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: dxf_rgb2aci.m
    path of file: ./repos/EMTO/buckling
    
    the code of the file until where you have to start completion: function ACI = dxf_rgb2aci(RGB)
%DXF_RGB2ACI Convert RGB color to ACI color.
%   DXF_RGB2ACI(ACI) Converts into m-by-3 RGB matrix into ACI (AutoCAD 
%   Color Index) vector. The routine tries to find RGB color that is 
%   matching best to the ACI color value.
%   
%   See also DXF_POLYLINE
%

    
function ACI = dxf_rgb2aci(RGB)
%DXF_RGB2ACI Convert RGB color to ACI color.
%   DXF_RGB2ACI(ACI) Converts into m-by-3 RGB matrix into ACI (AutoCAD 
%   Color Index) vector. The routine tries to find RGB color that is 
%   matching best to the ACI color value.
%   
%   See also DXF_POLYLINE
%
%   Copyright 2011 Grzegorz Kwiatek
%   $Revision: 1.0.3 $  $Date: 2011.11.17 $

if size(RGB,2) ~= 3
  throw(MException('dxflib:dxf_rgb2aci','Input matrix must be m-by-3 size.'));
end