Example datafile

A simple example of plotting a 3-d data file is

     splot 'datafile.dat'

where the file "datafile.dat" might contain:

     # The valley of the Gnu.
        0 0 10
        0 1 10
        0 2 10

        1 0 10
        1 1 5
        1 2 10

        2 0 10
        2 1 1
        2 2 10

        3 0 10
        3 1 0
        3 2 10

Note that "datafile.dat" defines a 4 by 3 grid ( 4 rows of 3 points each ). Rows are separated by blank records.

Note also that the x value is held constant within each dataline. If you instead keep y constant, and plot with hidden-line removal enabled, you will find that the surface is drawn 'inside-out'.

Actually for grid data it is not necessary to keep the x values constant within an dataline, nor is it necessary to keep the y values the same along the perpendicular datalines. gnuplot requires only that the number of points be the same for each dataline.