Please try out the examples shown below (and throughout this book) on your own computer. You can find the necessary input files in the doc directory of the plt distribution (where you will also find the LATEX sources for this book, and a printable PostScript version of it). For this tutorial, you will need only one file from the plt distribution, a text data file named heartrate.data, which begins:
6.46389 58.0645 7.49722 59.0164 8.51389 63.3431 9.46111 65.2568 10.3806 57.2944 11.4278 57.754
As the excerpt above shows, heartrate.data contains two columns of numbers; in all, there are 297 rows (lines) in the file. The numbers on the left (in column 0) represent elapsed time in seconds, and those on the right (in column 1) indicate instantaneous heart rate in beats per minute. (See doc/Makefile in the plt distribution if you are interested in knowing more about these data.)