I was reading a paper by G.Newell 1964, and the paper's notation was different from the modern ones.
He postulated a law on car-following which dictates :
$$ v_j(t) = \frac{dy_j(t)}{dt} = V_j - V_j exp\{-\lambda_jV^{-1}_j[y_{j-1}(t-\Delta)-y_j(t-\Delta)]\}$$
And I am not sure if :
$exp\{-\lambda_jV^{-1}_j[y_{j-1}(t-\Delta)-y_j(t-\Delta)]\}$
is supposed to mean :
$e^{-\lambda_jV^{-1}_j[y_{j-1}(t-\Delta)-y_j(t-\Delta)]}$
Or simply a differential equation named "exp"
Since back then, car following modeling was much more linear in its relations.
Thank you in advance!