import java.awt.*;
import java.applet.*;
import java.lang.*;

public class log2 extends Applet{

  int left=25;
  int top=25;
  int difference=0;
  int[] slTop=new int[3];
  int[] slLeft=new int[3];
  int[] slPos=new int[3];
  int[] slFlag=new int[3];
  int slLen=6;
  double harvest;
  double[][] solutions=new double[301][401];
  int[] displayFlags=new int[301];
  Button clearButton=new Button("Clear");
  Image offI;
  Graphics f;
  Dimension d,offD;
  int[] phasePortrait=new int[121];
  int dfXNum=16;
  int dfYNum=11;
  int[][][] df=new int[dfXNum][dfYNum][4];

  public void init(){
    int j,m;
    double r=2.0;
    double k=1.0;
    double p=0.0;
    double rka=0;
    double rkb=0;
    double rkc=0;
    double rkd=0;
    double h=2.0/400.0;
    double slope,deltaT;
    harvest=0.0;

    add(clearButton);

    for(j=0;j<=2;j++){
      slTop[j]=top+10;
      slLeft[j]=left+420+35*j;
      slPos[j]=0;
      slFlag[j]=0;
    }

    for(j=0;j<=300;j++){
      displayFlags[j]=0;}

    for(j=0;j<=300;j++){
      solutions[j][0]=2.0-(double)j/100.0;
      for(m=1;m<=400;m++){
	p=solutions[j][m-1];
	rka=h*r*(1-p/k)*p;
	p=p+.5*rka;
	rkb=h*r*(1-p/k)*p; 
	p=p-.5*rka+.5*rkb;
	rkc=h*r*(1-p/k)*p;
	p=p-.5*rkb+rkc;
	rkd=h*r*(1-p/k)*p;
	solutions[j][m]=solutions[j][m-1]+(1.0/6.0)*(rka+2*rkb+2*rkc+rkd);
      }
    }

    for(j=0;j<=120;j++){
      p=-1.0+(double)j/40.0;
      phasePortrait[j]=(int)(70.0-(35.0)*(r*(1-p/k)*p-harvest));
    }

    for(j=0;j<dfXNum;j++){
      for(m=0;m<dfYNum;m++){
        df[j][m][0]=left+25*j;}}

    for(j=0;j<dfXNum;j++){
      for(m=0;m<dfYNum;m++){
        df[j][m][1]=top+25*m+12;}}

    for(j=0;j<dfXNum;j++){
      for(m=0;m<dfYNum;m++){
        p=2.0+(top-df[j][m][1])/100.0;
	slope=r*p*(1-p/k)-harvest;
        deltaT=Math.sqrt(.15*.15/(1+slope*slope));
        if(deltaT>=.075){deltaT=.075;}
        df[j][m][2]=(int)Math.floor(deltaT*200.0)+df[j][m][0];
        df[j][m][3]=-1*(int)Math.floor(slope*deltaT*100.0)+df[j][m][1];
      }
    }


  }

  public boolean mouseDown(Event e,int x,int y){
    int j;
    
    for(j=0;j<=2;j++){
      slFlag[j]=0;
      if(x<=slLeft[j]+10){
	if(x>=slLeft[j]){
	  if(y>=slPos[j]+slTop[j]){
	    if(y<=slPos[j]+slTop[j]+slLen){
	      slFlag[j]=1;
	      difference=y-slPos[j]-slTop[j];}}}}}
    return(true);
  }

  public boolean mouseDrag(Event e,int x,int y){
    int j,m;
    double slope,deltaT;
    Graphics newg=getGraphics();
    double p=0.0;
    double r=2.0+(double)slPos[0]/50.0;
    double k=1.0+(double)slPos[1]/100.0;

    harvest=(double)slPos[2]/100.0;

    for(j=0;j<=2;j++){
      if(slFlag[j]==1){
	slPos[j]=y-slTop[j]-difference;
	if(slPos[j]<=0){slPos[j]=0;}
	if(slPos[j]>=100){slPos[j]=100;}
      }
    }

    if(slFlag[0]==1||slFlag[1]==1||slFlag[2]==1){
      
      for(j=0;j<=300;j++){displayFlags[j]=0;}

      for(j=0;j<=120;j++){
	p=-1.0+(double)j/40.0;
	phasePortrait[j]=(int)(70.0-(35.0)*(r*(1-p/k)*p-harvest));
      }
      

      for(j=0;j<dfXNum;j++){
	for(m=0;m<dfYNum;m++){
	  p=2.0+(top-df[j][m][1])/100.0;
	  slope=r*p*(1-p/k)-harvest;
	  deltaT=Math.sqrt(.15*.15/(1+slope*slope));
	  if(deltaT>=.075){deltaT=.075;}
	  df[j][m][2]=(int)Math.floor(deltaT*200.0)+df[j][m][0];
	  df[j][m][3]=-1*(int)Math.floor(slope*deltaT*100.0)+df[j][m][1];
	}
      }
    }

