[GRASSLIST:9202] Re: vector map

[Glynn Clements]

andrea pastino wrote:

> Maybe i made a silly question : given A and B distance
> is sqrt( (xa-xb)^2 + (ya - yb)^2 ) but i wanted to
> know if i need any correction parameter. 
> i still don't manage to compute distances in grass.
> thank you very much and sorry for new mail

For small distances, the plane distance (Pythagoras) is adequate. For
longer distances, you have to convert the coordinates to lat/lon and
compute the geodesic (great circle) distance.

Look at the functions in lib/gis/geodist.c for reference.

-- 
Glynn Clements <glynn at gclements.plus.com>