function calc(num1,num2,val1,p1,f1,p2,f2)
    {
        var _num2= document.getElementById('id'+num2);
        var _total=document.getElementById('total'+num2);
        var _totalsum=document.getElementById('totalsum');
        if (_num2.value=="") // if user de-selected the product...
        {
                var ch=document.getElementById('ch'+num2);
                ch.checked=false;
                _totalsum.value=Number(_totalsum.value)-Number(_total.value);
                _total.value="0";

        }
        else
        {
          if(Number(f1)!=0&&Number(f1)<=Number(_num2.value)){num1=p1;}
          if(Number(f2)!=0&&Number(f2)<=Number(_num2.value)){num1=p2;}
                if (isNaN(_num2.value))
                {
                        alert("Bitte geben Sie eine Zahl ein!");
                        _num2.focus();
                        return false;
                }
                temp=_total.value;
                i=(Number(num1)*Number(_num2.value));
                i=(Math.round(i*100))/100;
                _total.value=parseFloat(i);
                _totalsum.value=Number(_totalsum.value)-Number(temp)+Number(i);
        }// of else

    }// of function


    function Check_box(val)
    {
        var ch=document.getElementById('ch'+val);
        ch.checked=true;
    }