about using gnuplot

wiki:gnuplot is a command-line program that can generate two- and three-dimensional plots of functions, data, and data fits. It is frequently used for publication-quality graphics as well as education. The program runs on all major computers and operating systems (GNU/Linux, Unix, Microsoft Windows, Mac OS X, and others). It is a program with a fairly long history, dating back to 1986. Despite its name, this software is not distributed under the GNU General Public License (GPL), opting for its own more restrictive open source license instead.

Firstly, I need to install it in PC.

In Ubuntu, it is convenient because of apt-get

typing in terminal: sudo apt-get insatall gnuplot

If u work on Windows, please download it from :  http://sourceforge.net/projects/gnuplot/?source=directory  and install it. :>

Secondly, we need some tutorials about gnuplot. u can find many on Internet when u search in google. Then Open gnuplot.:>

I try to draying a simple frequency spectrum.We know that the real signal has a  conjugate symmetry sprectrum. Now I create a wavefile.dat.

-24 0

-23 16

-22 20

-21 24

-20 30

-19 32

-18 36

-17 38

-16 38

-15 24

-14 0

24 0

23 16

22 20

21 24

20 30

19 32

18 36

17 38

16 38

15 24

14 0

I just want to draw 2D picture so there r two column. 1st is X axis and 2nd is Y axis.

typing code in terminal:

gnuplot> unset key

gnuplot> set xrange[-30:30]  

gnuplot> set yrange[0:60]  

gnuplot> set zeroaxis lt -1 lw 2

gnuplot> set arrow 1 from 25,0 to 30,0 filled size 2,15,60 lw 2

gnuplot> set arrow 2 from 0,55 to 0,60 filled size 2,15,60 lw 2

gnuplot> set arrow 3 from -19,0 to -19,45 filled size 2,15,60 lw 0.8 lt 0 nohead

gnuplot> set arrow 4 from 19,0 to 19,45 filled size 2,15,60 lw 0.8 lt 0 nohead  

gnuplot> set label 1 "-Fc-B/2" at -26,-2

gnuplot> set label 2 "-Fc+B/2" at -16,-2

gnuplot> set label 3 "Fc-B/2" at 13,-2 

gnuplot> set label 4 "Fc+B/2" at 23,-2  

gnuplot> set label 5 "Fc" at 19,-2

gnuplot> set label 6 "-Fc" at -20,-2

gnuplot> set xlabel "Frequency" font"0,15"  

gnuplot> set ylabel "Power" font"0,15"      

gnuplot> plot "./ wavefile.dat " with lines

gnuplot> set xtics 0    

gnuplot> replot

gnuplot> set bmargin 2

gnuplot> replot

gnuplot> set bmargin 4

There r the picture.