Gnuplot Version 6.0 Release Notes

Version 6.0 is the start of a new stable release series. Work on gnuplot 6 has proceeded in parallel with the incremental updates to version 5.4 over the past three years. The new version introduces extensions to the gnuplot command language, support for new output protocols, and additional plotting styles. Backward compatibility is given high priority in gnuplot development, so users should find no significant changes required for techniques or code they are currently using with gnuplot 5.

Gnuplot development is tracked in a git repository on SourceForge. You can generate a complete history of changes using "git log" after downloading:

    git clone -b branch-6-0-stable git://git.code.sf.net/p/gnuplot/gnuplot-main
    git log

Release Notes date: 08-Dec-2023

Features introduced in version 6

For a detailed list of new features, with illustrations, see http://gnuplot.info/docs_6.0/NewFeatures.html

For more example plots see
http://gnuplot.info/demo_6.0/

• Function blocks and scoped variables
• Larger collection of special and complex-valued functions
• New plot styles
  • 2D plot style `with surface` works in 2D polar coordinates to produce a solid-fill gridded representation of the plane. This is analogous to the use of dgrid3d and pm3d to produce a 3D gridded surface.
  • 2D plot style `with sectors` renders one annular segment ("sector") for each line of input data. This style can generate pie and donut charts, windrose charts, and a polar equivalent to sparse-matrix heatmaps.
  • 2D plot style `with lines` now has a filter option `sharpen`. This filter detects spikes in a function plot that would be missed or under-represented due to coarse sampling. It adds an additional sampling point at the location of each such peak.
  • 3D plot style `with contourfill` produces 2D or 3D surfaces with distinct z-ranges indicated by solid color fill.
• Hulls, masks, and smoothing
  • A cluster of 2D points can be replaced by a bounding polygon ("hull"). Both convex hulls and concave hulls (χ-shapes) are supported.
  • Any hull or other closed path can be used as a mask to display only selected regions of a pm3d surface or image plot.
  • New smoothing option "smooth path" can be used on 2D and 3D curves that are not monotonic on x or y. This allows smoothing of hulls.
• Named palettes
  • The current palette can be saved to a named colormap for future us.
  • A predefined palette named "viridis" is provided.
  • Plots can specify a previously saved palette by name. This permits the use of multiple palettes in a single plot command.
  • Named palettes can be edited to contain an alpha channel.
• New built-in functions and array operations
  • palette(z) returns the current RGB palette color mapping for z.
  • rgbcolor("name") returns the 32bit ARGB value for a named color.
  • index(Array, element) returns the first index i for which Array[i] is equal to element.
  • split("string", "separator") unpacks the fields in a string into an array of strings.
  • join(array, "separator") is the complement to split(). It concatenates the elements of a string array into a single string.
  • `stats <non-existent file>` yields a testable value with no error; useful to avoid errors or warnings in scripts.
• Program control flow
  • New syntax if {...} else if {...} else {...}
  • XDG base directory conventions for configuration files are supported.
  • `unset warnings` suppresses output of warning messages to the console.
  • The `fit` command is protected by exception handling. Control always returns to the next line of input even in the case of fit errors. On return FIT_ERROR is non-zero if an error occurred.
  • "Watchpoints" are target values associated with individual plots in a graph. As that plot is drawn, each component line segment is monitored to see if its endpoints bracket the target value of a watchpoint coordinate (x, y, or z) or function f(x,y). If a match is found, the [x,y] coordinates of the match point are saved for later use. Possible uses include
    • find the intersection points of two curves
    • find zeros of a function
    • find and notate where a dependent variable or function f(x,y) crosses a threshold value
    • use the mouse to track values along multiple plots simultaneously
• New terminals and terminal options
  • Terminals that display graphics in the same window as text entry now support pseudo-mousing; i.e. they respond to arrow keys and other hot-key bindings during "pause mouse".
  • New terminals kittygd and kittycairo provide in-window graphics for terminal emulators that support the kitty protocol.
  • New terminal webp generates a single frame or an animation sequence using webp encoding. Frames are generated using pngcairo, then encoded through the WebPAnimEncoder API.
  • New terminal block for text-mode pseudo-graphics uses Unicode block or Braille characters to offer improved resolution compared to the dumb or caca terminals.
  • latex terminals standalone mode updated to work with texlive2023
• Miscellaneous other new features
  • Multiplots can now be saved, replotted, and resized interactively. This is a change from all previous gnuplot versions, where only the most recent component of a multiplot could be replotted.
  • Time unit settings for major and minor axis tics. For example, minor tic marks can be placed at exactly one month intervals.
  • The character sequence $# in a using specifier evaluates to the total number of columns available in the current line of data. "plot FOO using 0:(column($# - 1))" plots the last-but-one field of each row.
  • keyword binvalue=avg plots the average, rather than the sum, of binned data.
  • "set colorbox bottom" places the color box underneath the plot.
  • "set pm3d spotlight" adds a user-controlled spotlight to the lighting model.
  • New key layout options to force specific width or number of columns. Automatic positioning of the key on the page can be manually tweaked by giving an offset.
  • "set isotropic" adjusts the axis scaling in both 2D and 3D plots such that x, y, and z axes all have the same scale.
  • Text rotation angles are not limited to integral degree values.
  • Data-driven color assignments in plot style "histograms".

