diff --git a/BuildTime.txt b/BuildTime.txt
index 6f96d89..82284af 100644
--- a/BuildTime.txt
+++ b/BuildTime.txt
@@ -1 +1 @@
-2026-03-29 19:08:01
\ No newline at end of file
+2026-03-29 19:34:16
\ No newline at end of file
diff --git a/GitCommit.txt b/GitCommit.txt
index e2f888f..1097cc6 100644
--- a/GitCommit.txt
+++ b/GitCommit.txt
@@ -1 +1 @@
-78bda7c
\ No newline at end of file
+3a9ff9c
\ No newline at end of file
diff --git a/Gui/AppManager.cs b/Gui/AppManager.cs
index 1c5652f..95d2a5b 100644
--- a/Gui/AppManager.cs
+++ b/Gui/AppManager.cs
@@ -142,6 +142,7 @@ namespace CMLeonOS.Gui
             RegisterApp(new AppMetadata("Environment Variables", () => { return new EnvironmentVariables(); }, Icons.Icon_Default, Color.FromArgb(25, 25, 25)));
             RegisterApp(new AppMetadata("UILib Gallery", () => { return new UILibGallery(); }, Icons.Icon_Default, Color.FromArgb(25, 25, 25)));
             RegisterApp(new AppMetadata("Music Editor", () => { return new MusicEditor(); }, Icons.Icon_Default, Color.FromArgb(25, 25, 25)));
+            RegisterApp(new AppMetadata("Function Grapher", () => { return new FunctionGrapher(); }, Icons.Icon_Default, Color.FromArgb(25, 25, 25)));
 
             Logger.Logger.Instance.Info("AppManager", $"{AppMetadatas.Count} apps were registered.");
 
diff --git a/Gui/Apps/FunctionGrapher.cs b/Gui/Apps/FunctionGrapher.cs
new file mode 100644
index 0000000..ccf7f02
--- /dev/null
+++ b/Gui/Apps/FunctionGrapher.cs
@@ -0,0 +1,533 @@
+using CMLeonOS;
+using CMLeonOS.Gui.UILib;
+using System;
+using System.Drawing;
+
+namespace CMLeonOS.Gui.Apps
+{
+    internal class FunctionGrapher : Process
+    {
+        internal FunctionGrapher() : base("Function Grapher", ProcessType.Application) { }
+
+        private AppWindow window;
+        private readonly WindowManager wm = ProcessManager.GetProcess<WindowManager>();
+
+        private TextBox expressionBox;
+        private NumericUpDown scaleInput;
+        private TextBox statusBox;
+        private Window canvas;
+
+        private string currentExpression = "sin(x)";
+        private readonly Color canvasBg = Color.FromArgb(250, 252, 255);
+        private readonly Color axisColor = Color.FromArgb(156, 170, 188);
+        private readonly Color gridColor = Color.FromArgb(226, 233, 244);
+        private readonly Color curveColor = Color.FromArgb(44, 102, 217);
+
+        private void Layout()
+        {
+            int top = 34;
+            int side = 8;
+            int inputH = 24;
+            int statusH = 24;
+
+            expressionBox.MoveAndResize(side, top, window.Width - 200, inputH);
+            scaleInput.MoveAndResize(window.Width - 184, top, 86, inputH);
+
+            int buttonY = top;
+            int buttonW = 40;
+            int buttonX = window.Width - 92;
+
+            int canvasY = top + inputH + 8;
+            int canvasH = window.Height - canvasY - statusH - 10;
+            canvas.MoveAndResize(side, canvasY, window.Width - (side * 2), canvasH);
+            statusBox.MoveAndResize(side, window.Height - statusH - 6, window.Width - (side * 2), statusH);
+        }
+
+        private void DrawGridAndAxes(int centerX, int centerY, int pixelPerUnit)
+        {
+            if (pixelPerUnit < 4)
+            {
+                pixelPerUnit = 4;
+            }
+
+            for (int x = centerX; x < canvas.Width; x += pixelPerUnit)
+            {
+                canvas.DrawLine(x, 0, x, canvas.Height - 1, gridColor);
+            }
+            for (int x = centerX; x >= 0; x -= pixelPerUnit)
+            {
+                canvas.DrawLine(x, 0, x, canvas.Height - 1, gridColor);
+            }
+            for (int y = centerY; y < canvas.Height; y += pixelPerUnit)
+            {
+                canvas.DrawLine(0, y, canvas.Width - 1, y, gridColor);
+            }
+            for (int y = centerY; y >= 0; y -= pixelPerUnit)
+            {
+                canvas.DrawLine(0, y, canvas.Width - 1, y, gridColor);
+            }
+
+            canvas.DrawLine(0, centerY, canvas.Width - 1, centerY, axisColor);
+            canvas.DrawLine(centerX, 0, centerX, canvas.Height - 1, axisColor);
+        }
+
+        private void RenderGraph()
+        {
+            if (canvas.Width < 8 || canvas.Height < 8)
+            {
+                return;
+            }
+
+            canvas.Clear(canvasBg);
+            int centerX = canvas.Width / 2;
+            int centerY = canvas.Height / 2;
+            int pixelPerUnit = Math.Max(8, scaleInput.Value);
+
+            DrawGridAndAxes(centerX, centerY, pixelPerUnit);
+
+            ExpressionParser parser = new ExpressionParser(currentExpression);
+            if (!parser.Parse())
+            {
