spot: spot price
strike: strike price
time: time to maturity in years
rate: risk-free interest rate to the exercise date in percent
volatility: annualized volatility of the asset in percent for the period through to the exercise date
cost_of_carry: net cost of holding the underlying asset (for common stocks, the risk free rate less the dividend yield), defaults to 0
OPT_BS_GAMMA uses the Black-Scholes model to calculate the 'gamma' of a European option struck at strike on an asset with spot price spot. The gamma of an option is the second derivative of its price with respect to the price of the underlying asset.
Gamma is expressed as the rate of change of delta per unit change in spot. Gamma is the same for calls and puts.