[GRASS-user] Error with r.mapcalc

[António Rocha]

I have a Python script with the following:
   # Conversion to at-sensor brightness temperature       
    grass.mapcalc("$raster_file= $K2/log(($K1/$L)+1)", 
raster_file=raster_file, K2=K2, K1=K1,L= tempL)
    grass.mapcalc("$raster_file= if($raster_file < 0, null(), 
$raster_file)", raster_file=raster_file)

When it runs the second grass.mapcalc I get the following error:
ERROR: Unable to close raster map
ERROR: An error occurred while running r.mapcalc

Why am I obtaining this error? and How can I avoid it?
Thanks
Antonio



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