r3.mapcalc: 3D map algebra for GRASS GIS. GRASS G3D library is required.

(c) Copyright 2000: GeoModel s.r.o. Bratislava, Slovakia, 
    http://www.geomodel.sk

If necessary, please contact the authors at hofierka@geomodel.sk or 
paudits@gssr.sk

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the
   Free Software Foundation, Inc.,
   59 Temple Place - Suite 330,
   Boston, MA  02111-1307, USA.

Note: This program is based partly on r.mapcalc (2D) grass command.
