Struct Int4Vector 

pub struct Int4Vector {
    pub data: Vec<u8>,
    pub dims: usize,
    pub params: Int4Params,
    pub norm: f32,
}

Unstable: INT4 quantization format is under active design; struct layout may change.

Quantized INT4 vector with packed nibble storage.

Fields

data: Vec<u8>

Unstable: packed nibble data; bit packing scheme may change.

dims: usize

Unstable: number of original dimensions.

params: Int4Params

Unstable: quantization parameters; may be separated from the vector.

norm: f32

Unstable: L2 norm; may be removed or moved.

Implementations

impl Int4Vector

pub fn from_f32(vector: &[f32]) -> Self

Unstable: quantization format; nibble packing may change.

Each pair of consecutive dimensions is packed into one byte:

• High nibble (bits 7..4) = even-indexed value
• Low nibble (bits 3..0) = odd-indexed value

pub fn to_f32(&self) -> Vec<f32>

Unstable: dequantization output semantics may change.

Reverses the quantization: v[i] = q[i] / scale - max_abs

Precision

INT4 unsigned symmetric quantization maps [-max_abs, max_abs] to [0, 15] (16 levels), so the quantization step size is 2 * max_abs / 15. The maximum per-element round-trip error is bounded by half a step: max_abs / 15.

For a 384-dim unit-norm embedding (max_abs ≈ 1.0), expect element-wise absolute error ≤ 0.067 and relative dot-product error ≤ 15% (see test_int4_dot_product_vs_f32 and test_int4_roundtrip_accuracy). Use Int8 tier when higher fidelity is required.

pub fn dot_product(&self, other: &Int4Vector) -> f32

Unstable: INT4 dot product approximation; formula may change.

Returns the dequantized dot product suitable for cosine distance computation.

pub fn cosine_similarity(&self, other: &Int4Vector) -> f32

Unstable: INT4 cosine similarity approximation; delegates to dot_product.

pub fn cosine_distance(&self, other: &Int4Vector) -> f32

Unstable: complement of cosine_similarity; definition may evolve.

Trait Implementations

impl Clone for Int4Vector

fn clone(&self) -> Int4Vector

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Int4Vector

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

Formats the value using the given formatter.