plenv is used to define the scales and axes for simple
plenv starts a new picture on the next subpage (or a new
page if necessary), and defines the ranges of the variables required.
The routine will also draw a box, axes, and numeric labels if
requested. The syntax for
Note: Logarithmic axes only affect the appearance of the axes and
their labels, so it is up to the user to compute the logarithms prior
to passing them to
plenv and any of the other routines. Thus, if a
graph has a 3-cycle logarithmic axis from 1 to 1000, we need to set
log10(1) = 0.0, and
log10(1000) = 3.0.
For greater control over the size of the plots, axis labeling and
tick intervals, more complex graphs should make use of the functions
plbox, and routines for
manipulating axis labeling