[GRASS-dev] r.mapcalc division by 0

[Glynn Clements]

Helena Mitasova wrote:

> I noticed that the man page for r.mapcalc gives confusing
> information about division by 0. It says:
> 
> Division by 0 and modulus by 0 are acceptable and give a 0 result.
> 
> but later on:
> Division by zero should result in NULL.
> 
> I tried it and the second is true (it results in NULL)
> 
> And then there is an example
> 
> To produce a binary representation of the raster map layer a so that  
> category 0 remains 0 and all other categories become 1:
> mask = a/a
> 
> but what you get is a map with 1 and NULL.
> 
> I assume these are leftovers from pre-NULL times?

Most likely. Fixed in CVS.

-- 
Glynn Clements <glynn at gclements.plus.com>