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.You llfind the gnuplot program under the /usr/bin directory.The gnuplot program (see Figure 17.6) is a complete, interactive plotting program, and wasoriginally designed to graph math functions and data.In this regard it is somewhat similarto other commercial formula-interpretation and plotting programs.It can read and save files,and has built-in help, so you can query the program while you use it.Using gnuplot is simple.The program has five different command-line options, but manyaspects of the program may be controlled interactively or as commands in a loaded gnuplot 270 Hour 17data file.One common use of the command-line option may be to control the point size (inpixels) of drawing lines using the -pointsize option, as in the following example:# gnuplot -pointsize 2Figure 17.6.The gnuplot programcan help you visualizemathematical formulasor spreadsheet data.You can use and plot many types of mathematical expressions, and according to the gnuplotdocumentation, any C, Pascal, FORTRAN, or BASIC language mathematical statementmay be used.For example, Figure 17.6 shows a graphic plot of the expression (x*y)-(x+y).Once you have finished, type quit to exit the program.You can find more documentation, the gnuplot FAQ, and updates to the gnuplot program athttp://www.cs.dartmouth.edu/gnuplot_info.htmlTipsMany, many different financial and math applications are available for Linux.This hour hasbarely scratched the surface.You ll find financial applications that can help you manageinvestment portfolios, track stock prices, or aid in developing cost estimates for constructionprojects.You ll also find hundreds of specialized programs you can use in solving specialcomputing needs for other sciences.One of the best sites for perusing some of the best of theseapplications ishttp://SAL.KachinaTech.COM/You ll also find a number of financial tools for Linux, along with source code, athttp://sunsite.unc.edu/pub/Linux/apps/financial1 7 Personal Productivity Tools 271PARTI VHour 18Personal Productivity1 8ToolsThis hour shows you some calendars, commands, and X11 clients you can useto help your personal productivity.Whether it s keeping a diary or creatingreminders, you ll learn how to use these tools under Linux to keep you on trackand on schedule with your life.Each program or technique discussed in this hour can be accomplished withsoftware you ll find on the CD-ROM that came with your book.After readingthis discussion, you ll find additional ways to use these programs to craft yourown set of tools and techniques for personal productivity. 272 Hour 18Scheduling Personal Reminders andTasks with the at CommandIf you need to keep track of important schedules, set reminders, or run programs unattended,you can use the at command.This command, found under the /usr/bin directory, willschedule commands, or jobs, to be run at a time you specify.For example, if you re workingon a project but need to remember to catch your car pool, you can enter a quick at job fromthe command line.Your system should allow you to use the at commands by default.If itdoes not, see Hour 24, Scheduling, on how to enable at commandfacilities for your system.TIME SAVERThe following shows the at command for the car pool example:# at 16:15xmessage -display :0.0 The car pool is leaving in 15 minutes. EOTJob 4 will be executed using /bin/shThis will tell the at command to run the xmessage program to display the text of your messageabout your car pool on the specified X11 display.The -display command-line option willtell the xmessage command which screen to show the message on, usually 0.0, which you canfind with# printenv | fgrep DISPLAYThis command line searches a listing of your environment variables (discussed in Hour 6, Using the Shell ) and prints the value of the DISPLAY variable
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