Graphics Options
================

The `g g' (`calc-graph-grid') command turns the "grid" on and off.  It
is off by default; tick marks appear only at the edges of the graph.
With the grid turned on, dotted lines appear across the graph at each
tick mark.  Note that this command only changes the setting in
`*Gnuplot Commands*'; to see the effects of the change you must give
another `g p' command.

The `g b' (`calc-graph-border') command turns the border (the box that
surrounds the graph) on and off.  It is on by default.  This command
will only work with GNUPLOT 3.0 and later versions.

The `g k' (`calc-graph-key') command turns the "key" on and off.  The
key is a chart in the corner of the graph that shows the
correspondence between curves and line styles.  It is off by default,
and is only really useful if you have several curves on the same
graph.

The `g N' (`calc-graph-num-points') command allows you to select the
number of data points in the graph.  This only affects curves where
neither "x" nor "y" is specified as a vector.  Enter a blank line to
revert to the default value (initially 15).  With no prefix argument,
this command affects only the current graph.  With a positive prefix
argument this command changes or, if you enter a blank line, displays
the default number of points used for all graphs created by `g a' that
don't specify the resolution explicitly.  With a negative prefix
argument, this command changes or displays the default value
(initially 5) used for 3D graphs created by `g A'.  Note that a 3D
setting of 5 means that a total of `5^2 = 25' points will be computed
for the surface.

Data values in the graph of a function are normally computed to a
precision of five digits, regardless of the current precision at the
time. This is usually more than adequate, but there are cases where it
will not be.  For example, plotting `1 + x' with `x' in the interval
`[0 .. 1e-6]' will round all the data points down to 1.0!  Putting the
command `set precision N' in the `*Gnuplot Commands*' buffer will
cause the data to be computed at precision N instead of 5.  Since this
is such a rare case, there is no keystroke-based command to set the
precision.

The `g h' (`calc-graph-header') command sets the title for the graph.
This will show up centered above the graph.  The default title is
blank (no title).

The `g n' (`calc-graph-name') command sets the title of an individual
curve.  Like the other curve-manipulating commands, it affects the
most recently added curve, i.e., the last curve on the list in the
`*Gnuplot Commands*' buffer.  To set the title of the other curves you
must first juggle them to the end of the list with `g j', or edit the
`*Gnuplot Commands*' buffer by hand.  Curve titles appear in the key;
if the key is turned off they are not used.

The `g t' (`calc-graph-title-x') and `g T' (`calc-graph-title-y')
commands set the titles on the "x" and "y" axes, respectively.  These
titles appear next to the tick marks on the left and bottom edges of
the graph, respectively.  Calc does not have commands to control the
tick marks themselves, but you can edit them into the `*Gnuplot
Commands*' buffer if you wish.  See the GNUPLOT documentation for
details.

The `g r' (`calc-graph-range-x') and `g R' (`calc-graph-range-y')
commands set the range of values on the "x" and "y" axes,
respectively.  You are prompted to enter a suitable range.  This
should be either a pair of numbers of the form, `MIN:MAX', or a blank
line to revert to the default behavior of setting the range based on
the range of values in the data, or `$' to take the range from the top
of the stack.  Ranges on the stack can be represented as either
interval forms or vectors: `[MIN .. MAX]' or `[MIN, MAX]'.

The `g l' (`calc-graph-log-x') and `g L' (`calc-graph-log-y') commands
allow you to set either or both of the axes of the graph to be
logarithmic instead of linear.

For 3D plots, `g C-t', `g C-r', and `g C-l' (those are letters with
the Control key held down) are the corresponding commands for the "z"
axis.

The `g z' (`calc-graph-zero-x') and `g Z' (`calc-graph-zero-y')
commands control whether a dotted line is drawn to indicate the "x"
and/or "y" zero axes.  (These are the same dotted lines that would be
drawn there anyway if you used `g g' to turn the "grid" feature on.)
Zero-axis lines are on by default, and may be turned off only in
GNUPLOT 3.0 and later versions.  They are not available for 3D plots.

The `g s' (`calc-graph-line-style') command turns the connecting lines
on or off for the most recently added curve, and optionally selects
the style of lines to be used for that curve.  Plain `g s' simply
toggles the lines on and off.  With a numeric prefix argument, `g s'
turns lines on and sets a particular line style.  Line style numbers
start at one and their meanings vary depending on the output device.
GNUPLOT guarantees that there will be at least six different line
styles available for any device.

The `g S' (`calc-graph-point-style') command similarly turns the
symbols at the data points on or off, or sets the point style.  If you
turn both lines and points off, the data points will show as tiny
dots.

Another way to specify curve styles is with the `LineStyles' and
`PointStyles' variables.  These variables initially have no stored
values, but if you store a vector of integers in one of these
variables, the `g a' and `g f' commands will use those style numbers
instead of the defaults for new curves that are added to the graph.
An entry should be a positive integer for a specific style, or 0 to
let the style be chosen automatically, or -1 to turn off lines or
points altogether.  If there are more curves than elements in the
vector, the last few curves will continue to have the default styles.
Of course, you can later use `g s' and `g S' to change any of these
styles.

For example, `'[2 -1 3] RET s t LineStyles' causes the first curve to
have lines in style number 2, the second curve to have no connecting
lines, and the third curve to have lines in style 3.  Point styles
will still be assigned automatically, but you could store another
vector in `PointStyles' to define them, too.