Vadim V. Zhytnikov wrote:
>
> Daniel Lemire wrote:
>
>
>>I get the following weird error message... anyone can explain what it means?
>>
>>(C1) ode2(d(y(x),x)=1/y(x),y(x),x);
The ODE2 package seems to expect that there is a macro defined called
$status. I wrote
(defmacro $status (&rest x) nil)
and the problem went away. It seems to want to know something about
the status of "feature".
The other problem is that d(y(x),x) has nothing to do with
derivatives in Macsyma. 'diff(y(x),x) is OK, as is
diff(y(x),x), which returns "unevaluated" unless y(x) is
defined as a function.
You could also do ode2('diff(y,x) ....,y,x)
in which case 'diff is vital. diff(y,x) is otherwise
simplified to 0.
or you could do depends(y,x) followed by ..
ode2(diff(y,x) ...., y, x)
in which case diff(y,x) is evaluated to diff(y,x)..
>>
>>Error: The variable $FEATURE is unbound.
>>Fast links are on: do (si::use-fast-links nil) for debugging
>>Error signalled by MACSYMA-TOP-LEVEL.
>>Broken at MACSYMA-TOP-LEVEL. Type :H for Help.
>>MAXIMA>>
>>
>
> Try
> ode2('diff(y(x),x)=1/y(x),y(x),x);
> it works.
>
> On the other hand
> ode2(d(y(x),x)=1/y(x),y(x),x);
> indeed gives an error. This must
> be fixed.
>
>
> --
> Vadim V. Zhytnikov
>
> <vvzhy@mail.ru>
> <vvzhy@td.lpi.ac.ru>
> <vvzhy@yandex.ru>
>
>
>
>
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