In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text are shown as follows: "To make a file with data that forms a parabola flipped upside down, tell gnuplot to set table 'parabola.text'"

A block of code is set as follows:

set y2tics -100, 10
set ytics nomirror
plot sin(1/x) axis x1y1,100*cos(x) axis x1y2

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

set samples 1000
set parametric
plot sin(7*t), cos(11*t) notitle

Any command-line input or output is written as follows:

plot 'randomnormal.text' volatile

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "We clicked on the tab Add plot commands to get the window."