Hi, So I'm trying to solve the 2D Ising Model using a simple Monte Carlo algorithm, for small square lattices, imposing periodic boundary conditions. Before I compute any thermodynamic quantities though, I want to study the energetics of the system with only nearest-neighbour interactions. I want to visualize the system at every iteration of the Monte Carlo loop. The idea is to store the state of the lattice in a matrix, with each site storing the value +1 for spin up, and -1 for spin down. A computer program I've written in C with a friend generates a data file with the state of the matrix. I then use a pipe to call gnuplot from within this program, to plot the file. However, I notice that the plot window appears only after the pipe is closed -- presumably it is then that gnuplot is actually executed the first time, with all the arguments sent through the pipe. This means the plot window does not show up at a specific time of your choice, and in fact shows up at the end of the program. Now, I want to visualize the matrix at every iteration, so for that, I need to call gnuplot (through the same pipe pointer) in every iteration, so that the existing plot is updated. How can this be done? If I just naively include a plot command (through fprintf), then the plot shows up for the first time after some 20 or 30 iterations (depending on the size of the lattice). Thanks in advance!