# module `concrete.fhe.extensions.relu`
Declaration of `relu` extension.
---
## function `relu`
```python
relu(x: Union[Tracer, Any]) → Union[Tracer, Any]
```
Rectified linear unit extension.
Computes: x if x >= 0 else 0
**Args:**
x (Union[Tracer, Any]): input to apply ReLU
**Returns:**
Union[Tracer, Any]: Tracer that represent the operation during tracing result of ReLU on `x` otherwise