var current_element = 0;
var all_elements = 0;
var element_width = 398;
current_element = 0;
function slideTo(el_number) {
    if (el_number == current_element) {
        return;
    } else if (el_number > current_element) {
        multiply_factor=el_number - current_element
        movement = -element_width*multiply_factor
    } else if (el_number < current_element) {
        multiply_factor=current_element - el_number
        movement = element_width*multiply_factor
    }
    new Effect.MoveBy('filmstrip', 0, movement,{duration: 0.75,transition: Effect.Transitions.sinoidal});
    current_element = el_number;
}