# forge.ta.correlation

```python
forge.ta.correlation(a: ArrayLike, b: ArrayLike, period: int = 30) -> np.ndarray
```

Rolling correlation of two series over the last ``period`` bars, from -1 to 1.

A window where either series is missing a value or does not move has no value. The two series
can come from two symbols aligned on the same bars: ``d["GBPUSD"].close`` in a strategy, or a
declared second symbol in an indicator. Example: ``ta.correlation(close, other, 30)``.

Since Forge API 1.