Opened 4 years ago

## #19947 new defect

# conversion SR to asymptotic ring

Reported by: | cheuberg | Owned by: | |
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Priority: | major | Milestone: | sage-7.1 |

Component: | asymptotic expansions | Keywords: | |

Cc: | dkrenn, behackl | Merged in: | |

Authors: | Reviewers: | ||

Report Upstream: | N/A | Work issues: | |

Branch: | Commit: | ||

Dependencies: | Stopgaps: |

### Description

It should be possible to convert a symbolic expression to an asymptotic expansion:

sage: A.<x1> = AsymptoticRing('x^QQ', QQ) sage: A(x^2+x+1) sage: A((x + 1)/(x - 1)) Traceback (most recent call last): ... ValueError: (x + 1)/(x - 1) is not in Exact Term Monoid x^QQ with coefficients in Rational Field. > *previous* ValueError: Factor x + 1 of (x + 1)/(x - 1) is neither a coefficient (in Rational Field) nor growth (in Growth Group x^QQ). sage: ((x+1)/(x-1)).subs(x=x1) Traceback (most recent call last): ... TypeError: no canonical coercion from Asymptotic Ring <x^QQ> over Rational Field to Symbolic Ring

Substitution is probably harder than conversion. Related to #19429.

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