Function lbv_default 

pub fn lbv_default(
    field: &[f64],
    mask: &[u8],
    nx: usize,
    ny: usize,
    nz: usize,
    vsx: f64,
    vsy: f64,
    vsz: f64,
) -> (Vec<f64>, Vec<u8>)

LBV with default parameters

Note: QSM.jl uses multigrid-preconditioned CG which converges in ~max(dims) iterations. Our Gauss-Seidel SOR needs more iterations, so we use 3*max(dims) with a floor of 500.