[GRASS5] [bug #3704] (grass) d.rast.arrow does not save a line in the monitor history

[Hamish]

Hi,

It is my feeling that magnitudes must be positive; other cases are
ambiguous.

If negative or NULL magnitudes are found, an error is written if you
have debug turned on high (g.gisenv). My test map was negative
bathymetry and the warning messages were too many for everyday use.

an example of U,V data to polar coordinates will be given in the help
page.

r.to.vect(line) then d.rast.arrow of a river flow + accum. would be
interesting as it only draws arrows on non-null data.

hope that covers questions, I'm in a rush to get off to the the fjords
for a few days.


Hamish