diego / Finance_BlackScholesATMOptionValue / 0.1.0

Calculates the Black-Scholes option value of an atm call option.@param volatility The Black-Scholes volatility.@param optionMaturity The option maturity T.@param forward The forward, i.e., the expectation of the index under the measure associated with payoff unit. @param payoffUnit The payoff unit, i.e., the discount factor or the anuity associated with the payoff. @return Returns the value of a European at-the-money call option under the Black-Scholes model