Confluence of singularities of differential equation: a Lie algebra   contraction approach
  We investigate here the confluence of singularities of Mathieu differential equation by means of the Lie algebra contraction of the Lie algebra of the motion group M(2) on the Heisenberg Lie algebra H(3). A similar approach for the Lam\'e equation in terms of the Lie algebra contraction of $SO_0(2,1)$ on the Lie algebra of the motion group M(2) is outlined. 
Mohammed Brahim Zahaf (LPQ3M, LAPTH), Dominique Manchon