# SiLU activation

Compile and evaluate PLLM's bounded experimental Q7 SiLU component.

[View canonical HTML](https://pllm.run/sdk/build/operators/activation-silu/)

Document ID: `pllm.docs.operators.activation-silu`  
Release: `0.1.0`

PLLM implements one bounded SiLU primitive using numeric graph
`pllm.numeric.silu.quadratic_q7.v1`. Compilation requires the explicit
`pllm/arithmetic-garbling-silu-q7/v1` nonlinear component and
`pllm/bounded-independent-elements/v1` protected scheduler. It encodes `[-1, 1]` at scale 128,
evaluates `x / 2 + x² / 4`, rounds ties to even, and rejects inputs outside the
locked domain. Across all 257 encoded inputs, absolute error against SiLU is at
most `0.02285`. One compiled Q7 SiLU region is capped at 128 elements in this
initial bounded slice.

The protected implementation uses modulus 257 across the bounded Q7 input and
output domains. Client wire
encodings and evaluator gates remain separate. Evaluator material is serialized
for transport within one process, registered when issued, bound to the compiled
plan, and consumed once after exact payload authentication. This is an experimental
reference component, not a complete Qwen execution profile, a cross-process replay
protocol, or a production-security claim.

## Python SDK example

```python
from pathlib import Path

from pllm import lower_model
from pllm.nonlinear import ArithmeticGarblingSiluQ7
from pllm.schedulers import BoundedIndependentElementsProtectedTensorSchedule

fixture = Path("crates/pllm-models/tests/fixtures/mini-coder-4b-c87892d-config.json")
plan = lower_model(fixture.read_bytes(), batch=1, max_input_tokens=16, max_new_tokens=4)
silu = next(
    operation
    for operation in plan.prefill["operations"]
    if operation["operator"] == "silu"
)
assert silu["id"] == "layer.0.silu"
assert silu["output_shape"] == (1, 16, 9728)
assert ArithmeticGarblingSiluQ7().component == "pllm/arithmetic-garbling-silu-q7/v1"
assert BoundedIndependentElementsProtectedTensorSchedule(
    max_elements=128
).params["max_elements"] == 128
```

API: [Python SDK objects and signatures](/sdk/reference/python/pllm/#objects-and-signatures)

Run this example from a PLLM source checkout; package installations do not include
the model-adapter test fixture. `ModelPlan.prefill` and its operation records are
read-only mappings.

The semantic plan preserves SiLU as an explicit operator. A separately validated
compile request can lower a bounded SiLU region to the internal native Q7 evaluator,
but PLLM does not expose that evaluator through the stable Python runtime facade.