On Thu, Mar 26, 2009 at 9:58 PM, Ondrej Certik <ond...@certik.cz> wrote:
>
> Hi,
>
> today I had to solve some function for my chemical kinetics class, so
> I tried it in sympy first and I was surprised it just worked:
Do you have a nicely documented description of the algorithm sympy
uses to implement its solve? E.g., Maxima at least claims in the
documentation to describe what its solve does.
William
>
> In [1]: var("E R T A beta")
> Out[1]: (E, R, T, A, β)
>
> In [2]: eq = Eq(E/(R*T**2), A/beta * exp(-E/(R*T)))
>
> In [3]: eq
> Out[3]:
> -E
> ───
> R⋅T
> E A⋅ℯ
> ──── = ──────
> 2 β
> R⋅T
>
> In [4]: solve(eq, E)
> Out[4]:
> ⎡ ⎛A⋅T⎞⎤
> ⎢R⋅T⋅LambertW⎜───⎟⎥
> ⎣ ⎝ β ⎠⎦
>
>
> or if you don't use fixed width fonts:
>
> In [5]: print eq
> E/(R*T**2) == A*exp(-E/(R*T))/beta
>
> In [6]: print solve(eq, E)
> [R*T*LambertW(A*T/beta)]
>
>
> And then Sage:
>
> sage: var("E R T A beta")
> (E, R, T, A, beta)
> sage: eq = (E/(R*T**2) == A/beta * exp(-E/(R*T)))
> sage: eq
> E/(R*T^2) == A*e^(-(E/(R*T)))/beta
> sage: solve(eq, E)
> [E == A*R*T^2*e^(-(E/(R*T)))/beta]
>
> So it seems Maxima can't do it. Nor sympy in Sage though for some
> reason, even though sympy 0.6.3 outside sage can do it, so it shows
> some sage <-> sympy conversion bug. After we release 0.6.4, I'll look
> into that, in the meantime I created an issue for it:
>
> http://code.google.com/p/sympy/issues/detail?id=1353
>
>
> Ondrej
>
> >
>
--
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org
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