#!/bin/sh
# Parameters: 1, 2, 3 - number of LANDSAT band
# written by Markus Neteler 21. Jul. 1998, 5. Jan. 1999
#            neteler@geog.uni-hannover.de 

# submodule of i.oif
if test "$1" = ""; then
echo "You must use i.oif instead of i.oifcalc (this is a submodule)"
exit
fi

# calculate SUM of Stddeviations:
$GISBASE/etc/i.oif/m.cutmatrix /tmp/i.oif.stddev 1 $1 >  /tmp/i.oif.sum
$GISBASE/etc/i.oif/m.cutmatrix /tmp/i.oif.stddev 1 $2 >> /tmp/i.oif.sum
$GISBASE/etc/i.oif/m.cutmatrix /tmp/i.oif.stddev 1 $3 >> /tmp/i.oif.sum

cat /tmp/i.oif.sum | awk 'BEGIN {sum = 0.0} 
NR == 1{}
	{sum += $1 ; N++}
END{
print sum > "/tmp/i.oif.calc"
}'

# calculate SUM of absolute(Correlation values):
$GISBASE/etc/i.oif/m.cutmatrix /tmp/i.oif.correlation $1 $2 >  /tmp/i.oif.sum
$GISBASE/etc/i.oif/m.cutmatrix /tmp/i.oif.correlation $1 $3 >> /tmp/i.oif.sum
$GISBASE/etc/i.oif/m.cutmatrix /tmp/i.oif.correlation $2 $3 >> /tmp/i.oif.sum

cat /tmp/i.oif.sum | awk 'BEGIN {sum = 0.0}
NR == 1{}
        {sum += sqrt($1*$1) ; N++}  # sqrt(x^2) is my ABS-function
END{
print sum >> "/tmp/i.oif.calc"
}'

# Calculate OIF index:
#     Divide (SUM of Stddeviations) and (SUM of Correlation)
cat /tmp/i.oif.calc | awk 'BEGIN {}
{count = divisor; divisor = $1;}      # value shift - no better idea ;-)
END{
print count / divisor
}'