Anthony,

In actuality, Jmol uses a simple transformation matrix for its internal representation of the viewing perspective.

Is your concern that Jmol internally is using an odd convention, or that
there should be an option for outputting the current rotation of the model
in other formats?

As far as I know, the only reason we were interested in the Rx*Ry*Rz
idea is that some would like to be able for the user to rotate the
model freely, then set that position using simple chime rotations.

In terms of output, the axis angle convention is available in the latest beta version as well. See the "show axisangle" and "moveto" commands, as shown in
http://www.stolaf.edu/people/hansonr/jmol/docs/examples/moveto.htm


Are you saying you'd like to have

show euler

or

show quaternion

along with

show axisangle

?

Bob Hanson



Anthony Stone wrote:

I haven't been following this thread, but as I have pointed out on
this list before, the standard way to set up an arbitrary 3D rotation
is not Rx*Ry*Rz but Rz*Ry*Rz (Euler angle rotation). (Some people use
Rz*Rx*Rz which is essentially the same.)

There is an alternative approach, using quaternions, which provides
the formula for a rotation through a specified angle about a specified
axis.

I suggest that Jmol should use one of these standard, well-documented,
approaches rather than introducing something different.


-- Robert M. Hanson, [EMAIL PROTECTED], 507-646-3107 Professor of Chemistry, St. Olaf College 1520 St. Olaf Ave., Northfield, MN 55057 mailto:[EMAIL PROTECTED] http://www.stolaf.edu/people/hansonr




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