CHAPTER 2

TRAINING WORK UNDERTAKEN

2.1 WOKWI SOFTWARE:

Wokwi is an online simulation platform primarily used for designing and prototyping electronic

circuits. It allows users to create, test, and debug circuits using various components like

Arduino, ESP32, sensors, and LEDs without the need for physical hardware. This is especially

useful for students, hobbyists, and developers working on embedded systems and IoT projects.

Wokwi is a powerful tool for learning and experimenting with electronics without the cost and

complexity of physical hardware. The working of Wokwi involves several key steps, from creating a

circuit design to writing and testing code.

Fig:-2.1 (Wokwi Software)

2.2. Blynk Cloud Software: Overview

Blynk is a popular IoT (Internet of Things) platform that enables users to control hardware

remotely, visualize sensor data, store it, and create sophisticated automation systems. Blynk

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Cloud is the cloud infrastructure of the platform, acting as a bridge between hardware devices

(like ESP8266, ESP32, Arduino, etc.) and a mobile app or web dashboard, allowing users to

build IoT solutions without worrying about backend setup.

1. Blynk App (iOS & Android): A mobile app where users create the user interface to

control their devices.

2. Blynk Server (Blynk Cloud): The server that handles the communication between the

devices and the mobile app. Blynk Cloud is the free, hosted version of the server.

3. Blynk Libraries: These libraries allow your hardware (like Arduino or ESP8266) to

communicate with the Blynk Cloud.

Fig:-2.2 (Blynk Software)

2.3. What is Arduino?

Arduino is an open-source electronics platform based on easy-to-use hardware and software. It

consists of microcontroller boards (e.g., Arduino Uno, Nano, Mega) that can read inputs (such

as light, temperature, or button presses) and control outputs (such as LEDs, motors, or displays)

based on the programming loaded onto them. The main advantage of Arduino is its simplicity

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and flexibility, allowing hobbyists, students, and professionals to create various interactive

projects, from simple sensors to advanced robotics.

Fig:- 2.3 (Arduino Software)

2.4. What is a Breadboard?

A breadboard is a reusable platform used for constructing electronic circuits without the need

for soldering. It allows you to quickly and easily build temporary prototypes or experiment

with circuits by inserting components such as resistors, capacitors, LEDs, or integrated circuits

(ICs) into the breadboard’s holes. Breadboards are extremely useful for prototyping because

they allow components to be connected and tested in a flexible way. Once the design works, the

circuit can be transferred to a more permanent form (like soldering on a printed

circuit board).

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2.4.1. Advantages of a Breadboard:

 No Soldering Required: Circuits can be built and modified without any permanent

connections.

 Reusability: Breadboards can be used repeatedly for different projects.

 Quick Prototyping: Ideal for testing and iterating designs quickly.

2.4.2. Breadboard Layout Diagram:

Fig:-2.4 (Breadboard)

This image shows how various components, like resistors, LEDs, and wires, can be connected on a

breadboard for prototyping.

2.5. What is ESP32?

ESP32 is a powerful, low-cost, low-power system-on-chip (SoC) microcontroller developed by

Espressif Systems. It is popular for its integrated Wi-Fi and Bluetooth functionalities, making

it ideal for IoT (Internet of Things) projects and wireless communication applications. The

ESP32 is highly versatile and has more advanced features than its predecessor, the ESP8266.

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It's commonly used in projects that need connectivity, like smart home devices, wireless

sensors, wearables, and more.

2.5.1. Common ESP32 Models:

 ESP32-WROOM-32: One of the most popular modules used in development boards.

 ESP32-WROVER: Similar to the WROOM but includes additional PSRAM (external

RAM), which is useful for memory-heavy applications like audio processing or image

recognition.

Fig. 2.5 (ESP32)

2.5.2. Advantages of ESP32:

 Cost-Effective: It's affordable, making it accessible for hobbyists and professionals

alike.

 Wi-Fi and Bluetooth: It has built-in dual-mode wireless capabilities, which eliminates

the need for external modules.

battery-powered devices.

 Rich Libraries and Community Support: There are extensive resources, libraries, and

community support available for ESP32.

