JAVA 标准正态分布分布函数

package math;

public class NormalDistribution {
public static double calc(double u){
double y=Math.abs(u);
double y2 = y*y;
double z=Math.exp(-0.5 * y2) * 0.398942280401432678;
double p=0;
int k=28;
double s = -1;
double fj=k;

if(y>3){
//当y>3时
for(int i=1;i<=k;i++){
p = fj / (y+p);
fj=fj - 1.0;
}
p = z / (y+p);
}else{
//当y<3时
for(int i=1;i<=k;i++){
p = fj * y2 / (2.0*fj +1.0 + s * p);
s = -s;
fj = fj - 1.0;
}
p = 0.5 - z * y / ( 1 - p );
}
if(u>0) p = 1.0 - p;
return p;
}
public static void main(String[] args) {
for(double d=0;d<5.0;d+=0.1){
System.out.println(d+","+calc(d));
}
}
}