AGI problems

The AGI database is normally kept in a separate HDS file (SG/4) for each machine in your $HOME directory. The command BEGPLOT opens the AGI database and reads database information relevant to the graphics device being used. During a PONGO plotting session, the database file is held open to update the database as the plotting session proceeds. At the end of plotting, when ENDPLOT is executed, the update of the database is completed and the database file is closed. If another non-PONGO application which uses AGI is run before the current PONGO plotting session has been ended (i.e. using ENDPLOT), it will be unable to access the AGI database and will subsequently fail. In the event of this happening, using the PONGO ENDPLOT command will restore the correct behaviour of the non-PONGO application.

What is more important, in order to use AGI successfully, is the use of ENDPLOT before exiting ICL or CL. Because PONGO keeps the AGI database file open throughout a plotting session it is possible to exit ICL or CL without having first executed ENDPLOT. If this is done, it is likely that the AGI database will not have been fully updated before being closed, with the result that the next time AGI is used it will behave inconsistently. PONGO crashing during a plotting session (hopefully, a rare event) can also result in a corrupted AGI database. There is no solution to this problem other than to delete the database file and start again. The AGI database files are kept in the directory $HOME and have names of the form agi_<machine>.sdf, where <machine> is the name of the machine on which AGI is being used. This file may be deleted at any time before a BEGPLOT command or after an ENDPLOT command. The BEGPLOT command may then be used to begin a new PONGO plot, creating a new AGI database as a result.