获得两个GPS坐标之间的距离
private double gps2m(float lat_a, float lng_a, float lat_b, float lng_b) {
float pk = (float) (180/3.14169);
float a1 = lat_a / pk;
float a2 = lng_a / pk;
float b1 = lat_b / pk;
float b2 = lng_b / pk;
float t1 = FloatMath.cos(a1)*FloatMath.cos(a2)*FloatMath.cos(b1)*FloatMath.cos(b2);
float t2 = FloatMath.cos(a1)*FloatMath.sin(a2)*FloatMath.cos(b1)*FloatMath.sin(b2);
float t3 = FloatMath.sin(a1)*FloatMath.sin(b1);
double tt = Math.acos(t1 + t2 + t3);
return 6366000*tt;
}
