eq(1) = K_1*act1(x(2), x(6)) .* act2(x(2), x(3)).^2 - act3(x(4),x(8),T);
The difference between feval() and calling the function directly, is that feval() permits passing in a character vector that is the name of a function to invoke. So for example instead of the user passing in @sin the user might pass in 'sin'
Using function handles instead of character vectors is almost always preferred, but there are a couple of routines such as arrayfun() that have special code for some common functions that permits faster execution than if a function handle were used.
