r.mapcalc - numerical size limits?

[Keith Mitchell]

I have two maplayers with the following 
values in a corresponding cell:

layer		value
s.acc.p1a	15358027
w.acc.p1a	2452453

using the following command:

r.mapcalc 'test3=(w.acc.p1a*1000/s.acc.p1a)'

produces the following value in the cell

	"-119"

Why? - what are the limitations on numerical size.
In particular I have a number of pairs of map layers,
generated by the same set of equations that should,
mathematically, have the same ratios but do
not.  If GRASS has a numerical size constraint I would
like to know because it seems that the ratios are correct
until the numerical values get high.

GRASS 4.0
Sparc IPX
Keith M. Mitchell
University of Illinois
Department of Agronomy
1102 S. Goodwin Ave.
Urbana, Il. 61801
(217) 333-9648
keith at piked2.agn.uiuc.edu