# bfloat16 in numpy: `ml_dtypes`
- code repository: http://github.com/jax-ml/ml_dtypes
- tracking issue: https://github.com/numpy/numpy/issues/19808
```python=
>>> from ml_dtypes import bfloat16
>>> import numpy as np
>>> np.zeros(4, dtype=bfloat16)
array([0, 0, 0, 0], dtype=bfloat16)
```
## Goals
- Single dependency for JAX, tensorflow, and perhaps other libraries in the future
- Self-contained and permissively licensed, with eye toward possible future adoption in numpy core
## Problems
- No way to register new dtypes with `numpy.finfo`
- No way to make this a true subtype of `numpy.floating` because of hard-coded logic about float widths
- Saving as `*.npy` does not work because there is no unique char code for bfloat16