[Maxima-bugs] [ maxima-Bugs-1944012 ] solve() fails depending on equation order

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Bugs item #1944012, was opened at 2008-04-16 07:07
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Category: Lisp Core - Solving equations
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: solve() fails depending on equation order

Initial Comment:
Maxima version:  5.14.0
OS:  Windows XP SP2
Name:  Bob Walton (note:  setting up a SourceForge
account apparently isn't working, so I couldn't log in)
Email:  http://bwalton.com/cgi-bin/emailbob.pl

Problem:

q1:2*x-3;
q2:-96*z^2+48*z+32*y^2+9;
q3:48*z^2-16*z-17;
solve([q1,q2,q3],[x,y,z]);

generates:  

[]

which is incorrect.

Whereas:

solve([q1,q3,q2],[x,y,z]);

generates the correct answer:

[[
x = 3/2,
y = sqrt(67-4*sqrt(55))/(4*sqrt(6)),
z = (sqrt(55)+2)/12
],
[
x = 3/2,
y = -sqrt(67-4*sqrt(55))/(4*sqrt(6)),
z = (sqrt(55)+2)/12
],
[
x = 3/2,
y = sqrt(4*sqrt(55)+67)/(4*sqrt(6)),
z = -(sqrt(55)-2)/12
],[
x = 3/2,
y = -sqrt(4*sqrt(55)+67)/(4*sqrt(6)),
z = -(sqrt(55)-2)/12
]]

This problem arose when using solve() on the
results of poly_grobner -- generally solve()
works directly on the output of poly_grobner,
but not in this particular case.

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