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Python

"""
Tests execution of simulation.
"""
import numpy as np
import pytest
from concrete import fhe
@pytest.mark.parametrize("p_error", [0.5, 0.01, 0.005])
def test_tlu_error_rate(p_error):
"""
Test that error rates are realistic.
"""
repetition = max(1000, int(10 / p_error))
assert repetition < 10_0000, "Test will be too long"
conf = fhe.Configuration(p_error=p_error)
precision = 3
@fhe.compiler({"x": "encrypted"})
def tlu(x):
return fhe.univariate(lambda x: x)(x)
inputset = [np.array(list(range(0, 2**precision)))]
circuit = tlu.compile(inputset, conf)
nok_fhe = 0
nok_sim = 0
size = 0
for t in inputset * repetition:
fhe_value = circuit.encrypt_run_decrypt(t)
sim_value = circuit.simulate(t)
for v, fhe_v, sim_v in zip(t, fhe_value, sim_value):
size += 1
nok_fhe += v != fhe_v
nok_sim += v != sim_v
fhe_p_error = nok_fhe / size
sim_p_error = nok_sim / size
assert p_error * size > 10 # test invalid if no more than 10 expected errors
assert fhe_p_error
assert sim_p_error
# the sample size is not big => we accept significant releative error
assert fhe_p_error == pytest.approx(p_error, rel=0.75)
assert sim_p_error == pytest.approx(p_error, rel=0.75)
assert fhe_p_error == pytest.approx(sim_p_error, rel=0.75)
@pytest.mark.parametrize("p_error", [0.01, 1e-120])
def test_approx_tlu_error_rate(p_error):
"""
Test that error rates are realistic in approximate mode.
"""
conf = fhe.Configuration(p_error=p_error)
precision = 8
lsbs_to_remove = 5
def rnd(x):
return (x + 2 ** (lsbs_to_remove - 1)) // 2**lsbs_to_remove
@fhe.compiler({"x": "encrypted"})
def tlu(x):
rounded = fhe.round_bit_pattern(
x,
lsbs_to_remove=lsbs_to_remove,
overflow_protection=False,
exactness=fhe.Exactness.APPROXIMATE,
)
return fhe.univariate(rnd)(rounded)
inputset = [np.array(list(range(0, 2**precision - 2**lsbs_to_remove)))]
circuit = tlu.compile(inputset, conf)
nok_fhe = 0
nok_sim = 0
size = 0
for t in inputset * 30:
fhe_values = circuit.encrypt_run_decrypt(t)
sim_values = circuit.simulate(t)
for x, fhe_v, sim_v in zip(t, fhe_values, sim_values):
r = rnd(x)
size += 1
nok_fhe += r != fhe_v
nok_sim += r != sim_v
print(r, fhe_v, sim_v)
fhe_p_error = nok_fhe / size
sim_p_error = nok_sim / size
# error rate is always significant (>3%) in approximate mode
assert p_error + 0.005 < fhe_p_error
assert p_error + 0.005 < sim_p_error
assert fhe_p_error < 0.2 + p_error
assert sim_p_error < 0.2 + p_error
assert fhe_p_error == pytest.approx(sim_p_error, rel=0.75)