#!/bin/sh
#
#	drft06rr_dredgetime
#
#	Called by script drft06rr_dredgemap.  It is used to calculate
#	velocities along track and figure out when the ship is stopped
#	and also print out positions every 15 minutes.  
#
#	Paul Wessel, Nov 15, 2001
#
gmtset D_FORMAT %.12lg
cat << EOF > vel.awk
BEGIN {
	s = 0
	ds = 0
	s15 = 0
	old_s15 = 0
}
{
	if (NR > 1)
	{
		ds = \$7 - old_s
		dt = (\$6 - old_t) * 24.0
		v = ds / dt
		hh = substr(\$3, 8, 2)
		mm = substr(\$3, 10, 2)
		s15 += ds;
		if (mm%15 == 0) {
			printf "%s\t%s\t%s\t%s\t%.3lf\t%lg\n", \$4, \$5, hh, mm, v, s15 - old_s15
			old_s15 = s15
		}
	}
	old_s = \$7
	old_t = \$6
}
EOF
gmtconvert $1.xyt -fi0x,1y,2T -fo0x,1y,2t > tmp
paste $1.xyt tmp | mapproject -Gn -f0x,1y | awk -f vel.awk
rm -f vel.awk tmp