raster comparison

Hi Grass users,

What's the best way to compute the RMS between two raster maps ?
Is there another way to compare 2 raster maps with a global index ?
The raster maps are supposed to be continuous, such a DEM,
(and not discontinuous such a classified map).

Thank's a lot

--
Francois DELCLAUX
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UMR HydroSciences Montpellier
BP 5045 34032 Montpellier Cedex FRANCE
http://www.mpl.ird.fr/hydrologie/mevhysa
mailto: delclaux@msem.univ-montp2.fr
Tel : (33) (0)4 67 14 90 11 Fax : (33) (0)4 67 14 47 74
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