gnuplot documentation

150 gnuplot 4.3 72 SPLOT
72 Splot
splot is the command for drawing 3D plots (well, actually projections on a 2D surface, but you knew
that). It can create a plot from functions or data read from files in a manner very similar to the plot
command. splot provides only a single x, y, and z axis; there is no equivalent to the x2 and y2 secondary
axes provided by plot.
See plot (p. 64) for features common to the plot (p. 64) command; only differences are discussed in
detail here.
Syntax:
splot {}
{}
| "" {datafile-modifiers}}
{} {with }
{, {definitions,} ...}
where either a or the name of a data file enclosed in quotes is supplied. The function can
be a mathematical expression, or a triple of mathematical expressions in parametric mode.
By default splot draws the xy plane completely below the plotted data. The offset between the lowest
ztic and the xy plane can be changed by set ticslevel. The orientation of a splot projection is controlled
by set view. See set view (p. 139) and set ticslevel (p. 136) for more information.
The syntax for setting ranges on the splot command is the same as for plot. In non-parametric mode,
the order in which ranges must be given is xrange, yrange, and zrange. In parametric mode, the
order is urange, vrange, xrange, yrange, and zrange.
The title option is the same as in plot. The operation of with is also the same as in plot, except that
the plotting styles available to splot are limited to lines, points, linespoints, dots, and impulses;
the error-bar capabilities of plot are not available for splot.
The datafile options have more differences.
See also show plot (p. 118).
72.1 Data-file
As for plot, discrete data contained in a file can be displayed by specifying the name of the data file,
enclosed in quotes, on the splot command line.
Syntax:
splot ’’ {binary }
{matrix}
{index }
{every }
{using }
The special filenames "" and "-" are permitted, as in plot.
In brief, binary and matrix indicate that the data are in a special form, index selects which data sets
in a multi-data-set file are to be plotted, every specifies which datalines (subsets) within a single data
set are to be plotted, and using determines how the columns within a single record are to be interpreted.
The options index and every behave the same way as with plot; using does so also, except that the
using list must provide three entries instead of two.
The plot options thru and smooth are not available for splot, but cntrparam and dgrid3d provide
limited smoothing capabilities.
Data file organization is essentially the same as for plot, except that each point is an (x,y,z) triple. If
only a single value is provided, it will be used for z, the datablock number will be used for y, and the
index of the data point in the datablock will be used for x. If two or four values are provided, gnuplot
uses the last value for calculating the color in pm3d plots. Three values are interpreted as an (x,y,z)
triple. Additional values are generally used as errors, which can be used by fit.