Ising model with montecarlo algorithm

Hi this is my code for ising model, using montecarlo for my physik project. actually I don't have any errorr, but this is not the result that I want. for plott I want different results. I want my results be like the pictueres I've attached. the code is attached too. any suggestion would be great. thank you in advance. p.s: actually I'm using Octave.