Usage: <tt>input = [ <i>ng  gID_1  gID_2  &hellip; gID_ng</i> ] R0toR_by_group</tt>

<p>
Copy <tt>R0</tt> array back to <tt>R</tt> for all atoms whose
group id (<tt>group[i]</tt>) matches one of those specified by <tt>input</tt>.

<p>
Also see <tt>R0toR</tt>.


