GNU Octave is software featuring a high-level programming language, primarily intended for numerical computations. Octave helps in solving linear and nonlinear problems numerically, and for performing other numerical experiments using a language that is mostly compatible with Matlab. It may also be used as a batch-oriented language. Since it is part of the GNU Project, it is free software under the terms of the GNU General Public License.
Octave is one of the major free alternatives to Matlab, others being FreeMat and Scilab. Scilab, however, puts less emphasis on (bidirectional) syntactic compatibility with Matlab than Octave does.
Maps, Directions, and Place Reviews
History
The project was conceived around 1988. At first it was intended to be a companion to a chemical reactor design course. Real development was started by John W. Eaton in 1992. The first alpha release dates back to January 4, 1993 and on February 17, 1994 version 1.0 was released. Version 4.0.0 was released on May 29, 2015.
The program is named after Octave Levenspiel, a former professor of the principal author. Levenspiel is known for his ability to perform quick back-of-the-envelope calculations.
Mathworks Machine Learning Video
Developments
In addition to use on desktops for personal scientific computing, Octave is used in academia and industry. For example, Octave was used on a massive parallel computer at Pittsburgh supercomputing center to find vulnerabilities related to guessing social security numbers.
Dramatic acceleration with OpenCL or CUDA is also possible with use of GPUs.
Technical details
- Octave is written in C++ using the C++ standard library.
- Octave uses an interpreter to execute the Octave scripting language.
- Octave is extensible using dynamically loadable modules.
- Octave interpreter has an OpenGL-based graphics engine to create plots, graphs and charts and to save or print them. Alternatively, gnuplot can be used for the same purpose.
- Octave includes a Graphical User Interface (GUI) in addition to the traditional Command Line Interface (CLI); see #User interfaces for details.
Octave, the language
The Octave language is an interpreted programming language. It is a structured programming language (similar to C) and supports many common C standard library functions, and also certain UNIX system calls and functions. However, it does not support passing arguments by reference.
Octave programs consist of a list of function calls or a script. The syntax is matrix-based and provides various functions for matrix operations. It supports various data structures and allows object-oriented programming.
Its syntax is very similar to Matlab, and careful programming of a script will allow it to run on both Octave and Matlab.
Because Octave is made available under the GNU General Public License, it may be freely changed, copied and used. The program runs on Microsoft Windows and most Unix and Unix-like operating systems, including macOS.
Notable features
Command and variable name completion
Typing a TAB character on the command line causes Octave to attempt to complete variable, function, and file names (similar to Bash's tab completion). Octave uses the text before the cursor as the initial portion of the name to complete.
Command history
When running interactively, Octave saves the commands typed in an internal buffer so that they can be recalled and edited.
Data structures
Octave includes a limited amount of support for organizing data in structures. In this example, we see a structure "x" with elements "a", "b", and "c", (an integer, an array, and a string, respectively):
Short-circuit boolean operators
Octave's '&&' and '||' logical operators are evaluated in a short-circuit fashion (like the corresponding operators in the C language), in contrast to the element-by-element operators '&' and '|'.
Increment and decrement operators
Octave includes the C-like increment and decrement operators '++' and '--' in both their prefix and postfix forms. Octave also does augmented assignment, e.g. 'x += 5'.
Unwind-protect
Octave supports a limited form of exception handling modelled after the 'unwind_protect' of Lisp. The general form of an unwind_protect block looks like this:
As a general rule, GNU Octave recognizes as termination of a given 'block' either the keyword 'end' (which is compatible with the Matlab language) or a more specific keyword 'end_block'. As a consequence, an 'unwind_protect' block can be terminated either with the keyword 'end_unwind_protect' as in the example, or with the more portable keyword 'end'.
The cleanup part of the block is always executed. In case an exception is raised by the body part, cleanup is executed immediately before propagating the exception outside the block 'unwind_protect'.
GNU Octave also supports another form of exception handling (compatible with the Matlab language):
This latter form differs from an 'unwind_protect' block in two ways. First, exception_handling is only executed when an exception is raised by body. Second, after the execution of exception_handling the exception is not propagated outside the block (unless a 'rethrow( lasterror )' statement is explicitly inserted within the exception_handling code).
