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[Lars Schylberg]

This example was in in one issue of Grass Clippings last year.  I
think it came from Dr. Fred Limp (Growing with Grass).  This shows how
you could loop over a time t variable and get a spread model for 100
time intervals.  Other ways could be to have a loop that finish when a
certain criterion is fullfilled.  That could be some criterion that is
analysed with r.stats and awk in the loop. I have some scritps with loops 
with r.mapcalc and that finishes when one category is removed completely with
with a filter in r.mapcalc.

Lars

Lars Schylberg                          Email: larss at fmi.kth.se  
Dept. of Geodesy and Photogrammetry 
Royal Institute of Technology (KTH)     Tel.   +46 8 790 86 33   
S-100 44  STOCKHOLM, SWEDEN             Fax.   +46 8 790 66 10


#!/bin/sh
#
#  I skipped usuall begining with input check and so on.
#
IN=$1
#
#
#  do the spread model
#
echo 't = if( t[-1,-1] > 0, t[-1,-1]-1, \' > spread
echo '    if( t[-2,-1] > 0, t[-2,-1]-3, \' >> spread
echo '    if( t[-1,-2] > 0, t[-1,-2]-3, t ))) ' >> spread
#
#  loop to show the spread model
#
g.copy rast=$IN,t
d.rast t
i=1
while [ $i != 100 ]
do 
   r.mapcalc < spread
   d.rast t
   i=`expr $i + 1`
done