You can use the below function:
function varargout=dp2xy(varargin)
%DP2XY Calculate chromaticity from dominating wavelength and spectral purity.
% XY=DP2XY(DP,CWF) with size(DP)=[M N ... P 2] returns
% matrix XY with same size.
%
% XY=DP2XY(D,P,CWF) with size(D,P)=[M N ... P] returns
% matrix XY with size [M N ... P 2].
%
% [X,Y]=DP2XY(DP,CWF) with size(DP)=[M N ... P 2] returns
% matrices X and Y, each with size [M N ... P].
%
% [X,Y]=DP2XY(D,P,CWF) with size(D,P)=[M N ... P]
% returns equally sized matrices X and Y.
% CWF is a color weighting function specification. It can be a string,
% e.g. 'D50/2', or a struct, see MAKECWF. If omitted or empty, the
% default cwf, DCWF is used.
%
% Example:
% Show the locus of xy with the spectral purity = 0.5 in the chromaticity plane
%
% lam=linspace(380,720,20);
% [x,y]=dp2xy(lam,.5*ones(size(lam)));
% plot(x,y, 'LineWidth', 2)
% hold on
% helmholtz
% hold off
% axis equal
%
% See also: I_DP2XY, XY2DP, MAKECMF, OPTGETPREF
% Part of the OptProp toolbox, $Version: 2.1 $
% Author: Jerker Wågberg, More Research & DPC, Sweden
% Email: ['jerker.wagberg' char(64) 'more.se']
% $Id: dp2xy.m 23 2007-01-28 22:55:34Z jerkerw $
varargout=cell(1,max(1,nargout));
[err,varargout{:}]=optproc([2 0 1 0 0],1,@i_dp2xy,varargin{:});
error(err);
For additional reference you can follow the link given below:
https://www.mathworks.com/matlabcentral/fileexchange/13788-optprop-a-color-properties-toolbox?s_tid=srchtitle_wavelength%20calculation%20of%20cie1931_1
