Opened 4 years ago

Last modified 3 months ago

# Better normalization for fraction field elements - follow up

Reported by: Owned by: Matthias Köppe major sage-9.8 commutative algebra Travis Scrimshaw, Clemens Heuberger, Salvatore Stella, Jakob Kroeker, Ben Hutz, Robert Bradshaw, Ralf Stephan, Erik Massop, John Cremona, Marc Mezzarobba, Julian Rüth N/A

### Description (last modified by Matthias Köppe)

This is a follow-up on #16268 (and #16993), where the following further improvements were suggested:

• clearing denominators in the numerator and denominator instead of making the leading coefficient of the denominator monic when that makes sense (i.e., for printing, and perhaps for computations in nested rational function fields, but making it fast enough requires some work),
• also normalizing the leading coefficients over non-fields where that makes sense (see also discussion at #16993).

Related:

• #15297 Elements from a Field of Fractions that compare equal should have equal hashes

### comment:1 Changed 4 years ago by Matthias Köppe

Description: modified (diff)

### comment:2 Changed 3 years ago by Yuan Zhou

Unexpected (-1) factor in the numerator and denominator of a `sage.rings.fraction_field_element.FractionFieldElement`.

SageMath version 9.1.beta3.

```sage: P.<a,b,c>=QQ[]
sage: f = 1/a/(b-a)/(c-a)+1/b/(a-b)/(c-b)+1/c/(a-c)/(b-c); f
(-1)/(-a*b*c)
sage: f.numerator()
-1
sage: f.denominator()
-a*b*c
```

### comment:3 Changed 3 years ago by Matthias Köppe

Milestone: sage-8.4 → sage-9.1

### comment:4 Changed 3 years ago by Matthias Köppe

Milestone: sage-9.1 → sage-9.2

pushing these forward to 9.2

### comment:5 Changed 2 years ago by Matthias Köppe

Milestone: sage-9.2 → sage-9.3

### comment:6 Changed 22 months ago by Matthias Köppe

Milestone: sage-9.3 → sage-9.4

Setting new milestone based on a cursory review of ticket status, priority, and last modification date.

### comment:7 Changed 17 months ago by Matthias Köppe

Milestone: sage-9.4 → sage-9.5

### comment:8 Changed 12 months ago by Matthias Köppe

Milestone: sage-9.5 → sage-9.6

### comment:9 Changed 8 months ago by Matthias Köppe

Milestone: sage-9.6 → sage-9.7

### comment:10 Changed 3 months ago by Matthias Köppe

Milestone: sage-9.7 → sage-9.8
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