Fort 77 and gnuplot iterative output jpegs

AI Thread Summary
A Fortran 77 simulation program is generating graphical outputs using gnuplot for each timestep, but the output JPEG files are being overwritten due to the same filename being used. The user seeks a solution to create unique filenames for each timestep's output, such as particles0.jpeg, particles1.jpeg, and so on. Suggestions include modifying the Fortran code to generate dynamic filenames within the loop that handles the plotting. A referenced resource may provide guidance on handling filenames in Fortran. The discussion emphasizes the need for a method to preserve each graphical output for later compilation into an MPEG.
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Hello,

I have currently written a Fortran 77 simulation program that I need to display graphically for each timestep. So far it calls the system to have gnuplot open an include file that has the gnuplot script to plot from my data files and produce a jpeg. What I would like to do is have it do is make a jpeg for every time step that I can combine together into an mpeg so that I can watch how my system evolves graphically.

Here is what I have so far for this part of the code:

call system ("gnuplot particles.in")

Then it goes to the include file with the gnuplot script

set size 1, 1
set term jpeg 1200, 800
set output "particles0.jpeg"
plot "partx0.txt","party0.txt","partz0.txt"So for the partx0,party0, and partz0 text files, my fortran program opens them at the beginning of the time step loop, writes the data into two columns into each of them, then closes them and calls the system to have gnuplot look at the include file.

Everything works great except that at every timestep while the program is running, since the text files reset and get a new batch of data and the include file points to the same jpeg as the output, it keeps resetting the picture.

So if anyone knows what I would have to do in the fortran code or the gnuplot script to make it make as many pictures as I have timesteps (ie. particles0.jpeg,particles1.jpeg, particles2.jpeg,particles3.jpeg,...,particlest.jpeg for t timesteps) it would be very much appreciated. I have searched everywhere for the answer and the very few I found were for C, not Fort 77.

Thank you in advance!
 
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Well, I don't know anything about fortran. But the part the pictures are created is in a loop, right? So you might be looking for http://www.math.yorku.ca/~akuznets/gnufor2/index.html". Read the "character(len=*) :: filename" part.

When you try this, post the your result here, please! I'm learning fortran and this would be very helpful on the future.
 
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