Repost: Solve: same or new bug?
- To: mathgroup at smc.vnet.net
- Subject: [mg17661] Repost: Solve: same or new bug?
- From: Thomas Gawlick <Thomas.Gawlick at uni-vechta.de>
- Date: Fri, 21 May 1999 03:37:44 -0400
- Organization: University of Vechta
- Sender: owner-wri-mathgroup at wolfram.com
In the following example Mathematica happens to find a "general
solution'" that does not special to a solution for numerical
specialization of the paramters a,e.
m:=Sqrt[1-a^2]
g:=(x*(a+y)-m*(a+y+e))^2+y^2*(a+y+e)^2-(a+y+e)^2
gx:=D[g,x]
gy:=D[g,y]
Solve[{g==0,gx==0,gy==0},{x,y}]
{{x -> 0, y -> -a - e},
{x -> (a*(1 - a^2)^(1/2)*e)/(-1 + a^2), y -> -a},
{x -> (a*(1 - a^2)^(1/2)*e)/(-1 + a^2), y -> -a}}
% /. {a->.5,e->.1}
{{x -> 0, y -> -0.6}, {x -> -0.057735, y -> -0.5},
{x -> -0.057735, y -> -0.5}}
a:=.5; e:=.1
Solve[{g==0,gx==0,gy==0},{x,y}]
{{x -> 0., y -> -0.6}}
Is the reason for this that Mathematica checks numerical solutions only?
Another small question: How do you achieve to clear ALL variables?
--
Best regards
Thomas Gawlick
---
Dr.rer.nat. Thomas Gawlick
Hochschulassistent fur Didaktik der Mathematik
Hochschule Vechta, 49364 Vechta