pub fn update_hessian_bfgs_powell_mix(
hessian: &DMatrix<f64>,
delta_x: &DVector<f64>,
delta_g: &DVector<f64>,
) -> DMatrix<f64>Expand description
BFGS/Powell mixture following Bofill weighting.
Uses Bofill’s φ parameter to blend BFGS and Powell updates. Provides smooth transition between methods based on local curvature.