The inverse of the *α*-transformation.

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`x` |
A matrix with Euclidean data. However, they must lie within the feasible, acceptable space. See references for more information. |

`a` |
The value of the power transformation, it has to be between -1 and 1. If zero values are present it has to be greater than 0. If |

`h` |
If h = TRUE this means that the multiplication with the Helmer sub-matrix will take place. It is set to TRUe by default. |

The inverse of the *α*-transformation is applied to the data. If the data lie outside the *α*-space, NAs will be returned for some values.

A matrix with the pairwise distances.

Michail Tsagris

R implementation and documentation: Michail Tsagris <mtsagris@yahoo.gr> and Giorgos Athineou <athineou@csd.uoc.gr>

Tsagris M.T., Preston S. and Wood A.T.A. (2016). Improved classification for compositional data using the *α*-transformation. Journal of Classification (to appear). http://arxiv.org/pdf/1506.04976v2.pdf

Tsagris M.T., Preston S. and Wood A.T.A. (2011). A data-based power transformation for compositional data. In Proceedings of the 4th Compositional Data Analysis Workshop, Girona, Spain. http://arxiv.org/pdf/1106.1451.pdf

```
alfa, alfadist
```

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