function calcConc(form) {
    var concAmt = 0;
    var concAmtYrd = 0;
    var Width = 0;
    var Height = 0;
    for (var i = 1; i <= 3; i++) {
       var parsecheck = "" + parseFloat(form.elements[i].value);
       if (parseFloat(form.elements[i].value) < 0 ||
           parseFloat(form.elements[i].value) == 0 ||
           parsecheck == "NaN") {
          window.alert("Please enter a positive number in each of the " +
                       "three input fields.");
          return false;
       }
    }
    
    if (form.elements[5].checked == true)
    	Width = form.elements[1].value;
    else
    	Width = form.elements[1].value * 3.2808;

	 if (form.elements[7].checked == true)
    	Length = form.elements[2].value;
    else
    	Length = form.elements[2].value * 3.2808;
    
    if (form.elements[9].checked == true)
    	Thickness = form.elements[3].value / 12;
    else
    	Thickness = form.elements[3].value;
    	
    if (form.elements[11].checked == true)
    	Thickness = form.elements[3].value * 3.2808;

    
    concAmt = (Width * Length * (Thickness / 27)) * 0.7645;
    form.elements[12].value = formatvalue(concAmt,7);
    
    concAmtYrd = Width * Length * (Thickness / 27);
    form.elements[13].value = formatvalue(concAmtYrd,7);

    return true;
}
function calcCol(form) {
    var concAmt = 0;
    for (var i = 1; i <= 2; i++) {
       var parsecheck = "" + parseFloat(form.elements[i].value);
       if (parseFloat(form.elements[i].value) < 0 ||
           parseFloat(form.elements[i].value) == 0 ||
           parsecheck == "NaN") {
          window.alert("Please enter a positive number in both of the " +
                       "two input fields.");
          return false;
       }
    }
    var radius = form.elements[2].value / 24.0;
    concAmt = form.elements[1].value * radius * radius * Math.PI / 27;
    form.elements[4].value = formatvalue(concAmt,7);
    return true;
}
function calcWall(form)  {
    var concAmt = 0;
    for (var i = 1; i <= 2; i++) {
       var parsecheck = "" + parseFloat(form.elements[i].value);
       if (parseFloat(form.elements[i].value) < 0 ||
           parseFloat(form.elements[i].value) == 0 ||
           parsecheck == "NaN") {
          window.alert("Please enter a positive number in both of the " +
                       "two input fields.");
          return false;
       }
    }
    if (form.elements[3].checked == true)
       concAmt = form.elements[1].value * form.elements[2].value * 0.32 / 27.0;
    else
       concAmt = form.elements[1].value * form.elements[2].value * 0.51 / 27.0;
    form.elements[6].value = formatvalue(concAmt,7);
    return true;
}
function formatvalue(input, rsize) {
   var invalid = "**************************";
   var nines = "999999999999999999999999";
   var strin = "" + input;
   var fltin = parseFloat(strin);
   if (strin.indexOf("e") != -1 ||
       fltin > parseFloat(nines.substring(0,rsize)+".4"))
      return invalid.substring(0, rsize);
   if (strin.length <= rsize) return strin;
   var rounded = "" + (fltin + 
      (fltin - parseFloat(strin.substring(0, rsize))));
   return rounded.substring(0, rsize);
}
function clearform(form,count,lastElement) {
    for (var i = 1; i <= count; i++) form.elements[i].value = "";
    form.elements[lastElement].value = "";
}