Report on Scholarpedia-contribution ,,Barkley model´´ by Dwight Barkley:
Overall the contributions is well written and gives a good account on the topic. There should be a few corrections (see below). I also list some additional info which may be worth giving.
Page 1: Introduction: Consider to insert a sentence like ,,The Barkley model is often used as a qualitative model in excitable and oscillatory pattern forming systems like the Belousov-Zhabotinsky reaction and other systems that are well described by the interaction of an activator and an inhibitor component.´´
Captions figure 1, 2: I would replace the somewhat technical ,,spiral wave solution´´ resp. ,,scroll wave solution´´ by ,,spiral waves´´ resp. ,,scroll wave´´.
Important: Figure 4 is missing in the version I have. Figure 3 on page 2 is immediately followed by Figure 5.
Page 4, top: Can you give an estimate of the largest possible time step in the explicit Euler scheme ?
Page 4, bottom, treatment of diffusion: Use a comma in the indices to have consistent notation, i. e. replace i-1j by i-1,j etc.
Page 5, top: It would be good to have a remark on the maximal \Delta t imposed by the explicit discretization of the diffusion, e. g. \Delta t < (\Delta x)^2/ 2 d where d is the dimension (d = 2,3).
Page 6, software: Add the phrase ,,in two resp. three dimensions´´ at the end of the sentence starting with ,,Two open source….´´.
I also think that this article is clearly written. Since the main use of Barkley model is spiral wave simulations, I think it would be useful to add a Zykov-Winfree "flower garden" diagram for this model (eg the location in parameter space of steadily rotating spiral waves, meandering spiral waves,...).