#### Overview of this book

gnuplot is the world's finest technical plotting software, used by scientists, engineers, and others for many years. It is in constant development and runs on practically every operating system, and can produce output in almost any format. The quality of its 3d plots is unmatched and its ability to be incorporated into computer programs and document preparation systems is excellent. gnuplot Cookbook ñ it will help you master gnuplot. Start using gnuplot immediately to solve your problems in data analysis and presentation. Quickly find a visual example of the graph you want to make and see a complete, working script for producing it. Learn how to use the new features in gnuplot 4.4. Find clearly explained, working examples of using gnuplot with LaTeX and with your own computer programming language. You will master all the ins and outs of gnuplot through gnuplot Cookbook. You will learn to plot basic 2d to complex 3d plots, annotate from simple labels to equations, integrate from simple scripts to full documents and computer progams. You will be taught to annotate graphs with equations and symbols that match the style of the rest of your text, thus creating a seamless, professional document. You will be guided to create a web page with an interactive graph, and add graphical output to your simulation or numerical analysis program. Start using all of gnuplot's simple to complex features to suit your needs, without studying its 200 page manual through this Cookbook.
gnuplot Cookbook
Credits
www.PacktPub.com
Preface
Free Chapter
Plotting Curves, Boxes, Points, and more
Annotating with Labels and Legends
Applying Colors and Styles
Combining Multiple Plots
Programming gnuplot and Dealing with Data
The Third Dimension
Using and Making Graphical User Interfaces
Surveying Special Topics
Finding Help and Information
Index

## Fitting the grid to the data

gnuplot, by default, arranges our graph with a set of ticmarks at equally spaced intervals, with gridlines to match (if we turn the grid on). If we want to make it easy to read off the values of a particular set of points, we can do better:

### How to do it…

The following script will create the previous figure:

```set term pngcairo dashed
set out 'xsquared.png'
set samples 6
set key top left
set for [n = 1 : 4] arrow from first n, 0 to first n, n**2 back \ nohead lt 7
set for [n = 1 : 4] arrow from first 0, n**2 to first n, n**2 back \ nohead lt 7
set for [n = 0 : 5] ytics (n**2)
plot [0:5] x**2 with linespoints pt 7 ps 3```

### How it works…

We have included explicit `set terminal` and `set out` commands because we want our linetype specifications to select a dashed line; if you prefer to use colored lines where the figure has a dashed line, you can omit the `dashed` keyword.

We set a small number of samples because we want to illustrate the technique with a handful of points, that typically...