Chapter 13  3-DIMENSIONAL_PLOTS
 
TOPDRAWER will do a variety of 3-d  plots.   You  can  plot  a  series  of
separate graphs superimposed on a third axis, or you can enter an array of
data to be plotted with hidden line removal.  The array of data is entered
by the READ MESH command.  The mesh is then plotted by the HISTOGRAM ,JOIN
or PLOT commands.
     1.  HISTOGRAM BLOCK produces a block or "Lego" plot of mesh data.
     2.  JOIN produces a mesh surface.
     3.  SET THREE OFF;PLOT produces a scatter plot of mesh data.
     4.  CONTOUR produces a contour plot.

     Axes  are  not  automatically added to 3-d graphs so you must use the
command PLOT AXES.  You may turn each axis on  separately  using  the  SET
AXIS  command  and then PLOT AXES X,Y,Z to place each axis in a convenient
location.

     The  command  SET  THREE  is used to specify the "viewpoint" of a 3-d
plot.  SET SCALE is also used to specify the range and type  of  scale  to
use along each of the X,Y,Z axes.

     3-d  plots  may also be built from a series of 2-d plots.  To do this
you must provide z values and:
     TD:SET THREE ON
Then  either JOIN, HISTOGRAM or PLOT is used to plot the data.  Normally Z
is the dependent variable, and X,Y are the independent variables.  If this
rule is violated, 3-d histograms will not be correctly plotted.  Your data
may be moved with the SWAP command if you need to get it into the  correct
variables.