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: vectorAngle.m
    path of file: ./repos/matGeom/matGeom/geom2d
    
    the code of the file until where you have to start completion: function alpha = vectorAngle(v1, varargin)
%VECTORANGLE Horizontal angle of a vector, or angle between 2 vectors.
%
%   A = vectorAngle(V);
%   Returns angle between Ox axis and vector direction, in radians, in
%   counter-clockwise orientation.
%   The result is normalised between 0 and 2*PI.
%
%   A = vectorAngle(V1, V2);
%   Returns the angle from vector V1 to vector V2, in counter-clockwise
%   order, in radians.
%
%   A = vectorAngle(..., 'midAngle', MIDANGLE);
%   Specifies convention for angle interval. MIDANGLE is the center of the
%   2*PI interval containing the result. See <a href="matlab:doc
%   ('normalizeAngle')">normalizeAngle</a> for details.
%
%   Example:
%   rad2deg(vectorAngle([2 2]))
%   ans =
%       45
%   rad2deg(vectorAngle([1 sqrt(3)]))
%   ans =
%       60
%   rad2deg(vectorAngle([0 -1]))
%   ans =
%       270
%        
%   See also 
%     vectors2d, angles2d, normalizeAngle
%

% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2007-10-18
% Copyright 2007-2023 INRA - Cepia Software Platform

%% Initializations

    
function alpha = vectorAngle(v1, varargin)
%VECTORANGLE Horizontal angle of a vector, or angle between 2 vectors.
%
%   A = vectorAngle(V);
%   Returns angle between Ox axis and vector direction, in radians, in
%   counter-clockwise orientation.
%   The result is normalised between 0 and 2*PI.
%
%   A = vectorAngle(V1, V2);
%   Returns the angle from vector V1 to vector V2, in counter-clockwise
%   order, in radians.
%
%   A = vectorAngle(..., 'midAngle', MIDANGLE);
%   Specifies convention for angle interval. MIDANGLE is the center of the
%   2*PI interval containing the result. See <a href="matlab:doc
%   ('normalizeAngle')">normalizeAngle</a> for details.
%
%   Example:
%   rad2deg(vectorAngle([2 2]))
%   ans =
%       45
%   rad2deg(vectorAngle([1 sqrt(3)]))
%   ans =
%       60
%   rad2deg(vectorAngle([0 -1]))
%   ans =
%       270
%        
%   See also 
%     vectors2d, angles2d, normalizeAngle
%

% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2007-10-18
% Copyright 2007-2023 INRA - Cepia Software Platform

%% Initializations

% default values
v2 = [];
midAngle = pi; % normalize angles between 0 and 2*PI

% process input arguments
while ~isempty(varargin)
    var = varargin{1};
    if isnumeric(var) && isscalar(var)
        % argument is normalization constant
        midAngle = varargin{1};
        varargin(1) = [];
        
    elseif isnumeric(var) && size(var, 2) == 2
        % argument is second vector
        v2 = varargin{1};
        varargin(1) = [];
        
    elseif ischar(var) && length(varargin) >= 2
        % argument is option given as string + value
        if strcmpi(var, 'cutAngle') || strcmpi(var, 'midAngle')
            midAngle = varargin{2};
            varargin(1:2) = [];
            
        else
            error(['Unknown option: ' var]);
        end