g_filter(1) GROMACS suite, VERSION 4.5.4-dev-20110404-bc5695c g_filter(1)
NAME
g_filter - frequency filters trajectories, useful for making smooth movies
VERSION 4.5.4-dev-20110404-bc5695c
SYNOPSIS
g_filter -f traj.xtc -s topol.tpr -n index.ndx -ol lowpass.xtc -oh highpass.xtc -[no]h -[no]version -nice int -b time -e time -dt time
-[no]w -nf int -[no]all -[no]nojump -[no]fit
DESCRIPTION
g_filter performs frequency filtering on a trajectory. The filter shape is cos(pi t/A) + 1 from -A to +A, where A is given by the option
-nf times the time step in the input trajectory. This filter reduces fluctuations with period A by 85%, with period 2*A by 50% and with
period 3*A by 17% for low-pass filtering. Both a low-pass and high-pass filtered trajectory can be written.
Option -ol writes a low-pass filtered trajectory. A frame is written every -nf input frames. This ratio of filter length and output
interval ensures a good suppression of aliasing of high-frequency motion, which is useful for making smooth movies. Also averages of prop-
erties which are linear in the coordinates are preserved, since all input frames are weighted equally in the output. When all frames are
needed, use the -all option.
Option -oh writes a high-pass filtered trajectory. The high-pass filtered coordinates are added to the coordinates from the structure
file. When using high-pass filtering use -fit or make sure you use a trajectory that has been fitted on the coordinates in the structure
file.
FILES
-f traj.xtc Input
Trajectory: xtc trr trj gro g96 pdb cpt
-s topol.tpr Input, Opt.
Structure+mass(db): tpr tpb tpa gro g96 pdb
-n index.ndx Input, Opt.
Index file
-ol lowpass.xtc Output, Opt.
Trajectory: xtc trr trj gro g96 pdb
-oh highpass.xtc Output, Opt.
Trajectory: xtc trr trj gro g96 pdb
OTHER OPTIONS
-[no]hno
Print help info and quit
-[no]versionno
Print version info and quit
-nice int 19
Set the nicelevel
-b time 0
First frame (ps) to read from trajectory
-e time 0
Last frame (ps) to read from trajectory
-dt time 0
Only use frame when t MOD dt = first time (ps)
-[no]wno
View output .xvg, .xpm, .eps and .pdb files
-nf int 10
Sets the filter length as well as the output interval for low-pass filtering
-[no]allno
Write all low-pass filtered frames
-[no]nojumpyes
Remove jumps of atoms across the box
-[no]fitno
Fit all frames to a reference structure
SEE ALSO
gromacs(7)
More information about GROMACS is available at <http://www.gromacs.org/>.
Mon 4 Apr 2011 g_filter(1)