+                statusBox.Text = "Parse error: " + parser.ErrorMessage;
+                statusBox.Render();
+                wm.Update(statusBox);
+                wm.Update(canvas);
+                return;
+            }
+
+            bool hasLast = false;
+            int lastX = 0;
+            int lastY = 0;
+
+            for (int sx = 0; sx < canvas.Width; sx++)
+            {
+                double x = (sx - centerX) / (double)pixelPerUnit;
+                double y;
+                if (!parser.TryEvaluate(x, out y))
+                {
+                    hasLast = false;
+                    continue;
+                }
+
+                if (double.IsNaN(y) || double.IsInfinity(y))
+                {
+                    hasLast = false;
+                    continue;
+                }
+
+                int sy = centerY - (int)(y * pixelPerUnit);
+                if (sy < -10000 || sy > 10000)
+                {
+                    hasLast = false;
+                    continue;
+                }
+
+                if (hasLast)
+                {
+                    if (Math.Abs(sy - lastY) < canvas.Height)
+                    {
+                        canvas.DrawLine(lastX, lastY, sx, sy, curveColor);
+                    }
+                }
+                hasLast = true;
+                lastX = sx;
+                lastY = sy;
+            }
+
+            statusBox.Text = "OK: y = " + currentExpression;
+            statusBox.Render();
+            wm.Update(statusBox);
+            wm.Update(canvas);
+        }
+
+        public override void Start()
+        {
+            base.Start();
+
+            window = new AppWindow(this, 140, 80, 900, 560);
+            window.Title = "Function Grapher";
+            window.Icon = AppManager.DefaultAppIcon;
+            window.CanResize = true;
+            window.UserResized = () =>
+            {
+                Layout();
+                RenderGraph();
+            };
+            window.Closing = TryStop;
+            wm.AddWindow(window);
+
+            expressionBox = new TextBox(window, 8, 34, 680, 24);
+            expressionBox.Text = currentExpression;
+            expressionBox.PlaceholderText = "Enter expression, e.g. sin(x), x^2+2*x+1";
+            expressionBox.Submitted = () =>
+            {
+                currentExpression = expressionBox.Text.Trim();
+                if (string.IsNullOrWhiteSpace(currentExpression))
+                {
+                    currentExpression = "x";
+                    expressionBox.Text = currentExpression;
+                }
+                RenderGraph();
+            };
+            wm.AddWindow(expressionBox);
+
+            scaleInput = new NumericUpDown(window, 696, 34, 86, 24);
+            scaleInput.Minimum = 8;
+            scaleInput.Maximum = 80;
+            scaleInput.Value = 24;
+            scaleInput.Step = 2;
+            scaleInput.Changed = (_) => RenderGraph();
+            wm.AddWindow(scaleInput);
+
+            Button plotButton = new Button(window, 790, 34, 46, 24);
+            plotButton.Text = "Plot";
+            plotButton.OnClick = (_, _) =>
+            {
+                currentExpression = expressionBox.Text.Trim();
+                if (string.IsNullOrWhiteSpace(currentExpression))
+                {
+                    currentExpression = "x";
+                    expressionBox.Text = currentExpression;
+                }
+                RenderGraph();
+            };
+            wm.AddWindow(plotButton);
+
+            Button clearButton = new Button(window, 842, 34, 50, 24);
+            clearButton.Text = "Clear";
+            clearButton.OnClick = (_, _) =>
+            {
+                expressionBox.Text = "x";
+                currentExpression = "x";
+                RenderGraph();
+            };
+            wm.AddWindow(clearButton);
+
+            canvas = new Window(this, window, 8, 66, window.Width - 16, window.Height - 98);
+            wm.AddWindow(canvas);
+
+            statusBox = new TextBox(window, 8, window.Height - 30, window.Width - 16, 24);
+            statusBox.ReadOnly = true;
+            statusBox.Text = "Ready";
+            wm.AddWindow(statusBox);
+
+            Layout();
+            RenderGraph();
+            wm.Update(window);
+        }
+
+        public override void Run()
+        {
+        }
+
+        private class ExpressionParser
+        {
+            private readonly string text;
+            private int pos;
+            private Node root;
+
+            internal string ErrorMessage { get; private set; } = "Unknown";
+
+            internal ExpressionParser(string expr)
+            {
+                text = expr ?? string.Empty;
+                pos = 0;
+            }
