weighted_left_tail_cdf: Weighted Left-Tail Cumulative Distribution Function
Description
This function generates a vector of the weighted left-tail cumulative distribution function of a given vector of values. The weight of of each variable is determined by its position in the vector. For example, with a vector of length 5, element 1 will have weight 5/(5+4+3+2+1). Element 1 will have weight 5/(5+4+3+2+1)