Opened 4 years ago

## #22414 new defect

# check for subs of AsymptoticExpansion

Reported by: | dkrenn | Owned by: | |
---|---|---|---|

Priority: | major | Milestone: | sage-7.6 |

Component: | asymptotic expansions | Keywords: | |

Cc: | cheuberg, behackl | Merged in: | |

Authors: | Reviewers: | ||

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

Branch: | Commit: | ||

Dependencies: | Stopgaps: |

### Description

sage: A.<n> = AsymptoticRing('n^ZZ', QQ, default_prec=3) sage: n n sage: _.subs(n=1/(2-1/n)) 1/2 + 1/4*n^(-1) + 1/8*n^(-2) + O(n^(-3)) sage: _.subs(n=1/(2-1/n)) O(1)

is wrong (the two substitutions are equal to the identity).

Similarly,

sage: n.subs(n=1/(2-1/n)) 1/2 + 1/4*n^(-1) + 1/8*n^(-2) + O(n^(-3)) sage: _.subs(n=A(1/2)) O(1)

Aim: add a check `1/f`

is `o(1)`

to `.subs(n=f)`

.

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