/**copyright by Emanuele Dalla Torre - Technion 2002*/
/*
Misuration Unit
	Uo=1 --> Uo= 1ev
	a=1 --> a = 1 A
	b=1 --> b = 1 A
	k=1 --> k = 1/(a+b)
	z=1 --> E = 1Uo
Dominium
	-PI <= k <= PI
	0 <= z <= maxZ
*/

class KronigPenney
	{
	final long MAXTIME=(long)15e3;
	final double MIN=1e-3, MAX=1e3;
	final String errorMsg1="I couldn't find any band", errorMsg2= " OR one or more values are not correct:", errorMsg3="d-b>"+MIN+" , "+MIN+"<=U*b<="+MAX+" , 1<=number<=10";
	final double HbarC=1975.8, mC2=0.511e6;
	double a, b, Uo; //please don't write from other classes!
	int number,effective,valency;//if zero --> nothing shown, if greater then zero --> something shown
	KPBand[] band;

	//public static void main (String[] s)
	//	{KPWindow f=new KPWindow();}

	void set(double a, double b, double Uo,int number, int effective, int valency)
		{
		this.a=a;
		this.b=b;
		this.Uo=Uo;
		this.number=((a>=MIN)&&(b>=0)&&(b*Uo>=MIN)&&(b*Uo<=MAX))?number:0;
		this.effective=(effective<=number)?effective:0;
		this.valency=(valency<=number-1)?valency:0;
		band=new KPBand[100];
		scan();
		}

	private void scan() //calculate minZ, maxZ
		{
		double step=1e-10;
		double newZ=step, newcosdk=cosdk(newZ), newK=k(newZ);
		double oldZ ,oldcosdk, oldK;
		int n=1;//found bands
		long counter=0;
		boolean permitted=false;
		
		long start=System.currentTimeMillis();
		while ((n<=number)&&( (counter>0)||(System.currentTimeMillis()<start+MAXTIME) ))
			{
			oldK=newK; oldZ=newZ;

			newZ=oldZ+step;
			if((n==1)&&(!permitted))
				{
				oldcosdk=newcosdk;
				newcosdk=cosdk(newZ);
				step=(-1)*((newZ-oldZ)/(newcosdk-oldcosdk))*(newcosdk/100);
				}

			newK=k(newZ);//calculate twice!!!!
			if ((!Double.isNaN(newK))&&(!permitted))
				{
				band[n-1]=new KPBand(newZ,newZ,(n%2==1));
				permitted=true;
				}
			if ((Double.isNaN(newK))&&(permitted))
				{
				permitted=false;
				band[n-1].maxZ=oldZ;
				n++;
				}
			if (counter++==1e4)counter=0;
			//System.out.print("Z="+newZ+"newcosdk= "+newcosdk+" band= "+n+"step= "+step+"dervate= "+Math.abs(newZ-oldZ)/(Math.abs(newcosdk-oldcosdk)+0.01)+"\n");
			}
		n--;
		number=n;

		}

	double getMe(double d2)
		{return(HbarC*HbarC)/(d2*Uo*mC2);}

	double getMaxZ()
		{return band[number-1].maxZ;}

	double cosdk(double z)//solving Kronig Penney
		{
		double alfa=sqrt(2*mC2*Uo/(HbarC*HbarC));
		double value;
		if (z<1)
			{value=((1-2*z)/(2*sqrt(z*(1-z))))*sin(alfa*a*sqrt(z))*sinh(alfa*b*sqrt(1-z))
					+cos(alfa*a*sqrt(z))*cosh(alfa*b*sqrt(1-z));}
		else{value=((1-2*z)/(2*sqrt(z*(z-1))))*sin(alfa*a*sqrt(z))*sin(alfa*b*sqrt(z-1))
					+cos(alfa*a*sqrt(z))*cos(alfa*b*sqrt(z-1));}
		return value;
		}

	double k(double z)
		{
		double value=cosdk(z);
		if ((value<(float)1)&&(value>(float)-1)){return (Math.acos(value)/(a+b));}
		else return (Double.NaN);
		}

	static double cosh(double a) {return ((Math.exp(a)+Math.exp(-a))/2);}
	static double sinh(double a) {return ((Math.exp(a)-Math.exp(-a))/2);}
	static double cos(double a) {return Math.cos(a);}
	static double sin(double a) {return Math.sin(a);}
	static double sqrt(double a) {return Math.sqrt(a);}
	}