2D random walk confined in a circular domain with reflective boundaries

2D random walk confined in a circular domain with reflective boundaries

Generates a random walk (RW) with m steps. The x and y components of each step are drawn from a normal distribution with standard deviation sigma. The RW is confined to a circle of diameter d with reflecting boundary conditions. X0 and Y0 are the initial coordinates of the random walk inside the circle. Output is a vector of positions of the particle.