[GRASS5] Angle of Line Function?

[Jeshua Lacock]

Greetings,

I would greatly appreciate any help with developing a simple function 
that returns the angle (in degrees) of a line when given two points 
(x1, y1 and x2, y2).

Embarrassingly I have spent days trying to figure this out (that's 
what I get for using the teachers edition of geometry in high 
school!!).  ;->

I have ran across a function on the web, but somehow it seems really off:
     angle = (((Atan((northingDifference/eastingDifference)))*180)/PI)

The points that I am using are UTM coordinates.

I realize that this may seem slightly of topic, however I will 
contribute the developed module when I am done.  I figure that this 
function should be a piece of cake for all of you brilliant people 
out there.

An example set of coordinates are:

  x1  = 265,000
  y1  = 4,155,000

  x2 = 305,000
  y2 = 4,154,000


Thanks,
Jeshua Lacock
Cartographer/Owner
http://SierraMaps.com
http://3dTopoMaps.com
Telephone: (760) 935-4481

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