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: csFilter.m
    path of file: ./repos/Image-Harmonization-Dataset-iHarmony4/Lalonde and Efros/colorStatistics/3rd_party/segmentationBerkeley/lib/matlab
    
    the code of the file until where you have to start completion: function [f] = csFilter(sigma,support)
% function [f] = csFilter(sigma,support)
%
% Compute unit L1-norm zero-mean difference-of-Gaussians
% center-surround filter.
%
% INPUTS
%	sigma		2-element vector of inner/outer sigma.
%	[support]	Make filter +/- this many sigma.
%
% OUTPUTS
%	f	Square filter.
%
% David R. Martin <dmartin@eecs.berkeley.edu>

    
function [f] = csFilter(sigma,support)
% function [f] = csFilter(sigma,support)
%
% Compute unit L1-norm zero-mean difference-of-Gaussians
% center-surround filter.
%
% INPUTS
%	sigma		2-element vector of inner/outer sigma.
%	[support]	Make filter +/- this many sigma.
%
% OUTPUTS
%	f	Square filter.
%
% David R. Martin <dmartin@eecs.berkeley.edu>
% March 2003

nargchk(1,2,nargin);
if nargin<2, support=3; end