GNU Octave Version 6

Summary of important user-visible changes

November 26, 2020

News for version  8   7   6   5   4.4   4.2   4   3.8   3.6   3.4   3.2   3   2   1   (Release History)

General improvements

  • The intersect, setdiff, setxor, union, and unique functions accept a new sorting option "stable" which will return output values in the same order as the input, rather than in ascending order.

  • Complex RESTful web services can now be accessed by the webread and webwrite functions alongside with the weboptions structure. One major feature is the support for cookies to enable RESTful communication with the web service.

    Additionally, the system web browser can be opened by the web function.

  • The linspace function now produces symmetrical sequences when the endpoints are symmetric. This is more intuitive and also compatible with recent changes made in Matlab R2019b.

  • The underlying algorithm of the rand function has been changed. For single precision outputs, the algorithm has been fixed so that it produces values strictly in the range (0, 1). Previously, it could occasionally generate the right endpoint value of 1 (See bug #41742). In addition, the new implementation uses a uniform interval between floating point values in the range (0, 1) rather than targeting a uniform density (# of random integers / length along real number line).

  • Numerical integration has been improved. The quadv function has been re-written so that it can compute integrands of periodic functions. At the same time, performance is better with ~3.5X fewer function evaluations required. A bug in quadgk that caused complex path integrals specified with "Waypoints" to occasionally be calculated in the opposite direction was fixed.

  • The edit function option "editinplace" now defaults to true and the option "home" now defaults to the empty matrix []. Files will no longer be copied to the user’s HOME directory for editing. The old behavior can be restored by setting "editinplace" to false and "home" to "~/octave".

  • The format command supports two new options: uppercase and lowercase (default). With the default, print a lowercase ‘e’ for the exponent character in scientific notation and lowercase ‘a-f’ for the hex digits representing 10-15. With uppercase, print ‘E’ and ‘A-F’ instead. The previous uppercase formats, E and G, no longer control the case of the output.

    Additionally, the format command can be called with multiple options for controlling the format, spacing, and case in arbitrary order. For example:

      format long e uppercase loose

    Note, in the case of multiple competing format options the rightmost one is used, and, in case of an error, the previous format remains unchanged.

  • L-value references (e.g., increment (++), decrement (–), and all in-place assignment operators (+=, -=, *=, /=, etc.)) are no longer allowed in anonymous functions.

  • New warnings have been added about questionable uses of the colon ‘:’ range operator. Each has a new warning ID so that it can be disabled if desired.

    • Octave:colon-complex-argument : when any arg is complex
    • Octave:colon-nonscalar-argument : when any arg is non-scalar


  • The regexp and related functions now correctly handle and require strings in UTF-8 encoding. As with any other function that requires strings to be encoded in Octave’s native encoding, you can use native2unicode to convert from your preferred locale. For example, the copyright symbol in UTF-8 is native2unicode (169, "latin1").

  • The startup file octaverc can now be located in the platform dependent location for user local configuration files (e.g., ${XDG_CONFIG_HOME}/octave/octaverc on Unix-like operating systems or %APPDATA%\octave\octaverc on Windows).

  • The command

    dbstop in CLASS at METHOD

    now works to set breakpoints in classdef constructors and methods.

Graphics backend

  • The use of Qt4 for graphics and the GUI is deprecated in Octave version 6 and no further bug fixes will be made. Qt4 support will be removed completely in Octave version 7.

  • The legend function has been entirely rewritten. This fixes a number of historical bugs, and also implements new properties such as "AutoUpdate" and "NumColumns". The gnuplot toolkit—which is no longer actively maintained—still uses the old legend function.

  • The axis function was updated which resolved 10 bugs affecting axes to which "equal" had been applied.

  • Graphic primitives now accept a color property value of "none" which is useful when a particular primitive needs to be hidden (for example, the Y-axis of an axes object with "ycolor" = "none") without hiding the entire primitive "visibility" = "off".

  • A new property "FontSmoothing" has been added to text and axes objects that controls whether anti-aliasing is used during the rendering of characters. The default is "on" which produces smooth, more visually appealing text.

  • The figure property "windowscrollwheelfcn"is now implemented. This makes it possible to provide a callback function to be executed when users manipulate the mouse wheel on a given figure.

  • The figure properties "pointer", "pointershapecdata", and "pointershapehotspot" are now implemented. This makes it possible to change the shape of the cursor (pointer in Matlab-speak) displayed in a plot window.

  • The figure property "paperpositionmode" now has the default "auto" rather than "manual". This change is more intuitive and is Matlab compatible.

  • The appearance of patterned lines "LineStyle" = ":"|"--"|"-." has been improved for small widths ("LineWidth" less than 1.5 pixels) which is a common scenario.

