package jhplot.bsom;

/* 
 * @(#)Matrix.java	1.3	20/9/96 Akio Utsugi
 */

import java.util.Random;
import java.lang.Math;

/**
 * Matrix is a class for matrix objects with basic linear calculation methods.
 * @version 1.2 17 Sep 1996
 * @author  Akio Utsugi 
 */
public class Matrix
{
    final static double small = 1e-8;
    
    int row, col;
    double value[][];


/**
 * Construct a square matrix object.
 * @param n size
 */
    public Matrix(int n)
    {
	this(n, n);
    }
    
/**
 * Construct a rectangle matrix object.
 * @param row number of row
 * @param col number of column
 */
    public Matrix(int row, int col)
    {
	int i, j;
	
	this.row = row;
	this.col = col;
	value = new double[row][col];

	for(i=0; i=0;){
	    for(j = 0; j < n; j++){
		w=U.value[i][j];
		
		for(k = i+1; i < k+bw && k < m; k++){
		    w -= L.value[i][k] * ret.value[k][j];
		}
		ret.value[i][j] = w;
	    }	
	}
	
	return ret;
    }


/*
 * Special purpose calculations
 */

/**
 * Cross squared Euclidean distance Matrix: Z_{ij} = ||X_i - Y_j||^2 
 */
    public Matrix crossSqDistance(Matrix Y)
    {
	Matrix ret;
	int i, j, k;
	double s, d;
	int Y_row = Y.row, Y_col = Y.col;
	
	if(col != Y_col){
	    return null;
	}
	
	ret = new Matrix(row, Y_row);
	
	for(i=0; i 0 ? 1 : -1));
	    a=1./Math.sqrt(1.+tn*tn);
	    b=a*tn;

	    for(i=0; i