Grid
Grid [clist]
Control the plotting of a grid, where "[clist]" is one or more
of "ON", "OFf", "X # #", "Y # #". For "Grid ON", the major tic marks
are expanded to place a grid over the entire plot. "Grid OFf" turns
off the grid replacing the tic marks. PGPLOT automatically selects
the location of the major and minor tic marks. The "Grid" command
allows you to override this selection. For example, "Grid X 10,2"
would divide the x-axis into 10 major divisions and then divide each
major division into 2 minor divisions. Use "Grid X 0,0" to go back
to the default grid. The number -1 can be used to suppress the plotting
of tic marks. Thus, "Grid X -1 0" would only plot minor tic marks
on the x-axis and "Grid Y -1 -1" would prevent any tic marks from
being plotted on the y-axis.
IMPORTANT: PGPLOT only places major tic marks at locations where
the least significant digit of the range increments by integer amounts.
If you attempt to force PGPLOT to violate this condition, then
unexpected things may happen. For example, suppose you had used
"R Y 0 .15", in which case the range is 0.15 and the least significant
digit is 0.01. Then using "Grid Y 3,2" would place grid lines at
intervals of 0.05. However, if you had tried "Grid Y 2,2", then the
grid lines would occur at intervals of 0.075, where the last digit (5)
is not a significant digit. In this case, the plot will be incorrectly
labeled. "Grid X 1.5,2" is legal and would correctly produce labels
at intervals of 0.1. (Of course, only one label would actually be
plotted in this case.)
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