return dx and dy for a survey course.
arguments:
- course (string)
a survey course in the following format: bearing:length where bearing is (+-)?[NSEW]dd.mm.ss[NSEW] (optional + or -, followed by N, S, E or W, followed by degrees minutes and seconds, followed by N, S, E, or W) and length is in feet, or some other linear measure
results:
- returns list [dx, dy] relative change in x and y with respect
to north (x along WE direction, y along SN direction)
example:
>>> from decida.surveycourse2vector import surveycourse2vector
>>> dx, dy = surveycourse2vector("N40.21.00W:305.53")
>>> print dx, dy
-197.816952676 232.845515598
>>> dx, dy = surveycourse2vector("N00.00.00E:100.00")
6.12323399574e-15 100.0