计算轴承误差

Question

这是我正在使用的公式：

 double lat1 = [self getRadiansFromDegress:self.LocationLatitude];
    double lat2 = [self getRadiansFromDegress:PointOfInterest.latitude];

    double x = sin(lonDiff) * cos(lat2);
    double y = cos(lat1)*sin(lat2) - sin(lat1)*cos(lat2)*cos(longDiff);

    double bearingRad = atan2(x,y);
    double bearingDeg = [self getDegreesFromRadians:bearingRad];
    NSLog(@"Bearing: %f", bearingDeg);

对于lat1 = 30.61

lat2 = 30.620954

lon1 = -96.342

lon2 = -96.345238

longDiff = -0.003238

根据这个网站：http://www.yourhomenow.com/house/haversine.html我应该得到大约345度，但我的代码返回-86.028010度。谁能明白为什么会这么不同呢？

Answer 1

在atan2你交换了x和y。 正确的顺序是y，x：

正确

double bearingRad = atan2(y, x);

另见：

#include <math.h>
double atan2( double y, double x );