fhelium.backend.rns.moddown

Auxiliary-basis removal in coefficient and NTT representations.

moddown_qp_to_q

function View source

def moddown_qp_to_q(source, tensors, attributes): ...

Remove P from a coefficient-domain QP polynomial or component bundle.

moddown_ntt_qp_to_q

function View source

def moddown_ntt_qp_to_q(source: torch.Tensor, tensors: Mapping[str, torch.Tensor], attributes: Mapping[str, object], *, coefficient_c0: torch.Tensor | None=None) -> torch.Tensor: ...

Return ${\hat{x}}_Q/P+{\mathrm{NTT}}_Q(-r/P)$.

source holds NTT/Montgomery residues over active QP. Inverting only the P rows determines the coefficient representative $r\in [0,P)$ used by coefficient-domain ModDown. Applying that same ModDown to zero Q rows produces $-r/Pmod{q}_i$. Its forward NTT is added to the retained Q evaluations multiplied by $P^{-1}$. The result is a non-aliasing active-Q NTT/Montgomery tensor; source storage is unchanged. When coefficient_c0 is supplied, it is added to component zero's coefficient correction before the forward NTT, adding NTT(c0) without another transform. The input c0 remains unchanged.

NativeModDownImplementation

class View source

NativeModDownImplementation(name: str = 'native-key-switch-moddown', supports_in_place: bool = False, operation_types: tuple[type[Operation], ...] = (rns.ModDownQpToQOp, rns.ModDownNttQpToQOp))

Divide QP accumulators by P in coefficient or NTT representation.

Attributes

Name	Type	Default/value
name	str	'native-key-switch-moddown'
supports_in_place	bool	False
operation_types	tuple[type[Operation], ...]	(rns.ModDownQpToQOp, rns.ModDownNttQpToQOp)
tensor_requirements		staticmethod(native_moddown_requirements)
prepare_operation		prepare_native_moddown

resource_requirements

method

def resource_requirements(invocation: OperationInvocation) -> tuple[ResourceRequirement, ...]: ...

execute

method

def execute(invocation: OperationInvocation, values: tuple[torch.Tensor, ...], resources: tuple[BoundResource, ...], *, in_place: bool) -> tuple[torch.Tensor, ...]: ...