in my code I have to save data repeatedly to the same mat.file so I am using the -append command. This works fine, however, sometimes I get a permission denied error saying that it cannot save. This seems to occur randomly (i.e. I have no idea when it will happen or after how many times). What can be causing this? I am only running one matlab instance and one function so the file should not be open anymore as the next line of code is only executed when the previous save is finished, no?