Variable-length argument lists
Octave has a mechanism for handling functions that take an unspecified number of arguments without explicit upper limit. To specify a list of zero or more arguments, use the special argument varargin as the last (or only) argument in the list.
Variable-length return lists
A function can be set up to return any number of values by using the special return value varargout. For example:
C++ integration
It is also possible to execute Octave code directly in a C++ program. For example, here is a code snippet for calling rand([10,1]):
C and C++ code can be integrated into GNU Octave by creating oct files, or using the Matlab compatible MEX files.
Matlab compatibility
Octave has been built with Matlab compatibility in mind, and shares many features with Matlab:
- Matrices as fundamental data type.
- Built-in support for complex numbers.
- Powerful built-in math functions and extensive function libraries.
- Extensibility in the form of user-defined functions.
Octave supposedly treats incompatibility with Matlab as a bug; therefore, it could be considered a software clone, which does not infringe software copyright as per Lotus v. Borland court case.
Matlab scripts from the MathWorks' FileExchange repository are compatible with Octave, but can't be used legally due to the Terms of use. While often provided and uploaded by users under an Octave compatible and proper Open source BSD license, the fileexchange's Terms of use prohibit any usage beside MathWorks proprietary Matlab.
Syntax compatibility
There are a few purposeful, albeit minor, syntax additions:
- Comment lines can be prefixed with the # character as well as the % character;
- Various C-based operators ++, --, +=, *=, /= are supported;
- Elements can be referenced without creating a new variable by cascaded indexing, e.g. [1:10](3);
- Strings can be defined with the " character as well as the ' character;
- When the variable type is single, Octave calculates the "mean" in the single-domain (Matlab in double-domain) which is faster but gives less accurate results;
- Blocks can also be terminated with more specific Control structure keywords, i.e., endif, endfor, endwhile, etc.;
- Functions can be defined within scripts and at the Octave prompt;
- All operators perform automatic broadcasting or singleton expansion.
- Presence of a do-until loop (similar to do-while in C).
Function compatibility
Many of the numerous Matlab functions are available in GNU Octave, some of them are accessible through packages via Octave-forge, but not all Matlab functions are available in GNU Octave. List of unavailable functions exists in Octave, and developers are seeking for help to implement them. Looking for function __unimplemented.m__, leads to the list of unimplemented functions.
Unimplemented functions are also categorized in Image, Mapping, Optimization, Signal, and Statistics packages.
When an unimplemented function is called the following error message is shown:
User interfaces
Octave comes with an official graphical user interface (GUI) and a integrated development environment (IDE) based on Qt. It is available since Octave 3.8, and has become the default interface (over the command line interface) with the release of Octave 4.0. Several 3rd-party graphical front-ends have been developed. It was well received: "[Octave] now has a very workable GUI."
GUI applications
WIth Octave code, the user can create GUI applications [1]. Here is some examples.
Button, edit control, checkbox
Textbox
Listbox with message boxes.
