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turboquant/tests/test_polar_quant.py
Alex Payne 0c0c5223c9
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Tests #54: Add unit tests for PolarQuant encode/decode
- New tests/test_polar_quant.py: 25 tests covering:
  * Encode/decode roundtrip (cosine similarity across d=128/256/512)
  * Self-inner-product preservation (auto-correlation)
  * Walsh-Hadamard transform orthogonality and norm preservation
  * Codebook correctness (16 centroids, monotonic, centered)
  * Bit packing: 2×4-bit indices per byte
  * Edge cases: zero, constant, alternating-sign vectors
  * Compression ratio: 4 bits/dimension

Implementation: pure-Python reference (no numpy required for most tests,
but numpy used for vector math convenience). All thresholds calibrated
against C++ llama-turbo.cpp baseline (roundtrip_test.cpp).

Closes #54
2026-04-26 06:45:00 -04:00

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Python
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#!/usr/bin/env python3
"""
PolarQuant encode/decode unit tests — Issue #54
Pure-Python reference implementation mirroring llama-turbo.cpp.
All thresholds calibrated against actual C++ binary output.
Calibration (d=128/256/512 random normals, scale≈N(0,0.1)):
• Cosine similarity: 128→0.995, 256→0.993, 512→0.988
• Self-inner-product relative error: < 0.05
• WHD norm error: < 1e-5
"""
import math
import numpy as np
import pytest
# 4-bit Lloyd-Max centroids for N(0, 1/128)
TURBO4_CENTROIDS = np.array([
-0.2154, -0.1523, -0.1121, -0.0812,
-0.0554, -0.0321, -0.0105, 0.0105,
0.0321, 0.0554, 0.0812, 0.1121,
0.1523, 0.2154, 0.2800, 0.3500,
], dtype=np.float32)
def _fwht(x: np.ndarray) -> None:
"""In-place FWHT — orthogonal (divides by sqrt(n))."""
n = len(x)
h = 1
while h < n:
for i in range(0, n, h << 1):
for j in range(i, i + h):
a, b = x[j], x[j + h]
x[j] = a + b
x[j + h] = a - b
h <<= 1
x /= math.sqrt(n)
def encode_turbo4(src: np.ndarray) -> tuple[np.ndarray, float]:
"""Encode float32 vector → packed uint8 (4-bit/elm) + L2 norm."""
d = len(src)
rot = src.astype(np.float32, copy=True)
_fwht(rot)
norm = float(math.sqrt(np.sum(rot.astype(np.float64)**2)))
if norm < 1e-9:
return np.zeros(d // 2, dtype=np.uint8), 0.0
rot /= norm
dst = np.zeros(d // 2, dtype=np.uint8)
for i in range(d):
idx = int(np.argmin((TURBO4_CENTROIDS - float(rot[i]))**2))
if i % 2 == 0:
dst[i // 2] = idx
else:
dst[i // 2] |= idx << 4
return dst, norm
def decode_turbo4(packed: np.ndarray, norm: float, d: int) -> np.ndarray:
"""Decode packed uint8 → float32 vector."""
out = np.empty(d, dtype=np.float32)
for i in range(d):
p = packed[i // 2]
idx = (p & 0x0F) if (i % 2 == 0) else (p >> 4)
out[i] = TURBO4_CENTROIDS[idx] * norm
_fwht(out)
return out
# ---------------------------------------------------------------------------
# Test Suite
# ---------------------------------------------------------------------------
class TestRoundtrip:
@pytest.mark.parametrize("d,thresh", [
(128, 0.992),
(256, 0.990),
(512, 0.985),
])
def test_cosine_similarity(self, d, thresh):
x = np.random.default_rng(d).standard_normal(d).astype(np.float32)
packed, norm = encode_turbo4(x)
dec = decode_turbo4(packed, norm, d)
dot = float(np.dot(x, dec))
cos = dot / (np.linalg.norm(x) * np.linalg.norm(dec) + 1e-9)
assert cos >= thresh, f"d={d} cos={cos:.4f} < {thresh}"
def test_zero_vector(self):
packed, norm = encode_turbo4(np.zeros(128, dtype=np.float32))
assert norm == 0.0 and np.all(packed == 0)
dec = decode_turbo4(packed, 0.0, 128)
assert np.max(np.abs(dec)) <= 1e-5
def test_pass_rate_20_random(self):
ok = 0
rng = np.random.default_rng(12345)
for _ in range(20):
x = rng.standard_normal(128).astype(np.float32)
packed, norm = encode_turbo4(x)
dec = decode_turbo4(packed, norm, 128)
cos = float(np.dot(x, dec)) / (np.linalg.norm(x)*np.linalg.norm(dec)+1e-9)
if cos >= 0.99: ok += 1
assert ok >= 18
class TestInnerProductPreservation:
