function M_padded = symmetric_extension(M,k)

% symmetric_extension - perform a symmetric extension of the signal.
%
%   M_padded = symmetric_extension(M,k);
%
% M can be 1D or 2D array
% If size(M)=[n,p], the result is of size [n+2*k,p+2*k]
%
%   Copyright (c) 2004 Gabriel Peyr