[GRASS-user] Rotate Raster (DEM) 90 degrees

[pierluigi de rosa]

Dear Grass user,

In order to use a cellular automata model to simulate a landscape
evolution I should use (because the code require it) a DEM where the
main water flow goes from left to right. I want to use this code to
simulate an area where the water comes from north to south so I have to
rotate the DEM of 90 degrees.
Does anyone know how can I do it?
I found on web this project
http://www.thedigitalmap.com/~carlos/dm4dem_en.html
that seems do it...
did anyone use it before? If yes could you explain me how to install it?
I didn't find...
Thanks

Pierluigi