The gfactor I had before was unnecessary. It's enough to have ratsimp(...),
gcd:'subres / 'red
This is more-or-less documented under ? gcd:
To take the gcd when an algebraic is present, e.g., `gcd (<x>^2 -
2*sqrt(2)*<x> + 2, <x> - sqrt(2))', `algebraic' must be `true' and
`gcd' must not be `ez' [ADD: or 'spmod']
I think it would be better to start with a black-box description (about
algebraics) than to name the different algorithms (though that is I suppose
useful for people with very large or 'difficult' cases).
Examples:
makelist(rat((x^2-2)/(x-sqrt(2))),gcd,'[ez,subres,red,spmod]),algebraic:true
=> [(x^2-2)/(x-sqrt(2)),x+sqrt(2),x+sqrt(2),(x^2-2)/(x-sqrt(2))]
just like
makelist(rat((x^2+1)/(x+%i)),gcd,'[ez,subres,red,spmod]),algebraic:true;
=> [(x^2+1)/(x+%i),x-%i,x-%i,(x^2+1)/(x+%i)]
On Sat, May 28, 2011 at 13:17, Barton Willis <willisb at unk.edu> wrote:
> OK:
>
> (%i41) radcan(exp(((t-2*%i)*x^2)/(4*t-2*%i))), gcd : 'red;
> (%o41) %e^(((t-2*%i)*x^2)/(4*t-2*%i))
>
> OK (I think) but messy:
>
> (%i42) radcan(exp(((t-2*%i)*x^2)/(4*t-2*%i))), gcd : 'spmod;
> (%o42)
> %e^(((32*t^6-144*%i*t^5-240*t^4+200*%i*t^3+90*t^2-21*%i*t-2)*x^2)/(128*t^6-384*%i*t^5-480*t^4+320*%i*t^3+120*t^2-24*%i*t-2))
>
> I wasn't able to transform (%o42) back to exp(((t-2*%i)*x^2)/(4*t-2*%i)).
>
> --Barton
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