2.5.3. Disadvantages of ESP32:

 Learning Curve: For beginners, it may have a steeper learning curve than simpler

microcontrollers like the Arduino Uno.

 Limited GPIO Pins: In some applications, the number of available GPIO pins may be

insufficient.

2.6. LED (Light Emitting Diode):

An LED is a semiconductor device that emits light when an electric current passes through it.

It's a type of diode, meaning it allows current to flow in only one direction, which is why it has

a positive (anode) and negative (cathode) leg.

Fig:-2.6 (LED)

2.6.1. How LEDs Work:

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When a suitable voltage is applied across the leads of an LED, electrons recombine with holes

within the semiconductor, releasing energy in the form of photons (light). The color of the light

is determined by the energy band gap of the semiconductor material.

2.6.2. Common Uses of LEDs:

 Indicators: Used in devices to show status (on/off, activity).

 Lighting: LED bulbs are used in homes, vehicles, and flashlights for energy-efficient

lighting.

 Displays: Used in screens, billboards, and digital displays.

2.7. Wires:

Wires are used to connect components in an electronic circuit, allowing electricity to flow

between them. They come in different colors, thicknesses, and types (solid core, stranded core,

etc.).

Fig.2.7 (Wires)

2.7.1. Types of Wires:

 Solid Core Wires: These are single, solid strands of wire. They are stiff and hold their

shape, making them useful for breadboarding and prototyping.

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  Stranded Wires: Made up of multiple thin strands of wire twisted together. They are

more flexible and durable than solid-core wires, ideal for applications where the wire

needs to bend frequently.

 Jumper Wires: These are short wires with connectors on both ends, commonly used for

connecting components on breadboards or between development boards like Arduino or

Raspberry Pi.

2.8. USB Cable:

A USB cable is commonly used to connect devices like microcontrollers (Arduino, ESP32,

Raspberry Pi) to a computer for programming and powering the device.

2.8.1. Types of USB Cables:

 USB-A to Micro-USB: Commonly used with development boards like Arduino Nano,

ESP8266, and ESP32.

 USB-A to USB-B: Used with larger Arduino boards like the Arduino Uno and Mega.

 USB-A to USB-C: Newer standard, used in some modern development boards and

phones.

Fig.2.8 (USB cable)

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2.9. What is a Push Button?

A push button is a simple switch mechanism used to control a circuit. When pressed, it either

completes or interrupts the flow of current, allowing an electronic device or circuit to perform

an action. Push buttons are widely used in everyday electronics like doorbells, calculators, and

control panels, as well as in DIY electronics projects.

Fig.2.9 (Push Button)

2.9.1. Types of Push Buttons:

1. Momentary Push Button: The most common type. It only completes the circuit while

it is being pressed, and once released, the circuit is broken.

 Normally Open (NO): The circuit is open (no current flows) when the button is not

pressed. Pressing the button closes the circuit, allowing current to flow.

 Normally Closed (NC): The circuit is closed (current flows) when the button is not

pressed. Pressing the button opens the circuit, stopping the flow of current.

2. Latching Push Button: Also known as a toggle or lock switch. Once pressed, it stays

in the "on" state until pressed again to return to the "off" state.

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2.10. What is the HC-SR04 Ultrasonic Distance Sensor?

The HC-SR04 is a popular ultrasonic distance sensor used to measure distances between the

sensor and an object. It works by emitting ultrasonic sound waves and measuring the time it

takes for the sound to bounce back after hitting an object. This time is then used to calculate the

distance between the sensor and the object. It is widely used in applications like obstacle

avoidance in robots, level detection, and proximity sensing in various DIY and commercial

projects.

Fig.2.10 (HC-SR04 Ultrasonic Distance Sensor)

2.10.1. How HC-SR04 Works:

The HC-SR04 sensor has two main components:

1. Transmitter (Trig Pin): Sends out ultrasonic pulses at a frequency of 40 kHz.

2. Receiver (Echo Pin): Receives the reflected sound waves (echo) and calculates the time

it took for the echo to return.

2.10.2. Advantages of the HC-SR04:

 Affordable: Inexpensive, making it suitable for hobbyists and educational purposes.

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  Easy to Use: Simple interface, with only four pins and straightforward communication

with microcontrollers.

