Function wavelet_block 

fn wavelet_block(
    plan: &WaveletPlan,
    cfg: &GampCfg,
    st: &mut GampState,
    lambda: &mut f64,
    tau_r_meas_1: f64,
    r_hat_meas_1: &[f64],
    wave_mask: &[bool],
) -> f64

Shared wavelet-domain GAMP block (identical between AWGN and mixture stages).

Returns the relative change in x_hat_meas (||Δx|| / ||x||) used for the GAMP inner-loop convergence test.