  We derive a Kronecker product approximation for the micromagnetic long range
interactions in a collocation framework by means of separable sinc quadrature.
Evaluation of this operator for structured tensors (Canonical format, Tucker
format, Tensor Trains) scales below linear in the volume size. Based on
efficient usage of FFT for structured tensors, we are able to accelerate
computations to quasi linear complexity in the number of collocation points
used in one dimension. Quadratic convergence of the underlying collocation
scheme as well as exponential convergence in the separation rank of the
approximations is proved. Numerical experiments on accuracy and complexity
confirm the theoretical results.
