pub fn assemble_block_triangular_t(
v_per_term: &[Array2<f64>],
r_per_term: &[Option<Array2<f64>>],
) -> Array2<f64>Expand description
Assemble a block-upper-triangular lift T from per-block diagonal
V_b matrices and strictly-upper residualisation blocks R_{a→b}.
r_per_term[b] (when Some) packs ALL strictly-upper off-diagonal
columns for block b stacked row-wise across all earlier-priority
blocks a < b: nrows = Σ_{a<b} v_per_term[a].nrows(),
ncols = v_per_term[b].ncols(). The assembled T carries V_b on
the diagonal and −R_{a→b} at (a, b). r_per_term[0] must be
None (no earlier block to residualise against).