[gmx-users] make_ndx: execlude one group from another

[Erik Marklund]

  Thomas Schlesier skrev 2010-09-23 13.03:
> Hi all,
> I'm trying to execlude all atoms of group 2 (140 atoms) from group 1 
> (300 atoms), so that i have a new group 3 (with 160 atoms).
> | is for merging with OR
> & for merging with AND
> so ! should be for merging with NOT
> But i tried
> 1 ! 2
> 2 ! 1
> but in both cases make_ndx complains about syntax errors
> Syntax error: "! 1" ; or same with "! 2"
> To use NOT instead of ! doesn't work. But using AND insted of & also 
> doesn't work.
>
> So what's the right command for merging with the NOT option?
>
> Greetings Thomas
I guess that's because ! is not a binary operator. If you want the union 
of 1 and all that is not in 2, then try '1 | ! 2'.

-- 
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Erik Marklund, PhD student
Dept. of Cell and Molecular Biology, Uppsala University.
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erikm at xray.bmc.uu.se    http://folding.bmc.uu.se/