This function implements equation (2.19), the recursive estimation for updating the relative loss in the variance of the holding portfolio in the overlapping scheme.
rUpdateOverlapping(Psi, c, prev_R, K)a vector of shrinkage coefficients.
a numeric between 0 and 1. It is the concentration ration.
a numeric greater than 0, the previous value of the relative loss
a numeric parameter.
a number