Finding cities close to one another using longitude and latitude Each user in my db is associated to a city (with it's longitude and latitude)  How would I go about finding out which cities are close to one another?  i.e. in England, Cambridge is fairly close to London.  So If I have a user who lives in Cambridge. Users close to them would be users living in close surrounding cities, such as London, Hertford etc.  Any ideas how I could go about this? And also, how would I define what is close? i.e. in the UK close would be much closer than if it were in the US as the US is far more spread out.   Ideas and suggestions. Also, do you know any services that provide this sort of functionality?  Thanks
MySQL Great Circle Distance (Haversine formula) I've got a working PHP script that gets Longitude and Latitude values and then inputs them into a MySQL query. I'd like to make it solely MySQL. Here's my current PHP Code:  if ($distance != "Any" &amp;&amp; $customer_zip != "") { //get the great circle distance      //get the origin zip code info     $zip_sql = "SELECT * FROM zip_code WHERE zip_code = '$customer_zip'";     $result = mysql_query($zip_sql);     $row = mysql_fetch_array($result);     $origin_lat = $row['lat'];     $origin_lon = $row['lon'];      //get the range     $lat_range = $distance/69.172;     $lon_range = abs($distance/(cos($details[0]) * 69.172));     $min_lat = number_format($origin_lat - $lat_range, "4", ".", "");     $max_lat = number_format($origin_lat + $lat_range, "4", ".", "");     $min_lon = number_format($origin_lon - $lon_range, "4", ".", "");     $max_lon = number_format($origin_lon + $lon_range, "4", ".", "");     $sql .= "lat BETWEEN '$min_lat' AND '$max_lat' AND lon BETWEEN '$min_lon' AND '$max_lon' AND ";     }   Does anyone know how to make this entirely MySQL? I've browsed the Internet a bit but most of the literature on it is pretty confusing.
How do I identify which Linux distro is running? We have some new hardware in our office which runs its own customized Linux OS.   How do I go about figuring which distro it's based on? Projectile/orbital motion over very long distance We know the optimum angle for greatest horizontal displacement when launching an object with projectile motion is 45 degrees.  How to solve the angle when it is real long distance around the earth where we cannot assume that gravity is constant but is given by $F=\frac {-GMm}{r^2}$. I use differetial equation to solve it and obtain 45 degrees.   First, for the vertical distance $y$, change $v=u-gt$ to $y'=u-y''t$. Then solve it to obtain a function $y(t)$. When $y'(t)=0$ we have the time for maximum vertical distance. Then insert the value to horizontal equation.   Can anyone guide me through this problem because I am not confident with my working Texture Channel animated, doesn't appear in viewport I'm creating an educational video, and for efficiency, I'm using a Cyclic repeater to repeat an on-page/off-page effect.  Every loop, I have the texture channel switch to the next image, rather than duplicating all the objects/animations. This works properly and appears when rendering the animation, but does not appear in the viewport. It sticks to the original UV image that was mapped.  Is there a way to have this change appear in the viewport? Using strtok with a std::string I have a string that I would like to tokenize. But the C strtok() function requires my string to be a char*. How can I do this simply?  I tried:  token = strtok(str.c_str(), " ");    which fails because it turns it into a const char*, not a char* Minecraft Vanilla 1.9 crash with problematic frame ig8icd64.dll Proof: How many digits does a number have? $\lfloor \log_{10} n \rfloor +1$ I read recently that you can find the number of digits in a number through the formula $\lfloor \log_{10} n \rfloor +1$ What's the logic behind this rather what's the proof? Determining true mean from noisy observations My Visual Studio (2008) Editor has stopped to underline Errors (this nifty wavy red lines). I can't really tell when, but it can be related to the installation of .Net Framework 3.5 SP 1 or the MVC Beta (which I guess is unlikely). Furthermore have I installed and uninstalled both CodeRush and Resharper for evaluation purposes (decided not to keep either one of them).  Does anyone know the problem and how to restore this functionality again? What is a simple example of an unprovable statement? If $n = 51! +1$, then find number of primes among $n+1,n+2,\ldots, n+50$ If $n = 51! +1$, Then find no of primes among $n+1,n+2,\ldots, n+50$  Really speaking, I don't have any clue ... Reclassifying raster layer with certain colors for value ranges in QGIS? I'm using QGIS. I want a raster layer with 6 different colors each color representing a certain value range (e.g. -1 to 0 red, 0 to 0.2 orange).  