We got an introduction to contour plots in Chapter 8, The Third Dimension, where we saw that the contours can be drawn in a sequence of dash-dot styles; the contour values can then be identified by referring to the legend that gnuplot constructs for us automatically.
There is another style of contour plot that incorporates numerical labels directly on the contours. gnuplot does not support this style directly, but can be tricked into compliance, as shown in the following figure:
Type the following script:
unset key unset surf set view map set contour base unset clabel set xrange [0:5] set yrange [0:5] set ...