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: circ_mean.m
    path of file: ./repos/Image-Harmonization-Dataset-iHarmony4/Xue et al/dependency/CircStat2011f
    
    the code of the file until where you have to start completion: function [mu ul ll] = circ_mean(alpha, w, dim)
%
% mu = circ_mean(alpha, w)
%   Computes the mean direction for circular data.
%
%   Input:
%     alpha	sample of angles in radians
%     [w		weightings in case of binned angle data]
%     [dim  compute along this dimension, default is 1]
%
%     If dim argument is specified, all other optional arguments can be
%     left empty: circ_mean(alpha, [], dim)
%
%   Output:

    
function [mu ul ll] = circ_mean(alpha, w, dim)
%
% mu = circ_mean(alpha, w)
%   Computes the mean direction for circular data.
%
%   Input:
%     alpha	sample of angles in radians
%     [w		weightings in case of binned angle data]
%     [dim  compute along this dimension, default is 1]
%
%     If dim argument is specified, all other optional arguments can be
%     left empty: circ_mean(alpha, [], dim)
%
%   Output:
%     mu		mean direction
%     ul    upper 95% confidence limit
%     ll    lower 95% confidence limit 
%
% PHB 7/6/2008
%
% References:
%   Statistical analysis of circular data, N. I. Fisher
%   Topics in circular statistics, S. R. Jammalamadaka et al. 
%   Biostatistical Analysis, J. H. Zar
%
% Circular Statistics Toolbox for Matlab

% By Philipp Berens, 2009
% berens@tuebingen.mpg.de - www.kyb.mpg.de/~berens/circStat.html

if nargin < 3
  dim = 1;
end