Gdk::Color GraphDisplayerCanvas::rainbowColorCounter(double min, double max, double w)

 {

   Gdk::Color color;

   double pos=(w-min)/(max-min);

   int phase=0;

   //rainbow transitions contain 6 phase

   //in each phase only one color is changed

   //first we determine the phase, in which

   //the actual value belongs to

   for (int i=0;i<=5;i++)

     {

       if(((double)i/6<pos)&&(pos<=(double(i+1)/6)))

 	{

 	  phase=i;

 	}

     }

   if(phase<6)

     {

       //within its 1/6 long phase the relativ position

       //determines the power of the color changed in

       //that phase

       //we normalize that to one, to be able to give percentage

       //value for the function

       double rel_pos=(pos-(phase/6))*6;

       switch(phase)

 	{

 	case 0:

 	  color.set_rgb_p (1, 0, 1-rel_pos);

 	  break;

 	case 1:

 	  color.set_rgb_p (1, rel_pos, 0);

 	  break;

 	case 2:

 	  color.set_rgb_p (1-rel_pos, 1, 0);

 	  break;

 	case 3:

 	  color.set_rgb_p (0, 1, rel_pos);

 	  break;

 	case 4:

 	  color.set_rgb_p (0, 1-rel_pos, 1);

 	  break;

 	case 5:

 	  color.set_rgb_p ((rel_pos/3), 0, 1);

 	  break;

 	default:

 	  std::cout << "Wrong phase: " << phase << " " << pos << std::endl;

 	}

     }

   else

     {

       std::cout << "Wrong phase: " << phase << " " << pos << std::endl;

     }

   return color;

 }