Enum FansiKernel 

pub enum FansiKernel {
    Discrete,
    Continuous,
}

The dipole kernel a FANSI-family solver (NDI, nlTV, nlTGV, L1-QSM, WH-QSM, HD-QSM) uses.

FANSI’s solvers take the kernel as an input (params.K), and every FANSI script, like the QSM-CI wrappers of the verified originals (FANSI-toolbox 93044a3, HD-QSM c456a94), builds it with dipole_kernel_angulated(N, voxel_size, B0_dir), whose default mode = 1 is the discrete kernel FansiKernel::Discrete. HDQSM.m ships no kernel and is “based on” FANSI; its wrapper uses the same function. The discrete kernel is consistent with the unit forward differences these solvers regularise with (both come from the same E_j).

Decision (Ashley, 2026-11-02; QSM.rs#399–#403): the FANSI-family ports use FANSI’s own discrete kernel by default, as the originals do; the continuous kernel the rest of the crate uses is kept as an option. Measured with the continuous kernel against the verified originals (QSM-CI parity run 41384710780, sim / KKI χ NRMSE): NDI 10.6 / 9.5 %, nlTV 11.0 / 9.5 %, nlTGV 11.0 / 9.6 %, L1-QSM 14.4 / 15.5 %, WH-QSM 21.4 / 50.7 %, HD-QSM 9.1 / 7.1 %; a numpy transcription of ndi.m on the original’s own inputs is 0.0001 % from it with the discrete kernel and 10.6 % with the continuous one. With the discrete kernel every pair is at rounding (each method’s module docs, “Parity”). The phantom measurements quoted in the methods’ te docs were re-measured with the discrete kernel (QSM.rs#418); the echo-time choices they support did not change.

Variants

Discrete

FANSI’s dipole_kernel_angulated mode 1 (FANSI-toolbox 93044a3): the kernel of unit forward differences, E_j = (1 - exp(2*pi*i*k_j/N_j)) / r_j with the voxel size r normalised by its maximum, D = 1/3 - |sum_j E_j*b_j|^2 / sum_j |E_j|^2, D(0) = 0 (fansi_dipole_kernel).

Continuous

The continuous kernel 1/3 - (k.b)^2/|k|^2 of [crate::kernels::dipole::dipole_kernel] (dipole_kernel_angulated mode 0 up to its k normalisation).

Implementations

impl FansiKernel

pub fn build(self, grid: &Grid, bdir: (f64, f64, f64)) -> Vec<f64>

The kernel in FFT order, i + nx*(j + ny*k).

Trait Implementations

impl Clone for FansiKernel

fn clone(&self) -> FansiKernel

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for FansiKernel

impl Debug for FansiKernel

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for FansiKernel

fn default() -> FansiKernel

Returns the “default value” for a type.

impl Eq for FansiKernel

impl PartialEq for FansiKernel

fn eq(&self, other: &FansiKernel) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for FansiKernel

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for FansiKernel