[GRASSLIST:2357] NDVI...why i get an all 0 raster file?

[Luis Coronado]

Hi there people!.
Im trying to add several ratio bands to my ETM+ data set of the north
region of Costa Rica. I calculated all the ETM+#/ETM+# with
mapcalculator.sh and r.mapcalc, and both work fine. But, when trying to
obtain the NDVI, the result was a raster file full of 0's.
I now that this isnt the result because i also did the same with IDRISI.

Any tip here?
-*-*-*-*-*-*-*-*
NDVI=(BAND4-BAND3)/(BAND4+BAND3)
*-*-*-*-*-*-*-*-
-- 
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
Luis Coronado Chacon
guaiacum at sol.racsa.co.cr
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*