Struct GdiisOptimizer 

pub struct GdiisOptimizer {
    pub max_vectors: usize,
    pub cosine_check: CosineCheckMode,
    pub coeff_check: CoeffCheckMode,
    a_matrix: TriangularMatrix,
    a_inv: TriangularMatrix,
    scale: f64,
    el2_min: f64,
    solver: DiisCoeffSolver,
}

Main GDIIS optimizer.

Implements the full GDIIS algorithm with validation checks.

Fields

max_vectors: usize

Maximum number of vectors to store

cosine_check: CosineCheckMode

Cosine check mode

coeff_check: CoeffCheckMode

Coefficient check mode

a_matrix: TriangularMatrix

Overlap matrix A

a_inv: TriangularMatrix

Inverse of A

scale: f64

Current scale factor

el2_min: f64

Minimum error norm squared

solver: DiisCoeffSolver

DIIS coefficient solver

Implementations

impl GdiisOptimizer

pub fn new(max_vectors: usize) -> Self

Creates a new GDIIS optimizer.

pub fn reset(&mut self)

Resets the optimizer state.

pub fn compute_step( &mut self, coords: &VecDeque<DVector<f64>>, errors: &VecDeque<DVector<f64>>, _hessians: &VecDeque<DMatrix<f64>>, ) -> Result<(DVector<f64>, Vec<f64>, usize), GdiisError>

Computes a GDIIS step.

Arguments

• coords - History of coordinate vectors
• errors - History of error vectors (gradients or Newton steps)
• hessians - History of Hessian matrices (for error vector computation)

Returns

Tuple of (new_coords, coefficients, n_used) or error.

fn initialize_matrices( &mut self, errors: &VecDeque<DVector<f64>>, n: usize, ) -> Result<(), GdiisError>

Initializes overlap matrices from error vectors.

fn extend_matrices( &mut self, errors: &VecDeque<DVector<f64>>, n: usize, ) -> Result<(), GdiisError>

Extends matrices with new error vector.

fn validate_coefficients( &self, coeffs: &[f64], n_used: usize, ) -> Result<(), GdiisError>

Validates DIIS coefficients.

GDIIS coefficient check logic:

• CMax = 15.0
• CMin = 1 - CMax = -14 for IChkC != 1
• CMin = 4 * (1 - CMax) = -56 for IChkC == 1 (Regular mode)

fn validate_cosine( &self, residuum: &DVector<f64>, last_error: &DVector<f64>, n_used: usize, ) -> Result<(), GdiisError>

Validates GDIIS step using cosine check.