# [Chimera-users] measure crossing angles for axes

Thomas Goddard goddard at cgl.ucsf.edu
Tue Feb 9 11:52:50 PST 2010

```Hi Tom,

The Chimera capabilities to create axes and measure angles are still
being developed.  I put a Python script called angle.py on our scripts
web page that will report the angle between two axes created with the
"measure rotation" command.

http://plato.cgl.ucsf.edu/trac/chimera/wiki/Scripts

If the axes are model numbers 2 and 3 you would use the script by typing
a command

runscript /Users/goddard/angle.py #2 #3

The angle will be shown in the status line and in the reply log (menu

We have three different objects representing an axis in Chimera now:
1) pairs of atoms, 2) a bond, 3) an axis object, and a variety of
dialogs and commands that use axes

Structure Measurements dialog

http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/structuremeas/structuremeas.html#axes

Command "define axis"

http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/define.html

Command "turn"

http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/turn.html

Command "measure rotation"

http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/measure.html#rotation

The axis objects are relatively new and we need to make all our tools
that use axes follow uniform conventions.

Tom

> I have used the "measure rotation" command to create several axes. In
> each case, a marker set (to show the axis) is generated that consists of
> 2 pseudoatoms and 1 bond.
> Is there a simple way to measure the crossing angle between 2 such axes?
> If the marker set had 3 atoms, I could probably use the Axes/Planes
> tools to do this.
>
> Thanks,
> Tom

```