 Good Range: Can measure distances between 2 cm and 4 meters with reasonable

accuracy.

 Non-contact: Measures distance without requiring physical contact with the object.

2.10.3. Technical Specifications:-

Table: 2.1 (specification of HC-SR04 Ultrasonic Distance Sensor)

Operating Voltage DC 5V
Operating Current 15mA
Operating Frequency 40KHz
Max Range 4m
Min Range 2cm
Ranging Accuracy 3mm
Measuring Angle 15 degree
Trigger Input Signal 10µS TTL pulse
Dimension 45 x 20 x 15mm

2.11. What is a Relay?

A relay is an electromechanical switch used to control high-voltage or high-current circuits

using a low-voltage or low-current signal. It allows one circuit to control another circuit,

typically isolating the two. This makes relays useful in many applications where controlling

large loads or switching between different circuits is necessary.

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 Fig. 2.11 (Relay)

2.11.1 How Does a Relay Work?

A relay operates on the principle of electromagnetism. It consists of an electromagnet (coil), a

movable contact (armature), and one or more stationary contacts. When a small current flows

through the coil, it generates a magnetic field that moves the armature, which either makes or

breaks a connection with the stationary contacts, thus controlling a separate high-power circuit.

2.11.2. Advantages of Relays:

 Electrical Isolation: Relays provide electrical isolation between the control circuit (low

voltage) and the load (high voltage), preventing damage to sensitive components.

 Control Large Loads: Relays can control high-power devices like motors, heaters, and

lights that cannot be driven directly by microcontrollers.

 Durability: Electromechanical relays can handle large current loads and are durable in

high-power applications.

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2.11.3. Disadvantages of Relays:

 Mechanical Wear: Electromechanical relays have moving parts that can wear out over

time, leading to failure.

 Slower Switching: Compared to solid-state relays, electromechanical relays have

slower switching times because of their mechanical movement.

 Noise: Relays can produce audible clicking sounds when switching, which might be

undesirable in some applications.

2.12. What is a 16x2 LCD?

A 16x2 LCD (Liquid Crystal Display) is a type of display module that can show 16 characters

per line and has a total of 2 lines. It is commonly used in various electronic projects to provide

a visual interface for displaying text, numbers, and other data. The 16x2 LCD is widely used

due to its simplicity, affordability, and versatility in displaying information from

microcontrollers like Arduino, Raspberry Pi, and others.

Table: 2.2 (LCD pins and ESP32 pins)

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2.12.1. Working Principle:

The 16x2 LCD works by controlling the state of liquid crystals between two polarizing filters.

When an electric current is applied to the liquid crystals, they change orientation, allowing light

to pass through or be blocked, thus creating visible characters or graphics on the display.

2.12.2. Advantages of 16x2 LCD:

 Easy to Use: Simple to interface with microcontrollers and widely supported by

libraries.

 Cost-Effective: Inexpensive compared to other display options.

 Low Power Consumption: Operates at low voltages, making it suitable for battery-

powered applications.

2.13. Libraries:-

libraries are packages of code that can be used to add function nality to a project.

2.13.1. Libraries in wokwi:-

Custom libraries can be created in Wokwi by including the library name, "@wokwi:", and the

unique identifier of the library's zip file on Wokwi's servers. Custom libraries can be copied to

other projects by copying the relevant lines from libraries.txt.

2.13.2. Arduino libraries:-

These are small packages of code written by others to perform a specific function. For example,

a library can add support for a specific sensor. Arduino libraries can be found in three places:

the IDE installation folder, the core folder, and the libraries folder in the sketchbook.

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2.13.3. Blynk ESP-32 wifi:

The Blynk library for ESP32 in Wokwi allows you to connect your ESP32 board to the Blynk

Cloud, which is an IoT platform that lets you control hardware remotely:

 Blynk library: Connects your ESP32 board to the Blynk Cloud.

2.13.4. Blynk_Async_ESP_BT_WF:-

The Blynk Async ESP32_BT_WF library is specifically designed to enable asynchronous

communication between the ESP32, Blynk, and either WiFi or Bluetooth, allowing you to build

smart IoT applications. If you're using Wokwi (an online simulator for electronics).

