Hi Urs, On 20 Okt., 13:08, Urs Hackstein <urs.hackst...@googlemail.com> wrote: > f.parent() gives indeed "Symbolic Ring". But at the beginning I defined > > P.<s> = CC[] > P.fraction_field()
Then we really need to know how you define f. Recall that in the other thread on that subject, I pointed out how easy it is to start with a polynomial and end with a symbolic expression: The symbol "I" is a symbolic expression. It is recognised as an element of CC, but nevertheless its parent is the symbolic ring: sage: I in CC True sage: I.parent() Symbolic Ring Hence, when you add the generator s of the polynomial ring with I, then you obtain a symbolic expression, not a polynomial, even though the sum is recognised as an element of the polynomial ring: sage: P.<s> = CC[] sage: s.parent() Univariate Polynomial Ring in s over Complex Field with 53 bits of precision sage: (s+I).parent() Symbolic Ring sage: s+I in P True This can be avoided by explicitly defining "I" to be the generator of CC: sage: I = CC.0 sage: I 1.00000000000000*I sage: (s+I).parent() Univariate Polynomial Ring in s over Complex Field with 53 bits of precision Best regards, Simon -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
