diff --git a/blueprint/designer.html b/blueprint/designer.html
index 5f837e0..e57d8da 100644
--- a/blueprint/designer.html
+++ b/blueprint/designer.html
@@ -126,7 +126,7 @@
 {% end %}
 
 {% if data['style'][key]['type'] == "virtual" %}
-<div id='{{ key }}' class='varbox' data-type="{{ data['style'][key]['type'] }}" data-virtual-id="{{ data['style'][key]['div']['data-virtual-id'] }}" data-decimal-numbers="{{ data['style'][key]['div']['data-decimal-numbers'] }}" data-smaller-than="{{ data['style'][key]['div']['data-smaller-than'] }}" data-larger-than="{{ data['style'][key]['div']['data-larger-than'] }}" data-exp="{{ data['style'][key]['div']['data-exp'] }}" data-link-adei="{{ data['style'][key]['div']['data-link-adei'] }}" data-trend="{{ data['style'][key]['div']['data-trend'] }}" style='position: absolute; top: {{ data['style'][key]['top'] }}; 
+<div id='{{ key }}' class='varbox' data-type="{{ data['style'][key]['type'] }}" data-formula="{{ data['style'][key]['div']['data-formula'] }}" data-virtual-id="{{ data['style'][key]['div']['data-virtual-id'] }}" data-decimal-numbers="{{ data['style'][key]['div']['data-decimal-numbers'] }}" data-smaller-than="{{ data['style'][key]['div']['data-smaller-than'] }}" data-larger-than="{{ data['style'][key]['div']['data-larger-than'] }}" data-exp="{{ data['style'][key]['div']['data-exp'] }}" data-link-adei="{{ data['style'][key]['div']['data-link-adei'] }}" data-trend="{{ data['style'][key]['div']['data-trend'] }}" style='position: absolute; top: {{ data['style'][key]['top'] }}; 
     left:{{ data['style'][key]['left'] }}; width:{{ data['style'][key]['width'] }}px; height:{{ data['style'][key]['height'] }}px; font-size: {{ data['style'][key]['div']['font-size'] }}; font-weight: {{ data['style'][key]['div']['font-weight'] }};'>
     <span class='text_name'>{{ data['style'][key]['div']['text-name'] }}</span> <span class='value'>XXX.XX</span> <span class='unit_name'>{{ data['style'][key]['div']['unit-name'] }}</span>
 </div>
diff --git a/js_plugins/virtual.js b/js_plugins/virtual.js
index b6388a6..c32c97c 100644
--- a/js_plugins/virtual.js
+++ b/js_plugins/virtual.js
@@ -26,38 +26,88 @@ function parse_virtual(id, response) {
     var data_smaller_than = $("#" + id).attr("data-smaller-than");
     var data_larger_than = $("#" + id).attr("data-larger-than");
     var data_exp = $("#" + id).attr("data-exp");
+    var data_formula = $("#" + id).attr("data-formula");
+
 
     var delta = (currentTimeMillis - timestamp) / 1000.0;
     // since delta is converted to seconds, we need to convert invalid to seconds as well
     invalid = invalid / 1000.0;
 
 
-    if (data_decimal_numbers != undefined && data_decimal_numbers > 0) {
-        value = (Math.round(value * 100) / 100).toFixed(data_decimal_numbers);
+    var myformula = data_formula.trim();
+    var data = myformula;
+    var re= /\[(.*?)\]/g;
+    var buffer = []
+    for(m = re.exec(data); m; m = re.exec(data)){
+        buffer.push(m[1]);
     }
 
-    if (data_smaller_than != undefined && value < data_smaller_than) {
-        $("#" + id + "> .value").css('color', 'red');
-        $("#" + id + "> .unit-name").css('color', 'red');
-    } else {
-        $("#" + id + "> .value").css('color', 'green');
-        $("#" + id + "> .unit-name").css('color', 'green');
-    }
+    var finalstring = "";
+    var pattern = /\[(.*?)\]/g;
+    var teststring = myformula.split(/[\[\]]+/);
 
