I would like to use Julia to solve the following problem, any suggestions are welcome :)
The attached image (obtained in Julia) represents the phase of a wavefunction (in radians) on a square lattice, where m and n label the lattice sites. Computationally speaking, it is the density plot of a 41x41 real matrix. How can I numerically compute the total change in phase as one goes around a closed loop centered on the site $m=n=0$?
