hi, 

I am a newcomer user(maple16) and am trying to make a graph of energy * time forced oscillation
but I'm having this problem

script:

> restart;

> x := unapply(A*exp(-b*t/(2*m))*cos(`ϖ`*t+phi)
                  +Fmax*cos(psi*t-theta)/sqrt((k-m*psi)^2+b^2*psi^2), t);

> v := unapply(diff(x(t), t), t);

> E := unapply((1/2)*m*v^2+(1/2)*k*x^2, m, v, k, x);

> E2 := subs(v = v(t), x = x(t), phi = arctan(-vo/(xo*omega...