Available Graph System Routines And Global Variables - Texas Instruments TI-89 Developer's Manual

Chapter 17: Graphing
When two graph mode is entered, memory for another backup graph screen is
reserved. This one is the size of the largest window allowed in any split screen
setting. If there is not enough heap available, a memory error will be displayed.
The calculator will be in two graph mode but a memory error will be shown every
time the Graph application is selected for Graph 2. This does not affect the other
graph related applications for Graph 2 or anything in Graph 1. The Table,
Y= Editor, and Window editor for Graph 2 are all still available. Graph databases
can still be opened or created. To be able to show the Graph application for
Graph 2, the calculator must be returned to one graph mode and enough
variables must be deleted or archived to make room for the backup screen
before re-entering two graph mode.
The Graph application also uses lots of temporary memory while graphing.
Anytime a user-defined function or program is executed, a temporary folder is
created for the local variables. During graphing, the same folder is used for all
the graph functions so that time is not wasted by constantly creating and deleting
the temporary folder for each separate function. Many arrays of data are needed
for 3D graphs, and sequence mode and differential equation mode both need to
save lists of previously computed values. In addition, functions created by the
Graph or Table commands are stored in another temporary folder which is
deleted by executing the ClrGraph command or activating the Y= Editor
application.
17.6.

Available Graph System Routines and Global Variables

Any TI-BASIC graph command not specifically listed here can be accessed by
entering the command as a string and executing it as described in section
8.4. Interfacing with TI-BASIC.
Graph Global Variables:
gr_active — Pointer to the GR_WIN_VARS structure containing graph
gr_other
gr_flags
Graph System Routines:
CkValidDelta
cmd_clrdraw
cmd_clrgraph
TI-89 / TI-92 Plus Developer Guide
information for the active graph.
— Pointer to the GR_WIN_VARS structure containing graph
information for the nonactive graph in two graph mode.
— Structure containing flags used by the Graph application.
— Verify that x, y, or the step value of the
independent graph variable has a valid exponent.
— Calculator command ClrDraw.
— Calculator command ClrGraph.
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Beta Version January 26, 2001