@lkedward to get things moving, why don’t I target this kernel to start: https://github.com/LKedward/focal/blob/a5235fef89fd0909689618e22fd68347d2d6c1d6/examples/nbody.cl. If I can generate this from Fortran, would you be interested in exploring how to integrate this with Focal somehow? It will take time to get everything working robustly, but one has to start somewhere and then keep improving it.