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/** * Created by Wandergis on 2015/7/8. * provided Baidu coordinates (BD09), geodetic coordinates (MARS coordinates, GCJ02), and WGS84 coordinate system between the conversion *///define some constants var X_pi = 3.14159265358979324 * 3000.0/180.0;var PI = 3.1415 926535897932384626;var a = 6378245.0;var ee = 0.00669342162296594323;/** * Baidu coordinate system (BD-09) and Mars coordinate system (GCJ-02) conversion * That is, Baidu to Google, high De * @param bd_lon * @param bd_lat * @returns {*[

/** * Provides the conversion between Baidu coordinates (BD09), National geodetic coordinates (MARS coordinates, GCJ02), and WGS84 coordinate system*///Define some constantsvarX_PI = 3.14159265358979324 * 3000.0/180.0;varPI = 3.1415926535897932384626;varA = 6378245.0;varEE = 0.00669342162296594323;/** * Baidu coordinate system (BD-09) and Mars coordinate system (GCJ-02) conversion * That is, Baidu to Google, German * @param bd_lon * @param bd_lat * @returns {*[]}*/functionbd09togcj02 (Bd_lon, Bd

With the advent of LBS applications, it is particularly important to implement location-based search in databases. First, design a simple data table to store latitude and longitude information: CREATE TABLE `index` ( `id` int(11) NOT NULL AUTO_INCREMENT, `lat` double NOT NULL, `lng` double NOT NULL, PRIMARY KEY (`id`)) ENGINE=MyISAM DEFAULT CHARSET=utf8; After the creation is complete, we can check whether it looks like this. mysql> desc `index`;

Tags: tsp otto vma LVM DDN ref dem AAAAA DVRBased on user coordinates, locate the nearest merchant to the database:Using the TP framework/*** Four points of a square that calculates the distance around a certain latitude and longitude* Earth radius with an average radius of 6371km* @param LNG float longitude* @param lat float latitude* @param distance Float the radius of the circle in which the point is located, the circle is tangent to this square, a

short-circuit current. It has a well-developed Arc Extinguishing structure and sufficient cut-off capability. 5. load switch: the construction of the load switch is similar to that of the classified isolation switch, but a simple arc extinguishing device is installed. It also has an obvious disconnection point, with a certain degree of cut-off capability, can be operated with load, but cannot directly disconnect the short-circuit current, if needed, it depends on the High-Voltage Fuses connecte

data is as follows: {"Results": [{"address_components": [{"long_name": "1178", "short_name": "1178", "types ": ["street_number"] },{ "long_name": "Heping Avenue", "short_name": "Heping Avenue", "types": ["Route"]}, {"long_name": "Wuchang District", "short_name": "Wuchang District", "types": ["sublocality", "political"] },{ "long_name ": "Wuhan", "short_name": "Wuhan", "types": ["locality", "political"] },{ "long_name": "Hubei Province", "short_name ": "Hubei Province", "types": ["administrativ

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Search for nearby locations, for example, within 500 meters of coordinates (39.91, 116.37), first figure out the range of coordinates for the "500 meters near the given coordinates". Although it is a circle, we can first find out the circle's external square, and then take the square latitude and longitude range to search the database. The red part is the required search scope, and the green part is the actual search scope./** * Get around coordinates * Enter description here ... * @param unknow

spherical calculation formulas on wiki Wikipedia: Great-circle distance Haversine formula Assume that the latitude and longitude of the known points are $lng, respectively $latThe query that implements the Longitude range first,To make φ1 =φ2 in the Haversin formula, you get:The calculation in PHP is:/$lat The latitude of the known point $dlng = asin(sin($distancecos( Deg2rad ($lat))); $DLNG rad2deg ($dlng); // Convert radiansThen