Function stable_normal_equations 

pub fn stable_normal_equations(
    a: &Array2<Float>,
    b: &Array1<Float>,
    rcond: Option<Float>,
) -> Result<Array1<Float>>

Numerically stable solution to normal equations using QR decomposition

Solves the least squares problem min ||Ax - b||^2 using QR decomposition instead of forming A^T A explicitly, which improves numerical stability.

Arguments

• a - Design matrix of shape (n_samples, n_features)
• b - Target values of shape (n_samples,)
• rcond - Cutoff for small singular values. If None, use machine precision.

Returns

• Solution vector x of shape (n_features,)