Changes between 6.0 -rc1 and -rc2

• New plot style "with contourfill" generates 2D and 3D contour plots with solid fill areas rather than lines.
• Support building against Qt6
  • ./configure falls back to Qt5 if the Qt6 libraries are not found
• Japanese documentation updated
  • added missing file title-ja.tex, build dependencies for mingw
• New configure option --enable-stable-sort
  • Use mergesort rather than qsort if the system provides it.
  • If neither mergesort nor glibc stable qsort is available, modify internal gnuplot structures to contain a secondary sort key
• Render color gradient in colorbox as a pixel array
  • cairo, qt terminals
• "reset session" restores initial state of all linetype properties
  • previously only the colors were restored
  • now it also reinitializes linewidth, point and dash properties
• postscript terminal now handles pixmaps
• svg terminal now correctly tracks pattern-fill color

Changes between 6.0-rc2 and -rc3

• Replotting and mousing multiplots
  • new commands "remultiplot" O new command "set mouse multiplot" (NB: reverted in 6.0)
  • command sequence to regenerate full multiplot is saved to a datablock
• Additional keyentry options to construct custom keys
  • keyentry "text" can be used to place a secondary title in the key
• Minor fixes
  • correct build of postscript terminal when libgd and cairo are not present
  • strip trailing CR from function blocks read from a dos file
  • use 64-bit integers for iteration
  • "unset pointintervalbox" disables the box rather than setting it to default size
  • setting minitic scale to 0 does not disable the corresponding grid lines
  • use of stacked histograms with variable number of data columns

Changes between 6.0-rc3 and full release 6.0

• Replotting and mousing multiplots
  • now working much more comprehensively
  • revert "set mouse multiplot" as a separate command; it's now always in effect
• "plot with polygons" now guarantees that the border of each polygon is a closed curve
• pdf output from the cairo terminals now conforms to %PDF-1.5

Notes for packagers and testers

Obsolete or deprecated components

The "gnuplot mode" elisp and TeX files for use with emacs are now maintained as a separate project: https://github.com/bruceravel/gnuplot-mode so there is no longer a configuration option --with-lisp-files.

LaTeX-related terminal drivers latex, emtex, eepic, and tpic are no longer built by default. Their closest equivalent is the new pict2e terminal, but LaTeX users who want support for the full range of gnuplot plot styles are recommended to use the cairolatex or tikz terminals.

Configuration options for interactive use

The 6.0 source code supports three primary cross-platform interactive modes in addition to several platform-specific modes.

1. Qt

   The qt terminal supports interactive display with menu-driven output to png, svg or pdf. If either Qt6 or Qt5 is detected by the configure script, this will be the default terminal. It is now the fastest and most full-featured interactive terminal option.

   To disable this terminal or force use of Qt5 even if Qt6 is present

   • ./configure --with-qt=qt5
   • ./configure --without-qt
2. Cairo/pango/wxWidgets

   This set of terminals includes pngcairo, pdfcairo, epscairo, and cairolatex for output to a file. The wxt terminal provides interactive display All of these will be built by default if the configuration script finds the required libcairo, libpango, libcairo, libwxgtk, and related support libraries

   To disable these terminals:

   • ./configure --without-cairo
   • ./configure --with-cairo --disable-wxwidgets
3. X11 (the "classic" interactive interface)

   This used to be the preferred interactive interface, but the newer wxt and qt terminals offer nicer output and a wider range of features.

Output to files

Of course the terminals (output modes) present in previous gnuplot versions are also still available. These include, among many more obscure options:

• PostScript (*.ps or *.eps)
• svg
• png/jpeg/gif output via libgd graphics library
• png/pdf/eps output via cairo graphics library
• TeX/LaTeX including TikZ and ConTeXt
• Bitmapped output to support older devices (e.g. HP deskjet, epson, and seiko printers, pbm bitmapped graphics files) is available if needed but is no longer configured in by default.

  ./configure --with-bitmap-terminals

Output of inline graphics to terminal emulator or linux console

The sixel and kitty terminals display graphics in-line with the commands typed in a suitable terminal emulator window. For example "xterm -ti 340" emulates a vt340 with indexed color sixel graphics. The KDE desktop konsole terminal provides RGB color sixel graphics and 32-bit color + alpha channel graphics using the kitty protocol. The yaft terminal emulator can provide sixel graphics at linux console level with no x11 or other windowing system active.

Generating interactive plots for web display

• Mouseable output for display on the web can be created using either the canvas terminal (HTML5 2D canvas element) or the svg terminal. Both allow zooming, toggling plot elements on/off, and user-scriptable hot keys.

Other Notes

Installation

You can download a source tarball for the current gnuplot version from the gnuplot development site on SourceForge.

http://sourceforge.net/projects/gnuplot

Some platform-specific installation tips are given in the INSTALL file of the source package; the short version for linux/unix-like systems is to unpack the tarball and then

build it:
      cd gnuplot-6.0.0 ; ./configure ; make
test it:
      make check
install it:
      make install

Pay careful attention to the output of the ./configure script. It may indicate that some output modes have been omitted because the necessary support libraries were not found. In general you need to have previously installed the "-devel-" versions of these libraries.

Support

Please report all bugs and installation problems to the bug tracker on SourceForge:

https://sourceforge.net/p/gnuplot/bugs/

Development

Gnuplot development is ongoing. The development branch contains preliminary implementations of new features. The current development version is 6.1. Once version 6.0 is released, bugfixes will appear in patchlevel releases 6.0.1, 6.0.2, etc., approximately twice a year or as needed to correct a serious regression.