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_stats.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 stats = circ_stats(alpha, w, d)
%
% stats = circ_stats(alpha, w)
%   Computes descriptive statistics for circular data.
%
%   Input:
%     alpha   sample of angles in radians
%     [w      weightings in case of binned angle data]
%     [d    spacing of bin centers for binned data, if supplied 
%           correction factor is used to correct for bias in 
%           estimation of r]
%
%   Output:
%     stats   structure containing descriptive statistics
%
% References:
%   Statistical analysis of circular data, N. I. Fisher

    
function stats = circ_stats(alpha, w, d)
%
% stats = circ_stats(alpha, w)
%   Computes descriptive statistics for circular data.
%
%   Input:
%     alpha   sample of angles in radians
%     [w      weightings in case of binned angle data]
%     [d    spacing of bin centers for binned data, if supplied 
%           correction factor is used to correct for bias in 
%           estimation of r]
%
%   Output:
%     stats   structure containing descriptive statistics
%
% 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 

alpha = alpha(:);
if nargin<2
  w = ones(size(alpha));
end