#### 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

## Making an impulse plot

Impulse or stick plots are another way to represent discrete points. If the line thickness is made large, the impulse plot can be made to look like a bar chart.

### How to do it…

The following script illustrates the use of the `impulses` style:

```set samples 30
plot [0:2*pi] sin(x) with impulses lw 2```

### How it works…

The first command set the number of points used to sample or plot the function. The plot command tells gnuplot to use the impulse style, which draws a line from the x-axis to each y value; the thickness of the line is given by `lw 2`.

### There's more…

A "stem plot" is sometimes used in electrical engineering. It is similar to the impulse plot, but with a mark at the end of each stick; this allows the eye to more easily follow the trend of the data; conversely, the sticks make it easier to read the graph, especially when the data is sparse, compared with a simple point plot. Use the following recipe to create a stem plot of a decaying sine wave, illustrated in the following figure:

```set samples 50
plot [0:4*pi] exp(-x/4.)*sin(x) with impulses lw 2 notitle,\exp(-x/4.)*sin(x) with points pt 7```

As you can see, we have plotted the same function twice. The first time through plot the impulses, as in the previous script, and the second time we plot the function again `with points` to draw the dots.

The previous plot shows a typical exponentially damped sine wave; it represents, for example, the motion of a pendulum with friction.