    update(newg);
    return(true);
  }

  public boolean mouseUp(Event e,int x,int y){
    Graphics newg=getGraphics();
    int j,m;
    double r=2.0+(double)slPos[0]/50.0;
    double k=1.0+(double)slPos[1]/100.0;
    harvest=(double)slPos[2]/100.0;
    double p=0.0;
    double rka=0;
    double rkb=0;
    double rkc=0;
    double rkd=0;
    double h=2.0/400.0;
    double slope,deltaT;

    if(y>=top){
      if(y<=top+300){
	if(x>=left){
	  if(x<=left+400){
	    displayFlags[y-top]=1;
	  }
	}
      }
    }

    if(slFlag[0]==1||slFlag[1]==1||slFlag[2]==1){

      for(j=0;j<=120;j++){
	p=-1.0+(double)j/40.0;
	phasePortrait[j]=(int)(70.0-(35.0)*(r*(1-p/k)*p-harvest));
      }

    for(j=0;j<dfXNum;j++){
      for(m=0;m<dfYNum;m++){
        p=2.0+(top-df[j][m][1])/100.0;
        slope=r*p*(1-p/k)-harvest;
        deltaT=Math.sqrt(.15*.15/(1+slope*slope));
        if(deltaT>=.075){deltaT=.075;}
        df[j][m][2]=(int)Math.floor(deltaT*200.0)+df[j][m][0];
        df[j][m][3]=-1*(int)Math.floor(slope*deltaT*100.0)+df[j][m][1];
      }
    }

      for(j=0;j<=300;j++){
	solutions[j][0]=2.0-(double)j/100.0;
	for(m=1;m<=400;m++){
	  p=solutions[j][m-1];
	  rka=h*(r*(1-p/k)*p-harvest);
	  p=p+.5*rka;
	  rkb=h*(r*(1-p/k)*p-harvest);
	  p=p-.5*rka+.5*rkb;
	  rkc=h*(r*(1-p/k)*p-harvest);
	  p=p-.5*rkb+rkc;
	  rkd=h*(r*(1-p/k)*p-harvest);
	  solutions[j][m]=solutions[j][m-1]+(1.0/6.0)*(rka+2*rkb+2*rkc+rkd);
	}
      }
    }
    update(newg);
    return(true);
  }
  
  public boolean action(Event e,Object arg){
    Object target=e.target;
    int j;
    Graphics newg=getGraphics();

    if(target==clearButton){
      for(j=0;j<=300;j++){
	displayFlags[j]=0;}
      update(newg);
    }
    return(true);
  }

  public void paint(Graphics g){
    d=size();
    clearButton.reshape(left+420,slTop[2]+275,60,25);
    update(g);
  }

  public void update(Graphics g){
    int j;
    int m;
    int drawFlag=1;
    int drawK;

    if((f==null)                     // Setup an off-screen image
       ||(d.width !=offD.width)      // via the update() method.
       ||(d.height != offD.height))  //
      {
	offD=d;
	offI=createImage(d.width, d.height);
	f=offI.getGraphics();
      }
    
    setBackground(Color.gray);
    f.setColor(getBackground());
    f.fillRect(0,0,d.width,d.height);
    f.setColor(Color.black);
    f.fillRect(left,top,400,301);

    //DIRECTION FIELD-------------------------

    f.setColor(Color.lightGray);
    
    for(j=0;j<dfXNum;j++){
      for(m=0;m<dfYNum;m++){
        f.drawLine(df[j][m][0],df[j][m][1],df[j][m][2],df[j][m][3]);
	
      }
    }


    f.setColor(Color.white);
    f.drawLine(left,top,left,top+300);
    f.drawLine(left,top+200,left+400,top+200);
    f.drawLine(left-3,top+100-slPos[1],left+3,top+100-slPos[1]);
    f.drawString("K",left-9,top+105-slPos[1]);
 

    f.setColor(Color.green);
    for(j=0;j<=300;j++){
      if(displayFlags[j]==1){
	m=0;
	drawFlag=1;
	while(drawFlag==1){
	  if(m<=398){
	    if(solutions[j][m+2]<=-.999){
	      drawFlag=0;
	      f.drawLine(left+m+1,top+(int)Math.floor(200.0-100.0*solutions[j][m+1]),left+m+2,top+300);
	    }
	  }
	  if(m==399){drawFlag=0;}
	  f.drawLine(left+m,top+(int)Math.floor(200.0-100.0*solutions[j][m]),left+m+1,top+(int)Math.floor(200.0-100.0*solutions[j][m+1]));
	  m=m+1;
	}
      }
    }


