B.2 Using CDF's IDL Interface

This section assumes that you are using the ``definitions'' file provided with the CDF distribution (and that it has been properly configured and named by your system manager). The ``definitions'' file is a command file named DEFINITIONS.COM on VMS systems and a script file named definitions.<shell> on UNIX systems (where <shell> is the shell being used). The ``definitions'' file defines the logical name IDL_STARTUP on VMS systems and the environment variable IDL_STARTUP on UNIX systems to the full directory path of an IDL startup file provided with the CDF distribution. When IDL is started, this startup file is automatically executed (because IDL_STARTUP is defined). The startup file performs the following functions...

1. Makes known to IDL the functions/procedures that are used to call the CDF library (and perform other utility operations).
2. Sets IDL's internal paths. These are used when searching for a batch file to be executed or when locating online help files.
3. Executes a batch file (cdf.pro) that creates a number of local variables necessary for calling CDF functions/procedures and then interpreting the results.

A list of messages should be displayed indicating the CDF functions/procedures that have been compiled.

If you are already using your own startup file (pointed to by your definition of IDL_STARTUP), you should remove the definition of IDL_STARTUP from the CDF ``definitions'' file being used and do one of the following...

1. Add the contents of the CDF/IDL startup file to your own startup file.
2. Have your startup file execute the CDF/IDL startup file.

The definition of IDL_STARTUP in the CDF ``definitions'' file being used points to the location of the CDF/IDL startup file.