2.13.5 Afstandsensor-HCSR04 Library:

1. Simplifies Distance Measurement

2. Manages Timing and Signal Processing

3. Calculates Distance Using Speed of Sound

4. Error Handling and Range Validation

5. Customizable Maximum Range

6. Flexible Pin Assignment

7. Non-Blocking Measurement

8. Unit Conversion

2.13.6 Use Cases for the HC-SR04 with Afstandsensor-HCSR04 Library:

1. Robotics

2. Security Systems

3. Liquid Level Monitoring

4. Parking Sensors

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 5. Proximity Alerts

2.13.7. Liquid Crystal library:-

The LiquidCrystal library is a widely used library in Arduino and ESP-based projects that

allows for easy interfacing with LCD displays that use the controller or compatible models.

These LCDs are commonly available in sizes like 16x2 (16 characters by 2 lines) or 20x4, and

the library provides a simple way to control them.

2.13.8 How to Use the LiquidCrystal Library:

1. Include the Library:

 The LiquidCrystal library comes pre-installed with the Arduino IDE, so there’s no

need to download it separately.

2. Wiring the LCD:

 4-bit mode wiring example for a 16x2 LCD:

 RS → Arduino digital pin

 E → Arduino digital pin

 D4, D5, D6, D7 → Arduino digital pins

 VSS → Ground

 VDD → 5V (power)

 V0 → Potentiometer (for contrast adjustment)

 RW → Ground (for write-only mode)

 A and K → Backlight pins (optional)

2.13.9 Use Cases for LiquidCrystal Library:-

1. Displaying Sensor Data

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 2. User Interfaces

3. Timers and Clocks

4. Status Indicators

5. Game Displays

2.13.10. BlynkNcpDriver Library:-

1. Facilitates Communication with Blynk Cloud:

 The BlynkNcpDriver library enables your microcontroller (like ESP32 or similar) to

communicate seamlessly with the Blynk Cloud or Blynk IoT platform by using an

NCP module. This allows the microcontroller to send and receive data to/from the

cloud for IoT projects.

2. Network Co-Processor (NCP) Management

3. Supports Multiple Network Interfaces

4. Integration with Blynk IoT

5. Optimized Resource Management

6. Compatibility with Wokwi

7. Real-Time IoT Applications

8. Simplified Setup for Beginners

2.13.11. ESP_DoubleResetDetectorlibrary:-

The ESP_DoubleResetDetector library is a useful tool for ESP32 and ESP8266-based

projects, allowing you to detect when the microcontroller has been reset twice within a short
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period of time. This feature is often used to trigger specific actions, such as entering

configuration mode, factory reset, or enabling OTA (Over-the-Air) updates.

2.13.12. Role of the ESP_DoubleResetDetector Library:

1. Detects Double Resets:

 The main purpose of the ESP_DoubleResetDetector library is to detect when the

ESP32 or ESP8266 has been reset twice within a defined time interval (usually a few

seconds).

 When a double reset is detected, the device can switch to a special mode, like entering

a Wi-Fi setup portal, configuration mode, or OTA update mode.

2. Useful for Entering Configuration Mode:

 In many IoT projects, you might want to allow users to change the Wi-Fi credentials or

other settings without physically accessing the device. By using the

ESP_DoubleResetDetector, you can make the device detect a double reset and enter a

configuration mode where the user can update settings via a web portal or similar

interface.

 This is particularly useful for headless devices or those that are difficult to physically

access once deployed.

3. Trigger OTA (Over-the-Air) Updates:

 Another common use of the library is to trigger an OTA update process. After

detecting a double reset, the device can switch into an OTA mode where it downloads

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 new firmware updates from a remote server.

 This allows developers to update the firmware of ESP-based devices remotely without

requiring physical access to the device.

4. Factory Reset or Safe Mode:

 You can also use the ESP_DoubleResetDetector to perform a factory reset by

erasing the stored configuration and resetting the device to its default state after

detecting a double reset.

 Additionally, the library can be used to put the device into a "safe mode" to

troubleshoot issues or prevent the device from running problematic code during

startup.

5. Non-Volatile Storage for Reset Detection:

 The library works by storing the first reset's timestamp in non-volatile memory

(NVS) or EEPROM, and if a second reset occurs within the defined time window, it is

detected as a double reset.

