Convergence of a numerical scheme for a coupled Schr\"odinger--KdV system

We prove the convergence in a strong norm of a finite difference semi-discrete scheme approximating a coupled Schr"odinger–KdV system on a bounded domain. This system models the interaction of short and long waves. Since the energy estimates available in the continuous case do not carry over to the discrete setting, we rely on a suitably truncated problem which we prove reduces to the original one. We present some numerical examples to illustrate our convergence result.