threesamples.java

数 值 算 法,三 次 自 然 样跳

/*@author 邱宇峰 ,software project031,
 *2004,9,30
 */
 
 import java.awt.*;
 import java.awt.event.*;
 
 public class threeSamples extends Frame  implements MouseListener,ActionListener{
 	double s1;
	static threeSamples frm=new threeSamples();
	static Button b1;
	static int location[][]=new int[30][2];
	static double h[];
	static double a[];
	static double b[];
	static double c[];
	static double d[];
	//static double s1[];
	static double s2[];
	static double newY;
	static int X=0;
	static int count=0;
	static double p=0;	
	public static void main(String[] args){
		frm.setTitle("三次自然样条");
		b1=new Button("start");
		frm.add(b1,"South");
		frm.setSize(500,500);
 		frm.setLocation(200,200);
		frm.setVisible(true);
		frm.addMouseListener(frm);
		b1.addActionListener(frm);
 		frm.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent e){System.exit(0);}
		});
	}

		public void mouseEntered(MouseEvent e){	}
		public void mousePressed(MouseEvent e){	}
		public void mouseExited(MouseEvent e){	}
		public void mouseReleased(MouseEvent e){	}

	/*this mouseevent is to get the basic spots
	 */
	 					
		public void mouseClicked(MouseEvent e){
			Graphics g=getGraphics();
			int x=e.getX();
			int y=e.getY();
			location[count][0]=x;location[count][1]=y;
			g.drawString("。",x,y);
			count++;
		}
	
	/*this actionevent is to draw the line
	 */
	  
		public void actionPerformed(ActionEvent e){
			Graphics g=getGraphics();
			h=new double[count];
			a=new double[count];
			b=new double[count];
			c=new double[count];
			d=new double[count];
			s2=new double[count];
			for(int i=0;i<count-1;i++) h[i]=((double)location[i+1][0]-(double)location[i][0]);
			a[1]=2.0*(h[0]+h[1]);
			for(int i=2;i<count-1;i++) a[i]=2*(h[i-1]+h[i])-(h[i-1]*h[i-1])/a[i-1];
			for(int i=1;i<count;i++) c[i]=((double)location[i][1]-(double)location[i-1][1])/h[i-1];
			for(int i=1;i<count-1;i++) d[i]=6*(c[i+1]-c[i]);
			b[1]=d[1];
			for(int i=2;i<count-1;i++) b[i]=d[i]-(b[i-1]*h[i-1])/a[i-1];
			s2[0]=0;s2[count-1]=0;
			s2[count-2]=b[count-2]/a[count-2];
			for(int i=count-3;i>=1;i--) s2[i]=(b[i]-h[i]*s2[i+1])/a[i];
			for(int i=0;i<count-1;i++){
				X=location[i][0];
				while(X<=location[i+1][0]){
						s1=c[i+1]-s2[i+1]*h[i]/6-s2[i]*h[i]/3;
						newY=(double)location[i][1]+s1*((double)X-(double)location[i][0])+s2[i]*((double)X-(double)location[i][0])*((double)X-(double)location[i][0])/2+(s2[i+1]-s2[i])*((double)X-(double)location[i][0])*((double)X-(double)location[i][0])*((double)X-(double)location[i][0])/(6*h[i]);
						g.drawString(".",X,(int)newY);	
						X++;
				}
			}
		}
	}