entry of external column data in BCS? I have a document library, Resumes, that has a large number of resumes in it. There is a regular column on that library, called EmployeeID, that is already populated.  I have an external content type ( ECT ) that is mapped to a table that lists EmployeeID and several other columns of information. I added this ECT to the library as an External Column.    I am looking for a good way to automatically go through all items in the document library, and copy the value from the "regular" EmployeeID column into the External EmployeeID column and have it update the other columns from the ECT. Any techniques are useful (PowerShell, Object Model, Workflow?) When we have tried this in the past with workflows the setting of the External Column did not report failure, but didn't actually trigger a lookup of the other data and the value didn't seem to actually get saved.  [Update] I have been working on this and am getting closer. I am using PowerShell to access the list and set the external column ID field to the value I want it to be.  The problem is that it doesn't seem to be triggering a lookup of the external data when that field is set.  my "list" (a document library) has a few normal fields and a set of external columns mapped to an ECT "EmplData".  When you use the GUI to add or edit the properties of an item, it works. When I use PowerShell to do the following:  $spList = $spWeb.Lists["Resumes"] $spListItem = $spList.GetItemById(1) $spListItem["EmplData_ID"] = "00300"    $spListItem.Update()   Sometime the external ID field gets updated when I the refresh the web page, other times it says "(blank)". In all cases it does not load in the other fields.  Is there some Update method that updates the rest of the elements?  I gather from research that these are called "secondary fields", is the method to update the secondary fields based on the external item ID available in PowerShell cmdlets someplace?  [Update] I am finding that if I use:  $spListItem["EmplData"] = "000300"   instead of $spListItem["EmplData_ID"] = "00300" it gets around the problem of the column showing "(blank)".   I still need to figure how to make it update the other external columns (also known as "secondary columns" I think) How to prove that we are living in a 3+1D world? Yes, I know the topic has been discussed before. I know that Meta already has threads that complain about how flagging doesn't work. I wanted to give a practical example.  Today, a  came in to the  chat and asked the :  Hey guys, as soon as I embed javascript, all my html elements are gone. Even if the script is empty!? ...Can anyone help out? The example is really minimalistic &lt;script type='text/javascript' src=&quot;http://ajax.googleapis.com/ajax/libs/jquery/2.0.3/jquery.min.js&quot;/&gt; &lt;script type='text/javascript' src=&quot;script.js&quot;/&gt; These lines make everything vanish. script.js is empty! I use google chrome and the file is on localhost  Some context:  The JS room encourages people to come and ask questions that are too small/badly put for main. The room encourages people to just ask questions rather than ask to ask. In fact we even have a bot that prompts users to just ask if they have a question whenever they join. The above user has a good Q to A ratio having 1K rep in the main site and over 80 answers. The user has no negative context in the chat. No previous offenses or anything like that.  That message got 7 flags  Had a mod (ThiefMaster) not been present and invalidated those flags in time that user would have probably been suspended from the chat. This is bad, it sends the wrong message and it is very rude. Now, some other rooms don't allow people to just come and ask questions right away so maybe users from other rooms validated the flag. Maybe users thought he was being rude? I don't know. I do know that we don't want this sort of negative atmosphere in the JS room (and I'm sure other useful rooms such as PHP don't want it either), we have enough on our hands trying to maintain a community while helping people joining and handing with vamps/trolls. Possible solutions:  Drop spam/offensive flags altogether. Make spam/offensive flags room specific for big enough (tm) rooms. Give room owners just the ability to invalidate spam/offensive flags. Rank correlation statistics comparison I am trying to understand the relative behavior of the following rank correlation statistics:   Spearman coefficient Kendall Tau / Concordance percentage Normalized Gini coefficient (area under curve of percentage captured versus percentage observations) Normalized Area under ROC curve (for binary classifiers)   I don't believe any of these are functionally related to the others.  The accepted answer  references  and Spearman and Kendall are highly correlated (as one would expect).  Are there good intuitions behind/discussions of relative (across datasets) or absolute (for a given dataset) differences for (any pair of) these measures? Is it possible that $a_n>0$ and $\sum a_n$ converges then $na_n \to 0$? (without assuming $a_n$ is decreasing) How to get the IPV4 address for an interface from /proc Is there a clean, simple way to get an IP address for a network interface from /proc, similar to the way I can get the MAC address for a network interface? Ideally I would just type cat /proc/&lt;foo&gt;/{interface_name} and get the IPv4 address.  I'd rather not run anything other than cat. I am stuck on how to calculate the following limit: $$\lim_{x\to\infty}x\left(\left(1 + \frac{1}{x}\right)^x - e\right).$$  Definitely, it has to be through l'Hôpital's rule. We know that $\lim_{x\to\infty} (1+(1/x))^x = e$. So, I wrote the above expression as $$\lim_{x\to\infty}\frac{\left(1 + \frac{1}{x}\right)^x - e}{1/x}.$$Both numerator and denominator tend to zero as x tends to infinity. I applied l'Hôpital's rule twice, but I got the limit equal to infinity which is clearly wrong. In the book, it says that the limit should be $-e/2$.  Any help please? Also, in case someone managed to solve it, please tell me which numerator and denominator did you apply your l'Hôpital's rule to in both cases? Thanks a lot  Also, guys can you tell me how to write equations in this forum? Thanks. From io.Reader to string in Go How to construct semi direct products between Q and H There is a semi direct product if you go $\theta: Q \rightarrow Aut(H)$.  $H = C_{17}, Q = C_2$.  $Aut(H)\cong C_{16}$.  From here, how do I construct the semi direct products?   I said, in $C_{16}$, there are two elements of order that divide $2$, which are $1$ and $2$. Therefore there are two semi direct products. Also $17 \times 2 = 34$ tells me that in both semi direct products there will be $34$ elements.  How do I construct the semi direct products from here though? How do I address unchecked cast warnings? Eclipse is giving me a warning of the following form:     Type safety: Unchecked cast from Object to HashMap   This is from a call to an API that I have no control over which returns Object:  HashMap&lt;String, String&gt; getItems(javax.servlet.http.HttpSession session) {   HashMap&lt;String, String&gt; theHash = (HashMap&lt;String, String&gt;)session.getAttribute("attributeKey");   return theHash; }   I'd like to avoid Eclipse warnings, if possible, since theoretically they indicate at least a potential code problem.  I haven't found a good way to eliminate this one yet, though.  I can extract the single line involved out to a method by itself and add @SuppressWarnings("unchecked") to that method, thus limiting the impact of having a block of code where I ignore warnings.  Any better options?  I don't want to turn these warnings off in Eclipse.  Before I came to the code, it was simpler, but still provoked warnings:  HashMap getItems(javax.servlet.http.HttpSession session) {   HashMap theHash = (HashMap)session.getAttribute("attributeKey");   return theHash; }   Problem was elsewhere when you tried to use the hash you'd get warnings:  HashMap items = getItems(session); items.put("this", "that");  Type safety: The method put(Object, Object) belongs to the raw type HashMap.  References to generic type HashMap&lt;K,V&gt; should be parameterized.