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GNU Octave

GNU Octave 4.3.0+ running on Linux
Developer(s)	John W. Eaton and many others
Initial release	4 January 1993; 32 years ago (4 January 1993) (first alpha release) 17 February 1994; 31 years ago (17 February 1994) (version 1.0)

Stable release	9.2.0 / 7 June 2024; 13 months ago (7 June 2024)

Written in	C++ (main), Octave itself (scripts), C (wrapper code), Fortran (linear algebra wrapper code)
Operating system	Windows, macOS, Linux, BSD
Available in	18 languages
Type	Scientific computing
License	2007: GPL-3.0-or-later 1992: GPL-2.0-or-later

GNU Octave is a special computer program. It's like a powerful calculator and drawing tool for scientists and engineers. It helps them solve tricky math problems and do experiments using numbers.

Octave is great for working with science and numbers. It can solve problems that are straight (linear) or curvy (nonlinear) using math. It's also very similar to another popular program called MATLAB. Because it's part of the GNU Project, it's free software. This means anyone can use it, change it, and share it!

What is GNU Octave?

GNU Octave is a scientific programming language. This means you can write special instructions (code) for it to do complex math. It's designed to help people work with numbers and data.

Solving Math Problems

Octave is really good at solving math problems. It can handle things like:

Finding answers to equations.
Working with large sets of numbers, called matrices.
Creating graphs and charts from data.

It's often used in schools and businesses. People use it to understand information better.

Octave's Story

The idea for Octave started around 1988. It was first meant to help with a class about designing chemical reactors. A person named John W. Eaton began working on it fully in 1992.

First Steps

The very first test version came out on January 4, 1993. Then, the first official version, 1.0, was released on February 17, 1994.

Who is Octave Levenspiel?

The program is named after Octave Levenspiel. He was a professor who taught the main creator of Octave. Professor Levenspiel was known for being able to do quick math in his head. He could solve problems easily, even on the back of an envelope!

How Octave Grew

Over the years, Octave has been updated many times. Here are some important moments:

In 1992, the actual work on the program began.
By 1994, the first official version (1.0.0) was released.
In 2007, version 3.0 came out, which was a big step forward.
On May 29, 2015, version 4.0.0 was released. This version added a stable GUI, which made it much easier to use.
Newer versions, like Octave 9.1.0 in March 2024, keep improving its graphics and how well it works with MATLAB.

Where Octave is Used

Besides being used on personal computers, Octave is also used in big projects.

For example, it was used on a huge supercomputer to find weaknesses in guessing social security numbers. This shows how powerful it can be for complex tasks.
It can also use special computer parts called GPUs to speed up calculations. This is like using a super-fast graphics card to do math even quicker!

How Octave Works

Octave is built using a programming language called C++. It uses an interpreter to understand and run the commands you give it.

Key Features

Making Plots: Octave has a built-in graphics engine. This helps it create cool plots, graphs, and charts from your data. You can save or print these pictures.
User Interfaces: You can use Octave in two main ways:
- GUI (Graphical User Interface): This is a friendly window with buttons and menus, like most apps you use.
- CLI (Command-line interface): This is a text-based way to use Octave, where you type commands directly.

The Octave Language

The Octave language is a programming language that you can type commands into. It's a structured programming language, which means you write code in a clear, organized way. It's similar to the C language.

Working with Data

Octave is great for working with matrices. These are like big grids of numbers. It has many tools to do math with these grids.
It can also handle different kinds of data, like numbers, text, and lists.
You can even use object-oriented programming in Octave, which is a way to organize your code into reusable parts.

Like MATLAB

The way you write code in Octave is very similar to MATLAB. This means that if you write a program carefully, it can often run on both Octave and MATLAB!

Free and Flexible

Because Octave is free software, you can freely change it, copy it, and use it. It works on many different computer systems, including Microsoft Windows, Linux, Android, and macOS.

Cool Features of Octave

Finishing Your Words

When you are typing commands, Octave can help you finish words. If you press the TAB key, Octave will try to guess what you are typing. This helps you type faster and avoid mistakes.

Remembering Commands

Octave remembers the commands you type. If you want to use a command again, you can easily find it in the history and use it without typing it all over again.

Organizing Data

Octave lets you organize data into "structures." Imagine you have a box (the structure) and inside it, you can put different items (elements) like a number, a list of numbers, or some text.

octave:1> x.a = 1; x.b = [1, 2; 3, 4]; x.c = "string";
octave:2> x.a
ans =  1
octave:3> x.b
ans =

   1   2
   3   4

octave:4> x.c
ans = string
octave:5> x
x =

  scalar structure containing the fields:

    a = 1
    b =

       1   2
       3   4

    c = string

In this example, `x` is a structure. `x.a` holds a number, `x.b` holds a grid of numbers, and `x.c` holds text.

