# Octave guide

In this guide I tell you about **GNU Octave**, an open source and free software similar to Matlab that allows you to solve mathematical calculations and geometric problems (eg matrices, linear algebra, mathematical analysis, etc.).

**What are the strengths of Octave?**

- It's free. You can install and use it freely. It does not require registration.
- It can be installed on a PC with a Windows, Linux or Mac operating system.
- Octave commands are very similar to Matlab. The syntax is almost identical.

**How to use Octave?**

You can use Octave in two different ways

- as a scientific calculator via the command line
- as a programming language for writing and saving script files

This is the Octave GUI

Octave **main menu** (File, Edit, Debug, Window, Help, News) is at the top

In the central part of the interface there is the **command window** that allows you to use Octave interactively.

On the left there are several panels:

- file manager
- workspace
- historic commands

In the bar at the bottom there is the **Editor** item that allows you to write and save scripts on Octave.

**How to install GNU Octave**

You can download the installation file directly on the official website www.gnu.org/software/octave/

It is available for any PC operating system: Linux, Windows, MacOS, BSD

If you use Linux you can also find it among the applications that can be installed in the various repositories

In this guide I'll explain some practical examples of using Octave.

- How to perform elementary math operations

Learn about the mathematical operators used by Octave to carry out basic mathematical operations.

- How to make the rational approximation of a real number

In this lesson, I will explain how to transform a real number into a sum of fractions.

- How do you spell pi, infinity, imaginary unit or Euler's number?

Octave uses specific predefined constants to indicate pi, the infinity symbol, Euler's number, and the imaginary unit.

- How to calculate logarithms

In this lesson, I will explain how to calculate natural logarithms, logarithms with base 10 or 2 using Octave's pre-defined functions, and how to calculate logarithms with any other base.

- How to perform operations with complex numbers

In this guide, I will explain how to perform mathematical operations with complex numbers.

- How to calculate the limit of a function

In this lesson I'll explain how to calculate the limit of a function for x that tends to a point or to plus or minus infinity

- How to calculate the derivative of a function

In this guide I'll explain how to calculate the first, second or nth derivative of a function..

- Calculating Indefinite Integrals (antiderivative)

In this lesson, we will explore the process of determining the indefinite integral of a function. - How to compute the definite integral of a function

In this lesson, we will learn how to compute the definite integral of a function between two integration limits.

- How to find the solution of a differential equation

In this lesson, I will explain how to calculate a homogeneous or non-homogeneous differential equation of the first or second order.

- How to create a vector

In this lesson, we will learn how to define a vector in Octave and the main vector operations.

- How to create matrices

In this lesson, I will demonstrate how to create a square or rectangular matrix.

- Solving a system of linear equations

In this lesson, I will guide you through the process of solving a system of linear equations using vector calculus in Matlab to determine the solutions.