Radiobuttons
Packages
Octave have also packages available for free. Those packages are located at Octave-Forge [2]. Available packages are:
- bim - Package for solving Diffusion Advection Reaction (DAR) Partial Differential Equations
- bsltl - The BSLTL package is a free collection of OCTAVE/MATLAB routines for working with the biospeckle laser technique
- cgi - Common Gateway Interface for Octave
- communications - Digital Communications, Error Correcting Codes (Channel Code), Source Code functions, Modulation and Galois Fields
- control - Computer-Aided Control System Design (CACSD) Tools for GNU Octave, based on the proven SLICOT Library
- data-smoothing - Algorithms for smoothing noisy data
- database - Interface to SQL databases, currently only postgresql using libpq
- dataframe - Data manipulation toolbox similar to R data
- dicom - Digital communications in medicine (DICOM) file io
- divand - divand performs an n-dimensional variational analysis (interpolation) of arbitrarily located observations
- doctest - The Octave-Forge Doctest package finds specially-formatted blocks of example code within documentation files
- econometrics - Econometrics functions including MLE and GMM based techniques
- fem-fenics - pkg for the resolution of partial differential equations based on fenics
- financial - Monte Carlo simulation, options pricing routines, financial manipulation, plotting functions and additional date manipulation tools
- fits - The Octave-FITS package provides functions for reading, and writing FITS (Flexible Image Transport System) files
- fpl - Collection of routines to export data produced by Finite Elements or Finite Volume Simulations in formats used by some visualization programs
- fuzzy-logic toolkit - A mostly MATLAB-compatible fuzzy logic toolkit for Octave
- ga - Genetic optimization code
- general - General tools for Octave
- generate_html - This package provides functions for generating HTML pages that contain the help texts for a set of functions
- geometry - Library for geometric computing extending MatGeom functions
- gsl - Octave bindings to the GNU Scientific Library
- image - The Octave-forge Image package provides functions for processing images
- image-acquisition - The Octave-forge Image Acquisition package provides functions to capture images from connected devices
- instrument-control - Low level I/O functions for serial, i2c, parallel, tcp, gpib, vxi11, udp and usbtmc interfaces
- interval - The interval package for real-valued interval arithmetic allows one to evaluate functions over subsets of their domain
- io - Input/Output in external formats e.g Excel
- level-set - Routines for calculating the time-evolution of the level-set equation and extracting geometric information from the level-set function
- linear-algebra - Additional linear algebra code, including general SVD and matrix functions
- lssa - A package implementing tools to compute spectral decompositions of irregularly-spaced time series
- ltfat - The Large Time/Frequency Analysis Toolbox (LTFAT) is a Matlab/Octave toolbox for working with time-frequency analysis, wavelets and signal processing
- mapping - Simple mapping and GIS .shp and raster file functions
- miscellaneous - Miscellaneous tools that don't fit somewhere else
- mpi - Octave bindings for basic Message Passing Interface (MPI) functions for parallel computing
- msh - Create and manage triangular and tetrahedral meshes for Finite Element or Finite Volume PDE solvers
- mvn - Multivariate normal distribution clustering and utility functions
- nan - A statistics and machine learning toolbox for data with and w/o missing values
- ncarray - Access a single or a collection of NetCDF files as a multi-dimensional array
- netcdf - A MATLAB compatible NetCDF interface for Octave
- nurbs - Collection of routines for the creation, and manipulation of Non-Uniform Rational B-Splines (NURBS), based on the NURBS toolbox by Mark Spink
- ocs - Package for solving DC and transient electrical circuit equations
- octclip - This package allows to do boolean operations with polygons using the Greiner-Hormann algorithm
- octproj - This package allows to call functions of PROJ
- optics - Functions covering various aspects of optics
- optim - Non-linear optimization toolkit
- optiminterp - An optimal interpolation toolbox for octave
- parallel - Parallel execution package
- quaternion - Quaternion package for GNU Octave, includes a quaternion class with overloaded operators
- queueing - The queueing package provides functions for queueing networks and Markov chains analysis
- secs1d - A Drift-Diffusion simulator for 1d semiconductor devices
- secs2d - A Drift-Diffusion simulator for 2d semiconductor devices
- secs3d - A Drift-Diffusion simulator for 3d semiconductor devices
- signal - Signal processing tools, including filtering, windowing and display functions
- sockets - Socket functions for networking from within octave
- sparsersb - Interface to the librsb package implementing the RSB sparse matrix format for fast shared-memory sparse matrix computations
- splines - Additional spline functions
- statistics - Additional statistics functions for Octave
- stk - The STK is a (not so) Small Toolbox for Kriging
- strings - Additional functions for manipulation and analysis of strings
- struct - Additional structure manipulation functions
- symbolic - The Octave-Forge Symbolic package adds symbolic calculation features to GNU Octave
- tisean - Port of TISEAN 3
- tsa - Stochastic concepts and maximum entropy methods for time series analysis
- vibes - The VIBes API allows one to easily display results (boxes, pavings) from interval methods
- video - A wrapper for ffmpeg's libavformat and libavcodec, implementing addframe, avifile, aviinfo and aviread
- vrml - 3D graphics using VRML
- windows - Provides COM interface and additional functionality on Windows
- zeromq - ZeroMQ bindings for GNU Octave
Source of the article : Wikipedia
EmoticonEmoticon