Smart Logic Operators

Octave has special logical operators like `&&` (and) and `||` (or). These are "short-circuit" operators. This means if the first part of the condition is enough to know the answer, Octave won't even check the second part. This can make your programs run a little faster.

Quick Math Shortcuts

Octave includes shortcuts for adding or subtracting one from a number (`++` and `--`). You can also use shortcuts to change a number by adding, subtracting, multiplying, or dividing it by another number (like `x += 5` which means `x = x + 5`).

Handling Errors Gracefully

Sometimes, a program might run into a problem or an "exception." Octave has ways to handle these errors so your program doesn't just crash. It can run a special "cleanup" part of the code even if an error happens. This helps make sure things are left tidy.

Flexible Function Inputs and Outputs

Octave functions can be very flexible. They can be set up to take a different number of inputs each time you use them. They can also return a different number of results. This is useful when you don't know exactly how many pieces of information a function will need or give back.

Working with MATLAB

Octave is designed to be very similar to MATLAB. This means if you know MATLAB, you'll find Octave easy to use.

Shared Features

Both Octave and MATLAB share many features:

They both treat matrices (grids of numbers) as a basic type of data.
They both understand complex numbers (numbers with a real and an imaginary part).
They have many powerful math tools built-in.
You can add your own custom functions to both.

Octave tries to be as compatible with MATLAB as possible. If something doesn't work the same way, it's usually seen as something that needs to be fixed!

Small Differences

While very similar, Octave has a few small differences:

You can use `#` or `%` to start a comment line.
It supports more shortcuts for math operations, like `++` or `+=`.
You can use `"` or `'` to define text (strings).
You can define functions right inside your scripts or when you are typing commands.

Functions Available

Many of the functions you find in MATLAB are also in Octave. Some are part of the main Octave program, and others are in special add-on packages called "Octave Forge." If a function isn't available, Octave will tell you.

How You Use Octave

Octave comes with an official GUI (a visual window with buttons). This GUI makes it much easier to use, especially for beginners. It became the main way to use Octave starting with version 4.0.

Other programs have also been made to help people use Octave, especially for learning how to code.

Making Your Own Apps

You can even use Octave code to create simple GUI applications! This means you can make windows with buttons, text boxes, and check boxes. Here are some examples of what you can create:

Buttons, text boxes, and checkboxes:

# create figure and panel on it
f = figure;
# create a button (default style)
b1 = uicontrol (f, "string", "A Button", "position",[10 10 150 40]);
# create an edit control
e1 = uicontrol (f, "style", "edit", "string", "editable text", "position",[10 60 300 40]);
# create a checkbox
c1 = uicontrol (f, "style", "checkbox", "string", "a checkbox", "position",[10 120 150 40]);

A text box for input:

prompt = {"Width", "Height", "Depth"};
defaults = {"1.10", "2.20", "3.30"};
rowscols = [1,10; 2,20; 3,30];
dims = inputdlg (prompt, "Enter Box Dimensions", rowscols, defaults);

A list box with messages:

my_options = {"An item", "another", "yet another"};
[sel, ok] = listdlg ("ListString", my_options, "SelectionMode", "Multiple");
if (ok == 1)
  msgbox ("You selected:");
  for i = 1:numel (sel)
    msgbox (sprintf ("\t%s", my_options{sel(i)}));
  endfor
else
  msgbox ("You cancelled.");
endif

Radio buttons:

# create figure and panel on it
f = figure;
# create a button group
gp = uibuttongroup (f, "Position", [ 0 0.5 1 1])
# create a buttons in the group
b1 = uicontrol (gp, "style", "radiobutton", "string", "Choice 1", "Position", [ 10 150 100 50 ]);
b2 = uicontrol (gp, "style", "radiobutton", "string", "Choice 2", "Position", [ 10 50 100 30 ]);
# create a button not in the group
b3 = uicontrol (f, "style", "radiobutton","string", "Not in the group","Position", [ 10 50 100 50 ]);

Extra Tools (Packages)

Octave also has many extra tools called "packages." These packages add more functions and abilities to Octave. You can find them on websites like Octave-Forge. Anyone can create and share their own packages too!

Other Similar Programs

Besides MATLAB, there are other free programs like Octave, such as Scilab and Julia. Octave is known for being very similar to MATLAB, which makes it a popular choice for many users.