function to compute expected shortfall from volatility for normal random variables.
volaToExpectedShortfall(x, alpha = 0.01, sup = F, ...)
a numeric vector of positive volatilities.
a numeric value. The alpha-Expected Shortfall, must take values between 0 and 1.
a logical value. If TRUE
the function returns the upper
expected shortfall and otherwise the lower. Default is set to FALSE
.
additional parameters.
a numeric vector, the expected shortfalls.