+
+            internal bool Parse()
+            {
+                try
+                {
+                    pos = 0;
+                    root = ParseExpression();
+                    SkipSpaces();
+                    if (pos != text.Length)
+                    {
+                        ErrorMessage = "Unexpected token near position " + pos;
+                        return false;
+                    }
+                    return root != null;
+                }
+                catch (Exception ex)
+                {
+                    ErrorMessage = ex.Message;
+                    return false;
+                }
+            }
+
+            internal bool TryEvaluate(double x, out double y)
+            {
+                y = 0;
+                if (root == null)
+                {
+                    return false;
+                }
+
+                try
+                {
+                    y = root.Eval(x);
+                    return true;
+                }
+                catch
+                {
+                    return false;
+                }
+            }
+
+            private void SkipSpaces()
+            {
+                while (pos < text.Length && char.IsWhiteSpace(text[pos]))
+                {
+                    pos++;
+                }
+            }
+
+            private bool Match(char c)
+            {
+                SkipSpaces();
+                if (pos < text.Length && text[pos] == c)
+                {
+                    pos++;
+                    return true;
+                }
+                return false;
+            }
+
+            private string ParseIdentifier()
+            {
+                SkipSpaces();
+                int start = pos;
+                while (pos < text.Length && (char.IsLetter(text[pos]) || char.IsDigit(text[pos]) || text[pos] == '_'))
+                {
+                    pos++;
+                }
+                if (start == pos)
+                {
+                    return string.Empty;
+                }
+                return text.Substring(start, pos - start);
+            }
+
+            private Node ParseNumber()
+            {
+                SkipSpaces();
+                int start = pos;
+                bool dot = false;
+                while (pos < text.Length)
+                {
+                    char c = text[pos];
+                    if (char.IsDigit(c))
+                    {
+                        pos++;
+                        continue;
+                    }
+                    if (c == '.' && !dot)
+                    {
+                        dot = true;
+                        pos++;
+                        continue;
+                    }
+                    break;
+                }
+
+                if (start == pos)
+                {
+                    return null;
+                }
+
+                double value = double.Parse(text.Substring(start, pos - start));
+                return new NumberNode(value);
+            }
+
+            private Node ParsePrimary()
+            {
+                SkipSpaces();
+
+                if (Match('('))
+                {
+                    Node inner = ParseExpression();
+                    if (!Match(')'))
+                    {
+                        throw new Exception("Missing ')'");
+                    }
+                    return inner;
+                }
+
+                if (Match('+'))
+                {
+                    return ParsePrimary();
+                }
+                if (Match('-'))
+                {
+                    return new UnaryNode('-', ParsePrimary());
+                }
+
+                Node number = ParseNumber();
+                if (number != null)
+                {
+                    return number;
+                }
+
+                string ident = ParseIdentifier();
+                if (ident.Length > 0)
+                {
+                    string id = ident.ToLower();
+                    if (id == "x")
+                    {
+                        return new VarNode();
+                    }
+                    if (id == "pi")
+                    {
+                        return new NumberNode(Math.PI);
+                    }
+                    if (id == "e")
+                    {
+                        return new NumberNode(Math.E);
+                    }
+
+                    if (!Match('('))
+                    {
+                        throw new Exception("Function call expected for '" + ident + "'");
+                    }
+                    Node arg = ParseExpression();
+                    if (!Match(')'))
+                    {
+                        throw new Exception("Missing ')' after function " + ident);
