compass bearing from vector

[Kelly Elder]

requesting help for netless friend:

a colleague has a file of coordinates for start and stop x,y's
for a number of lines.  she wants a shell script that gives
her back compass bearings (what i call azimuths) for each pair
of coordinates.

given:
	x1 y1	X1 Y1
	x2 y2	X2 Y2
	x3 y3	X3 Y3
	-- --   -- --
	-- --   -- --
	xN yN	XN YN

she wants:

	x1 y1	X1 Y1   12
	x2 y2	X2 Y2   272
	x3 y3	X3 Y3   315
	-- --   -- --   --
	-- --   -- --   --
	xN yN	XN YN   52


better yet, would be a mouse program that lets her click on a
given displayed vector and produces an azimuth for the line
of choice.

seems the shell script would be simple to write in awk, but i
don't have the time.  seems the mouse program would be a pain
to write and i don't have the ability.  i would guess it has
already been done, or is part of the military grass modules.
seems like the bazooka folks would want this capability too.

please send any possibilities to me at:

	kelly at icess.ucsb.edu

thanks for your time!

kelly