HP 49g Graphing Calculator - Manual (Page 109)

If you chose to build your own table, the previous values are displayed.
Press
0 (CD0
to clear these values, and then enter values in the
independent variable column. As you enter values, corresponding
values for the dependent variables are displayed.
Special plotting and table variables
All the information about a plot is automatically stored in a set of reserved
variables that you have direct access to. These variables are named EQ,
J^DAT, PPAR, VPAR, JPAR, and ZPAR. Similarly, the information
regarding tables is automatically stored in TPAR.
Although these variables are reserved—which means that you should not
use them as the name of some object you create—you can have different
versions of these variables, providing that each version is in a separate
directory.
EQ
EQ contains the current equation or the name of the variable containing
the current equation. Specifically, EQ can contain:
• A single algebraic object or the name of a variable containing a single
algebraic object.
• A real number—or complex number in the case of a parametric plot—
or the name of a variable containing a real or complex number.
• A program that takes no parameters and yields exactly one result, or
the name of a variable that contains such a program.
• A list containing any combination of the these possibilities.
IDAT
SDAT contains the current data matrix for statistical plots or the name of
the variable that contains the data matrix. It is the equivalent of EQ when
you are plotting a scatter plot, bar chart, or histogram.
PPAR
PPAR stores the plot window and plot setup parameters for non-statistical
plots. It is displayed as a list. In general, the objects in this list are:
! 0mim iAiiin); 0max> Утах)> independent variable, resolution, {axes-
intersection coord,irmtes), plot type, dependent varia,Ые }
PLoHing graphs Page 4-41