# tensorplay.distributions.register_kl

Source: https://www.tensorplay.cn/docs/generated/tensorplay.distributions.register_kl.html

```python
tensorplay.distributions.register_kl(type_p, type_q)
```

Decorator to register a pairwise function with [kl_divergence()](/docs/generated/tensorplay.distributions.kl_divergence.html#tensorplay.distributions.kl_divergence).
Usage:

```
@register_kl(Normal, Normal)
def kl_normal_normal(p, q):
    # insert implementation here
```

Lookup returns the most specific (type,type) match ordered by subclass. If
the match is ambiguous, a RuntimeWarning is raised. For example to
resolve the ambiguous situation:

```
@register_kl(BaseP, DerivedQ)
def kl_version1(p, q): ...
@register_kl(DerivedP, BaseQ)
def kl_version2(p, q): ...
```

you should register a third most-specific implementation, e.g.:

```
register_kl(DerivedP, DerivedQ)(kl_version1)  # Break the tie.
```

Parameters:

- type_p ([type](https://docs.python.org/3/builtins/functions.html#type)) – A subclass of [Distribution](/docs/generated/tensorplay.distributions.Distribution.html#tensorplay.distributions.Distribution).

- type_q ([type](https://docs.python.org/3/builtins/functions.html#type)) – A subclass of [Distribution](/docs/generated/tensorplay.distributions.Distribution.html#tensorplay.distributions.Distribution).