Dan:
FYI, to plot the soln to
x'=x+y+t, x(0) =1,
y'=x-y, y(0) =0,
for 0<t<1, you can use the SAGE commands
sage: f = lambda x,y,t: x+y+t
sage: g = lambda x,y,t: x-y
sage: vals = eulers_method_2x2(f, g, 0, 1, 0, 1/10, 1, method="none")
sage: soln_plot = line([[x[0],x[1]] for x in vals])
sage: show(soln_plot)
If the plot isn't smooth enough, let h=1/10 be a smaller value.
On Thu, May 8, 2008 at 4:32 AM, Dan Drake <[EMAIL PROTECTED]> wrote:
> 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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