Why is the speed of light in vacuum a universal constant?
If all motion is relative, how does light have a finite speed?
Word to describe someone who goes to all the events in town! I would like to create a XeLaTeX layout where  multicol's columns (two in this case, no figures, text only) are tilted where they meet. The lines still should be ordinary lines below each other, but the start/end points of each line should glide a bit each line for it to look something like this:  xxxxxxxxxx  xxxx xxxxxxxxxx  xxxx xxxxxxxxx  xxxxx xxxxxxxxx  xxxxx SECTION   xxxxxx xxxxxxxx  xxxxxx xxxxxxx  xxxxxxx xxxxxxx  xxxxxxx xxxxxx  xxxxxxxx xxxxxx  xxxxxxxx xxxxx  xxxxxxxxx xxxxx  xxxxxxxxx xxxx  SUBSECTION xxxx  xxxxxxxxxx   So not the whole column is tilted, but one gets narrower while the other one gets wider.  I've seen examples using \parshape, but those I found are based that one counts lines and more or less manually defines the shape. I also would need that LaTeX keeps the multicol functionality (page breaks, text flow, ...) and does this automatically on each page for a longer chapter.  How do I create such a layout? If multicol is not easy to mix with this layout, what would be an alternative? What is happening here, when I use squared loss in logistic regression setting? I am trying to use squared loss to do binary classification on a toy data set. I am using mtcars data set, use mile per gallon and weight to predict transmission type. The plot below shows the two types of transmission type data in different colors, and decision boundary generated by different loss function. The squared loss is $\sum_i (y_i-p_i)^2$ where $y_i$ is the ground truth label (0 or 1) and $p_i$ is the predicted probability $p_i=\text{Logit}^{-1}(\beta^Tx_i)$. In other words, I am replace logistic loss with squared loss in classification setting, other parts are the same. For a toy example with mtcars data, in many cases, I got a model &quot;similar&quot; to logistic regression (see following figure, with random seed 0).  But in somethings (if we do set.seed(1)), squared loss seems not working well.  What is happening here? The optimization does not converge? Logistic loss is easier to optimize comparing to squared loss? Any help would be appreciated.  Code d=mtcars[,c(&quot;am&quot;,&quot;mpg&quot;,&quot;wt&quot;)] plot(d$mpg,d$wt,col=factor(d$am)) lg_fit=glm(am~.,d, family = binomial()) abline(-lg_fit$coefficients[1]/lg_fit$coefficients[3],        -lg_fit$coefficients[2]/lg_fit$coefficients[3]) grid()  # sq loss lossSqOnBinary&lt;-function(x,y,w){   p=plogis(x %*% w)   return(sum((y-p)^2)) }  # this random seed is important for reproducing the problem set.seed(0)  x0=runif(3) x=as.matrix(cbind(1,d[,2:3])) y=d$am opt=optim(x0, lossSqOnBinary, method=&quot;BFGS&quot;, x=x,y=y)  abline(-opt$par[1]/opt$par[3],        -opt$par[2]/opt$par[3], lty=2) legend(25,5,c(&quot;logisitc loss&quot;,&quot;squared loss&quot;), lty=c(1,2)) How to make git mark a deleted and a new file as a file move? How to retrieve multiple rows from database in PHP For instance if me and my friend had a Pidgeot and we powered them all the way up. Could mine end up with like 525 and his at like 500? 12 hours delay with ATmega16A I am trying to turn on a LED for 5sec every 12 hours. I tried:  #include &lt;mega16.h&gt; #include &lt;delay.h&gt;  void main(void) {     DDRC.0 = 1;     PORTC.0 = 0;      while(1)     {              unsigned long i;        unsigned long j;        PORTC.0=1;         for(i=1; i&lt;432; i++)        {              delay_ms(100);          }         PORTC.0 = 0;         for(j=1; j&lt;100; j++)        {            delay_ms(50);          }     } }   but the LED was on for about 2 hour every week. A relative managed to change her password, yet can not input the correct password.  She does not want to reset the phone to avoid loss of data (pictures, contacts, messages, etc.).  Will the phone eventually stop accepting logon attempts? How should I determine whether a deck is legal in a particular format? I have a list of cards for a deck I want to build or buy. What should I do to check whether that deck is legal in a particular format (Standard, for example)? How do the Hat Dash points work? How could I adjust the size and placement of chapter heading in my custom class? I am using report class as my base. When I used titlesec package inside my custom class, it threw error     ! Package titlesec Error: Not allowed in `easy'   settings. Natural Sounding Text to Speech? I want to kill a whole process tree.  What is the best way to do this using any common scripting languages? I am looking for a simple solution. Restore All Databases Script I am migrating SQL Server DBs to a new instance.  I have been told that it is possible to dynamically build a RESTORE script from available backups in the system catalog.  Does anyone know of a sample script to do this?  Thanks! Looking for way to copy first line of text file to end of every line "Do you want to continue[Y/n]?" Why the upper case? I am new to Ubuntu and some little thing start to bug me. Such as when trying to install a program, Ubuntu asks,     Do you want to continue[Y/n]?   What is bugging me is why the letter "Y" is upper case and "n" is lower case. Do they have any significant reason why one is upper and the latter is lower? Whatever case I enter it doesn't change the outcome: it either continues or not. Are they trying to notify us that we can enter both and it won't change anything? error in count script for number of occurences Underfull \hbox in bibliography I am getting lots of "Underfull \hbox" warnings that point to the *.bbl file. It looks like these messages appear only when URLs are very long, like in the below example:  @techreport{nistguidesec,   author    = {Wayne Jansen and Timothy Grance},   title     = {Guidelines on Security and Privacy in Public Cloud Computing},   month    = {January},   note     = {Draft Special Publication 800-144. Available at \url{http://csrc.nist.gov/publications/drafts/800-144/Draft-SP-800-144_cloud-computing.pdf}}, }   In the produced PDF text is correctly hyphened and links are correctly split over several lines (I am using hyperref package)  How can I avoid annoying warning messages about "underfull \hbox" pointing to bibliography? What is the Unix command to create a hardlink to a directory in OS X? How do you create a hardlink (as opposed to a symlink or a Mac OS alias) in OS X that points to a directory? I already know the command "ln target destination" but that only works when the target is a file. I know that Mac OS, unlike other Unix environments, does allow hardlinking to folders (this is used for Time Machine, for example) but I don't know how to do it myself. Trouble with batch conversion of .png to .pdf using convert