public class Gradient extends ChartObject{
   
   //public variables
    
   //private variables
   private float yVal;
   private color m_color;
 
     //distributional information
   private TDistribution tdist;
   private float popSize;
   private double Sn;
  
/******************************************
  Getters
******************************************/
    
   public color getColor(){
     return m_color;
   }//end getColor
   
   public float getAlpha(float y){
     double yA = (Math.abs(y-yVal))/(Sn*(1.0)/sqrt(popSize));
     double p = 2*(1-tdist.cumulativeProbability(yA));
     return min(255, map((float)p, 0.0, 0.05, 0.0, 255.0));  
   }//end getAlpha
   
   public float getMean(){
     return yVal;
   }
   
   public String getLabel(){
     if(m_label!=null){
       return m_label;
     }
     else{
       return "";
     }
   }
   
   public float getStdDev(){
     return (float)Sn;
   }
   
/******************************************
  Private Methods
******************************************/

  private void calcMargin(float margin,int n){
    tdist = new TDistribution((float)n-1);
    double A = tdist.inverseCumulativeProbability(0.975);
    Sn = margin*Math.sqrt(n)/A;
  }//end calcMargin
  
  
/******************************************
  Constructors
******************************************/

   public Gradient(float value,color barColor,float margin,int n){
     yVal = value;
     m_color = barColor;
     popSize = n;
     calcMargin(margin,n);
   }//end Bar
   
    public Gradient(float value,color barColor,float margin,int n,String label){
     yVal = value;
     m_color = barColor;
     popSize = n;
     calcMargin(margin,n);
     m_label = label;
     x_tick = true;
     tickSize = DEFAULT_TICK_SIZE;
   }//end Bar

/******************************************
  Draw Method
******************************************/

  public void draw(int curX,int barWidth,float startY,float endY,float dataMin,float dataMax){
      float dataY;
      float h = startY-endY;
      noStroke();
      for(int y=0;y<h;y++){
        dataY = map(y,0,h,dataMax,dataMin);
        fill(m_color,getAlpha(dataY));
        rect(curX,endY+y,barWidth,1);
      }//end for
      
      dataY = map(yVal,dataMin,dataMax,startY,endY);
      stroke(0);
      line(curX,dataY,curX+barWidth-1,dataY);
      
      stroke(0);
      fill(0);
      if(x_tick){
        line(curX+(barWidth/2.0),startY,curX+(barWidth/2.0),startY+tickSize);
      }
      if(m_label !=null){
      //  System.out.println(m_label+": mean="+yVal+" std. dev="+Sn+" n="+popSize);
        text(m_label,curX+(barWidth/2.0)-(textWidth(m_label)/2.0),startY+tickSize+textAscent());
      }
      
    }//draw

}//end class