Function dipole_kspace_weights_ilsqr 

fn dipole_kspace_weights_ilsqr(
    d: &[f64],
    n_exp: f64,
    pa: f64,
    pb: f64,
) -> Vec<f64>

K-space weights for FastQSM (Equation 10)

Weights based on |D|^n with percentile normalization.