Riesz basis of Coifman and Meyer's local sine and cosine type

A Riesz basis is the image of an orthonormal basis under an invertible continuous linear mapping. In many interesting applications, perturbing an orthonormal basis in a controlled manner yields a Riesz basis. In this paper we find Riesz basis for of the form {b_Ik(x)sinλ_kx}, with b_Ik(x) bell functions, by perturbing the local sine and cosine orthonormal bases of Coifman and Meyer.