function A = mDCT_A_Matrix( M );

A = zeros( M );

k_i_values = sqrt( [ 1; 2*ones( M-1, 1 ) ]./M );

for i = 0:M-1
  k_i = k_i_values( i+1 );
  for k = 0:M-1
    A(i+1,k+1) = k_i*cos(pi*(2*k+1)*i/(2*M));
  end
end