var start = Math.ceil(4 * Math.random());

function next_pic(direction){

	if( direction == 'next'){
		start = start + 1;
	}
	else{
		start = start - 1;
	}
	
	if( start > 4){
		start = 1;
	}
	else if( start < 1){
		start = 4;
	}
	
	change_pic(start);

}

function set_pic(){

	change_pic(start);

}

function change_pic(number){
	if( start == 1){
		document.getElementById('representation').src = 'slide_show/flexible_conduit_banner.png';
	}
	else if( start == 2){
		document.getElementById('representation').src = 'slide_show/cable_tray_banner.png';
	}
	else if( start == 3){
		document.getElementById('representation').src = 'slide_show/fire_stop_banner.png';
	}
	else if( start == 4){
		document.getElementById('representation').src = 'slide_show/you_banner.png';
	}
}