Obtaining GTC

GTC is available without charge from Registration is required and use of the tool is subject to a non- exclusive, non-transferable and non-sublicensable limited end-user license agreement (License).


Before upgrading GTC on the computer, the previous version must be removed (see Uninstalling). Then follow the installation instructions (see Installing).


Prior to version 0.9.9, GTC was installed under Program files, or Program files (x86), in the Windows file system (typically, C:\Program files (x86)\GTC). If you have one of these earlier versions then remove GTC (see Uninstalling) and copy any user-defined files to a safe place before deleting the old GTC installation folder completely. After installing the new version of GTC, copy any user-defined files to an appropriate folder and update the GTC_LIB environment variable if necessary (see Windows environment variables).

By default, the installation creates a user lib folder under My GTC in the user’s home directory (typically, e.g., C:\Users\ If user-defined modules are copied here, there is no need to update the GTC_LIB environment variable.


Run setup.exe to install the GUM Tree Calculator software.

Installing GTC


  • Installation is for a single user only (administrator rights are not required during installation, but it may be necessary to reboot the computer).
  • The software will be installed under the user’s AppData folder (for example, C:\Users\\AppData\Local\GTC)
  • The user AppData folders are hidden by default (this can be changed in the Windows Explorer ‘Folder options’ settings).
  • The user’s path environment variable is modified and options are added to the Windows Explorer Extended Context Menu (see also Windows environment variables).
  • A GTC entry is created in the Windows Start Menu. This entry contains shortcuts to the GTC command prompt (see The Command Prompt), as well as help files and an editor (see The SciTE editor).

Several options in the installer software relate to the extended Windows Explorer context menu.

  • The context menu items for the SciTE editor and SendTo for GTC can be installed.
  • A user My GTC folder can be created, in which case a subfolder examples will be created, containing some of the files referred to in this manual; a lib folder will also be created and the path to this folder will be added to the user’s GTC_LIB environment variable (see Windows environment variables); a scripts folder will be created and the path to this folder will be added to the user’s GTC_SCRIPTS environment variable.
There are several options during installation


The Add / Remove Programs utility of the Windows Control Panel can be used to remove the software.

Alternatively, there is a link to uninstall.exe in the GTC Start Menu folder. The uninstall.exe program is located in the installation folder (e.g., C:\Users\\AppData\Local\GTC).


  • Uninstalling GTC will not remove any user-defined modules stored under the installation folder (e.g., in C:\Users\\AppData\Local\GTC\lib), nor does it affect any user changes to the environment variable GTC_LIB.


Several forms of documentation are provided, which can all be accessed from shortcuts in the GTC group in the Windows Start menu. Note that the HTML documentation is best viewed with the Mozilla Firefox browser.