// tjhNeuron.java

/** Implements an artificial neuron for a cell. The neuron controls how the cell will respond to the 
    environment around it. This neuron model does not include internal state. */

public class tjhNeuron extends Object
{
	//----------------------------------------------------------------------
	// static constants
	//----------------------------------------------------------------------

	/** The neuron has a fixed number of inputs */
	public static final int N_INPUTS=4;

	//----------------------------------------------------------------------
	// data
	//----------------------------------------------------------------------

	/** The matrix controls how the inputs are transformed into the output. 
	    The output is the dot product of the input vector and the matrix */
	protected int matrix[]; // each entry is -1, 0 or 1

	//----------------------------------------------------------------------
	// methods
	//----------------------------------------------------------------------

	/** default constructor */
	public tjhNeuron()
	{
		matrix = new int[N_INPUTS];		

		// initialize the matrix to zeros (no response, braindead)
		//for(int i=0;i<N_INPUTS;i++)
		//	matrix[i]=0;

		// initialize the matrix randomly
		for(int i=0;i<N_INPUTS;i++)
			matrix[i]=RandomEntry();
	}

	/** Returns an output given an input matrix */
	public int GetOutput(int input[])
	{
		// output is row of matrix multiplied by the input row
		int output=0;

		for(int i=0;i<N_INPUTS;i++)
		{
			output += input[i]*matrix[i];
		}
		if(output>1) output=1;
		else if(output<-1) output=-1;

		return output;
	}

	/** copies the specified neuron into this one */
	public void Copy(tjhNeuron other)
	{
		for(int i=0;i<N_INPUTS;i++)
			matrix[i]=other.matrix[i];
	}

	/** returns -1, 0 or 1 with equal probability */
	public static int RandomEntry()
	{
		if(Math.random()<0.33) return -1;
		else if(Math.random()<0.66) return 0;
		else return 1;
	}
}