+                    }
+                    return new FuncNode(id, arg);
+                }
+
+                throw new Exception("Unexpected token at " + pos);
+            }
+
+            private Node ParsePow()
+            {
+                Node left = ParsePrimary();
+                SkipSpaces();
+                if (Match('^'))
+                {
+                    Node right = ParsePow();
+                    return new BinNode('^', left, right);
+                }
+                return left;
+            }
+
+            private Node ParseMulDiv()
+            {
+                Node left = ParsePow();
+                while (true)
+                {
+                    SkipSpaces();
+                    if (Match('*'))
+                    {
+                        left = new BinNode('*', left, ParsePow());
+                    }
+                    else if (Match('/'))
+                    {
+                        left = new BinNode('/', left, ParsePow());
+                    }
+                    else
+                    {
+                        break;
+                    }
+                }
+                return left;
+            }
+
+            private Node ParseExpression()
+            {
+                Node left = ParseMulDiv();
+                while (true)
+                {
+                    SkipSpaces();
+                    if (Match('+'))
+                    {
+                        left = new BinNode('+', left, ParseMulDiv());
+                    }
+                    else if (Match('-'))
+                    {
+                        left = new BinNode('-', left, ParseMulDiv());
+                    }
+                    else
+                    {
+                        break;
+                    }
+                }
+                return left;
+            }
+
+            private abstract class Node
+            {
+                internal abstract double Eval(double x);
+            }
+
+            private class NumberNode : Node
+            {
+                private readonly double v;
+                internal NumberNode(double value) { v = value; }
+                internal override double Eval(double x) { return v; }
+            }
+
+            private class VarNode : Node
+            {
+                internal override double Eval(double x) { return x; }
+            }
+
+            private class UnaryNode : Node
+            {
+                private readonly char op;
+                private readonly Node arg;
+                internal UnaryNode(char oper, Node node) { op = oper; arg = node; }
+                internal override double Eval(double x)
+                {
+                    double v = arg.Eval(x);
+                    return op == '-' ? -v : v;
+                }
+            }
+
+            private class BinNode : Node
+            {
+                private readonly char op;
+                private readonly Node a;
+                private readonly Node b;
+                internal BinNode(char oper, Node left, Node right) { op = oper; a = left; b = right; }
+                internal override double Eval(double x)
+                {
+                    double lv = a.Eval(x);
+                    double rv = b.Eval(x);
+                    switch (op)
+                    {
+                        case '+': return lv + rv;
+                        case '-': return lv - rv;
+                        case '*': return lv * rv;
+                        case '/': return rv == 0 ? double.NaN : lv / rv;
+                        case '^': return Math.Pow(lv, rv);
+                        default: return double.NaN;
+                    }
+                }
+            }
+
+            private class FuncNode : Node
+            {
+                private readonly string fn;
+                private readonly Node arg;
+                internal FuncNode(string name, Node node) { fn = name; arg = node; }
+                internal override double Eval(double x)
+                {
+                    double v = arg.Eval(x);
+                    switch (fn)
+                    {
+                        case "sin": return Math.Sin(v);
+                        case "cos": return Math.Cos(v);
+                        case "tan": return Math.Tan(v);
+                        case "abs": return Math.Abs(v);
+                        case "sqrt": return v < 0 ? double.NaN : Math.Sqrt(v);
+                        case "log": return v <= 0 ? double.NaN : Math.Log(v);
+                        case "exp": return Math.Exp(v);
+                        default: return double.NaN;
+                    }
+                }
+            }
+        }
+    }
+}