Function select_blend_step 

pub fn select_blend_step(
    blend_state: &OptimizationState_blend,
    config: &Config,
    step: usize,
) -> DVector<f64>

Dispatcher for the blend experiment methods.

Routes to the correct blend step function based on config:

• use_hybrid_gediis = false (default): Calls gdiis_blend_step
• use_hybrid_gediis = true: Routes based on gediis_blend_mode:
  • "fixed": Calls fixed_blend_step (50/50 fixed blend)
  • "fixed_sequential": Calls fixed_sequential_blend_step (50/50 → GDIIS)
  • "gradient": Calls gradient_blend_step
  • "sequential": Calls sequential_blend_step

Uses blend_state.trust_radius for dynamic step control (initialized from config.max_step_size), enabling trust-region adaptation via adjust_trust_radius.

Arguments

• blend_state - Blend optimization state (immutable borrow).
• config - Configuration including step size and threshold parameters.
• step - Current optimization step number (for display).

Returns

The predicted new geometry.