Fast computation of the distance covariance `dcov`

and distance correlation `dcor`

. The computation cost is only O(n log(n)) for the distance correlation (see Chaudhuri, Hu, 2019, arXiv, elsevier). The functions are written entirely in C++ to speed up the computation.

## Usage

```
dcov(x, y) # To calculate the distance covariance
dcor(x, y) # To calculate the distance correlation
```

## Contributions and Issues

Feel free to raise an issue if you find something not working properly.

You are also very welcome to contribute to `dcccp`

. Please base your pull requests on the development branch. Note that this package focuses on performance, PR’s that improve the performance are particularly welcome.