Basic question on verbifying expressions



Hi,

I am new to Maxima, and I am having trouble trying to force Maxima to evaluate an expression with a noun. See the commented code below. I hope some of you can help.

Thanks in advance,
Rodrigo

/* I was calculating a Laplace transform, like below: */

ex1:exp(-3*t)*'diff(x(t),t);
lap_ex1:laplace(ex1,t,s);

/* Then I added an initial condition: */

atvalue(x(t),t=0,0);

/* And I managed to re-evaluate the expression: */

lap_ex1:ev(lap_ex1);

/* Now I what I wanted to do is to plug an specific x(t) into that expression: */

x(t):=1

/* Now the solution to the expression is trivial (it should be 1), but I can't figure how to tell Maxima to compute it for me */

lap_ex1:ev(lap_ex1);