This works instead:
parametric_plot([exp(-t)*e for e in evec],1,2)
where it's fine to replace evec by [1,2] (no need for vector([1,2]).
I think the problem is that exp(-t) * evec is a *vector* of functions
when a *list* of function is what the plot wants.
John
2008/5/8 Dan Drake <[EMAIL PROTECTED]>:
> I'm teaching ODEs right now and I'd like to plot the usual sort of
> solution to a 2-by-2 linear DE system, but the following doesn't work:
>
> sage: evec = vector([1,2])
> sage: var('t')
> sage: parametric_plot( exp(-t) * evec, 0, 2)
>
> The traceback's complaint is "<type 'exceptions.TypeError'>: function
> takes at most 1 positional arguments (2 given)".
>
> I know I could manually do (exp(-t), 2*exp(-t)), but the above form
> seems so natural. Is there a way to get that to work?
>
> Dan
>
> --
> --- Dan Drake <[EMAIL PROTECTED]>
> ----- KAIST Department of Mathematical Sciences
> ------- http://math.kaist.ac.kr/~drake
>
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>
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