public static double standardDeviation(double[] data,int opt){
  if (opt == 0)   return Math.sqrt(variance(data,opt));
 else   return Math.sqrt(variance(data,opt));
}

public static double standardDeviation ( double [ ] data , int opt ) { if ( opt == 0 ) return Math . sqrt ( variance ( data , opt ) ) ; else return Math . sqrt ( variance ( data , opt ) ) ; }
compute the standard deviation of the given data , this function can deal with nans
