solve ignores conjugate

[rwst]

Results of solving with solve can be wrong
due to conjugate being ignored.

This is due to a Maxima bug.

sage: eq_a = conjugate(z) == I + 1
sage: eq_a
conjugate(z) == (I + 1)
sage: sol_a = solve(eq_a, z, solution_dict=True)
sage: sol_a
[{z: I + 1}]

This is obviously wrong.

sage: [eq_a.subs(s) for s in sol_a]
[(-I + 1) == (I + 1)]

Note that SymPy does not return a wrong answer,
but does not solve either:

sage: sol_aa = solve(eq, z, solution_dict=True, algorithm='sympy')
sage: sol_aa
ConditionSet(z, Eq(conjugate(z) - 1 - I, 0), Complexes)

Maybe solve should work around the Maxima conjugate bug.

Initial report and discussion:

• https://groups.google.com/forum/?hl=en#!topic/sage-support/wiwEbgILB14

Reported again at #30570.

Related:

• Search "conjugate" in Maxima bug tracker

CC: @slel @zimmermann6

Component: symbolics

Keywords: solve, conjugate, maxima, wrong result

Issue created by migration from https://trac.sagemath.org/ticket/18488

[slel]

Changed keywords from none to solve, conjugate, maxima, wrong result

[slel]

comment:2

The "sage-support" discussion gives excerpts of posts
to the "maxima" mailing list.

A workaround discussed there consists in working with
real and imaginary parts and solving for those.

[mkoeppe]

comment:4

Moving to 9.4, as 9.3 has been released.