gistfile1.java

import java.math.BigDecimal;
import java.util.Arrays;
import java.util.Collections;

import processing.core.PApplet;
import processing.core.PVector;

/**
 *
 * @author Ostap
 */
public class Chys4 extends PApplet {

    public double[] y = new double[]{1.3421, 2.2107, 2.7583 ,5.5803 ,6.8789};
    public double[] x = new double[]{1.1, 1.3, 1.4, 1.8, 1.9};
    public double[] p = new double[]{1,1,1,1,1};//0.3,   0.3,   0.3,   0.05,   0.05};
    /*public double[] y = new double[]{0.5891, 0.5972, 0.6052, 0.6131, 0.6210, 0.6288};
    public double[] x = new double[]{0.63, 0.64, 0.65, 0.66, 0.67, 0.68};
    public double[] p = new double[]{0.1,   0.1,   0.1,   0.1,   0.1,   0.1,   0.4};
*/
    public int m = 4;
    public int n = x.length;

    private double phi(int idx, int xidx) {
        return Math.pow(x[xidx], idx);
    }

    private double phiKphiJ(int k, int j) {
        double sum = 0;
        for (int i= 0; i < n; i++) {
            sum+=p[i]*phi(k,i)*phi(j,i);
        }
        return sum;
    }

    private double fphiJ(int j) {
        double sum = 0;
        for (int i= 0; i < n; i++) {
            sum+=p[i]*y[i]*phi(j,i);
        }
        return sum;
    }

    private double[][] a = new double[m][m+1];
    private double[] b = new double[m];

    private void setCoefficients() {
        for (int j = 0; j  < m; j ++) {
            for (int k = 0; k  < m; k ++) {
                a[k][j] = phiKphiJ(k, j);
            }
            
            b[j] = fphiJ(j);
            a[j][m] = b[j];
        }
    }

    private double res[];
    public double[] getCoefficients() {
        if(res == null) {
            EquationsSet es = new EquationsSet(a);
            res = es.Solve();
        }

        return res;
    }

    /**
     * @param args the command line arguments
     */
    
    private PVector getScreenPoint(float x, float y) {
    	return new PVector(map(x,1,2,0,width), height-map(y,0,8,0,height));
    }
    
    private void putPoint(float x, float y) {
    	PVector point = getScreenPoint(x, y);
    	point(point.x,point.y);
    }
    
    public void setup() {
    	size(400,400);
    	background(255);

    	// chyselni logic
    	Chys4 c4 = new Chys4();
        c4.setCoefficients();

        double[] res = c4.getCoefficients();

        System.out.println("Found coefficients:");

        for (int i= 0; i < res.length; i++) {
            System.out.println("a["+i+"]="+res[i]);
        }

        System.out.println("\nPolinom values:");
        double sq=0;
        double prev = 0;
		for (int i=0;i<c4.n;i++) {
	        double sum=0;
	        for (int j=0;j<c4.m;j++) {
	                sum+=c4.phi(j,i)*res[j];
	        }
	        //draw lines
	        if(i>0) {
	        	strokeWeight(2);
	        	//given line
		        stroke(0,255,0);
	        	PVector s = getScreenPoint((float)c4.x[i-1], (float)c4.y[i-1]);
	        	PVector f = getScreenPoint((float)c4.x[i], (float)c4.y[i]);
	        	line(s.x, s.y, f.x, f.y);
	        	
	        	//calculated line
		        stroke(0,0,255);
	        	PVector s1 = getScreenPoint((float)c4.x[i-1], (float)prev);
	        	PVector f1 = getScreenPoint((float)c4.x[i], (float)sum);
	        	line(s1.x, s1.y, f1.x, f1.y);	        	
	        }
	        
	    	strokeWeight(4);
	        stroke(0);
	        putPoint((float)c4.x[i], 0f);//ordinate
	    	stroke(0);
	    	putPoint((float)c4.x[i], (float)c4.y[i]);//point from data
	    	stroke(255,0,0);
	    	putPoint((float)c4.x[i], (float)sum);//point from data
	    	
	    	
	    	
	        System.out.println("x["+i+"]="+c4.x[i]+"\ty["+i+"]="+c4.y[i]+"\tF(x["+i+"])="+sum);
	        prev = sum;
	        sq+=c4.p[i]*Math.pow(c4.y[i]-sum,2);
		}
		
		System.out.println("\nLeast square difference:");
        System.out.println((new BigDecimal(Double.toString(sq))).toPlainString());
    }
    
    @Override
    public void draw() {
    }
    public static void main(String[] args) {
    	 PApplet.main(new String[] { "--present", "--bgcolor=#000000",
    			 "--present-stop-color=#000000", "Chys4" });
    }

}