Opened 12 years ago

Closed 12 years ago

# creation of relative number fields when defining polynomial not integral no longer broken

Reported by: Owned by: was davidloeffler minor sage-duplicate/invalid/wontfix number fields

### Description

```sage: K.<a> = NumberField(x^2 + 1)
sage: L.<b> = NumberField(K['y'].0^2 + 1/2)
---------------------------------------------------------------------------
PariError                                 Traceback (most recent call last)

/Users/wstein/sage/build/sage-3.2.2.alpha0/<ipython console> in <module>()

/Users/wstein/sage/build/sage-3.2.2.alpha0/local/lib/python2.5/site-packages/sage/rings/number_field/number_field.pyc in NumberField(polynomial, name, check, names, cache, embedding)
374
375     if isinstance(R, NumberField_generic):
--> 376         S = R.extension(polynomial, name, check=check)
377         if cache:
378             _nf_cache[key] = weakref.ref(S)

/Users/wstein/sage/build/sage-3.2.2.alpha0/local/lib/python2.5/site-packages/sage/rings/number_field/number_field.pyc in extension(self, poly, name, names, check, embedding)
2570         if name is None:
2571             raise TypeError, "the variable name must be specified."
-> 2572         return NumberField_relative(self, poly, str(name), check=check, embedding=embedding)
2573
2574     def factor(self, n):

/Users/wstein/sage/build/sage-3.2.2.alpha0/local/lib/python2.5/site-packages/sage/rings/number_field/number_field.pyc in __init__(self, base, polynomial, name, latex_name, names, check, embedding)
4567
4568         self.__pari_relative_polynomial = pari(str(polynomial_y))
-> 4569         self.__rnf = self.__base_nf.rnfinit(self.__pari_relative_polynomial)
4570
4571         self.__base_field = base

/Users/wstein/sage/build/sage-3.2.2.alpha0/local/lib/python2.5/site-packages/sage/libs/pari/gen.so in sage.libs.pari.gen._pari_trap (sage/libs/pari/gen.c:38578)()

PariError: impossible inverse modulo:  (36)
> /Users/wstein/sage/build/sage-3.2.2.alpha0/gen.pyx(8050)sage.libs.pari.gen._pari_trap (sage/libs/pari/gen.c:38578)()

```

### comment:1 Changed 12 years ago by fwclarke

• Milestone changed from sage-3.4.2 to sage-3.4.1
• Priority changed from major to minor
• Summary changed from creation of relative number fields when defining polynomial not integral is broken to creation of relative number fields when defining polynomial not integral no longer broken

Seems to be fine now (3.4):

```----------------------------------------------------------------------
| Sage Version 3.4, Release Date: 2009-03-10                         |
| Type notebook() for the GUI, and license() for information.        |
----------------------------------------------------------------------
sage: K.<a> = NumberField(x^2 + 1)
sage: L.<b> = NumberField(K['y'].0^2 + 1/2)
sage: L
Number Field in b with defining polynomial y^2 + 1/2 over its base field
```

### comment:2 Changed 12 years ago by davidloeffler

• Component changed from number theory to number fields
• Owner changed from was to davidloeffler

### comment:3 Changed 12 years ago by davidloeffler

• Summary changed from creation of relative number fields when defining polynomial not integral no longer broken to [duplicate, positive review] creation of relative number fields when defining polynomial not integral no longer broken

In the above example, you can create the field L but you can't do much with it (for instance, `L.absolute_discriminant()` fails). But I would argue that this is covered by ticket #252. I propose closing this ticket as "duplicate".

### comment:4 Changed 12 years ago by mvngu

• Milestone changed from sage-4.1.1 to sage-duplicate/invalid/wontfix
• Resolution set to duplicate
• Status changed from new to closed
• Summary changed from [duplicate, positive review] creation of relative number fields when defining polynomial not integral no longer broken to creation of relative number fields when defining polynomial not integral no longer broken

Closing this as a duplicate of #252.

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