A vector containing a set of $n$ data elements.

**
Data Types: **`double`

The vector contains a set of n positive weights
summing to 1. The 1-sum requirement does not imply loss of
generality: it is just to avoid extra checks and the normalization
step inside the function.

**
Data Types: **`double`

A number between 0 and 1
indicating the fraction of total weights that should be considered
in partitioning the associated input data. Default is p=0.5, leading
to the weighted median.

**Example: **```
p,0.2
```

**
Data Types: **`double`