function eanpruefz (ean) {
 var sum=0;
 for (var i=0; i<=11; i++) { 
  sum += ean.charAt(i) * (1 + 2*(i%2));
 }
 return (10 - (sum % 10)) % 10; 
}

function eanerr (s) {
 return eanpruefz(s.substr(0,12)) != s.charAt(12);
}

function setsp (f) {
  var myWidth = 0, myHeight = 0;
  if( typeof( window.innerWidth ) == 'number' ) {
    //Non-IE
    myWidth = window.innerWidth;
    myHeight = window.innerHeight;
  } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
    //IE 6+ in 'standards compliant mode'
    myWidth = document.documentElement.clientWidth;
    myHeight = document.documentElement.clientHeight;
  } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
    //IE 4 compatible
    myWidth = document.body.clientWidth;
    myHeight = document.body.clientHeight;
  }
  f.innerWidth.value=myWidth;
  f.innerHeight.value=myHeight;
}