// THANK YOU! brazenly stolen from https://www.math.ucla.edu/~tom/distributions/normal.html // within the spreadsheet, of course, you can just use =NORMSDIST(X) function normalcdf(X){ //HASTINGS. MAX ERROR = .000001 var T=1/(1+.2316419*Math.abs(X)); var D=.3989423*Math.exp(-X*X/2); var Prob=D*T*(.3193815+T*(-.3565638+T*(1.781478+T*(-1.821256+T*1.330274)))); if (X>0) { Prob=1-Prob } return Prob } /** * Provides d1 for Black-Scholes. * * @param {30} DTE T-t in days to expiration […]