[GRASSLIST:807] Eliminating negative values on raster image

[Tim De Chant]

I have a raster map with negative values in it that I'd like to  
eliminate.  I know the values should not be negative, and I'd like to  
change any negative value to zero.  I have looked through the map  
calculator (r.mapcalc) to see if I could create an expression that  
would create such a map but haven't had any luck.  Could anyone help  
me out with writing one?  Thanks.

Tim
__________________________________________
Tim De Chant
     University of California, Berkeley
     Environmental Science, Policy, and Management
     137 Mulford Hall #3114
     Berkeley, CA 94720-3114
     (510) 643-3910