public static double cdf(double x,double mu,double sigma){
  if (x <= 0.) {
    return 0.;
  }
  return .5 * (1 + NormalDistribution.erf((Math.log(x) - mu) / (MathUtil.SQRT2 * sigma)));
}

public static double cdf ( double x , double mu , double sigma ) { if ( x <= 0. ) { return 0. ; } return .5 * ( 1 + NormalDistribution . erf ( ( Math . log ( x ) - mu ) / ( MathUtil . SQRT2 * sigma ) ) ) ; }
cumulative probability density function ( cdf ) of a normal distribution .
