function isargsecondarysource(varargin)
%ISARGSECONDARYSOURCE throws an error if not secondary sources
%
%   Usage: isargsecondarysource(args)
%
%   Input parameters:
%       args        - list of args
%
%   ISARGSECONDARYSOURCE(args) tests if all given args are a matrix
%   containing secondary source positions and directions and returns
%   an error otherwise.
%
%   See also: isargmatrix

%*****************************************************************************
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% The SFS Toolbox  allows to simulate and  investigate sound field synthesis *
% methods like wave field synthesis or higher order ambisonics.              *
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%*****************************************************************************


%% ===== Checking for vector =============================================
for ii = 1:nargin
   
    x0 = varargin{ii};
    
    if ~isnumeric(x0) || ndims(x0)~=2 || size(x0,2)~=7 
        error(['%s need to be a nx7 matrix containing the ', ...
            'secondary sources positions and directions ', ...
            'and weights.'], ...
            inputname(ii));
    end
    if ~all(abs(vector_norm(x0(:,4:6),2)-1)<1e-10)
        error(['The norm of the direction of %s is not 1. ', ...
            'You can use the direction_vector function to get ', ...
            'correct direction values.'],inputname(ii));
    end
end
