Maxima doesn't find an expected solution for a diff eq with desolve
- Subject: Maxima doesn't find an expected solution for a diff eq with desolve
- From: Jaime Villate
- Date: Mon, 28 Oct 2013 08:15:51 +0000
On 27-10-2013 21:31, Marcus Menzel wrote:
> eq: y(t) = -r*c*'diff(y(t),t)+m*sin(%omega*t);
> assume(%omega > 0)$
> sol:desolve( eq, y(t) );
>
> his result was:
> sol: y(t) = (m * sin(%omega*t)) / (%omega^2*c^2*r^2 + 1) -
> (%omega*c*m*r*cos(%omega*t)) / (%omega^2*c^2*r^2 + 1) +
> (%omega*c*m*r*%e^-((1*t)/(c*r))) / (%omega^2*c^2*r^2 + 1);
>
> my result is:
> y(t) = (m*sin(%omega*t))/(%omega^2*c^2*r^2+1) ?
> (%omega*c*m*r*cos(%omega*t))/(%omega^2*c^2*r^2+1) +
> ((y(0)*%omega^2*c^3*r^3+%omega*c^2*m*r^2+y(0)*c*r)*%e^(?t/(c*r)))/
> (c*r*(%omega^2*c^2*r^2+1))
Hi,
I think Mr. Lutus used the command:
atvalue(y(t),t=0,0);
(before desolve) and he forgot to say that.
Regards,
Jaime