In the layer style menu I can only approximate colors. Usage and example of the word “litotes” I've come across the word litotes, which means a rhetorical understatement. However, I’m having trouble understanding how to use it in colloquial English. Could someone please give an example? Reference for the subgroup structure of $\rm{PSL}_2(q)$ Non-Affine image transformations in .NET Are there any classes, methods in the .NET library, or any algorithms in general, to perform non- transformations? (i.e. transformations that involve more than just rotation, scale, translation and shear)  e.g.:      (source: )      Is there another term for s? How to prove that $\lim\limits_{\epsilon\rightarrow 0}\int_{-\infty}^{\infty}f_\epsilon(x)g(x)dx=g(0)$ (Dirac delta function)) I'm currently studying the Dirac delta function using a textbook which unfortunately provides only partial solutions to its explanations. Why does $\lim\limits_{\epsilon\rightarrow 0}\int_{-\infty}^{\infty}f_\epsilon(x)g(x)dx=g(0)$ if $ f_\epsilon=\frac{1}{2\epsilon}e^{-\frac{|x|}{\epsilon}}$? Any help is very much appreciated. Fractional Scaling 18.04 LTS Excel: I need a formula that will count months between two dates. If it's 1-15 it should be a half month. Any ideas? So I am trying to find a formula for excel. Bascically I have two dates and I need to know the number of months between them. But to add complexity, I need a rule in there that if the earlier date is the 1st to 15th it will be a whole month but if it is 16th to end of the month it will be a half month.  For example: Date 1: April 4, 2012 Date 2: December 31, 2012 Answer: Number of months would be 9 months  If Date 1 was April 16, 2012, with the same Date 2 of December 31, 2012, then the number of months would equal 8.5.  Can anyone help me with this one? You help would be greatly appreciated. many thanks Is there an alternative way to express "has them " other than "makes them "? For example, in the following sentence, can I replace have them with makes them, or is there another verb that more correctly I could use instead of has?     Since the manufacturers are so deeply involved, in some cases Wal-Mart even has them handle their own distribution, saving the retailer big bucks and increasing profit margins on cheaper goods.   Another example could be the following one.     The doctor sends my father and Uncle Johnnie out for all the ice they can get. Then he has them dump the ice in the bathtub, add cold water almost to the top, whereupon my aunt is wrestled into the tub and submerged. I wrote a question about blocking certain characters in passwords. It became tremendously unpopular, and it seemed like everyone wanted to rain on my parade every day.  Eventually, I "got it," agreed completely with what people were saying to me, and just wanted to withdraw my question so that my reputation didn't slide even further downhill.  Unfortunately, the system is designed such that I can't withdraw my question or redeem myself. Instead, I just get daily reputation attacks. That's a terrible system, and it needs to be changed. When you review papers submitted for publication, is there an “optimal” length for reviews? In my experience as an author and referee, I have seen a large range of review lengths (for reference, a paper in my field is typically between 3 and 8 printed pages):   Zero length: for some of the papers I have authored, the reviewer just clicked the “accept as is” or “reject” checkmark on the review sheet, without adding any comment (at least, not any comment visible to me). It's not so common, but it has happened. Short length: a lot of time, I received reviews who consisted of a single paragraph. Medium: one full page, maybe two pages.   Although I have never received any such long reviews, I have myself written on a few occasions reviews that exceed two pages, including once or twice a four or five-page review.  These were cases where the paper was good, but could be (in my view) much improved and some of the aspects/consequences had escaped the authors' consideration.  I am wondering how useful reviews of various length are to editors. I often consider that “unmotivated” reviews are useless, as they do not give any real insight about the paper to the editor. For example, if the editor gets two conflicting non motivated reviews, how is she to decide?  On the other hand, although I write some from time to time, I have never received long reviews, so… is this something frowned upon?