The symbolic Math Toolbox no longer uses strings. That threq the warning.
For the rest:
% % y''(t) - 6 * y'(t) + 9 * y(t) = 3 * sinh(t), y(0)=1
syms s t y(t) Y(s) Dy0
eqn = diff(y,2) -6*diff(y) + 9*y == 3*sinh(t); % Time-Domain Equation
Eqn = laplace(eqn) % ‘s’-Domain Equation
Eqn = subs(Eqn,{laplace(y(t), t, s), y(0), subs(diff(y(t), t), t, 0)}, {Y(s), 1, Dy0}) % Substitute To Create Readable Expression
Eqn = simplify(Eqn, 'Steps', 250) % Simplify
Ys = isolate(Eqn, Y) % ‘Solve’ For ‘Y(s)’
produces:
Ys =
Y(s) == -(Dy0 + s - Dy0*s^2 + 6*s^2 - s^3 - 9)/(s^4 - 6*s^3 + 8*s^2 + 6*s - 9)
that in LaTeX is:
.
