Create README.md for ScientificCalculator

Added comprehensive README for ScientificCalculator project, detailing features, usage, and project structure.

README.md

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+# ScientificCalculator
+
+A feature-rich scientific calculator implemented in C++ that provides advanced mathematical operations and a user-friendly interface.
+
+## Features
+
+- **Basic Arithmetic Operations**: Addition, subtraction, multiplication, and division
+- **Advanced Mathematical Functions**: 
+  - Trigonometric functions (sin, cos, tan)
+  - Inverse trigonometric functions (asin, acos, atan)
+  - Logarithmic functions (log, log10)
+  - Exponential functions (exp, pow)
+  - Square root and power operations
+- **Memory Functions**: Store, recall, and clear memory values
+- **Error Handling**: Comprehensive error detection and user-friendly error messages
+- **Clean Interface**: Simple and intuitive command-line interface
+
+## Requirements
+
+- C++ compiler (C++11 or later recommended)
+- Standard C++ library only (no external dependencies)
+
+## Building the Project
+
+### Prerequisites
+- C++ compiler (g++, clang++, or MSVC)
+- CMake (optional, for automated builds)
+
+### Compilation
+
+#### Using g++ (Linux/macOS)
+```bash
+g++ -std=c++11 -o ScientificCalculator main.cpp calculator.cpp
+```
+
+#### Using Makefile
+```bash
+make
+```
+
+#### Using CMake
+```bash
+mkdir build
+cd build
+cmake ..
+make
+```
+
+## Usage
+
+1. **Run the executable**:
+   ```bash
+   ./ScientificCalculator
+   ```
+
+2. **Basic Operations**:
+   ```
+   Enter an expression or command: 5 + 3
+   Result: 8
+   ```
+
+3. **Advanced Functions**:
+   ```
+   Enter an expression or command: sin(30)
+   Result: 0.5
+   ```
+
+4. **Memory Operations**:
+   ```
+   Enter an expression or command: memstore 10
+   Enter an expression or command: memadd 5
+   Enter an expression or command: memrecall
+   Result: 15
+   ```
+
+5. **Exit the calculator**:
+   ```
+   Enter an expression or command: exit
+   ```
+
+## Supported Operations
+
+### Basic Arithmetic
+- `+` : Addition
+- `-` : Subtraction
+- `*` : Multiplication
+- `/` : Division
+- `^` : Power operation
+
+### Trigonometric Functions
+- `sin(x)` : Sine
+- `cos(x)` : Cosine
+- `tan(x)` : Tangent
+- `asin(x)` : Arcsine
+- `acos(x)` : Arccosine
+- `atan(x)` : Arctangent
+
+### Logarithmic and Exponential Functions
+- `log(x)` : Natural logarithm
+- `log10(x)` : Base-10 logarithm
+- `exp(x)` : Exponential function
+- `sqrt(x)` : Square root
+- `pow(x, y)` : Power function
+
+### Memory Functions
+- `memstore x` : Store value in memory
+- `memadd x` : Add value to memory
+- `memsubtract x` : Subtract value from memory
+- `memrecall` : Recall memory value
+- `memclear` : Clear memory
+
+## Project Structure
+
+```
+ScientificCalculator/
+├── main.cpp              # Main program entry point
+├── calculator.cpp        # Core calculator implementation
+├── calculator.h          # Calculator class header
+├── README.md             # This file
+└── Makefile              # Build configuration (optional)
+```
+
+## Code Structure
+
+### Calculator Class
+The main calculator functionality is implemented in the `Calculator` class, which provides:
+- Expression parsing and evaluation
+- Mathematical function implementations
+- Memory management
+- Error handling
+
+### Key Components
+- **Expression Parser**: Handles input parsing and tokenization
+- **Evaluator**: Processes mathematical expressions and computes results
+- **Function Library**: Implements all supported mathematical functions
+- **Memory Manager**: Handles storage and retrieval of memory values
+
+## Error Handling
+
+The calculator includes comprehensive error handling for:
+- Invalid expressions
+- Division by zero
+- Domain errors (logarithm of negative numbers, etc.)
+- Memory overflow/underflow
+- Syntax errors
+
+Error messages are user-friendly and provide guidance for correct usage.
+
+## Examples
+
+### Basic Calculations
+```
+Enter an expression or command: 15 * 4 + 10 / 2
+Result: 65
+
+Enter an expression or command: 2 ^ 10
+Result: 1024
+```
+
+### Scientific Calculations
+```
+Enter an expression or command: sin(45) + cos(45)
+Result: 1.41421
+
+Enter an expression or command: log(100) * exp(2)
+Result: 18.4207
+```
+
+### Memory Operations
+```
+Enter an expression or command: memstore 25
+Enter an expression or command: memadd 15
+Enter an expression or command: memrecall
+Result: 40
+```
+
+## Contributing
+
+1. Fork the repository
+2. Create a feature branch
+3. Make your changes
+4. Test thoroughly
+5. Submit a pull request
+
+## License
+
+This project is open source and available under the MIT License.
+
+## Future Enhancements
+
+- Graphical user interface (GUI) implementation
+- Additional mathematical functions (hyperbolic functions, statistical functions)
+- Expression history and recall
+- Custom variable storage
+- Unit conversion capabilities
+- Complex number support
+
+## Contact
+
+For questions, suggestions, or contributions, please open an issue on the GitHub repository.