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: i_xy2dp.m
    path of file: ./repos/Image-Harmonization-Dataset-iHarmony4/Xue et al/dependency/optprop/i_conversions
    
    the code of the file until where you have to start completion: function DP=i_xy2dp(xyi,IllObs)
%I_XY2DP Calculate dominating wavelength and exitation purity.
%   DP=I_XY2DP(XY,CWF) with size(XY)=[M 2] returns matrix DP with
%   same size.
%
%   CWF is a color weighting function specification. It can be a

    
function DP=i_xy2dp(xyi,IllObs)
%I_XY2DP Calculate dominating wavelength and exitation purity.
%   DP=I_XY2DP(XY,CWF) with size(XY)=[M 2] returns matrix DP with
%   same size.
%
%   CWF is a color weighting function specification. It can be a
%   string, e.g. 'D50/2', or a struct, see MAKECWF. If empty, the
%   the default cwf, OPTGETPREF('cwf') is used.
%
%   Remark:
%      This is a low level function, that has a rigid parameter passing
%      mechanism and no error handling. It is only to be used when the
%      need for speed is imperative. In all other cases,
%      use XY2DP instead.
%
%   See also: XY2DP, I_DP2XY, MAKECWF, OPTGETPREF

% Part of the OptProp toolbox, $Version: 2.1 $
% Author:  Jerker Wågberg, More Research & DPC, Sweden
% Email: ['jerker.wagberg' char(64) 'more.se']

% $Id: i_xy2dp.m 24 2007-01-28 23:20:35Z jerkerw $

	VISUALIZE=0;
	xyo=i_xyz2xy(wpt(IllObs));
	[xyz,lam]=observer(cwf2obs(IllObs));
	xy=i_xyz2xy(xyz);
	low=ceil(size(xyz,1)/2);
	RealHigh=low-1+find(sqrt(sum(diff(xyz(low:end