public static double standardNormalPdf(double x){
  double a=1.0 / (Math.sqrt(2.0 * Math.PI));
  double b=-(x) * (x) / (2.0);
  return a * Math.exp(b);
}

public static double standardNormalPdf ( double x ) { double a = 1.0 / ( Math . sqrt ( 2.0 * Math . PI ) ) ; double b = - ( x ) * ( x ) / ( 2.0 ) ; return a * Math . exp ( b ) ; }
probability density function of the standard normal distribution
