Function ilsqr_with 

fn ilsqr_with(
    field: &[f64],
    mask: &[u8],
    grid: &Grid,
    bdir: (f64, f64, f64),
    params: &IlsqrParams,
    progress: impl FnMut(usize, usize),
    tracer: &impl Tracer,
) -> (Vec<f64>, Vec<f64>, Vec<f64>, Vec<f64>)

ilsqr with instrumentation hooks.