Octave

From the official website:

GNU Octave is a high-level interpreted language, primarily intended for numerical computations. It provides capabilities for the numerical solution of linear and nonlinear problems, and for performing other numerical experiments. It also provides extensive graphics capabilities for data visualization and manipulation. Octave is normally used through its interactive command line interface, but it can also be used to write non-interactive programs. The Octave language is quite similar to Matlab so that most programs are easily portable.

Installation

Install the octave package.

Run the GUI with octave --gui or the CLI with octave-cli.

Alternative graphical interfaces

The default octave GUI is included in the octave package. Alternatively, you can use one of the following unofficial GUIs:

Performance

Octave uses the blas package for linear algebra computation by default. However, this implementation does not take advantage of modern CPU instructions. To accelerate performance, the package can be installed as a drop-in replacement for blas. Other BLAS implementations can also be used depending on available hardware, such as for Intel CPUs or for NVIDIA GPUs.

To illustrate this point, the following code can be used to get an estimate for how many GFLOPS are being executed on an NxN matrix multiply:

N = 4096;
A = single(rand(N, N));
B = single(rand(N, N));
start = clock();
C = A * B;
elapsedTime = etime(clock(), start);
gFlops = 2 * N * N * N / (elapsedTime * 1e9)

Running the following code on an Intel Core i7-9750H:

After installing openblas and running the program on a single thread:

OMP_NUM_THREADS=1 octave ~/test_program.m

gFlops = 121.55

After letting openblas use all 12 threads available on the 9750H:

Octave-Forge

Octave provides a set of packages, similar to Matlab's Toolboxes, through Octave-Forge. The complete list of packages is here.

Packages can be installed #Using Octave's installer or #Using the AUR.

Using Octave's installer

Packages can be managed using Octave's installer. They are installed to ~/octave, or in a system directory with the -global option. To install a package:

octave:1> pkg install -forge packagename

To uninstall a package:

octave:3> pkg uninstall packagename

Some packages get loaded automatically by Octave, for those which do not:

octave:4> pkg load packagename

Loading all packages is discouraged, as it may affect performance and create name conflicts. If you however wish to load all packages, you can issue:

octave:5> cellfun (@(x) pkg ("load", x.name), pkg ("list"));

To see which packages have been loaded use pkg list, the packages with an asterisk are the ones that are already loaded.

A way to make sure that all packages gets loaded at Octave startup:

Using the AUR

Some packages may be found in the AUR (search packages). New Octave-forge packages for Arch can be created semi-automatically using the Octave-forge helper scripts for Arch Linux.

Plotting

Qt is the default plotting backend:

>> available_graphics_toolkits
ans =
{
  [1,1] = fltk
  [1,2] = qt
}
>> graphics_toolkit
ans = qt

Alternatively you can use either FLTK or Gnuplot backend (by installing ) and running the following command:

>> graphics_toolkit("gnuplot");

To make this change permanent add it to your file.

Reading Microsoft Excel Spreadsheets

You can open , and files with the or xlsread function, which requires the package:

octave:1> odsread('myfile.ods');
octave:1> xlsread('myfile.xls');
octave:1> xlsread('myfile.xlsx');

Converting to CSV format

Alternatively, first convert the files to using LibreOffice Calc (limited to 1024 columns) or Calligra Sheets (, limited to 32768 columns).

After the conversion is complete you can use the build-in Octave function csvread for files:

octave:1> csvread('myfile.csv');

Troubleshooting

Zsh Undecodable Token

If you get error

undecodable token: b(hex)[23m

when printing, install and relogin.

vi Mode Undecodable Token

Users with their configured for vi-mode, for example, as may have the Octave GUI prompt corrupted as . To remedy this, disable the setting for Octave, by changing the above to be

gollark: Please use the word objective appropriately or else.

gollark: Just because you have a vague probably made up on the spot criterion doesn't make judgements made using it objectively true.

gollark: And what makes this an objective fact?

gollark: You have an objective humour measurement? Do tell.

gollark: Most memes seem to use about the same set.