The subs command can be combined with double to evaluate a symbolic expression numerically. Suppose you have the following expressions
syms t M = (1 - t^2)*exp(-1/2*t^2); P = (1 - t^2)*sech(t);
and want to see how M and P differ graphically.
One approach is to type the following commands, but the resulting plot does not readily help you identify the curves.
ezplot(M); hold on; ezplot(P); hold off;
Instead, combine subs, double, and plot to produce a multicolored graph that indicates the difference between M and P.
T = -6:0.05:6; MT = double(subs(M, t, T)); PT = double(subs(P, t, T)); plot(T, MT, 'b', T, PT, 'r-.'); title(' '); legend('M','P'); xlabel('t'); grid;