  • Printing to EPS files now uses a tight bounding box ("-tight" argument to print) by default. This makes more sense for EPS files which are normally embedded within other documents, and is Matlab compatible. If necessary use the "-loose" option to reproduce figures as they appeared in previous versions of Octave.

  • The following print devices are no longer officially supported: cdr, corel, aifm, ill, cgm, hpgl, mf and dxf. A warning will be thrown when using those devices, and the code for supporting those formats will eventually be removed from a future version of Octave.

  • The placement of text subscripts and superscripts has been re-engineered and now produces visually attractive results similar to Latex.


  • pkg describe now lists dependencies and inverse dependencies (i.e., other installed packages that depend on the package in question).

  • pkg test now tests all functions in a package.

  • When unloading a package, pkg now checks if any remaining loaded packages depend on the one to be removed. If this is the case pkg aborts with an explanatory error message. This behavior can be overridden with the -nodeps option.

Matlab compatibility

  • The function unique now returns column index vectors for the second and third outputs. When duplicate values are present, the default index to return is now the "first" occurrence. The previous Octave behavior, or Matlab behavior from releases prior to R2012b, can be obtained by using the "legacy" flag.

  • The function setdiff with the "rows" argument now returns Matlab compatible results. The previous Octave behavior, or Matlab behavior from releases prior to R2012b, can be obtained by using the "legacy" flag.

  • The functions intersect, setxor, and union now accept a "legacy" flag which changes the index values (second and third outputs) as well as the orientation of all outputs to match Matlab releases prior to R2012b.

  • The function streamtube is Matlab compatible and plots tubes along streamlines which are scaled by the vector field divergence. The Octave-only extension ostreamtube can be used to visualize the flow expansion and contraction of the vector field due to the local crossflow divergence.

  • The interpreter now supports handles to nested functions.

  • The graphics properties "LineWidth" and "MarkerSize" are now measured in points, not pixels. Compared to previous versions of Octave, some lines and markers will appear 4/3 larger.

  • The meta.class property “SuperClassList” has been renamed “Superclasslist” for Matlab compatibility. The original name will exist as an alias until Octave version 8.1.

  • Inline functions created by the function inline are now of type “inline” when interrogated with the class function. In previous versions of Octave, the class returned was “function_handle”. This change is Matlab compatible. Inline functions are deprecated in both Matlab and Octave and support may eventually be removed. Anonymous functions can be used to replace all instances of inline functions.

  • The function javaaddpath now prepends new directories to the existing dynamic classpath by default. To append them instead, use the new "-end" argument. Multiple directories may now be specified in a cell array of strings.

  • An undocumented function gui_mainfcn has been added, for compatibility with figures created with Matlab’s GUIDE.

  • Several validator functions of type mustBe* have been added. See the list of new functions below.

Deprecated functions and properties

The following functions and properties have been deprecated in Octave 6 and will be removed from Octave 8 (or whatever version is the second major release after 6):

  • Functions

    Function Replacement
    runtests oruntests
  • The environment variable used by mkoctfile for linker flags is now LDFLAGS rather than LFLAGS. LFLAGS is deprecated, and a warning is emitted if it is used, but it will continue to work.

Removed functions and properties

The following functions and properties were deprecated in Octave 4.4 and have been removed from Octave 6.

  • Functions

    Function Replacement
    chop sprintf for visual results
    desktop isguirunning
    tmpnam tempname
    toascii double
    java2mat __java2mat__
  • Properties

    Object Property Value
    annotation edgecolor ("rectangle")  
    axes drawmode  
    figure doublebuffer  
    line interpreter  
    patch interpreter  
    surface interpreter  
    text fontweight "demi" and "light"
    uibuttongroup fontweight "demi" and "light"
    uicontrol fontweight "demi" and "light"
    uipanel fontweight "demi" and "light"
    uitable fontweight "demi" and "light"

Alphabetical list of new functions added in Octave 6

  • auto_repeat_debug_command
  • commandhistory
  • commandwindow
  • filebrowser
  • is_same_file
  • lightangle
  • mustBeFinite
  • mustBeGreaterThan
  • mustBeGreaterThanOrEqual
  • mustBeInteger
  • mustBeLessThan
  • mustBeLessThanOrEqual
  • mustBeMember
  • mustBeNegative
  • mustBeNonempty
  • mustBeNonNan
  • mustBeNonnegative
  • mustBeNonpositive
  • mustBeNonsparse
  • mustBeNonzero
  • mustBeNumeric
  • mustBeNumericOrLogical
  • mustBePositive
  • mustBeReal
  • namedargs2cell
  • newline
  • ode23s
  • ostreamtube
  • rescale
  • rotx
  • roty
  • rotz
  • stream2
  • stream3
  • streamline
  • streamtube
  • uisetfont
  • verLessThan
  • web
  • weboptions
  • webread
  • webwrite
  • workspace