On 2012-07-13, David Ronis <David.Ronis at McGill.CA> wrote:
> Thanks for the suggestions; however none of them seem to really do the
> trick. Here's a real example:
>
> kill(all);
> ansp: xi*((xi^2-k[0]^2)*log((abs(xi-k[0])/(xi+k[0]))^2)+4*k[0]*xi)
> /(k[0]*(Gamma+D*(xi^2-k[0]^2)))
>
> *((exp(-D*k[0]^2*(t[0]+t[3]))-exp(-2*Gamma*t[3]-D*k[0]^2*(t[0]-t[3])))
> /(Gamma-D*k[0]^2)
> +(exp(-Gamma*(t[0]+t[3])-D*xi^2*(t[0]-t[3]))
> +exp(-2*Gamma*t[3]-D*k[0]^2*(t[0]-t[3]))
> -exp(-D*k[0]^2*t[3]-(D*xi^2+Gamma)*t[0])
> -exp(-(Gamma+D*xi^2)*t[3]-D*k[0]^2*t[0]))/(Gamma-D*(xi^2+k[0]^2))
> );
>
> f:ratsimp(%);
Well, how real is it? Is f something found in the wild? Doesn't seem to
be, since f is constructed as ratsimp(ansp). It makes a difference in
this case since ratsimp rearranges the expression so that the exponents
are different, which means that reconstructing the original ansp from f
cannot be carried out by considering exponents alone.
But that may well be beside the point. What are some expressions which
you have actually encountered?
best
Robert Dodier