Along with data often comes error, uncertainty, or the general concept of a range of values associated with each plotted value. To express this in a plot, various conventions can be used; one of these is the "error bar", for which gnuplot has some special styles. The following figure shows an example of an error bar:
The previous figure has the same data that we used in our previous recipe, Plotting circles, plotted over a restricted range, and using the random number column to supply "errors", which are depicted here as vertical lines with small horizontal caps.
Keep the datafile
parabolaCircles.text ready again. ...