interface Evaluar
{
    double f(double x);    
}

class FuncZ implements Evaluar
{
    public double f (double x)
    {
        return Math.exp(-Math.pow(x,2.0) / 2.0) / Math.sqrt(2.0 * Math.PI);     
    }
}


class Integral
{
	public double sumaParcial(Double x, Double y, double h, Evaluar e)
	{
		double s = y.doubleValue();
		s += 4 * e.f(x.doubleValue() + h);
		x = new Double(x.doubleValue() + 2.0 * h);
		y = new Double(e.f(x.doubleValue()));
		s += y.doubleValue();
		return s;	
	}	
	
	public double fintegral(Double a, double b, int n, Evaluar e)
	{
		double s = 0.0;
		Double y = new Double(e.f(a.doubleValue()));
		if (n % 2 != 0) n++;
		double h = (b - a.doubleValue()) / n;
		int cont = 0;
		do
		{
			s += sumaParcial(a,y,h,e);
			cont += 2;
		} while(cont < n);
		
		s *= h / 3.0;
		return s;	
	}
}

class DistNormal
{
	FuncZ fz;
	Integral integral;
	
	public DistNormal()
	{
		fz = new FuncZ();
		integral = new Integral();	
	}	
		
	private double redondear4d(double num)
    {
        double aux = num * 10000;
        int tmp = (int) aux;
    
        return (double) tmp / 10000;     
    }   
	
	public double normal_acum(double z)
	{
		Double lim_inf = new Double(-3.60);
		double acum = 0.000159;
		double inc = 0.01;	
		do
		{
			acum += integral.fintegral(lim_inf,lim_inf.doubleValue() + inc , 4 , fz);
			lim_inf = new Double(lim_inf.doubleValue() + inc);	
		} while (lim_inf.doubleValue() < z - inc);
		return redondear4d(acum);
	}
	
	double dist_normal(double z)
	{
		return (z <= 0.0)? normal_acum(z) : 1.0 - normal_acum(-z);	
	}
	
	double func_z(double prob)
	{
		Double lim_inf = new Double(-3.60);
		double acum = 0.000159;
		double inc = 0.01;	
		do
		{
			acum += integral.fintegral(lim_inf,lim_inf.doubleValue() + inc , 4 , fz);
			lim_inf = new Double(lim_inf.doubleValue() + inc);	
		} while (acum < prob + 0.000159);
		return redondear4d(lim_inf.doubleValue() - inc);
		
	}
	
	double obtener_z(double prob)
	{
		return (prob <= 0.5)? func_z(prob) : -func_z(1.0 - prob);	
		
	}
	
	public static void main(String args[])
	{
		DistNormal d = new DistNormal();
		
		System.out.println("P(Z < 2.66) : " + d.dist_normal(2.66));	
		System.out.println("Z(0.9962) : " + d.obtener_z(0.9962));
	}
}