> ## Documentation Index
> Fetch the complete documentation index at: https://nixtla-old-docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Differences

# <kbd>module</kbd> `coreforecast.differences`

***

## <kbd>function</kbd> `num_diffs`

```python theme={null}
num_diffs(x: ndarray, max_d: int = 1) → int
```

Find the optimal number of differences

**Args:**

* <b>`x`</b> (np.ndarray):  Array with the time series.
* <b>`max_d`</b> (int, optional):  Maximum number of differences to consider. Defaults to 1.

**Returns:**

* <b>`int`</b>:  Optimal number of differences.

***

## <kbd>function</kbd> `num_seas_diffs`

```python theme={null}
num_seas_diffs(x: ndarray, season_length: int, max_d: int = 1) → int
```

Find the optimal number of seasonal differences

**Args:**

* <b>`x`</b> (np.ndarray):  Array with the time series.
* <b>`season_length`</b> (int):  Length of the seasonal pattern.
* <b>`max_d`</b> (int, optional):  Maximum number of differences to consider. Defaults to 1.

**Returns:**

* <b>`int`</b>:  Optimal number of seasonal differences.

***

## <kbd>function</kbd> `diff`

```python theme={null}
diff(x: ndarray, d: int) → ndarray
```

Subtract previous values of the series

**Args:**

* <b>`x`</b> (np.ndarray):  Array with the time series.
* <b>`d`</b> (int):  Lag to subtract

**Returns:**

* <b>`np.ndarray`</b>:  Differenced time series.

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