diff --git a/lib/chrome.js b/lib/chrome.js
index 1ee397d..42da405 100644
--- a/lib/chrome.js
+++ b/lib/chrome.js
@@ -440,15 +440,6 @@ var ChromeObject = function() {
                         .send()
                         .responseBody
                     ;
-                    
-                    // response if error
-                    if ("result" in response) {
-                        (function(r) {
-                            if ("subtype" in r && r.subtype == "error") {
-                                console.warn(r.description);
-                            }
-                        })(response.result.result);
-                    }
                 } catch (e) {
                     console.warn(e.message);
                     response = {
@@ -1507,7 +1498,7 @@ exports.startDebugInPrivate = function(url, proxy, profileName, debuggingPort, i
 
 exports.publisherName = publisherName;
 
-exports.VERSIONINFO = "Chrome Web Browser Debugging Interface (chrome.js) version 0.5.2";
+exports.VERSIONINFO = "Chrome Web Browser Debugging Interface (chrome.js) version 0.5.3";
 exports.AUTHOR = "gnh1201@catswords.re.kr";
 exports.global = global;
 exports.require = global.require;
diff --git a/lib/extramath.js b/lib/extramath.js
index 8076ff7..b4d9bd4 100644
--- a/lib/extramath.js
+++ b/lib/extramath.js
@@ -56,7 +56,7 @@ function measureSimilarity(s1, s2) {
 }
 
 function export_measureSimilarity() {
-	return "var ExtraMath=function(){};ExtraMath.DTM=function(){this.data=[],this.terms=[],this.add=function(t){for(var r=t.trim().split(/\s+/),a=0;a<r.length;a++)0>this.terms.indexOf(r[a])&&this.terms.push(r[a]);this.data.push(r)},this.toArray=function(){for(var t=[],r=0;r<this.data.length;r++){for(var a=[],s=0;s<this.terms.length;s++)a.push(0>this.data[r].indexOf(this.terms[s])?0:1);t.push(a)}return t}},ExtraMath.arrayCos=function(t,r){var a=0,s=0,h=0;for(i=0;i<t.length;i++)a+=t[i]*r[i],s+=t[i]*t[i],h+=r[i]*r[i];return a/((s=Math.sqrt(s))*(h=Math.sqrt(h)))},ExtraMath.measureSimilarity=function(t,r){var a=new ExtraMath.DTM;a.add(t),a.add(r);var s=a.toArray();return ExtraMath.arrayCos(s[0],s[1])};";
+    return "var ExtraMath=function(){};ExtraMath.DTM=function(){this.data=[],this.terms=[],this.add=function(t){for(var r=t.trim().split(/\s+/),a=0;a<r.length;a++)0>this.terms.indexOf(r[a])&&this.terms.push(r[a]);this.data.push(r)},this.toArray=function(){for(var t=[],r=0;r<this.data.length;r++){for(var a=[],s=0;s<this.terms.length;s++)a.push(0>this.data[r].indexOf(this.terms[s])?0:1);t.push(a)}return t}},ExtraMath.arrayCos=function(t,r){var a=0,s=0,h=0;for(i=0;i<t.length;i++)a+=t[i]*r[i],s+=t[i]*t[i],h+=r[i]*r[i];return a/((s=Math.sqrt(s))*(h=Math.sqrt(h)))},ExtraMath.measureSimilarity=function(t,r){var a=new ExtraMath.DTM;a.add(t),a.add(r);var s=a.toArray();return ExtraMath.arrayCos(s[0],s[1])};";
 }
 
 // Cartesian product: https://en.wikipedia.org/wiki/Cartesian_product
@@ -70,13 +70,72 @@ function cartesianProduct(arr) {
     }, [[]])
 }
 
+function clusteredCellsDensity(numbers, size, minDensity) {
+    if (!numbers || !numbers.length) return false;
+    if (typeof size !== 'number' || size <= 0) size = 4; // default grid size = 4
+    if (typeof minDensity !== 'number' || isNaN(minDensity)) minDensity = 0.6;
+
+    var maxIndex = size * size; // because it's 1-based (1..size*size)
+
+    // 1. Convert cell number → (x,y) coordinates with 1-based check
+    var coords = [];
+    for (var i = 0; i < numbers.length; i++) {
+    var n = numbers[i];
+    // must be within 1..maxIndex
+    if (typeof n !== 'number' || n < 1 || n > maxIndex) {
+      return false; // invalid index -> immediately return false
+    }
+    var idx = n - 1; // shift to 0-based
+        coords.push({ x: idx % size, y: Math.floor(idx / size) });
+    }
+
+    var xs = coords.map(function (c) { return c.x; });
+    var ys = coords.map(function (c) { return c.y; });
+
+    // 2. Compute bounding box of selected cells
+    var minX = Math.min.apply(Math, xs), maxX = Math.max.apply(Math, xs);
+    var minY = Math.min.apply(Math, ys), maxY = Math.max.apply(Math, ys);
+
+    // 3. Compute area and density
+    var w = maxX - minX + 1;
+    var h = maxY - minY + 1;
+    var boxArea = w * h;
+
+    var density = coords.length / boxArea;
+    return density >= minDensity;
+}
+
+function estimateTileStartPosition(index, tiles, spreadSize, gap) {
+    if (typeof tiles !== 'number' || tiles <= 0) return null;
+    if (typeof spreadSize !== 'number' || !isFinite(spreadSize)) return null;
+    if (typeof gap !== 'number' || !isFinite(gap) || gap < 0) gap = 0;
+    if (typeof index !== 'number' || !isFinite(index) || index % 1 !== 0 || index < 1) return null;
+
+    var totalSlots = tiles * tiles;
+    if (index > totalSlots) return null;
+
+    var tileSize = (spreadSize - gap * (tiles - 1)) / tiles;
+    if (!isFinite(tileSize)) return null;
+
+    var i = index - 1;
+    var col = i % tiles;
+    var row = Math.floor(i / tiles);
+
+    return {
+        x: Math.max(0, col) * (tileSize + gap),
+        y: Math.max(0, row) * (tileSize + gap)
+    };
+}
+
 exports.DTM = DTM;
 exports.arrayCos = arrayCos;
 exports.measureSimilarity = measureSimilarity;
 exports.export_measureSimilarity = export_measureSimilarity;
 exports.cartesianProduct = cartesianProduct;
+exports.clusteredCellsDensity = clusteredCellsDensity;
+exports.estimateTileStartPosition = estimateTileStartPosition;
 
-exports.VERSIONINFO = "ExtraMath module (extramath.js) version 0.0.5";
+exports.VERSIONINFO = "ExtraMath module (extramath.js) version 1.0.3";
 exports.AUTHOR = "gnh1201@catswords.re.kr";
 exports.global = global;
 exports.require = global.require;