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: graphCenter.m
    path of file: ./repos/matGeom/matGeom/graphs
    
    the code of the file until where you have to start completion: function center = graphCenter(v, e, l)
%GRAPHCENTER Center of a graph.
%
%   CENTER = graphCenter(V, E)
%   Computes the center of the graph given by V and E. The center of the
%   graph is the set of vertices whose eccentricity is minimal. The
%   function returns indices of center vertices.
%
%   CENTER = graphCenter(V, E, L)
%   Specifies the weight of each edge for computing the distances. Default
%   is to consider a weight of 1 for each edge.
%
%   Example
%     nodes = [20 20;20 50;20 80;50 50;80 20;80 50;80 80];
%     edges = [1 2;2 3;2 4;4 6;5 6;6 7];
%     figure; drawGraph(nodes, edges);
%     axis([0 100 0 100]); axis equal; hold on
%     C = graphCenter(nodes, edges)
%     C = 
%         4  
%
%   See also 
%   grPropagateDistance, grVertexEccentricity
%   graphRadius, graphDiameter, graphPeripheralVertices
%

% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr

    
function center = graphCenter(v, e, l)
%GRAPHCENTER Center of a graph.
%
%   CENTER = graphCenter(V, E)
%   Computes the center of the graph given by V and E. The center of the
%   graph is the set of vertices whose eccentricity is minimal. The
%   function returns indices of center vertices.
%
%   CENTER = graphCenter(V, E, L)
%   Specifies the weight of each edge for computing the distances. Default
%   is to consider a weight of 1 for each edge.
%
%   Example
%     nodes = [20 20;20 50;20 80;50 50;80 20;80 50;80 80];
%     edges = [1 2;2 3;2 4;4 6;5 6;6 7];
%     figure; drawGraph(nodes, edges);
%     axis([0 100 0 100]); axis equal; hold on
%     C = graphCenter(nodes, edges)
%     C = 
%         4  
%
%   See also 
%   grPropagateDistance, grVertexEccentricity
%   graphRadius, graphDiameter, graphPeripheralVertices
%

% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2010-09-07, using Matlab 7.9.0.529 (R2009b)
% Copyright 2010-2023 INRA - Cepia Software Platform

% ensure there is a valid length array
if nargin<3
    l = ones(size(e,1), 1);
end