HP 50g Graphing Calculator - Manual (Page 719)

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EQ (3)
The variable name EQ is reserved by the calculator to store the current equation
in plots or solution to equations (see chapter …). The soft menu key labeled EQ
in this menu can be used as it would be if you have your variable menu
available, e.g., if you press [ EQ ] it will list the current contents of that variable.
ERASE (4)
The function ERASE erases the current contents of the graphics window. In
programming, it can be used to ensure that the graphics window is cleared
before plotting a new graph.
DRAX (5)
The function DRAX draws the axes in the current plot, if any is visible.
DRAW (6)
The function DRAW draws the plot defined in PPAR.
The PTYPE menu under PLOT (1)
The PTYPE menu lists the name of all two-dimensional plot types pre-
programmed in the calculator. The menu contains the following menu keys:
These keys correspond to the plot types Function, Conic, Polar, Parametric, Truth,
and Diff Eq, presented earlier. Pressing one of these soft menu keys, while
typing a program, will place the corresponding function call in the program.
Press L
)@PLOT to get back to the main PLOT menu.
The PPAR menu (2)
The PPAR menu lists the different options for the PPAR variable as given by the
following soft menu key labels. Press L to move to next menus: