You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: subGrid.m
    path of file: ./repos/mtex/geometry/@SO3Grid
    
    the code of the file until where you have to start completion: function [G, ind] = subGrid(G,q,epsilon,varargin)
% sub-SO3Grid as epsilon neigborhood of a node

    
function [G, ind] = subGrid(G,q,epsilon,varargin)
% sub-SO3Grid as epsilon neigborhood of a node
%
% Syntax
%   G = subGrid(G,midpoint,radius)
% 
% Input
%  G        - @SO3Grid
%  midpoint - @quaternion
%  radius   - double
%
% Output
%  G - SO3Grid
%
% See also
%  SO3Grid/find S2Grid/subGrid

if nargin >= 3
  ind = find(G,q,epsilon,varargin{:});
  ind = any(ind,2);
elseif islogical(q) 
  ind = q;
else
  ind = false(length(G),1);
  ind(q) = true;
end