Since QGIS graphical modeler calculator did not lead to an answer, I'll try my luck here again. I created a simple model in QGIS 2.18.16 that shall calculate a distance based on the extent of a raster and a given number of divisions, set by the user as a parameter. Basically it shall resemble the Fishnet-tool from ArcGIS. The model looks like this:
The description in the calculator tells me the following:
According to this, I set up my formula like:
(e - d) / b # this should give me the segment length (g - f) / a # this should give me the segment height
The Log from the model run then gives me the following error message:
Parameters: FORMULA =(g-f)/a, NUMBER0 =2, NUMBER1 =3125884.941, NUMBER2 =3135324.941, NUMBER3 =None, NUMBER4 =None, NUMBER5 =None, NUMBER6 =None, NUMBER7 =None, NUMBER8 =None, NUMBER9 =None Failed Error executing algorithm Calculator Wrong formula: (None-None)/2
Unfortunately, the Documentation is empty. Can anyone tell me how to set up the variables correctly?