calculating a gps coordinate given a point, bearing and distance

Question

I have a problem which draws my back in some project for some time now.

I\'m basically looking to trap a polygon using x,y points drawn by some script I\'ve written. lat1

Answer 1

The sin and cos functions expect their arguments in radians, not in degrees. The asin and atan2 functions produce a result in radians, not in degrees. In general, one needs to convert input angles (lat1, lon1 and bearing) from degrees to radians using math.radians() and convert output angles (lat2 and lon2) from radians to degrees using math.degrees().

Note that your code has two other problems:

(1) It doesn't allow for travel across the 180-degrees meridian of longitude; you need to constrain your answer such that -180 <= longitude_degrees <= +180.

(2) If you are going to use this function extensively, you might like to remove the redundant calculations: sin(lat1), cos(dr), cos(lat1), and sin(dr) are each calculated twice.