ModifiedGivens

A modified Givens transformation produced by rotmg.

d1, d2, and x1 are the state returned by BLAS drotmg; flag is its dparam[0] selector. The four h properties always describe the materialized matrix, including entries that BLAS implies from flag rather than storing in dparam. Thus this type carries the complete transformation without exposing BLAS's unused parameter-array slots.