Hi, folks!


I have a problem about the measurement of torsional angle.
In the chimera users' guide about the command angle, as follows, it says that if I select the atoms simultaneously, the order information will get lost.
How can I keep the order information since I need it to calculate the angle I want exactly?
For example, in the following command I originally want to calculate the n-ca-c-n(182) dihedral,
angle :181.a@n,ca,c:182.a@n
but in fact  what chimera gave me was may be c-ca-n-n(182).

I want to calculate a lot of diheral information so I can not click one by one in the gui mode, I wonder is there any way  that I can get what I want .
Thanks!


Usage:
angle atom1 atom2 atom3 [ atom4 ]

Angle reports the bond angle for three specified atoms or the dihedral angle for four specified atoms. The order of specification is important, but atoms need not be connected. The angle value in degrees is reported in the status line and Reply Log.

The atoms can be specified collectively using the word selected, sel, or picked if the current selection contains only the three or four atoms of interest; the order in which the atoms were selected (most likely picked) is used. When order information is lacking (for example, the atoms were selected simultaneously), the angle actually measured may not be the one intended.

There are no automatic updates if the angle changes. A new command must be issued to measure the changed angle.



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Chao Wu

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