Opened 6 years ago

Last modified 6 weeks ago

## #22395 new defect

# ordering of (O-)terms: absolute values, real parts, etc.

Reported by: | dkrenn | Owned by: | |
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Priority: | major | Milestone: | |

Component: | asymptotic expansions | Keywords: | |

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

Authors: | Reviewers: | ||

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

Branch: | Commit: | ||

Dependencies: | Stopgaps: |

### Description

The following (although correct) is not ideal:

sage: A.<n> = AsymptoticRing('ZZ^n * n^ZZ', ZZ) sage: (-1)^n/n + O((-1)^n/n^2) + n + O(1/n^3) + O(1/n^(2+I)) (-1)^n*n^(-1) + O((-1)^n*n^(-2)) + n + O(n^(-I - 2))

The O-Terms could/should be combined. The O-Term `O((-1)^n*n^(-2))`

should be `O(n^-2)`

and `O(n^(-I - 2))`

should be `O(n^-2)`

.

The ordering is also not what one would expect, e.g.

sage: (-1)^n/n + O((-1)^n/n^2) + n^2 + O(1/n^3) + O(1/n^(2+I)) (-1)^n*n^(-1) + O((-1)^n*n^(-2)) + n^2 + O(n^(-I - 2))

and we would like to see the `n^2`

at the front.

### Change History (4)

### comment:1 Changed 6 years ago by

### comment:2 Changed 6 years ago by

Type: | PLEASE CHANGE → defect |
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### comment:4 Changed 6 weeks ago by

Milestone: | sage-7.6 |
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Replying to dkrenn:

Here I am not sure, if this is the same problem as above; if not, then we can either forget about it or open a new ticket for it.