getDensity(x, Bins)

Compute density distribution of the values in 'x'.
To check the result: plot(pBins, PDD), xlabel('x'), ylabel('Density')

INPUT

x : vector of values
Bins : Optional: bins used to compute the density. if Bins is not given in the call, the function
will use the default binning, given by: Bins = linspace(min(x), max(x), round(sqrt(length(x))))

OUTPUT

PDD : Probability Density Distribution. [ sum(PDD) == 1 ]
pBins : Return the value of the bins used to compute the distribution