I am trying to write a system of differential equations that can account for fecundity and maturation occurring at specific time steps throughout the years. Currently, this is the code that I have set up. What I want the function to do is when “mat” is equal to 1, I want all individuals from the x[0]:x[2] age classes to move to the next age class to where there are no individuals left at that age class at that time step.