[GRASS-user] r.mapcalc: compare two maps

[Rich Shepard]

   I want to compare two raster maps for any differences. The r.mapcalc
expression I used yielde no results ... unless getting the GRASS shell
prompt means there are no differences.

   Command and result:
> r.mapcalc "mapdiff = blocked_culvert - open_culvert"
>

   No differences? Wrong syntax?

TIA,

Rich