num::qr_form_block

Defined in header <linear/factorization/qr.hpp>

template <std::floating_point T>
void qr_form_block(T *V, T *Tm, const T *A, idx lda, idx m, idx k0, idx kb,
                   const T *tau) noexcept;

Form the compact-WY block reflector for columns [k0, k0 + kb).

Reads the reflector tails stored below the diagonal of the factored panel and their scalars tau, and writes V ((m - k0) x kb, unit lower trapezoidal, row stride kb) and the upper triangular T (kb x kb) with \(H_{k_0} \cdots H_{k_0 + k_b - 1} = I - V T V^T\).