# g_sgangle (1) - Linux Man Pages

## g_sgangle: computes the angle and distance between two groups

## NAME

g_sgangle - computes the angle and distance between two groups## SYNOPSIS

**g_sgangle**

**-f**

*traj.xtc*

**-n**

*index.ndx*

**-s**

*topol.tpr*

**-oa**

*sg_angle.xvg*

**-od**

*sg_dist.xvg*

**-od1**

*sg_dist1.xvg*

**-od2**

*sg_dist2.xvg*

**-[no]h**

**-nice**

*int*

**-b**

*time*

**-e**

*time*

**-dt**

*time*

**-[no]w**

**-[no]xvgr**

**-[no]one**

**-[no]z**

## DESCRIPTION

Compute the angle and distance between two groups. The groups are defined by a number of atoms given in an index file and may be two or three atoms in size. If -one is set, only one group should be specified in the index file and the angle between this group at time 0 and t will be computed. The angles calculated depend on the order in which the atoms are given. Giving for instance 5 6 will rotate the vector 5-6 with 180 degrees compared to giving 6 5.If three atoms are given, the normal on the plane spanned by those three atoms will be calculated, using the formula P1P2 x P1P3. The cos of the angle is calculated, using the inproduct of the two normalized vectors.

Here is what some of the file options do:

-oa: Angle between the two groups specified in the index file. If a group contains three atoms the normal to the plane defined by those three atoms will be used. If a group contains two atoms, the vector defined by those two atoms will be used.

-od: Distance between two groups. Distance is taken from the center of one group to the center of the other group.

-od1: If one plane and one vector is given, the distances for each of the atoms from the center of the plane is given seperately.

-od2: For two planes this option has no meaning.

## FILES

**-f**

*traj.xtc*

**Input**

**-n*** index.ndx*
**Input**

**-s*** topol.tpr*
**Input**

**-oa*** sg_angle.xvg*
**Output**

**-od*** sg_dist.xvg*
**Output, Opt.**

**-od1*** sg_dist1.xvg*
**Output, Opt.**

**-od2*** sg_dist2.xvg*
**Output, Opt.**

## OTHER OPTIONS

**-[no]h**

*no*

**-nice*** int*** 19**

**-b*** time*** 0 **

**-e*** time*** 0 **

**-dt*** time*** 0 **

**-[no]w***no *

**-[no]xvgr***yes *

**-[no]one***no *

**-[no]z***no *