 This storage ensures that the detection mechanism works even if the device loses

power temporarily between resets.

 This can limit flexibility in specialized applications.

2.14. Timer in plc:-

PLC timer is a instruction to control and operate the device for a specific duration. With

the timer, we can perform any specific operations for a particular time span. The timer

instruction is used to provide programming logic and to decide when to turn on or off the

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 circuit. It has both normally open (NO) or normally closed (NC) contact.

Fig 2.12 (Timer in PLC)

2.14.1 What are the types of the PLC Timer?

For the ladder diagram programming, the classification of the PLC programming timer is-

1. On Delay Timer (TON)

An on-delay timer (TON) is a programming instruction which use to start momentary pulses

for a set period of time. Let’s see, a simple construction of the AB PLC On-delay timer

programming instruction.

Fig.2.13 (ON Delay Timer)

2. Off Delay Timer (TOFF)

A off-delay (TOF) timer is a PLC programming instruction which use to switch off the output

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or system after a certain amount of time.

See here, a basic structure of AB PLC Off delay timer programming instruction.

Fig.2.14 (Off Delay PLC Timer)

3. Retentive On/Off Timer (RTO)

The main function of the RTO is used to hold or store the set (accumulated) time.

RTO is used in the case when there is a change in the rung state, power loss, or any

interruption in the system.

2.14.2 Timer Instructions Address for Multiple PLC Brands:-

We have seen three timers provide the time delay functions to control the PLC operations.

There are four main values that timer deals with.

 Timer Address

 Preset Value

 Timer Base Value

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  Accumulated value

Fig.2.15 ( Retentive Timer ON/OFF)

Each timer instruction has three very useful status bits. These bits are…

1. Enable bit (EN)

2. Timer Timing bit (TT)

3. Done Bit (DN).

2.15. What is the PLC Counter?

An instruction which is useful for sequential counting as digital signal pulse or the number of

digits.

2.15.1 How PLC Counter Works ?

The basic internal counter circuit requires auxiliary power supply (APS), an input-output

terminal, a counter circuit, and a digital display. We can see PLC counter internal structure as

given block diagram with their specific connected parts.

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 Fig.2.16 (Block Diagram of Counter)

2.15.2 What are the types of the PLC Counter?

Basically, PLC counter operates into four modes such as up mode, down mode, bidirectional

mode, and the quadrature mode. Counters in PLC are classified into three main different parts.

1. Up Counter (operates up mode)

2. Down Counter (operated in down mode)

3. Up/Down Counter (operates in bidirectional and quadrature mode)

1. Up Counter:-

Up counter counts from zero to the preset value. Basically, it increases the pulse or number. Up

counter is known as the ‘CTU’ or ‘CNT’ or ‘CC’ or ‘CTR’. Up counter function block

diagram:

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 Fig.2.17 (Up counter)

2. Down Counter:-

The down counter counts from the preset value to zero. It decreases the pulse or number. Down

counter is shortly known as the ‘CTD’ or ‘CD’.

Down counter function block diagram:

Fig.2.18 (Up- Down Counter)

The down counter counts from target value to the initial value by decreasing it. This initial

value must be less than the target value.

3. Up-Down Counter:-

The up-down counter counts the value from zero to the preset value or from the preset value to

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zero. In other words, this counter can be act as down counter or up counter.

Up-down counter is known as ‘CTUD’. For the bidirectional and quadrature operation

mode, the up-down counter is selected depending on the status (high or low) of the specified

count input terminal.

4. Up-down counter function block diagram:

Fig:2.19 (Down Counter)

2.16 PLC ladder logic of AND Gate:-

The output coil of an AND gate turns on when both inputs are on.

Fig.2.20 (Ladder Logic of AND Gate)

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2.17 Ladder logic of OR Gate:-

In ladder logic, an OR function is represented by two normal contacts placed on top of each

other.

