Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
//License from project: Apache License 

public class Main {
    private static final double RAD_PER_DEG = Math.PI / 180.0;
    private static final double EARTH_RADIUS_METERS = 6367000.0;

    public static double fastDistanceMeters(double latRad1, double lngRad1, double latRad2, double lngRad2) {
        if ((Math.abs(latRad1 - latRad2) > RAD_PER_DEG) || (Math.abs(lngRad1 - lngRad2) > RAD_PER_DEG)) {
            return accurateDistanceMeters(latRad1, lngRad1, latRad2, lngRad2);
        }
        // Approximate sin(x) = x.
        double sineLat = (latRad1 - latRad2);

        // Approximate sin(x) = x.
        double sineLng = (lngRad1 - lngRad2);

        // Approximate cos(lat1) * cos(lat2) using
        // cos((lat1 + lat2)/2) ^ 2
        double cosTerms = Math.cos((latRad1 + latRad2) / 2.0);
        cosTerms = cosTerms * cosTerms;
        double trigTerm = sineLat * sineLat + cosTerms * sineLng * sineLng;
        trigTerm = Math.sqrt(trigTerm);

        // Approximate arcsin(x) = x
        return EARTH_RADIUS_METERS * trigTerm;
    }

    public static double accurateDistanceMeters(double lat1, double lng1, double lat2, double lng2) {
        double dlat = Math.sin(0.5 * (lat2 - lat1));
        double dlng = Math.sin(0.5 * (lng2 - lng1));
        double x = dlat * dlat + dlng * dlng * Math.cos(lat1) * Math.cos(lat2);
        return (2 * Math.atan2(Math.sqrt(x), Math.sqrt(Math.max(0.0, 1.0 - x)))) * EARTH_RADIUS_METERS;
    }
}