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Thank you for your interest in gro! We kindly request that you do not redistribute gro or any documents associated with it.

After you get gro, read the installation guide.

macOS

Date	Release	Description
May 11, 2026	gro-1.0.0-mac.dmg	Compiled for Apple Silicon. Bumped to Qt6 and Chipmunk 7. After you download gro and open the .dmg file, you'll need to right-click and choose Open to avoid Apple's gatekeeper. Alas, Eric is not a registered Apple Developer so Apple is suspicious of him.
Aug. 23, 2012	gro_mac_beta.4.dmg	This version has an improved gui, reacting signals, more modifiable parameters, new examples, and the return of the command line. See the changelog below for more details. Note: gro needs to stay in the same directory as the examples and include folders that are included in the disk image.

Windows

Date	Release	Description
Aug. 23, 2012	gro_win_beta.4.zip	This version is (hopefully) the same as the mac version above, except compiled for Windows. Qt supposedly takes care of cross-compatability issues. Since the development team (i.e. Eric) uses a Mac to test everything, the Windows version might stil have some issues -- which you should please report if you find any.

Editors

You can use whatever editor is convenient for you to edit gro programs. For the Mac, you can use TextEdit, which should be in your Applications folder. VS Code is probably best. On Windows, you will likely need to install a good editor. In particular, Notepad will not work for editing .gro files, because it uses a Windows-specific encoding. A good choice for Windows is Notepad++, which you can install for free! Or use VS Code.

If you use emacs, you can add this gro mode to your .emacs file.

If you use Notepad++, Tyler Cloke, has made an xml definition file for gro. To use it, download the file to your computer, and then do View > User-Defined Dialog... > import > select gro.xml from Notepad++.

Changes

New in 1.0.0 (5/11/2026)

• Build system overhauled: qmake replaced with CMake (3.24+).
• Ported from Qt 5 to Qt 6 (tested on Qt 6.11).
• Ported the physics engine from Chipmunk 5.3.5 to Chipmunk 7.0.3.
• Dependencies (ccl, Chipmunk2D) are fetched automatically by CMake on first configure. New-dev setup is now just:

        brew install qt cmake bison flex m4
        git clone gro && cd gro && cmake -S . -B build && cmake --build build
  

• Builds natively on Apple Silicon (arm64).

New in beta.4 (8/23/2012)

• Reactions among signals can be declared with, for example, reaction ( {A,B},{C}, 1.0 ), which represents the reaction A+B->C. Here, A, B and C must be already delcared as signals. See the example spatial_oscillations.gro for a cool demo.
• You can now zoom in and out!
• Use set ( "population_max", n ) to change the maximum number of cells.
• Use the menu item Simulation->Increase Population Limit or command-M to increase the limit on the number of cells by 100.
• Use, for example, ecoli ( [ volume := 2.0 ], program p() ) to initialize the volume of an ecoli cell.
• Change the signal grid size and extent with set and "signal_grid_width", "signal_grid_height", "signal_element_size".
• The extent of the signal area is now indicated graphically in the gui by cross hatches.
• To run without the gui, invoke grong (which stands for gro, no gui), from the command line. grong is compiled without linking to Qt, so it is small.
• Examples of how to call grong from Mathematica are now included in the extras directory.

New in beta.3 (6/18/2012)

• Minor bug fixes with runtime error reports (divide by zero and index out-of-bounds on arrays) and printing to the console when a .gro file is being parsed but before the simulation starts.

New in beta.2 (6/15/2012)

• Finished porting all functionality of the old gui (exemplified in version a.5) to the new Qt gui, except -n does not work anymore. There will be a separate executable for the non-gui version included in the next release.
• Now works with Windows!
• File I/O via fopen and fprint.
• Turn on chemostat mode with chemostat(true|false) command.
• Chemostat width and height are settable parameters.

New in beta.1 (6/6/2012)

• New gui with buttons, separate work thread
• Releases are now in .dmg files
• The executable is now stuck in a Mac OS X .app bundle and has a pretty icon
• Themes are now settable in gro -- see gro.gro for examples
• print() now prints to the console -- and you can use html tags in what you print.

New in a.5 (5/10/2012)

• Now there's a changelog!
• Command line now available via ARGV, ARGC.
• New built in function: ( map_to_cells expr end ) returns expr evaluated for each cell. See examples/maptocells.gro.
• New keyword: ( foreach i in L do expr end ). See examples/foreach.gro.
• Default parameters are settable outside a cell and initialized in include/gro.gro. Also, many parameters now have "ecoli_" prefixes, to pave the way for cell-type specific parameters.
• You can now start the simulation automatically with start().
• run and tumble!
• The -n option (after the filename) starts gro without the gui.

Developed by The Klavins Lab, University Washington, Seattle, WA
Copyright © University of Washington. All rights reserved.