mkron.m

function y=mkron(varargin)
% y=mkron(x1,x2,x3,...) or y=mkron(x1,a)
% --------------------------------------
% Returns a Kronecker product of multiple input tensors x1,x2,x3... Needs
% at least 2 input arguments. Alternatively, one can provide one tensor x1
% and a scalar a to compute the repeated Kronecker product of x1 with
% itself.
%
% y         =   multiway array, Kronecker product of x1,x2,x3..
%
% x1,2,3,.. =   multiway array, tensors of arbitrary size but same order.
%
% a         =   scalar, only used when given with 1 input argument.
%
% Reference
% ---------
%
% 08/2014-2016, Kim Batselier

n=length(varargin);

if n<2
    error('Need at least 2 input arguments.')
end

% check whether second argument is a scalar, if so, then repeatedly apply
% kronecker product onto first argument
if isscalar(varargin{2})
    n=varargin{2};
    y=varargin{1};
    for i=2:n
        y=tkron(y,varargin{1});
    end    
else
    y=varargin{1};
    for i=2:n
        y=tkron(y,varargin{i});
    end
end

end