incremental $R^2$ update at every new sample
Efficient online linear regression
Connecting GSM SIM900A module with Ardunio I have bought an SIM900A Mini V4 GSM module. Here is the module,   I want to configure with arduino to send and receive SMS.   Do I have to connect TXD of this module--Tx of Arduino &amp; RXD of this module--Rx of Arduino or other way around?  There is no datasheet or documents on this new module.  When I search about RXD &amp; TXD, I found this in      TxD means "Data to be transmitted over the comms link" - which will clearly be an input to the modem;    Similarly, RxD means "Data that has been received from the comms link" - which will clearly be an output from the modem.    But I couldn't send or receive SMS using this configurations.  As I am new to this, It would be very helpful if anyone help on this.  Thank you in advance. Can I call a constructor from another constructor (do constructor chaining) in C++? As a  developer I'm used to running through constructors:    class Test {     public Test() {         DoSomething();     }      public Test(int count) : this() {         DoSomethingWithCount(count);     }      public Test(int count, string name) : this(count) {         DoSomethingWithName(name);     } }   Is there a way to do this in C++?  I tried calling the Class name and using the 'this' keyword, but both fail. Calculate work done by a hovering helicopter over time This is likely to be very simple, but...  How does one calculate work done by a hovering unmoving aircraft over time?  As in work in Joules.  In this scenario, to remain hovering the aircraft has to exert a force that counters gravity (which would be its mass times G, pointing in opposite direction of gravitational pull).  However, work is defined as newton per meter, and the aircraft does not move.  Meanwhile the battery charge or fuel is going to be expended, so the energy is spent.  The other question here:   is dealing with conservation energy and not calculating drain/work performed by hovering. Ease up on the Hot Network Question Randomness Whenever I refresh Stack Exchange sites or go to a question, the Hot Network Question list items are re-listed or re-ordered, quite dramatically it seems.  This seems like a .  It's actually a bit maddening to me to see the list change so frequently (or clearly I am refreshing too often or looking at it too much :-).  I understand the need to keep the list updated, but can the items in the list hold their positions a little more consistently?  The hot items can't be changing that fast. Does an unplugged hard drive used for data archival deteriorate? If I were to archive data on a hard drive, unplug it, and set it on a (not dusty, temperature-controlled) shelf somewhere, would that drive deteriorate much?  How does the data retention of an unplugged hard drive compare to tapes? Run command on another(new) terminal window I set a command block to /tp. It was supposed to activate only if you had 0 time left, and to activate the command block with a hopper clock to keep giving it power.   But it is not checking if you have 0 time left, so it keeps teleporting me. I can't get close enough to the command block to break it, so I'm stuck in a neverending teleport loop.  Any ideas? Modify a shape and have modifications apply to clones Is there any any "Symmetry Modifier" option in illustrator?   Let's say I want to create a head that is totally symmetric. I created one half then mirrored it to get another half. Flipped the other half, aligned them and joined them together with Pathfinder→Unite option.   Now I modified some portion of the right half outline. But how can I get that same modification to be updated on the left option? I thought it would happen automatically. A Python module and package loading confusion How to create SQL like composite key I have an object in which there are two fields i.e Phone no. &amp; email. The combination of these fields should be unique Right now I can create just one unique field But I want their composite to work like a unique field.   I know that I can create composite key in SQL but I dont know how to achieve this in salesforce. How to collapse unused parameters in moderncv? I am writing my CV using the moderncv package. I already have adjusted the CV to meet my needs. Therefore I amplified the maximum number of parameters possible in the \cventry command. However, now I have some ugly spacing in case I do NOT use all parameters (see second \cventry in the MWE for illustration):  Any suggestions to make the spacing collapse in case not all parameters are occupied? As you can see from the MWE I already have adjusted for \ifthenelse command. I use texlive 2014.  \documentclass[11pt,a4paper,sans]{moderncv} \moderncvstyle{banking} \moderncvcolor{blue} \usepackage[scale=0.7]{geometry} \name{John}{Doe} \title{Resume title} \address{street and number}{postcode city}{country} \phone[mobile]{+1~(234)~567~890}  \renewcommand*{\cventry}[9][.4em]{%  \begin{tabular*}{\textwidth}{l@{\extracolsep{\fill}}r}%  \ifthenelse{\equal{\bfseries #4}{}}{}{{\bfseries #4}} &amp; \ifthenelse{\equal{\bfseries #5}{}}{}{{\bfseries #5}} \\%   \ifthenelse{\equal{\itshape #3}{}}{}{{\itshape #3\ifthenelse{\equal{#6}{}}{}{, #6}}} &amp; \ifthenelse{\equal{\itshape #2}{}}{}{{\itshape #2}}\\%  \ifthenelse{\equal{#7}{}}{}{{#7}} &amp; \ifthenelse{\equal{#8}{}}{}{\\ {#8} &amp; \\}% \end{tabular*}%  }  \begin{document} \makecvtitle \section{Education} \cventry{Grade}{Degree}{Institution}{year--year}{M.Sc.}{Majors}{Majors}{} \cventry{}{Degree}{Institution}{City}{}{}{}{} \cventry{year--year}{Degree}{Institution}{City}{Grade}{Majors}{Majors}{} \end{document} How can I center a too wide table? I've been at this for almost two hours and no one seems to have the same problem as I and I doubt this will be solved but I'll try anyway.  this is the code  /tellraw @p ["Would you like to teleport?",{"text":"Yes","color":"green","bold":"true","clickEvent":{"action":"run_command","value":"/tp @p ~ ~4 ~ "},"hoverEvent":{"action":"show_text","value":{"text":"Confirm"}},{"text":"No","color":"red","bold":"true","clickEvent":{"action":"run_command","value":"/tellraw @p{"text":"Come back when you want to teleport"}"}}}]   this part is fine  /tellraw @p ["Would you like to teleport?",{"text":"Yes","color":"green","bold":"true","clickEvent":{"action":"run_command","value":"/tp @p ~ ~4 ~ "},"hoverEvent":{"action":"show_text","value":{"text":"Confirm"}}   it's just when I add this  ,{"text":"No","color":"red","bold":"true","clickEvent":{"action":"run_command","value":"/tellraw @p{"text":"Come back when you want to teleport"}"}}}]   Minecraft gives me the error:     Invalid JSON at line 1 column 203   I've tried to space it out and figure out what column 203 is but I can't, I don't know what I did. Anyone got any ideas? Can a Windows virus transfer to Ubuntu? Unable to change privacy settings upon install of Ubuntu 18.04 LTS Ubuntu 17.10 and later: can't change the input switching shortcut to alt+shift When I try to set the default combo for switching to different language layouts in my keyboard from Shift+Super+Space to Alt+Shift I can't.  I used to have this combo since Ubuntu 14 and even before that when I used to have Windows. Now for some stupid reason it does not allow (actually nothing happens its not like I get an error or the combo is used elsewhere). How could I bypass this bug? How to read a text file into GNU R with a multiple-byte separator? Editing a question with only a JSFiddle link does not work I can't edit a question that has a jsfiddle link because it has a lack of code. Can we get privileged users able to bypass restriction? The question had some really poor formatting and linking and I couldn't fix it. :  Html is not taking the css code Some of my html tags are not reacting by the css which i gaved them for example is offerbox not reaction to the html part. all html parts down from offerbox are not taking the styles that i gaved the enter code here http://jsfiddle.net/8Bw7M/  pic from the html and css  I feel that as a privileged user, I should be able to make the changes needed. This is related, but I'm not adding any new links. Purpose of hole in stove leading to oven I'm staying in a hotel and have access to a "electric coil stove" for one of the first times.  I accidentally turned on the oven light and saw that the light was shining up through only one of the stoves:    There's only a port from the oven into the top right stove, and note that the stove is not on.  Here's a view from within the oven:    Is there a hole here as a vent for the oven for some reason, or is this for the stove? I typically use a glass "flat-top stove" that doesn't have an oven underneath it. I've never seen a direct hole from a stove to the oven before, and have to wonder what the purpose is. closed form for $\binom{n}{0}+\binom{n}{3}+\binom{n}{6}+...+\binom{n}{n}$