spectra_utils.h

Shared helpers for spectra sampling

Shared helpers for spectra sampling

snap_to_cell(), used by both spectra_sample.h (locate()-based) and spectra_sample_restricted.h (foreach_level()-based). Both headers include this one instead of defining it themselves, so a comparison test can include both without a duplicate-symbol error.

#ifndef SNAP_TO_CELL_DEFINED
#define SNAP_TO_CELL_DEFINED

Snap a target height to the nearest cell centre. foreach_region returns the cell containing the point, so a height on a face resolves to one side arbitrarily – z = 0 is a face whenever the grid size is even.

double snap_to_cell (double h, int m)
{
  double del = L0/m;
  return Z0 + (floor ((h - Z0)/del) + 0.5)*del;
}

#endif