A formula like
An optional dataframe or list in which to find the components of the formula.
|xlab, ylab, zlab||
Optional axis labels to override the ones automatically obtained from the formula.
Additional arguments to pass to the default
Only simple formulas (the ones handled by the
xyz.coords function) are supported: a single variable on the left hand side (which will be plotted on the Z axis),
and a sum of two variables on the right hand side (which
will be the X and Y axis variables in the plot.)
persp3d method requires that the suggested package deldir is installed.
These functions are called for the side effect of drawing
the plots. The
plot3d method draws a scatterplot. The
persp3d method draws a surface plot.