import Jama.Matrix;

Cmplx[] binomial(double d, double theta, double phi, int Num, int axis) { //d:element spacing in units of lambda
											                   //theta:beam angle (in degrees)
											                   //phi:azimut angle (in degrees)
											                   //N:number of array elements
											                   //axix:indicates which axis is used-->1 for x axis
											                   //                                 -->2 for y axis

//This function uses a binomial algorithm to calculate the weights and phases in an unidirectional array of antennas 											 
	double N=Num;
	int N1=N-1;
	int a=1;
	double []v= new double[]{1.0, 1.0};  //define the vector we are going to use in the convolution
     double[] P=new double[N];            //define the vector we are going to obtain as a result of the convolution

	Cmplx[] z=new Cmplx[N];
	Cmplx[] f=new Cmplx[N];  //vectors of N elements Cmplx type

	double k;
	
	if (axis==1){
		k=(Math.sin(Math.toRadians(theta))*Math.cos(Math.toRadians(phi)));
	}
	if (axis==2){
		k=(Math.sin(Math.toRadians(theta))*Math.sin(Math.toRadians(phi)));
	}
	
	double ang=Math.acos(k);  //ang=arccos(sen(theta)*cos(phi))
	double cose=Math.cos(ang);//cose=cos(ang)
	double ps0=(2*Math.PI*d*cose); //find the phase that we are going to use to direct the array in the desired direction

	
	double[] y=new double[N];
	double[] fase=new double[N];  //vectors of N elements double type
	
	
	if (N1>=1){
		P=convolution(v, P, N1); //call to the convolucion.java function. In this case, it convolves the vector v with a vector of a dimension u = 1
                                   //We pass the vector v, the vector P and N1 (number of antennas in the array minus one)
	}                             //It returns the vector P with the result of the convolution, this vector P contains the weights of the array, since we are in a binomial algorithm
	if (N1==0){
		for (i=0; i<=N1; i++){
			P[i]=1.0;
		}
	}


	for (int n=0; n<N; n++){
		f[n]=new Cmplx(0,-((n-(N-1)/2)*ps0)); //create a complex vector, with 0 as the real part, where the imaginary part are the
									   //successive phases that we are going to multiply to the weights
								   
		z[n]=P[n]*(Cmplx.exp(f[n]));         //find the final result in the form of a complex number by multiplying the weights by the progressive phases, 
		                                     //thus directing the array towards the direction indicated by theta and phi
		                                     
		y[n]=Cmplx.abs(z[n]); //find the absolute of the complexes, that is, the weights
		fase[n]=(Math.atan2(z[n].imag, z[n].real)); //find the phase in radians
		if (fase[n]<0){ // if the phase is less than 0
			fase[n]=2*Math.PI+fase[n]; //add 2*pi
			}
		fase[n]=Math.toDegrees(fase[n]); //find the phase in degrees
	}
	
	writeFile("./mydatafiles/binomial.txt", y, fase);//write the weigths and phases in a text file
	return z;  //return the complex vector z, which contains the results of the algorithm
}