GNUFOR
a GNUPLOT / FORTRAN90 interface

GNUFOR is a FORTRAN77 library which provides an interface to the GNUPLOT plotting software.

GNUFOR makes it possible, while running a FORTRAN90 program on a UNIX system, to generate some data and request an immediate plot. This is done by issuing a SYSTEM command that starts up GNUPLOT, and feeding it the appropriate commands and data. The FORTRAN90 program pauses while the graph is displayed in an X window, and the user can admire the plots for a while, before hitting return and giving control back to the FORTRAN90 program.

Thanks to some suggestions of Morag Am-Shallem, the FORTRAN90 program can continue execution without waiting for GNUPLOT. In this way, for example, a program that was computing some quantity can, from time to time, display an updated plot of what it is doing. A user can glance at the picture from time to time, while the FORTRAN90 program merrily computes away. Something like this can be done with a C program that calls the GNUPLOT_I package.

To use this program, the command "gnuplot" must be in your path.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

GNUFOR is available in a FORTRAN77 version and a FORTRAN90 version.

Related Data and Programs:

GNUPLOT, FORTRAN77 programs which illustrate how a program can write data and command files so that gnuplot can create plots of the program results.

GNUPLOT_I, a C library which allows an executing C, C++, FORTRAN77 or FORTRAN90 program to interact with the GNUPLOT graphics program.

GNUPLOT_I_EXAMPLES, C programs which demonstrate the use of the GNUPLOT_I library for interactive runtime GNUPLOT graphics.

GNUPLOT_I_EXAMPLES, C++ programs which demonstrate the use of the GNUPLOT_I library for interactive runtime GNUPLOT graphics.

GRAPHICS_EXAMPLES_GNUPLOT, gnuplot scripts which illustrate how various kinds of data can be displayed and analyzed graphically using the interactive executable graphics program gnuplot.

SPRING_ODE2, a FORTRAN77 program which shows how gnuplot graphics can be used to illustrate a solution of the ordinary differential equation (ODE) that describes the motion of a weight attached to a spring.

Reference:

1. Philipp Janert,
   Gnuplot in Action: Understanding Data with Graphs,
   Manning, 2008,
   ISBN: 1-933988-39-8.
2. Thomas Williams, Colin Kelley, John Campbell, David Kotz, Russell Lang,
   gnuplot, An Interactive Plotting Program,
   The Free Software Foundation, 1990.
3. http://www.gnuplot.info/, the GNUPLOT Website.

Source Code:

• gnufor.f, the source code.
• gnufor.sh, commands to compile the source code.

Examples and Tests:

• gnufor_prb.f, a sample problem.
• gnufor_prb.sh, commands to compile, link and run the sample problem.
• gnufor_prb_output.txt, printed output from a run of the sample problem.

TEST01:

• test01_data.txt, data file #1.
• test01_commands.txt, command file #1.
• test01.png

TEST02:

• test02_data.txt, data file #2.
• test02_commands.txt, command file #2.
• test02.png

TEST03:

• test03_data.txt, data file #3.
• test03_commands.txt, command file #3.
• test03.png

TEST04:

• test04_data.txt, data file #4.
• test04_commands.txt, command file #4.
• test04.png

TEST05:

• test05_data.txt, data file #5.
• test05_commands.txt, command file #5.
• test05.png

TEST06:

• test06_data.txt, data file #6.
• table.txt, a table of data created for command file #6.
• test06_commands.txt, command file #6.
• test06.png

List of Routines:

• GET_UNIT returns a free FORTRAN unit number.
• RUN_GNUPLOT runs GNUPLOT with a given command file.
• TIMESTAMP returns the YMDHMS date as a timestamp.
• WRITE_VECTOR_DATA writes vector data to a file, for plotting by GNUPLOT.
• WRITE_VECTOR_PLOT writes GNUPLOT commands to plot vectors.
• WRITE_XY_DATA writes X(1:N), Y(1:N) data to a file.
• WRITE_XY_PLOT writes GNUPLOT commands to plot X(1:N), Y(1:N) data.
• WRITE_XYY_DATA writes a table of data to a file, for plotting by GNUPLOT.
• WRITE_XYY_PLOTS writes GNUPLOT commands to make multiple (X,Y) plots.
• WRITE_XYZ_DATA writes X(1:N), Y(1:N), Z(1:N) data to a file.
• WRITE_XYZ_PLOT writes commands to plot parametric (X,Y,Z) data.
• WRITE_XYZGRID_CONTOUR writes commands to plot contours of Z(X,Y).
• WRITE_XYZGRID_DATA writes a file of XYZ grid data.
• WRITE_XYZGRID_SURFACE writes a file of GNUPLOT commands to plot a 3D surface.

You can go up one level to the FORTRAN77 source codes.