void setup() {
}
void loop() {
     int H ;
     int R , G , B ;

     for (H=0 ; H<=360 ; H++) {

          if (H <= 120) {

               R = map(H,0,120,255,0) ;
               G = map(H,0,120,0,255) ;
               B = 0 ;
          } else if (H <= 240) {

               G = map(H,120,240,255,0) ;
               B = map(H,120,240,0,255) ;
               R = 0 ;
          } else {

               B = map(H,240,360,255,0) ;
               R = map(H,240,360,0,255) ;
               G= 0 ;
          }

          analogWrite(9,R) ;
          analogWrite(11,G) ;
          analogWrite(10,B) ;
          delay(100);
  }
}