Hi Sasha, Sorry, the "angle" command doesn't distinguish those. Maybe you can figure out some other way, such as by comparing two atom-atom distances, or measuring the distance from an atom to the plane: the "distance" command does have a "signed" option to distinguish which side of a plane the atom is on: <https://rbvi.ucsf.edu/chimerax/docs/user/commands/distance.html> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Resource for Biocomputing, Visualization, and Informatics Department of Pharmaceutical Chemistry University of California, San Francisco

On Apr 23, 2026, at 6:36 AM, Alexandra Zahradnikova via ChimeraX-users <chimerax-users@cgl.ucsf.edu> wrote:

Dear All, I am trying to calculate a set of angles between pairs of axes and planes. Example: sel #1/B:348,1052 @ca; define axis sel; sel #1:1052 @ca; define plane sel; angle #1.3 #1.4 My problem is that the angle is always reported positive, no matter whether the axis goes "up" or "down" from the plane, when "up" and "down" are defined relative to the orientation of the molecule. Is there any way how to distinguish between these two cases automatically? Thanks very much in advance. Best regards Sasha Zahradnikova