Fig:2.21(Ladder Logic of OR Gate)

2.18. Ladder Diagram of XOR Gate:-

Fig.2.22 (Ladder Logic of XOR Gate)

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2.19 ladder diagram of XNOR Gate:-

Fig.2.23 (Ladder Logic of XOR Gate)

2.20 ladder diagram of NAND gate:-

Fig:2.24 (Ladder Logic of NAND Gate)

2.21. ladder diagram of NOT Gate:-

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 Fig.2.25 (Ladder Logic of NOT Gate)

2.22. ladder diagram of NOR Gate :-

Fig.2.26 (Ladder Logic of NOR Gate)

2.23. RS Logix Micro Starter Lite :-

RS Logix Micro programming software allows you to cost-effectively create, modify and

monitor your applications programs by leveraging this powerful, yet easier-to- use design

package.

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 Fig.2.27 (RS Logix Micro Starter Lite)

2.23.1. RSLogix EMMULATE 500:-

RSLogix 500 is mostly used to support older automation systems that are controlled by SLC

or MicroLogix PLCs. RSLogix Emulate 500 emulates all the programmable logic controllers

in the AllenBradley SLC 500 family, including the MicroLogix 1000, 1200, and 1500

controllers

Fig.2.28 (RS Logix Emmulate)

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2.23.2. RS LINUX CLASSIC LITE:-

The primary purpose of Rslinx Classic and Enterprise Software is to provide connectivity

between different Rockwell Automation products, allowing them to communicate with

each other and with other devices on an industrial network.

2.24. Commands of Scilab:

Scilab is an open source software similar to MATLAB used for numerical computations, data

analysis, and simulation. Below is an overview of key commands and function commonly used

in Scilab:

1. Basic Operations

 Addition: +

 Subtraction: -

 Multiplication: *

 Division: /

 Power: ^

 Assignment: =

2. Matrices and Arrays

 Creating a matrix: A = [1, 2; 3, 4]

 Transposing a matrix: A'

 Inverse of a matrix: inv(A)

 Determinant of a matrix: det(A)

 Eigenvalues and eigenvectors: [V, D] = spec(A)

 Matrix multiplication: A * B

 Matrix element-wise multiplication: A .* B

 Identity matrix: eye(n)

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  Zeros matrix: zeros(m, n)

 Ones matrix: ones(m, n)

 Diagonal matrix: diag([1, 2, 3])

 Concatenation of matrices: [A, B] or [A; B]

3. Functions

 Defining a function:

scilab

Copy code

function y = f(x)

y = x^2 + 3*x + 2;

endfunction

 Calling a function: f(2)

4. Control Structures

 If-else:

scilab

Copy code

if x > 0 then

disp("Positive");

else

disp("Negative or Zero");

end

 For loop:

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 scilab

Copy code

for i = 1:10

disp(i);

end

 While loop:

scilab

Copy code

while condition

// your code

End

5. Plotting

 2D plot: plot(x, y)

 3D plot: plot3d(x, y, z)

 Multiple plots: subplot(m, n, p)

 Labels and title: xlabel("X-axis"), ylabel("Y-axis"), title("Plot Title")

6. Polynomials

 Defining a polynomial: p = poly([roots], "x")

 Finding roots: roots(p)

 Polynomial evaluation: horner(p, x)

7. Basic Functions

 Exponential: exp(x)

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  Logarithm: log(x) (natural), log10(x) (base 10)

 Sine and Cosine: sin(x), cos(x)

 Absolute value: abs(x)

 Square root: sqrt(x)

 Round: round(x)

8. File Operations

 Loading data from a file: load("filename")

 Saving data to a file: save("filename", variable)

 Reading from a file: fscanfMat("filename")

 Writing to a file: fprintfMat("filename", variable)

9. Statistical Functions

 Mean: mean(x)

 Variance: variance(x)

 Standard deviation: stdev(x)

 Maximum and Minimum: max(x), min(x)

10. Linear Algebra

 LU decomposition: [L, U] = lu(A)

 QR decomposition: [Q, R] = qr(A)

 Singular Value Decomposition: [U, S, V] = svd(A)

11. Differential Equations

 Solving ODE: ode(rhs_function, t0, t_end, initial_conditions)

12. Utilities

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  Clear workspace: clear

 Help documentation: help

 Exit Scilab: exit

This is just a subset of the commands available in Scilab. The software offers a wide range of

functions for different areas such as optimization, signal processing, control systems, and much

more. You can explore more commands and features by referring to the Scilab documentation.

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