Ask Your Question

What is _SAGE_VAR_(0)?

asked 2016-12-15 04:23:52 -0600

Clemens Heuberger gravatar image

Using SageMath 7.4, I do the following:

sage: var('u R omega')
sage: hs = (1+u^R).series(u==omega, 2); hs
(omega^R + 1) + (R*omega^R/omega)*(-omega + u) + Order((omega - u)^2)
sage: hs.subs({omega^R: -1}).simplify()
R*(omega - u)/omega + Order((omega - u)^2) + _SAGE_VAR_(0)

I am wondering what _SAGE_VAR_(0) shall be and how to get rid of it.

edit retag flag offensive close merge delete

1 answer

Sort by ยป oldest newest most voted

answered 2016-12-15 06:10:27 -0600

kcrisman gravatar image

updated 2016-12-15 08:50:32 -0600

That is a leftover from Maxima's translation back to Sage. Somehow it didn't get translated. Looking at the precise expression hs, I suspect probably _SAGE_VAR_(0) is what came out of omega^R + 1, which then becomes zero - but a symbolic zero. So we are probably missing a translation in series (or in general) when a symbolic zero is brought back from Maxima. I don't have a solution for that but those with time in the know should be able to get it from that.

Edit: This is definitely known and apparently even a fix is available, we need someone to review and test it.

See and which needs review.

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower


Asked: 2016-12-15 04:23:52 -0600

Seen: 105 times

Last updated: Dec 15 '16