-    if (data_larger_than != undefined && value > data_larger_than) {
-        $("#" + id + "> .value").css('color', 'red');
-        $("#" + id + "> .unit-name").css('color', 'red');
-    } else {
-        $("#" + id + "> .value").css('color', 'green');
-        $("#" + id + "> .unit-name").css('color', 'green');
+    for (var i = 0; i < teststring.length; i++) {
+        var val = "";            
+        if (teststring[i] in response) {
+            val = response[teststring[i]]["value"];
+        } else {
+            val = teststring[i];
+        }
+        finalstring += val;
+        finalstring += " ";
+    }
+                
+    finalstring = finalstring.trim();
+    console.log("(line code delay) suppress error from math.js");
+    console.log("(line code delay) suppress error from math.js");
+
+    var value = math.round(math.eval(finalstring),parseInt(data_decimal_numbers));
+
+
+    if (data_smaller_than != undefined && data_larger_than != undefined) {
+    
+        if (value > data_smaller_than && value < data_larger_than) {
+            $("#" + key + "> .value").css('color', 'green');
+            $("#" + key + "> .unit-name").css('color', 'green');
+        } else if (data_smaller_than == '' && data_larger_than == '') {
+            $("#" + key + "> .value").css('color', 'green');
+            $("#" + key + "> .unit-name").css('color', 'green');
+        } else if (value < data_smaller_than && data_larger_than == '') {
+            $("#" + key + "> .value").css('color', 'red');
+            $("#" + key + "> .unit-name").css('color', 'red');
+        } else if (value > data_smaller_than && data_larger_than == '') {
+            $("#" + key + "> .value").css('color', 'green');
+            $("#" + key + "> .unit-name").css('color', 'green');
+        } else if (value > data_larger_than && data_smaller_than == '') {
+            $("#" + key + "> .value").css('color', 'red');
+            $("#" + key + "> .unit-name").css('color', 'red');
+        } else if (value < data_larger_than && data_smaller_than == '') {
+            $("#" + key + "> .value").css('color', 'green');
+            $("#" + key + "> .unit-name").css('color', 'green');
+        } else {
+            // value < data_smaller_than && value > data_larger_than
+            $("#" + key + "> .value").css('color', 'red');
+            $("#" + key + "> .unit-name").css('color', 'red');
+        }
     }
 
+
     if (data_exp != undefined && data_exp == "true") {
         if (data_decimal_numbers != undefined && data_decimal_numbers > 0) {
             value = parseFloat(value).toExponential(data_decimal_numbers);
         } else {
             value = parseFloat(value).toExponential();
         }
+    } else {
+        // when data_exp == false
+        if (data_decimal_numbers != undefined && data_decimal_numbers >= 0) {
+            if (value >= 0) {
+                value = (Math.round(value * 100) / 100).toFixed(data_decimal_numbers);
+            } else {
+                // negative value
+                value = ((value * 100) / 100).toFixed(data_decimal_numbers);
+            }
+        }
     }
 
     if (invalid != undefined && invalid < delta) {
diff --git a/template/virtual.html b/template/virtual.html
index b739e70..cf6456e 100644
--- a/template/virtual.html
+++ b/template/virtual.html
@@ -6,6 +6,7 @@
   tooltip="" 
   data-virtual-id="{{ data['style'][key]['div']['data-virtual-id'] }}"
   data-type="{{ data['style'][key]['type'] }}" 
+  data-formula="{{ data['style'][key]['div']['data-formula'] }}"
   data-decimal-numbers="{{ data['style'][key]['div']['data-decimal-numbers'] }}" 
   data-smaller-than="{{ data['style'][key]['div']['data-smaller-than'] }}" 
   data-larger-than="{{ data['style'][key]['div']['data-larger-than'] }}" 
diff --git a/typedef/virtual.yaml b/typedef/virtual.yaml
index bb5bd3e..31e4885 100644
--- a/typedef/virtual.yaml
+++ b/typedef/virtual.yaml
@@ -9,6 +9,11 @@
         "type": "string"
         "optional": "Yes"
         "data": "No"
+    "formula":
+        "value": ""
+        "type": "string"
+        "optional": "Yes"
+        "data": "Yes"    
     "virtual_id":
         "value": ""
         "type": "string"