Simulated phase–energy–resolved X-ray pulse profiles for interpolation test 2, computed using four interpolation schemes applied to the NSX tables: (a) cubic interpolation in all dimensions; (b) as in (a), with negative intensities clipped to zero; (c) cubic interpolation in all dimensions with linear interpolation enforced at table boundaries; (d) the baseline configuration used in this work, cubic along two axes and linear along the remaining two, with linear interpolation enforced at table boundaries.