atoms angles from specific point

Dear all

I want to calculate angel between atoms in a group and a specific point.does any command exist for this calculation? one way i thought about, is to extract it from inner product of vectors. for this i need to do math function in coordinate of every atom exist in the group, is it possible? how?. and after that i need the summation of cos(angles) . any body can help me?

Regards and thanks in advance.

I can’t think of a way to do this on the fly. Probably better to

think about it as a post-processing operation, e.g. process a dump file.

There were new options added recently to compute bond/local (angle, etc)

to define a variable to operate on each bond, angle, etc. Perhaps

if something similar were added to compute pair/local it could compute

a variable for each pairwise interaction in a group (using a 3rd static

point to create angles). But that would require new coding.