I have come across some unexpected behavior in eliminate (Maxima
5.9.2, but I already saw it in 5.9.1):
,----
| (%i1) eliminate([c*x^2=a, c*x = b], [c]);
|
| (%o1) [- x (b x - a)]
OK, as expected.
| (%i2) eliminate([c*x^2=a, c*x = b], [x]);
|
| 2
| (%o2) [- c (a c - b )]
Unexpected: This seems to suggest that c=0 solves both equations. I
would have expected [ a*c - b^2 ] instead.
| (%i3) eliminate([a+x^5, x, f], [x]);
|
| 5
| (%o3) [f , a]
Unexpected: Why is f (which is free of x) affected at all?
`----
I do not see anything in the help text to suggest this behavior, and
solve(%o2, [c]) obviously gives a spurious solution c=0.
Is this
- an implementation bug, and if so, a known one?
- a documentation bug (missing, e.g., a warning against using solve on
the result of eliminate)?
- a user bug?
Best regards,
Albert.