solutions of simple polynomial equations not exact
Subject: solutions of simple polynomial equations not exact
From: Barton Willis
Date: Tue, 28 Nov 2006 10:51:54 -0600
Alternative: set algexact to true
(%i1) algsys([x^2 = 2*y, y^2 = x/2],[x,y]), algexact : true;
(%o1)
[[x=(2^(1/3)*sqrt(3)*%i-2^(1/3))/2,y=-(2^(2/3)*sqrt(3)*%i+2^(2/3))/4], <
junk deleted>
Barton
maxima-bounces at math.utexas.edu wrote on 11/28/2006 10:17:05 AM:
> The commercial Macsyma does this exactly. Perhaps you realize that
> 1.2599... is the cube root of 2, and 0.7937.. is 1/1.2599..
>
> The answer does require the solution of a cubic, and someone apparently
made
> the decision that you didn't want to see that exactly.
>
> You can get exact answers to
> x^2=r*y
> y^2=x/s
>
> and then substitute 2 for r and s.
>
>
> RJF