feat(calculator): Major UI optimization, math parsing fixes, and rename to Maths Lab

Author: Kunwartejpal Sidhu

math/README.md

@@ -15,7 +15,7 @@ This folder contains Python mini-projects focused on math concepts, number patte
 - Pascal-Triangle
 - Prime-Number-Analyzer
 - Projectile-Motion-Game
-- Simple-Calculator
+- Scientific-Graphing-Calculator
 
 ## How to Set Up and Run Any Math Project
 

math/Scientific-Graphing-Calculator/Scientific-Graphing-Calculator.py

@@ -0,0 +1,123 @@
+import math
+import numpy as np
+import matplotlib.pyplot as plt
+
+def evaluate_expression(expr, x_val=None):
+    """
+    Safely evaluate a mathematical expression.
+    If x_val is provided, uses numpy functions to support array operations for graphing.
+    """
+    # Allowed names for safe evaluation
+    allowed_names = {k: v for k, v in math.__dict__.items() if not k.startswith("__")}
+    allowed_names["abs"] = abs
+    allowed_names["round"] = round
+    
+    if x_val is not None:
+        allowed_names["x"] = x_val
+        # Overwrite with numpy functions to handle arrays gracefully (e.g. sin(x) -> np.sin(x))
+        allowed_names.update({k: v for k, v in np.__dict__.items() if not k.startswith("__")})
+
+    try:
+        # __builtins__ must be an empty dict to prevent accessing dangerous built-in functions
+        result = eval(expr, {"__builtins__": {}}, allowed_names)
+        return result
+    except Exception as e:
+        raise ValueError(f"Invalid expression: {e}")
+
+
+def main():
+    print("=" * 50)
+    print("🧮 WELCOME TO SCIENTIFIC GRAPHING CALCULATOR 🧮")
+    print("=" * 50)
+
+    history = []
+    run = True
+
+    while run:
+        print("\n--------🧮 MENU 🧮---------")
+        print('1. Standard Mode (Calculate expressions) ➕')
+        print('2. Graphing Mode (Plot equations) 📉')
+        print('3. View History 📜')
+        print('4. Exit 🚪')
+
+        user_choice = input('\n📌 Enter your choice (1-4): ').strip()
+
+        if user_choice == '4':
+            print('\n👋 Goodbye! Have a great day! 🌟\n')
+            run = False
+            break
+
+        if user_choice == '3':
+            if not history:
+                print("📜 No calculations yet.")
+            else:
+                print("\n------ 📜 Calculation History 📜 ------")
+                for item in history:
+                    print(item)
+            continue
+
+        if user_choice == '1':
+            print("\n--- ➕ Standard Mode ---")
+            print("Enter a mathematical expression (e.g., '2 + 3 * sin(pi/2)' or 'log(e)').")
+            print("Type 'back' to return to the main menu.")
+            while True:
+                expr = input("\n🔢 Expression: ").strip()
+                if expr.lower() == 'back':
+                    break
+                if not expr:
+                    continue
+                try:
+                    result = evaluate_expression(expr)
+                    print(f"✅ Result: {result}")
+                    history.append(f"{expr} = {result}")
+                except Exception as e:
+                    print(f"❌ Error evaluating expression: {e}")
+
+        elif user_choice == '2':
+            print("\n--- 📉 Graphing Mode ---")
+            print("Enter an equation in terms of 'x' (e.g., 'x**2 - 4*x + 4' or 'sin(x)').")
+            print("Type 'back' to return to the main menu.")
+            while True:
+                expr = input("\n📉 Equation f(x) = ").strip()
+                if expr.lower() == 'back':
+                    break
+                if not expr:
+                    continue
+                
+                try:
+                    # Generate x values
+                    x = np.linspace(-10, 10, 400)
+                    
+                    # Evaluate the user's expression
+                    y = evaluate_expression(expr, x_val=x)
+                    
+                    # Handle cases where the expression evaluates to a scalar (e.g., "5")
+                    if np.isscalar(y):
+                        y = np.full_like(x, y)
+
+                    # Plotting
+                    plt.figure(figsize=(8, 6))
+                    plt.plot(x, y, label=f"y = {expr}", color='blue')
+                    plt.title("Graphing Calculator")
+                    plt.xlabel("x")
+                    plt.ylabel("f(x)")
+                    
+                    # Add axis lines
+                    plt.axhline(0, color='black', linewidth=1)
+                    plt.axvline(0, color='black', linewidth=1)
+                    
+                    plt.grid(color='gray', linestyle='--', linewidth=0.5)
+                    plt.legend()
+                    
+                    print(f"📈 Showing plot for: y = {expr}. Close the plot window to continue.")
+                    plt.show()
+                    
+                    history.append(f"Graphed: y = {expr}")
+                except Exception as e:
+                    print(f"❌ Error graphing equation: {e}")
+
+        else:
+            print('❌ Invalid choice. Please enter a number between 1 and 4.')
+
+if __name__ == "__main__":
+    main()