"Stavros Macrakis" <stavros.macrakis@verizon.net> writes:
[ (C8) 'diff(y,x,2) + a*'diff(y,x) + b*y = c*x; ]
> > (C10) ode2(d8,y,x);
> > 2
> > Is 4 b - a positive, negative, or zero?
> >
> > positive;
> > Quotient by a polynomial of higher degree -- an error.
>
> This error is coming from the Integrate routine:
>
> integrate( x*%E^(a*x/2)*SIN(SQRT(b-a^2)*x) , x)
> => Quotient by...
>
> Another similar problem:
>
> integrate( x*%E^(a*x)*SIN(SQRT(b-a^2)*x/2) , x)
> => quotient is not exact
>
> Usually, this sort of problem is solved by changing GCD algorithm
> (setting the GCD variable), but in this case, all the GCD routines have
> the same problem.
The patch given in
http://www.math.utexas.edu/pipermail/maxima/2003/003694.html
fixes (C10) above. On the other hand, Maxima still fails to calculate
the two integrals above, but it succeeds after exchanging a and b,
that is, integrate(x*%e^(b*x/2)*sin(sqrt(a-b^2)*x), x); works.
Wolfgang