[GRASS-dev] calculating bearing

[Michael Barton]

Thanks. I've incorporated this into the measurement tool for wxgrass (for
non-latlon regions).

Michael


On 5/16/07 1:40 AM, "Hamish" <hamish_nospam at yahoo.com> wrote:

> Michael Barton wrote:
>> 
>> Is there a simple formula to calculate bearing if you have the
>> beginning xy of a line and the ending xy of the line?
> 
> trig:  angle = atan(y/x)    [or atan2()]
> 
> see Glynn's warnings in the archives about that going undefined at places.
> 
> see also:
>   g.manual m.cogo
> 
> it gets ugly with lat/lon great circle calculations as the bearing isn't
> steady. (but there are map projections that help with that)
> 
> I've got some matlab functions for doing this if m.cogo isn't your cup
> of tea.
> 
> 
> Hamish

__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton