Showing posts with label gnuplot. Show all posts
Showing posts with label gnuplot. Show all posts

Monday, 20 December 2010

Piecewise function plotter

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I've been working lately on a front-end application to draw and generate the piecewise-defined functions that are mainly used for the input fuzzy sets. This application is developed with Delphi and for generating the outputs it uses the GNUplot and the LateX equation editor. The application is called Thundax Piecewise v1.1 and you can download it from here. This win32 installation package contains the required files to work with the GNUplot. This software is for academical purposes and with it you can define the piecewise-defined functions without wasting your time trying to draw the graphs and the equations.

Using the application:
If you want to get the equations from the previous image, you only need to add the points (x,y) (defined as 4 points per graph), add the equation description, the range and the number of samples:

The description of the parameters:
  • Points per graph: default value = 4. Number of points that are used to define the function:
  • Range-x: Default value [0:30]. Range to be displayed at x-axis.

  • Range-y: Default value [-0.1:1.1]. Range to be displayed at y-axis.
  • Samples: default value = 1. Number of samples for the x-axis. In a range from 1 to 10 with a sample of 1 it will show all the numbers.

Once everything is done, you just need to let the application generate the graph output automatically using GNUPlot (If the function is not plotted, check the script and execute it into the GNUplot command prompt):
And then copy-and paste the output script to Latex editor and get the piecewise function for each one:
The only thing the applications does, is to parse the input data and transform it as scripts for the GNUplot and Latex. The conversion is pretty simple and the scripts examples are like these:
GNUPlot Script example:
cold(x)=(x<=40? 0: cold2(x))
cold2(x)=(x<=40 & x > 40? 1: cold3(x))
cold3(x)=(x<=50 & x > 40? -0.1*x + 5: cold4(x))
cold4(x)=(x<=50 & x > 50? 1: cold5(x))
cold5(x)=(x>50? 0:0)
cool(x)=(x<=40? 0: cool2(x))
cool2(x)=(x<=55 & x > 40? 0.066667*x  -2.666667: cool3(x))
cool3(x)=(x<=55 & x > 55? 1: cool4(x))
cool4(x)=(x<=65 & x > 55? -0.1*x + 6.5: cool5(x))
cool5(x)=(x>65? 0:0)
justright(x)=(x<=60? 0: justright2(x))
justright2(x)=(x<=65 & x > 60? 0.2*x  -12: justright3(x))
justright3(x)=(x<=65 & x > 65? 1: justright4(x))
justright4(x)=(x<=70 & x > 65? -0.2*x + 14: justright5(x))
justright5(x)=(x>70? 0:0)
warm(x)=(x<=65? 0: warm2(x))
warm2(x)=(x<=75 & x > 65? 0.1*x  -6.5: warm3(x))
warm3(x)=(x<=75 & x > 75? 1: warm4(x))
warm4(x)=(x<=85 & x > 75? -0.1*x + 8.5: warm5(x))
warm5(x)=(x>85? 0:0)
hot(x)=(x<=80? 0: hot2(x))
hot2(x)=(x<=90 & x > 80? 0.1*x  -8: hot3(x))
hot3(x)=(x<=90 & x > 90? 1: hot4(x))
hot4(x)=(x<=90 & x > 90? 1: hot5(x))
hot5(x)=(x>90? 0:0)
set yrange[-0.1:1.1]
set xtics 0, 15
set grid
set samples 1001
bind Close "exit gnuplot"
plot [40:90] cold(x) ,cool(x) ,justright(x) ,warm(x) ,hot(x)

Notice that we use the function bind Close "exit gnuplot" to bind the exit of the application once the user has closed the plotted graph. (And I think this function is available since version 4.4).
Latex Script example:
cold(x)=\begin{Bmatrix}{0}&\mbox{if}& x\leq40\\{1}&\mbox{if}& 40< x \leq40\\{-0.1*x + 5}&\mbox{if}& 40< x \leq50\\{1}&\mbox{if}& 50< x \leq50\\{0}&\mbox{if}& x > 50\end{matrix}\\
cool(x)=\begin{Bmatrix}{0}&\mbox{if}& x\leq40\\{0.066667*x  -2.666667}&\mbox{if}& 40< x \leq55\\{1}&\mbox{if}& 55< x \leq55\\{-0.1*x + 6.5}&\mbox{if}& 55< x \leq65\\{0}&\mbox{if}& x > 65\end{matrix}\\
justright(x)=\begin{Bmatrix}{0}&\mbox{if}& x\leq60\\{0.2*x  -12}&\mbox{if}& 60< x \leq65\\{1}&\mbox{if}& 65< x \leq65\\{-0.2*x + 14}&\mbox{if}& 65< x \leq70\\{0}&\mbox{if}& x > 70\end{matrix}\\
warm(x)=\begin{Bmatrix}{0}&\mbox{if}& x\leq65\\{0.1*x  -6.5}&\mbox{if}& 65< x \leq75\\{1}&\mbox{if}& 75< x \leq75\\{-0.1*x + 8.5}&\mbox{if}& 75< x \leq85\\{0}&\mbox{if}& x > 85\end{matrix}\\
hot(x)=\begin{Bmatrix}{0}&\mbox{if}& x\leq80\\{0.1*x  -8}&\mbox{if}& 80< x \leq90\\{1}&\mbox{if}& 90< x \leq90\\{1}&\mbox{if}& 90< x \leq90\\{0}&\mbox{if}& x > 90\end{matrix}\\

I'm still working on this project and for the next milestone I'll try to add the Weighted average method to calc the area of the graph and the ability to save the data of the project.

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Friday, 30 April 2010

Improving your monitoring applications with Gnuplot

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Why bother about building a plotting component when you could use a very good one from a third-party? That's what I thought while I was trying to build a plotting component for monitoring my applications. Then I remembered when I was doing some practices with Octave at college and when I was playing with it I thought that it was a very good application.
Afterwards I modified my log and monitoring files for adapting them to gnuplot, a portable command-line driven graphing utility for linux, OS/2, MS Windows, OSX, VMS, and many other platforms. With this, you only need to focus on writing the log files, and let gnuplot draw your files in nice plotting windows with a lot of powerful features like moving axes, changing the view, etc.
With simple commands like these:

C:\>gnuplot
        G N U P L O T
        Version 4.4 patchlevel 0
        last modified March 2010
        System: MS-Windows 32 bit

        Copyright (C) 1986-1993, 1998, 2004, 2007-2010
        Thomas Williams, Colin Kelley and many others

        gnuplot home:     http://www.gnuplot.info
        faq, bugs, etc:   type "help seeking-assistance"
        immediate help:   type "help"
        plot window:      hit 'h'

Terminal type set to 'wxt'
gnuplot> set isosample 40
gnuplot> set ticslevel 0
gnuplot> splot (x**2)*(y**2)
we can draw amazing plots like this:

And even better, if for example we are monitoring our cpu, then we can plot the results:


Now, you only need to know how the command line works and use it in your applications. I'm sure you'll enjoy it, and the best part is that you can save time.

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