The solution,
y = (%e)^( - t/2) * (%k1 * sin(((sqrt(3) * t)/2)) + %k2 * cos(((sqrt(3)
* t)/2))) - cos(t)
should, I think, be well within ODE2's capabilities.
Commercial Macsyma solves it almost instantly.
RJF
Moses Glasner wrote:
>Hello,
>
>I found that Maxima has trouble solving some very simple ode's, e.g.,
>
>(%i1) ode2('diff(y,t,2)+'diff(y,t)+y-sin(t),y,t);
>
>After a few minutes of churning maxima leaves the following message:
>
>!!! CMUCL has run out of dynamic heap space. You can control heap size
>!!! with the -dynamic-space-size commandline option.
>*A2 gc_alloc_new_region failed, nbytes=16.
> Generation Boxed Unboxed LB LUB Alloc Waste Trig WP GCs
>Mem-age
> 0: 1645 0 0 0 6734384 3536 2000000 0 0
>0.0000
> 1: 5480 1 0 0 22431040 19136 2000000 5479 0
>0.0000
> 2: 22108 1 0 0 90504704 53760 2000000 22107 0
> 0.0000
> 3: 101833 4 0 0 416906528 217824 2000000 101824
> 0 0.0000
> 4: 0 0 0 0 0 0 2000000 0 0
>0.0000
> 5: 0 0 0 0 0 0 2000000 0 0
>0.0000
> 6: 0 0 0 0 0 0 0 0 0
>0.0000
> Total bytes alloc=536576656
>
>
>I am running Mandrake 10.0 with the 2.6.3 kernel and Maxima 5.9.1
>compiled with cmucl 18e.
>
>If the ode is changed slightly or if Maxima is told to solve
>the complexified equation, then Maxima responds with the
>solution instantly. eg,
>
>(%i1) ode2('diff(y,t,2)+'diff(y,t)+2*y-sin(t),y,t);
>
>(%i2) realpart(second(ode2('diff(y,t,2)+'diff(y,t)+y-exp(%i*t),y,t)));
>
>Am I doing something to cause this behavior or is this a bug in ode2?
>
>Sincerely,
>Moses
>
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>
>