.TH g_principal 1 "Mon 4 Apr 2011" "" "GROMACS suite, VERSION 4.5.4-dev-20110404-bc5695c"
.SH NAME
g_principal - calculates axes of inertia for a group of atoms

.B VERSION 4.5.4-dev-20110404-bc5695c
.SH SYNOPSIS
\f3g_principal\fP
.BI "\-f" " traj.xtc "
.BI "\-s" " topol.tpr "
.BI "\-n" " index.ndx "
.BI "\-a1" " axis1.dat "
.BI "\-a2" " axis2.dat "
.BI "\-a3" " axis3.dat "
.BI "\-om" " moi.dat "
.BI "\-[no]h" ""
.BI "\-[no]version" ""
.BI "\-nice" " int "
.BI "\-b" " time "
.BI "\-e" " time "
.BI "\-dt" " time "
.BI "\-tu" " enum "
.BI "\-[no]w" ""
.BI "\-[no]foo" ""
.SH DESCRIPTION
\&\fB g_principal\fR calculates the three principal axes of inertia for a group
\&of atoms.
.SH FILES
.BI "\-f" " traj.xtc" 
.B Input
 Trajectory: xtc trr trj gro g96 pdb cpt 

.BI "\-s" " topol.tpr" 
.B Input
 Structure+mass(db): tpr tpb tpa gro g96 pdb 

.BI "\-n" " index.ndx" 
.B Input, Opt.
 Index file 

.BI "\-a1" " axis1.dat" 
.B Output
 Generic data file 

.BI "\-a2" " axis2.dat" 
.B Output
 Generic data file 

.BI "\-a3" " axis3.dat" 
.B Output
 Generic data file 

.BI "\-om" " moi.dat" 
.B Output
 Generic data file 

.SH OTHER OPTIONS
.BI "\-[no]h"  "no    "
 Print help info and quit

.BI "\-[no]version"  "no    "
 Print version info and quit

.BI "\-nice"  " int" " 19" 
 Set the nicelevel

.BI "\-b"  " time" " 0     " 
 First frame (ps) to read from trajectory

.BI "\-e"  " time" " 0     " 
 Last frame (ps) to read from trajectory

.BI "\-dt"  " time" " 0     " 
 Only use frame when t MOD dt = first time (ps)

.BI "\-tu"  " enum" " ps" 
 Time unit: \fB fs\fR, \fB ps\fR, \fB ns\fR, \fB us\fR, \fB ms\fR or \fB s\fR

.BI "\-[no]w"  "no    "
 View output \fB .xvg\fR, \fB .xpm\fR, \fB .eps\fR and \fB .pdb\fR files

.BI "\-[no]foo"  "no    "
 Dummy option to avoid empty array

.SH SEE ALSO
.BR gromacs(7)

More information about \fBGROMACS\fR is available at <\fIhttp://www.gromacs.org/\fR>.