I can't help you much but I can tell you this:
- The variable x cannot be continuous for us to use a numerical method, it must be an array. The length L (observed length of the string) is divided into small sections dx. So n is the number of those sections, aka the length of the array x.
- Yes, it is the position of the string at time 0
- mod(t/dt , 10) = 0 means that when you divide t/dt by 10 you get a whole number and the rest is 0. So the code under if mod(t/dt , 10) = 0 will be executed whenever t/dt is divisible by 10.
Also, this code seems incomplete, eg. dx and dt are not defined.
