GNU Octave Version 9

Summary of important user-visible changes

March 14, 2024

News for version  9   8   7   6   5   4.4   4.2   4   3.8   3.6   3.4   3.2   3   2   1   (Release History)

General improvements

  • dec2base, dec2bin, and dec2hex have all been overhauled. All three functions now accommodate negative inputs and fractional inputs, and repeated code between the functions has been reduced or eliminated. Previously only dec2bin and dec2hex accepted negative inputs but dec2base did not, and none of the three accepted fractional inputs. Now, dec2base (100*pi, 16, 4, 6), for example, returns a base-16 string with four places for the integer part and six places for the fractional part. Omitting the number of decimal places (the fourth input) retains old behavior for backward compatibility, except that non-integer inputs will no longer produce errors.

  • quiver and quiver3 now properly plot non-float numeric inputs by internally casting them to ‘double’ (bug #59695). Both functions now honor a previously ignored scaling factor input when there is only a single arrow (bug #39552), and quiver3 no longer produces an error when a scaling factor is given without x and y inputs. Both functions now also accept a scale factor of “off” which is equivalent to setting it to 0. When a linestyle with a base marker is set suppressing arrowhead display, subsequent name-value property pairs in the quiver/quiver3 function call will no longer turn arrowhead display back on (bug #64143). The linewidth property now also affects the line width of the base marker.

  • Classdef files now support breakpoints inside them.

  • The inputParser function has been re-architected for a 60% performance improvement.

  • The perms function has been made faster.

  • The audiowrite function now supports writing to MPEG audio formats—including MP3—if the sndfile library supports it.

  • oruntests: The current directory now changes to the directory containing the files with the tests for the duration of the test. This aligns the behavior of this function with Octave’s test suite. This also means that the file encoding specified in the .oct-config file for the respective directory is taken into account for the tests.

Graphical User Interface

  • The Graphical User Interface (GUI) of Octave is now compatible with Qt6. Qt6 is selected by default if the necessary Qt modules are detected and the used compiler is compatible. Support for building with Qt5 is still available but might be removed in a future version of Octave. Qt5 is used if configuring with --with-qt=5 or as a fallback if Qt6 cannot be used.

Graphics backend

  • The FLTK backend is not maintained and its use is discouraged. The recommended backend is qt. Enabling the fltk backend with graphics_toolkit fltk now emits a warning.

  • The set function now accepts any combination of name/value pairs, cell array of names / cell array of values, or property structures. This change is Matlab compatible.

  • When the hold function is used without arguments to toggle the current state, the resulting value is now displayed in the Command Window for informational purposes.

  • The axes graphics property "TickDir" now accepts the option "none", which will not draw tick marks but will still draw tick labels.

  • Stricter checks are performed for valid dimensions of the color data properties "CData" and "FaceVertexCData" when rendering patch objects.

Matlab compatibility

  • The inputParser function now implements the PartialMatching property for Parameter and Switch names. For Matlab compatibility, PartialMatching is now set to true by default which may change the behavior of existing code.

  • Overhauled mean, median, var, and std functions have been imported from statistics package v1.5.4 to compatibly implement ‘nanflag’ (bug #50571), ‘all’ (bug #58116), and ‘vecdim’ (bug #58089) options, preserve output class, and match expected output behavior for empty (bug #50583) and sparse inputs (bug #63291). Both median and mean can handle large integer values without overflow or precision concerns (bug #54567), and mean avoids errors due to limits of single precision by processing as doubles (bug #63848). median has also adopted the ‘outtype’ option from mean.

  • Code such as A = ones (3, 3); A(:, :, 1) = [] is now Matlab compatible.

  • mad function now produces Matlab compatible output using improved mean and median functions. ‘vecdim’ and ‘all’ options are now supported. mad ignores all NaN values (using ‘omitnan’ mean/median option) and produces expected output behavior for empty inputs.

  • mode now produces Matlab compatible output for empty inputs (bug #50583).

  • linspace and logspace now handle Inf inputs in a Matlab compatible way.

  • normalize now produces Matlab compatible output for inputs containing NaN values (bug #50571).

  • cov now processes the input form cov(x,y) with two separate data arrays x and y, as cov(x(:),y(:)) to maintain Matlab compatibility. It also accepts a NANFLAG option to allow ignoring NaN entries in input data (bug #c) and produces Matlab compatible outputs for empty inputs (bug #50583). corr and corrcoef internal code has been adapted to the new cov behavior with no change to user interface. Packages using the octave core’s cov that rely on the previous calling form may need to make similar adaptations. Calls for cov(x) with a vector x expecting a scalar return can get the previous results from cov(x)(2), and calls to cov(x,y) with x and y matrices expecting columnwise covariance calculation can obtain the previous results using cov([x,y])(1:nx, nx+1:end), where nx = columns(x).

