[GRASS-dev] r.mapcalc: verbose output for eval() function?

Markus wrote:

I am trying to see if an eval() function in my r.mapcalc
script does what it should. Is there a way to activate a
"verbose" mode which spits out for each pixel operation the
values of the used variables?

r.what for all layers in the calculation at a given test coord,
do the calc by hand, see if it matches? repeat until confident.

?,
Hamish