Struct SliceSignedDecompositionNonNativeIter 

pub struct SliceSignedDecompositionNonNativeIter<T>
where
    T: UnsignedInteger,
{ /* private fields */ }

An iterator-like object that yields the terms of the signed decomposition of a tensor of values.

Note

On each call to SliceSignedDecompositionNonNativeIter::next_term, this structure yields a new DecompositionTermSlice, backed by a Vec owned by the structure. This vec is mutated at each call of the next_term method, and as such the term must be dropped before next_term is called again.

Such a pattern can not be implemented with iterators yet (without GATs), which is why this iterator must be explicitly called.

Warning

This iterator yields the decomposition in reverse order. That means that the highest level will be yielded first.

Implementations

impl<T> SliceSignedDecompositionNonNativeIter<T>

where T: UnsignedInteger,

pub fn base_log(&self) -> DecompositionBaseLog

Returns the logarithm in base two of the base of this decomposition.

If the decomposition uses a base $B=2^b$, this returns $b$.

Example

use tfhe::core_crypto::commons::math::decomposition::SignedDecomposerNonNative;
use tfhe::core_crypto::prelude::{
    CiphertextModulus, DecompositionBaseLog, DecompositionLevelCount,
};
let decomposer = SignedDecomposerNonNative::<u32>::new(
    DecompositionBaseLog(4),
    DecompositionLevelCount(3),
    CiphertextModulus::try_new((1 << 32) - (1 << 16) + 1).unwrap(),
);
let decomposable = vec![1_340_987_234_u32; 2];
let decomp = decomposer.decompose_slice(&decomposable);
assert_eq!(decomp.base_log(), DecompositionBaseLog(4));

pub fn level_count(&self) -> DecompositionLevelCount

Returns the number of levels of this decomposition.

If the decomposition uses $l$ levels, this returns $l$.

Example

use tfhe::core_crypto::commons::math::decomposition::SignedDecomposerNonNative;
use tfhe::core_crypto::prelude::{
    CiphertextModulus, DecompositionBaseLog, DecompositionLevelCount,
};
let decomposer = SignedDecomposerNonNative::<u32>::new(
    DecompositionBaseLog(4),
    DecompositionLevelCount(3),
    CiphertextModulus::try_new((1 << 32) - (1 << 16) + 1).unwrap(),
);
let decomposable = vec![1_340_987_234_u32; 2];
let decomp = decomposer.decompose_slice(&decomposable);
assert_eq!(decomp.level_count(), DecompositionLevelCount(3));

pub fn next_term(&mut self) -> Option<DecompositionTermSliceNonNative<'_, T>>

Yield the next term of the decomposition, if any.

Note

Because this function returns a borrowed tensor, owned by the iterator, the term must be dropped before next_term is called again.

Example

use tfhe::core_crypto::commons::math::decomposition::{
    DecompositionLevel, SignedDecomposerNonNative,
};
use tfhe::core_crypto::prelude::{
    CiphertextModulus, DecompositionBaseLog, DecompositionLevelCount,
};
let decomposer = SignedDecomposerNonNative::<u32>::new(
    DecompositionBaseLog(4),
    DecompositionLevelCount(3),
    CiphertextModulus::try_new((1 << 32) - (1 << 16) + 1).unwrap(),
);
let decomposable = vec![1_340_987_234_u32; 2];
let mut decomp = decomposer.decompose_slice(&decomposable);
let term = decomp.next_term().unwrap();
assert_eq!(term.level(), DecompositionLevel(3));
assert_eq!(term.as_slice()[0], u32::MAX);