Lecture 11: First Program Fundamentals

Lecture 11: First Program

• Lecture topic: Memory variables, input, display, arithmetic expressions, math functions
• Topics covered in the first program lecture: This lecture will cover computer hardware & software, how to write a program, building a first program, memory, getting input, displaying output, arithmetic expressions, and sample programs.

Overview

• Lecture overview: The presentation covers a high-level overview of programming topics, encompassing computer hardware and software concepts, the process of writing programs, and the creation of a basic program.

Computer Hardware

• Components: Input/Output Devices, Central Processing Unit (CPU), Keyboard, Screen, Hard Disk.
• Internal structure: The CPU consists of Memory Unit (RAM), Control Unit, and Arithmetic Logic Unit (ALU).
• Functionalities: The Control Unit manages all components, Memory Unit stores data, ALU processes arithmetic and logical operations.

Hardware Functionality

• Control Unit: Manages all components, acting as a central controller.
• Memory Unit: Stores data temporarily.
• Arithmetic Logic Unit (ALU): Performs arithmetic and logical computations using data from memory.
• Input devices (Keyboard): Gather data from the user and send to computer's memory.
• Output devices (Screen): Display data stored in the computer's memory on the screen for user viewing.
• Storage devices (Hard Disk): Store data persistently. This data is transferred to RAM when required by the computer.

Software

• Instructions: A computer performs instructions sequentially to complete a task.
• Program: A sequence of instructions to achieve a specific goal, for example calculating area of a rectangle or a circle.
• Types of Instructions: The instructions can include getting input, displaying output, computing arithmetic expressions, and performing logical operations and loops.

How to Write a Program

• Stages: Identify needed input, define output, understand a relationship between input and output (algorithm), translate algorithm to code (programming), test program and match your result to human result.

Building Our First Program: Calculate Area of a Rectangle

• Human approach: Obtain values for height and width, multiply these values, and display the result.
• Algorithm: Get height, get width, calculate area (height * width), display area.
• Program: Write the code steps as MatLab lines utilizing input and disp commands.

Calculate Area of a Rectangle (Program and Testing)

• Program code snippet:
  • h = input('enter height: ');
  • w = input('enter width: ');
  • area = h * w;
  • disp(area);
• Example usage: enter height: 5, enter width: 4, Result 20.

Calculate Area of a Circle (Algorithm, Program, Testing)

• Algorithm: Get radius, calculate area (π * radius^2), display area.

• Program code: r = input('enter radius: ');, area = pi * r^2;, disp(area);

• Example run: enter radius: 5, result 49.348.

Calculate Number of Buses to Transfer Students (Algorithm)

• Get number of students (numS), Get bus capacity (busC);
• Calculate number of buses (numB): numB = ceil(numS/busC);
• Display number of buses (numB).

Calculate Number of Dozens and Remainder

• Algorithm:   - Enter a number (N)   - Calculate dozen (N/12) – integer division   - Calculate remainder (remainder of N / 12)   - Display calculated dozen, remainder.

• Program code:   - N = input('enter a number');   - dozen = fix(N/12);   - r = rem(N,12);   - disp(dozen);   - disp(r);

Memory

• Bytes: Memory is structured in bytes, each with its address.
• Binary numbers: Addresses are represented in binary form.
• Data types: Integers and floating-point numbers are stored using 4 or 8 bytes.
• Variable names: Programs use letters and numbers to identify locations/variables, e.g., A, A1.

Memory Location Names (Variables)

• Variable: A named memory location for storing a value.
• Naming rules: Variable names start with a letter followed by letters or numbers.
• Examples: A, A1, radius.
• Case sensitivity: MatLab is case-sensitive. area and Area are different variables.

Get input from user

• Function: h = input('enter height: ');
• Purpose: The input() command gets input from the user (e.g., 5). This allows the user to enter a value for the variable/memory location h.
• Displays to memory location: A statement like h = input ('enter value'); writes the value entered by the user in the memory location h allocated for the code.

Get an array from user

• Function: X = input('enter array elements: ');

• Purpose; The input() command gets multiple array (list) elements from the user.

Display to Screen (disp())

• Purpose: Displays the value of a variable or a result calculated from the code to the user's screen.

Arithmetic expressions

• Operations: Exponentiation (^), multiplication (*), division (/), addition (+), subtraction (-).
• Order of operations: Operations are executed in a specific order.
• Example: An expression a = x + y - 5 / (3 + z);

Summary

• Overviewing a comprehensive programming module that encompasses fundamental computer components such as hard-drive, and software concepts.