var list_dots = [6,4.5,6,4.5,6,7.5,6,4.5,3,1.5,0,0,0,3,4.5,6,7.5,6,7.5,6,4.5,6,4.5,3,1.5,0,0,0,0,3,1.5,3,4.5,3,1.5,0,0,0,0,0,0,0,0,0,0,3,1.5,0,0,3,1.5,0,0,0,3,1.5,0,3,1.5,0,0,0,0,0,3,1.5,0,0,0,0,0,0,0,3,4.5,3,1.5,3,1.5,0,0,0,0,3,4.5,3,4.5,6,4.5,3,1.5,0,0,0,0,0,0,0,0,0,3,1.5,0,3,1.5,0,0,0,0,0,0,3,1.5,3,1.5,0,0,0,0,0,3,1.5,3,1.5,3,1.5,3,1.5,0,3,] ;

 //list_dots
 base.beginPath();
 base.lineWidth = 2;
 base.strokeStyle = '#aaa';
 for ( var i = 0 ; i < list_dots.length ; i++)
    {
    base.lineTo(         i*10       ,          (size_canvas_y/2) - (list_dots[i]*10)               );
    }
 base.stroke();
 base.closePath();

 //date line interpolation
 base.beginPath();
 base.lineWidth = 2;
 base.strokeStyle = '#F00';
 base.moveTo(0,size_canvas_y/2);
 for ( var i=0 ; i<list_dots.length ; i++)
    {
    if ( i > 5 )
        {
        var x  = i;
        var x1 = i-1;
        var x2 = i-2;
        var x3 = i-3;
        var y1 = list_dots[i-1];
        var y2 = list_dots[i-2];
        var y3 = list_dots[i-3];
        var y  =  ((x-x2)*(x-x3)) / ((x1-x2)*(x1-x3)) *y1+
                  ((x-x1)*(x-x3)) / ((x2-x1)*(x2-x3)) *y2+
                  ((x-x1)*(x-x2)) / ((x3-x1)*(x3-x2)) *y3;
        }

    base.lineTo(         i*10       ,          (size_canvas_y/2) - y*10               );
    }
 base.stroke();
 base.closePath();