# HP 49g+ User Manual Page 722

Graphing calculator.

XVOL (N), YVOL (O), and ZVOL (P)
These functions take as input a minimum and maximum value and are used to
specify the extent of the parallelepiped where the graph will be generated
(the viewing parallelepiped).
These values are stored in the variable VPAR.
The default values for the ranges XVOL, YVOL, and ZVOL are –1 to 1.
XXRNG (Q) and YYRNG (R)
These functions take as input a minimum and maximum value and are used to
specify the ranges of the variables x and y to generate functions z = f(x,y).
The default value of the ranges XXRNG and YYRNG will be the same as those
of XVOL and YVOL.
EYEPT (T)
The function EYEPT takes as input real values x, y, and z representing the
location of the viewpoint for a three-dimensional graph. The viewpoint is a
point in space from which the three-dimensional graph is observed.
Changing the viewpoint will produce different views of the graph. The figure
below illustrates the idea of the viewpoint with respect to the actual graphic
space and its projection in the plane of the screen.
NUMX(U) and NUMY (V)
The functions NUMX and NUMY are used to specify the number of points or
steps along each direction to be used in the generation of the base grid from
which to obtain values of z = f(x,y).
VPAR (W)
This is just a reference to the variable VPAR.
RESET (X)
Resets parameters in screen to their default values.
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