I run into a problem that really suprised me. I have a program that solves a system of differential equations with different initial conditions. I wrote a cycle that goes through initial conditions, solves differential equations and saves the picture (displaying dynamic behaviour of the system) in the given directory. All seemed fine and working until I once checked one of the pictures by running the program on the only one initial condition. It turned out that the picture program gave me this time is not the one that program gave me earlier (while running through cycle). So I panicked and started checking other pictures and it turned out that some of them are right and some of them are not, remarkably, with no particular pattern.
I reckon that I somehow need to manage the memory, clear it after every iteration. (I'm not absolutely sure that problem is here but I just don't have another explanation why this thing could happen.)