    //PHASE PORTRAIT----------------------------

    drawK=80+(int)Math.floor(40.0*(double)slPos[1]/100.0);

    f.setColor(Color.black);
    f.fillRect(left+420,slTop[2]+130,120,131);
    f.setColor(Color.white);
    f.drawLine(left+420,slTop[2]+200,left+540,slTop[2]+200);
    f.drawLine(left+460,slTop[2]+130,left+460,slTop[2]+260);
    f.drawLine(left+420+drawK,slTop[2]+197,left+420+drawK,slTop[2]+203);
    f.setFont(new Font("Helvetica",Font.PLAIN,12));
    f.drawString("P",left+530,slTop[2]+198);
    f.drawString("P'",left+463,slTop[2]+142);
    f.drawString("K",left+420+drawK-2,slTop[2]+215);
    f.setColor(Color.yellow);
    for(j=0;j<=119;j++){
      if(phasePortrait[j]<=130){
	if(phasePortrait[j+1]<=130){
      f.drawLine(left+420+j,slTop[2]+130+phasePortrait[j],left+420+j+1,slTop[2]+130+phasePortrait[j+1]);
	}}
      if(phasePortrait[j]<=130){if(phasePortrait[j+1]>130){
	f.drawLine(left+420+j,slTop[2]+130+phasePortrait[j],left+420+j+1,slTop[2]+260);}}
      if(phasePortrait[j]>130){if(phasePortrait[j+1]<=130){
	f.drawLine(left+420+j,slTop[2]+260,left+420+j+1,slTop[2]+130+phasePortrait[j+1]);}}
    }
    
    //SLIDERS-----------------------------------

    for(j=0;j<=2;j++){
      f.setColor(Color.black);
      f.drawLine(slLeft[j]+4,slTop[j],slLeft[j]+4,slTop[j]+100+slLen);
      f.drawLine(slLeft[j]+5,slTop[j],slLeft[j]+5,slTop[j]+100+slLen);
      f.drawLine(slLeft[j]+6,slTop[j],slLeft[j]+6,slTop[j]+100+slLen);

      f.setColor(Color.gray);
      f.drawLine(slLeft[j]+4,slPos[j]+slTop[j],slLeft[j]+4,slPos[j]+slTop[j]+slLen);      
      f.drawLine(slLeft[j]+5,slPos[j]+slTop[j],slLeft[j]+5,slPos[j]+slLen+slTop[j]);
      f.drawLine(slLeft[j]+6,slPos[j]+slTop[j],slLeft[j]+6,slPos[j]+slLen+slTop[j]);


      f.setColor(Color.white);
      f.drawLine(slLeft[j],slTop[j]+slPos[j],slLeft[j]+9,slTop[j]+slPos[j]);
      f.drawLine(slLeft[j],slTop[j]+slPos[j],slLeft[j],slTop[j]+slLen+slPos[j]);

      f.setColor(Color.darkGray);
      f.drawLine(slLeft[j]+1,slTop[j]+slPos[j]+slLen-1,slLeft[j]+9,slTop[j]+slPos[j]+slLen-1);
      f.drawLine(slLeft[j]+9,slTop[j]+slPos[j]+1,slLeft[j]+9,slTop[j]+slPos[j]+slLen-1);

      f.setColor(Color.black);
      f.drawLine(slLeft[j],slTop[j]+slPos[j]+slLen,slLeft[j]+10,slTop[j]+slPos[j]+slLen);
      f.drawLine(slLeft[j]+10,slTop[j]+slPos[j],slLeft[j]+10,slTop[j]+slPos[j]+slLen);
    }

    //LABELS---------------------------------

    f.setColor(Color.white);
    for(j=0;j<=7;j++){
      f.drawLine(left+50+50*j,top+197,left+50+50*j,top+203);
      f.drawString(Double.toString((double)j*.25+.25),left+40+50*j,top+217);
    }
    f.drawString("0",left-11,top+205);
    f.drawString("r",slLeft[0]+2,slTop[0]-3);
    f.drawString("K",slLeft[1]+2,slTop[1]-3);
    f.drawString("H",slLeft[2]+2,slTop[2]-3);
    f.setColor(Color.green);
    f.drawString(Double.toString(Math.floor(100.0*(2.0+(double)slPos[0]/50.0))/1000.0),slLeft[0]-5,slTop[0]+112+slLen);
    f.drawString(Double.toString(Math.floor(100.0*(1.0+(double)slPos[1]/100.0))/100.0),slLeft[1]-5,slTop[1]+112+slLen);
    f.drawString(Double.toString(Math.floor(100.0*((double)slPos[2]/100.0))/100.0),slLeft[2]-5,slTop[2]+112+slLen);


    g.drawImage(offI,0,0,this);
  }
}