[GRASS-user] how to use r.mapcalc in GRASS

[Markus Neteler]

Hello Marion,

On Mon, Jul 2, 2018 at 12:18 PM, marion-brunet <marion-brunet at sfr.fr> wrote:
> Hello,
>
> I am trying to calculate the difference between two raster layers. For that,
> I am using GRASS in QGIS. I use the command r.mapcalc. In the field
> "expression to evaluate" I wrote
> r.mapcalc expression=diff =TIN_12_17-TIN_06_18

be sure to have white spaces around the - (minus)

TIN_12_17-TIN_06_18
--> TIN_12_17 - TIN_06_18

and, as Vero wrote, perhaps quotes. So, pls try:

r.mapcalc expression="diff =TIN_12_17 - TIN_06_18"

Best,
Markus