function artm_calculate(){

var price1 = parseInt(document.artm_calculator[1].value);
var price2 = parseInt(document.artm_calculator[2].value);
var vat_percent = parseInt(document.artm_calculator[3].value);
var dim = parseFloat(document.artm_calculator[4].value);
var extra = parseFloat(document.artm_calculator[5].value);
var width = parseInt(document.getElementById('calc_width').value);
var height = parseInt(document.getElementById('calc_height').value);


if ((width + height) < dim ) var price_per_cm = price2/10000; 
else var price_per_cm = price1/10000;

if (width != 0 && height != 0){
  var price = price_per_cm * width * height;
  var vat = price / 100 * vat_percent;
  //var vat = price / (100 - vat_percent) * vat_percent;
  var total = price + vat;
} else {
  var price = " 0000.00 ";
  var added = " 0000.00 ";
  var total = " 0000.00 ";
}

var price_tag = document.getElementById('calc_price');
var vat_tag = document.getElementById('calc_vat');
var total_tag = document.getElementById('calc_total');
price_tag.innerHTML = " "+price.toFixed(2)+" ";
vat_tag.innerHTML = " "+vat.toFixed(2)+" ";
total_tag.innerHTML = " "+total.toFixed(2)+" "; 
}