Syntax:
splot '<file_name>' {binary | matrix}
{index <index list>}
{every <every list>}
{using <using list>}
The special filenames "" and "-" are permitted, as in plot.
In brief, binary and matrix indicate that the 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 cntrparams and dgrid3d provide limited smoothing cabilities.
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 values are provided, gnuplot gives you an error message. Three values are interpreted as an (x,y,z) triple. Additional values are generally used as errors, which can be used by fit.
Single blank records separate datablocks in a splot datafile; splot treats datablocks as the equivalent of function y-isolines. No line will join points separated by a blank record. If all datablocks contain the same number of points, gnuplot will draw cross-isolines between datablocks, connecting corresponding points. This is termed "grid data", and is required for drawing a surface, for contouring (set contour) and hidden-line removal (set hidden3d). See also splot grid data
It is no longer necessary to specify parametric mode for three-column
splots.