"""
    Pearson Correlation

Find the pearson correlation between two variables.

# Example:

julia> PearsonCorrelation([12,11,16,17,19,21],[11,51,66,72,12,15])
-0.2092706263573845

Contribution by: [Aru Bhardwaj](https://github.com/arubhardwaj)


"""



function PearsonCorrelation(x, y)
    mean_x = sum(x)/length(x)
    mean_y = sum(y)/length(y)
    XY = (x.-mean_x).*(y.-mean_y)
    XXs = sum((x.-mean_x).*(x.-mean_x))
    YYs = sum((y.-mean_y).*(y.-mean_y))
    return(sum(XY)/(sqrt(XXs.*YYs)))
end