  • qz now handles input and output arguments in a Matlab compatible way. It always computes the complex QZ decomposition if there are only two input arguments, and it accepts an optional third input argument ‘real’ or ‘complex’ to select the type of decomposition. The output arguments are always in the same order independently of the input arguments, and the generalized eigenvalues are no longer returned (one can use the ordeig function for that purpose). The optional reordering of the generalized eigenvalues has been removed (one can use the ordqz function for that purpose).

  • pcolor now sets the axes limits to be just large enough to display the plotted data (equivalent of axis tight).

  • xlim, ylim, zlim functions can now query or set the limit calculation method which is one of “tickaligned”, “tight”, or “padded”.

  • optimget and optimset now produce an error on an ambiguous match of an incomplete option name instead of emitting a warning.

  • datevec when provided a date format will match date string characters up to the length of the format string. A date vector will be returned as long as the characters up to the format string length are a perfect match, and any trailing characters in the date string will be ignored. (bug #42241)

  • unwrap now produces compatible output for inputs with non-finite elements (Inf, NaN, NA). Such elements will now retained in the output but skipped over by the wrapping calculation. The function also permits logical inputs and specified operating dimensions larger than the number of dimensions in the input array.

  • The default string length for the function rats has changed from 9 to 13.

  • Continuing reminder of future breaking changes: There is ongoing work to implement a Matlab compatible string class that will differ from a vector of characters. In Octave, single-quoted character arrays are currently compatible with Matlab, but double-quoted forms are not, and are likely to change in future as a consequence of implementing Matlab-style string syntax. For example, ‘foo’ will remain a three-element character vector, but “foo” will become a single-element string object.

    What this means for user code: If your code currently relies on double-quoted strings (e.g., “foo”) representing character vectors as opposed to string objects, then start replacing all double-quoted strings with single-quoted strings in your code over time (e.g., replace “foo” with ‘foo’). Single-quoted strings will retain their current behavior. Further, if your code relies on backslash escape sequence interpretation in double-quoted strings (except in special cases like the printf family), that code may need to change as well.

Alphabetical list of new functions added in Octave 9

  • isenv
  • ismembertol
  • isuniform
  • tensorprod

Deprecated functions, properties, and operators

The following functions and properties have been deprecated in Octave 9 and will be removed from Octave 11 (or whatever version is the second major release after 9):

  • Core

    • The idx_vector::bool() function is obsolete and always returns true. Any uses can simply be removed from existing code with no loss of function.

    • The all_ok(const Array<octave::idx_vector>&) function in Array-util.h is obsolete and always returns true. Any uses can simply be removed from existing code with no loss of function.

    • The member variable octave_base_value::count is deprecated and will be removed from Octave 11. Replace all instances with the new name m_count.

The following features were deprecated in Octave 7 and have been removed from Octave 9.

  • Functions

      Function                   | Replacement
      disable_diagonal_matrix    | optimize_diagonal_matrix
      disable_permutation_matrix | optimize_permutation_matrix
      disable_range              | optimize_range
  • Operators

      Operator | Replacement
      .+       | +
      .+=      | +=
      .-       | -
      .-=      | -=
      **       | ^
      **=      | ^=
      .**      | .^
      .**=     | .^=
  • Interpreter

    • The use of '...' for line continuations inside double-quoted strings has been removed. Use '\' for line continuations inside strings instead.

    • The use of '\' as a line continuation outside of double-quoted strings has been removed. Use '...' for line continuations instead.

    • Support for trailing whitespace after a '\' line continuation has been removed. Delete unnecessary trailing whitespace.

  • For plot functions, the use of numbers to select line colors in shorthand formats was an undocumented feature that was removed in Octave 9.

  • The environment variable used by mkoctfile for linker flags is now LDFLAGS rather than LFLAGS. LFLAGS was deprecated in Octave 6 and has been removed.

Summary of bugs fixed for version 9.1.0:

  • Bugfixes to whos -file, urlread, mat2cell, set, savepath, loadpath, griddata, and the general interpreter stack-handling.

  • Better input validation for sparse, speye.

  • Memory usage reduced for movfun and movslice.

  • Memory usage reduced when saving to file, preventing OOM and data loss.

  • Memory usage improved when plotting grid tick marks.

  • Memory management made more robust in the GUI code and with several GUI components (variable editor, doc browser, etc).

  • Text encoding for non-UTF-8 generally made more robust. File editor now lists available encodings.

  • Octave on Windows now supports directory names and path names with non-ASCII characters (other platforms had it already for years). Windows paths now also allow relative paths on different drives.

  • Several race conditions removed in signal handler.

  • Better compatibility when linking to libc++.

  • Performance and stability improvements: avoid unnecessary string construction, use static casts instead of dynamic casts where possible, eliminate various isolated crash conditions.