package graph;
import java.util.Vector;

/**
 * A basic matrix class.  This really belongs in some
 * utility package...
 *
 * @author Michael Shilman (michaels@eecs.berkeley.edu)
 * @version $Id$
 */
public class Matrix implements Cloneable {
	//XXX other matrix types (float, etc.)
	/**
	 * The matrix class.
	 */
	public int[][] values = null;
	
	/**
	 * Construct a WxH-dimensioned matrix and
	 * zero out all of its values.
	 * 
	 * @param w		The width of the matrix.
	 * @param h 	The height of the matrix.
	 */
	public Matrix(int w, int h) {
		values = new int[w][h];
		for(int i = 0; i < w; i++) {
			for(int j = 0; j < h; j++) {
				values[i][j] = 0;
			}
		}
	}
	
	/**
	 * Make a copy of this matrix.
	 *
	 * @return 		The copied matrix.
	 */
	public Object clone() {
		int w = values.length;
		int h = values[0].length;
		Matrix m = new Matrix(w,h);
		for(int i = 0; i < h; i++) {
			for(int j = 0; j < w; j++) {
				m.values[i][j] = values[i][j];
			}
		}
		
		return m;
	}
	
	
	/**
	 * Return a Vector of int[] eigenvectors.  Not yet implemented.
	 */
	public Vector eigenVectors() {
		Vector result = new Vector();
		Matrix trans = transpose();
		return null;
	}
	
	
	/**
	 * Create a new matrix which is the transpose of this
	 * matrix.
	 */
	public Matrix transpose() {
		int w = values.length;
		int h = values[0].length;
		
		Matrix dup = new Matrix(h, w);
		for(int i = 0; i < h; i++) {
			for(int j = 0; j < w; j++) {
				dup.values[j][i] = values[i][j];
			}
		}
		
		return dup;
	}
	
	/**
	 * Calculate the determinant of the matrix.  Unimplemented.
	 */
	public int determinant() {
		return 0;
	}
	
	/**
	 * Multiply every element in the matrix by a scalar value.
	 *
	 * @param scalar	The scaling factor.
	 */
	public void multScalar(int scalar) {
		int w = values.length;
		int h = values[0].length;
		
		for(int i = 0; i < h; i++) {
			for(int j = 0; j < w; j++) {
				values[i][j] *= scalar;
			}
		}
	}
	
	/**
	 * Print the contents of the matrix into a string.
	 */
	public String toString() {
		String s = new String();
		
		int w = values.length;
		int h = values[0].length;
		for(int i = 0; i < h; i++) {
			for(int j = 0; j < w; j++) {
				s = s + " " + values[i][j];
			}
			s = s + "\n";
		}
		return s;
	}
}