Calculating power and energy of a signal in matlab
The Matlab function int needs a symbolic expression as an integrand, and a symbolic variable as an integration variable. In your example s and t are both vectors, and you can't use int in this case. If you want to compute the power or energy of discrete time signals, then you need to use the corresponding definitions:

$$E_x=\sum_{n=-\infty}^{\infty}|x_n|^2\\
P_x=\lim_{N\rightarrow\infty}\frac{1}{2N+1}\sum_{n=-N}^N|x_n|^2$$

In practice you will need to consider finite length signals unless you have an analytic formula for $x_n$ and some software package that can deal with the analytic evaluation of infinite sums. Obviously, finite length signals always have finite energy and $P_x=0$ according to above definition.