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How to calculate the distance between two points using GEODIST?
Article Introduction：GEODIST is a function used to calculate the straight line distance between two points on the earth. Before using it in Stata, it is required to install: sscinstallgeodist. 1. When using it, you need to specify the latitude and longitude parameters of the two points, such as geodistlat1lon1lat2lon2,gen(distance_km) to generate a unit distance of kilometers; 2. If you need a unit of miles, add the mile option; 3. Pay attention to ensuring that the latitude and longitude is in the decimal system format, the range is legal and the order of variables is correct; 4. During batch calculation, you can copy the reference point to all lines and execute the command. This method is suitable for store location selection, traffic analysis and other scenarios.
2025-09-08
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771
Implementing the Haversine Formula in PHP for Geospatial Distance Calculation
Article Introduction：To calculate the distance between two points on the earth, use the Haversine formula instead of the plane geometry, because the earth is approximately a sphere. 1. The Haversine formula calculates the distance of the large circle by latitude and longitude (converted to radians). The formula is: a=sin2(Δφ/2) cosφ??cosφ??sin2(Δλ/2), c=2?atan2(√a,√(1?a)), d=R?c, where R is the average radius of the earth (6371 kilometers). 2. When implemented in PHP, first convert the latitude and longitude from the decimal system to radians, calculate the difference, substitute the formula to find the distance, and select the units of kilometers or miles through the parameters. 3. Use examples to show that the distance between New York and Los Angeles is about 3944 kilometers or 2451 miles. 4. Note
2025-07-30
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935