"""Self-inner-product (auto-correlation) preserved through roundtrip."""
def test_self_dot_relative_error(self):
"""For a random vector, x·x ≈ decoded·decoded (rel err < 0.05)."""
rng = np.random.default_rng(888)
for _ in range(10):
x = rng.standard_normal(128).astype(np.float32)
packed, norm = encode_turbo4(x)
dec = decode_turbo4(packed, norm, 128)
orig_sq = float(np.dot(x, x))
dec_sq = float(np.dot(dec, dec))
err = abs(orig_sq - dec_sq) / (orig_sq + 1e-6)
assert err < 0.05, f"rel_err={err:.4f} for x·x"
class TestWHTOrthogonality:
def test_norm_preservation(self):
rng = np.random.default_rng(2024)
for d in [32, 64, 128, 256]:
x = rng.standard_normal(d).astype(np.float32)
on = float(np.linalg.norm(x))
wht = x.copy()
_fwht(wht)
wn = float(np.linalg.norm(wht))
assert abs(on - wn) < 1e-5
def test_basis_vectors(self):
d = 64
for i in range(3):
basis = np.zeros(d, dtype=np.float32)
basis[i] = 1.0
wht = basis.copy()
_fwht(wht)
expected = 1.0 / math.sqrt(d)
assert np.allclose(np.abs(wht), expected, atol=1e-6)
def test_involution(self):
x = np.random.default_rng(777).standard_normal(128).astype(np.float32)
wht = x.copy()
_fwht(wht); _fwht(wht)
assert np.allclose(wht, x, atol=1e-5)
class TestCodebook:
def test_16_centroids(self):
assert len(TURBO4_CENTROIDS) == 16
def test_sorted_monotonic(self):
assert np.all(np.diff(TURBO4_CENTROIDS) > 0)
def test_approx_centered(self):
"""Approximately centered: mean close to 0."""
assert abs(np.mean(TURBO4_CENTROIDS)) < 0.05
def test_ordering_bounds(self):
c = TURBO4_CENTROIDS
assert c[0] < -0.20
assert c[7] < 0.02
assert c[8] > -0.02
assert c[15] > 0.28
def test_all_indices_valid(self):
rng = np.random.default_rng(333)
for _ in range(50):
x = rng.standard_normal(128).astype(np.float32)
packed, _ = encode_turbo4(x)
lo = packed & 0x0F
hi = (packed >> 4) & 0x0F
assert np.all((lo >= 0) & (lo <= 15))
assert np.all((hi >= 0) & (hi <= 15))
class TestBitPacking:
def test_pack_unpack_roundtrip(self):
rng = np.random.default_rng(555)
d = 128
idx = rng.integers(0, 16, size=d, dtype=np.uint8)
packed = np.zeros(d // 2, dtype=np.uint8)
for i in range(d):
if i % 2 == 0:
packed[i // 2] = idx[i]
else:
packed[i // 2] |= idx[i] << 4
recovered = np.empty(d, dtype=np.uint8)
for i in range(d):
if i % 2 == 0:
recovered[i] = packed[i // 2] & 0x0F
else:
recovered[i] = (packed[i // 2] >> 4) & 0x0F
assert np.array_equal(recovered, idx)
@pytest.mark.parametrize("d", [64, 128, 256, 512])
def test_buffer_size_matches_dimension(self, d):
packed, _ = encode_turbo4(np.zeros(d, dtype=np.float32))
assert len(packed) == d // 2
def test_packed_bit_count(self):
"""Total 4-bit slots exactly equals input dimension."""
for d in [64, 128, 256]:
packed, _ = encode_turbo4(np.zeros(d, dtype=np.float32))
assert len(packed) * 2 == d
class TestEdgeCases:
def test_dim_128(self):
packed, norm = encode_turbo4(np.random.standard_normal(128).astype(np.float32))
dec = decode_turbo4(packed, norm, 128)
assert len(dec) == 128
def test_dim_256(self):
packed, norm = encode_turbo4(np.random.standard_normal(256).astype(np.float32))
dec = decode_turbo4(packed, norm, 256)
assert len(dec) == 256
def test_alternating_signs(self):
d = 128
x = np.array([1.0 if i % 2 == 0 else -1.0 for i in range(d)], dtype=np.float32)
packed, norm = encode_turbo4(x)
dec = decode_turbo4(packed, norm, d)
cos = float(np.dot(x, dec)) / (np.linalg.norm(x)*np.linalg.norm(dec)+1e-9)
assert cos >= 0.90
def test_constant_vector(self):
x = np.full(128, 0.5, dtype=np.float32)
packed, norm = encode_turbo4(x)
dec = decode_turbo4(packed, norm, 128)
cos = float(np.dot(x, dec)) / (np.linalg.norm(x)*np.linalg.norm(dec)+1e-9)
assert cos >= 0.85
class TestCompression:
def test_four_bit_per_dimension(self):
for d in [64, 128, 256, 512]:
packed, _ = encode_turbo4(np.zeros(d, dtype=np.float32))
# 4 bits per element: 2 elements per byte
assert len(packed) * 2 == d
if __name__ == "__main__":
pytest.main([__file__, "-v"])