This may potentially be the first unphysical string simulator in the world. Anyhow, please copy/add the file, 'UnphysicalGuitarSimulator' and 'ODESolver' to a single Matlab folder while following the MIT License protocol. Further, input values in the GUI that pops up after you run the 'UnphysicalGuitarSimulator' and enjoy the simulations of different kinds of strings (with Guitar-like values)! :)
Please go to the Wiki section and then choose the page, 'Unphysical String Simulator', for more information.
Please note: I use 'Guitar' and 'String' interchangeably even though it is not interchangeable from a strictly technical perspective but it is interchangeable from an approximate perspective.