Function single_echo_result 

fn single_echo_result(
    unwrapped: &[f64],
    mask: &[u8],
    te: f64,
    field_strength: f64,
    config: &FieldMappingConfig,
) -> FieldMappingResult

One echo’s field from its unwrapped phase: the masked mean a Laplacian unwrap leaves undetermined removed (so one echo gives the same field as each echo of a series does), then divided by the echo time.