# Splot

splot is the command for drawing 3D plots (well, actually projections on a 2D surface, but you knew that). It is the 3D equivalent of 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 the plot (p. ) command for many options available in both 2D and 3D plots.

Syntax:

         splot {<ranges>}
               {<iteration>}
               <function> | {{<file name> | <datablock name>} {datafile-modifiers}}
                          | <voxelgridname>
                          | keyentry
               {<title-spec>} {with <style>}
               {, {definitions{,}} <function> ...}

The splot command operates on a data generated by a function, read from a data file, or stored previously in a named data block. Data file names are usually provided as a quoted string. The function can be a mathematical expression, or a triple of mathematical expressions in parametric mode.

A new feature in version 5.4 is that splot can operate on voxel data. See voxel-grids (p. ), set vgrid (p. ), vxrange (p. ). At present voxel grids can be be plotted using styles with dots, with points, or with isosurface. Voxel grid values can also be referenced in the using specifiers of other plot styles, for example to assign colors.

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 xyplane. The orientation of a splot projection is controlled by set view. See set view (p. ) and set xyplane (p. ) for more information.

The syntax for setting ranges on the splot command is the same as for plot. In non-parametric mode, ranges must be given in the order

         splot [<xrange>][<yrange>][<zrange>] ...

In parametric mode, the order is

         splot [<urange>][<vrange>][<xrange>][<yrange>][<zrange>] ...

The title option is the same as in plot. The operation of with is also the same as in plot except that not all 2D plotting styles are available.

The datafile options have more differences.

As an alternative to surfaces drawn using parametric or function mode, the pseudo-file '++' can be used to generate samples on a grid in the xy plane.

See also show plot (p. ), set view map (p. ), and sampling (p. ).

Subsections

- Data-file
  - Matrix
    - Uniform
    - Nonuniform
    - Every
    - Examples
  - Example datafile
- Grid data
- Splot surfaces
- Voxel-grid