c实现utm转wsg84

以下是一个简单的C语言代码示例，用于将UTM坐标转换为WGS84经纬度坐标。

#include <stdio.h>
#include <math.h>

#define PI 3.14159265358979323846

double deg2rad(double deg) {
    return (deg * PI / 180);
}

double rad2deg(double rad) {
    return (rad * 180 / PI);
}

void utm2wgs84(double utm_x, double utm_y, int zone, int southhemi, double *lat, double *lon) {
    double k0 = 0.9996; // UTM缩放因子
    double a = 6378137.0; // WGS84椭球体长半轴
    double f = 1/298.257223563; // WGS84椭球体扁率
    double b = a * (1 - f); // WGS84椭球体短半轴
    double e = sqrt(1 - (b/a)*(b/a)); // WGS84椭球体第一偏心率
    double e2 = e*e; // WGS84椭球体第二偏心率
    double x = utm_x - 500000.0; // 计算相对于中央经线的偏移量
    double y = utm_y;
    if (southhemi) {
        y -= 10000000.0; // 南半球情况下，将y坐标减去10000000
    }
    double s = zone * 6.0 - 183.0; // 计算中央经线的经度
    double lat1 = y / (k0 * a);
    double M = lat1 / (1 - e2/4 - 3*e2*e2/64 - 5*e2*e2*e2/256); // 计算子午线弧长
    double mu = M / (a * (1 - e2/4 - 3*e2*e2/64 - 5*e2*e2*e2/256)); // 计算子午线曲率半径
    double phi1 = lat1 + (3*e2/8 - 27*e2*e2/128) * sin(2*lat1) + (21*e2*e2/256 - 55*e2*e2*e2/1280) * sin(4*lat1) + (151*e2*e2*e2/6144) * sin(6*lat1);
    double tan_phi1 = tan(phi1);
    double cos_phi1 = cos(phi1);
    double sin_phi1 = sin(phi1);
    double N1 = a / sqrt(1 - e2*sin_phi1*sin_phi1);
    double T1 = tan_phi1*tan_phi1;
    double C1 = e2*cos_phi1*cos_phi1/(1 - e2);
    double R1 = a*(1 - e2)/pow(1 - e2*sin_phi1*sin_phi1, 1.5);
    double D = x / (N1*k0);
    double lat = phi1 - (N1*tan_phi1/R1) * (D*D/2 - (5 + 3*T1 + 10*C1 - 4*C1*C1 - 9*e2)*D*D*D*D/24 + (61 + 90*T1 + 298*C1 + 45*T1*T1 - 252*e2 - 3*C1*C1)*D*D*D*D*D*D/720);
    double lon = s + (1/(cos_phi1*N1*k0)) * (D - (1 + 2*T1 + C1)*D*D*D/6 + (5 - 2*C1 + 28*T1 - 3*C1*C1 + 8*e2 + 24*T1*T1)*D*D*D*D*D/120);
    *lat = rad2deg(lat);
    *lon = rad2deg(lon);
}

int main() {
    double x = 398462;
    double y = 3987679;
    int zone = 50;
    int southhemi = 0;
    double lat, lon;
    utm2wgs84(x, y, zone, southhemi, &lat, &lon);
    printf("WGS84坐标：(%f, %f)\n", lat, lon);
    return 0;
}

注意，该代码仅适用于UTM投影下的WGS84椭球体。如果您需要将其他椭球体或其他投影系统下的坐标转换为WGS84坐标，请使用适当的算法和参数。