[GRASSLIST:10515] topidx calculation

[Wouter Buytaert]

Hi list,

I've got some problems with r.topidx.

I've used both normal elevation maps and preprocessed (with r.fill.dir) 
depressionless elevation maps, but the resulting topidx map is full of 
artifacts

- a lot of -10 values in the resulting topidx map
- with some elevation maps, a kind of gridlike raster pattern is produced, 
with a background of NULL values and a grid consisting of both -10 and 
positive values.

Any ideas?

cheers
wouter