fn sti_row(h: (f64, f64, f64), k: (f64, f64, f64), k2: f64) -> [f64; 6]Expand description
Build the row of the STI system for one orientation at one k-point.
This is the forward model written out against [X11, X12, X13, X22, X23, X33]. Both
reference implementations produce exactly this row.