There is plenty unknown about how to use raster calculator, for example:
- how to write NODATA (Null) value in expression
- is it possible to use within (polygonLayerName) to clip result
- between shown operators there is even "not equal" symbol, you need to find yourself it is "!=" etc.
Generally is there any manual/help/tutorial to QGIS raster calculator describing what is and is not possible to do with it?