Hi,
Some days ago I sent a bug report using the notebook link to the
google docs
form. I am unable to find that bug report on the web.
Anyway as the thing is trivial I wrote a patch myself.
The problem is that multivariate polynomials do not admit numerator
and
denominator
sage: K.<x,y>=QQ['x,y']
sage: f=x+y
sage: numerator(f)
---------------------------------------------------------------------------
AttributeError Traceback (most recent call
last)
/home/luisfe/.sage/temp/mychabol/5681/
_home_luisfe__sage_init_sage_0.py in
<module>()
/opt/SAGE/sage/local/lib/python2.5/site-packages/sage/misc/
functional.pyc in
numerator(x)
686 if isinstance(x, (int, long)):
687 return x
--> 688 return x.numerator()
689
690 def numerical_approx(x, prec=None, digits=None):
AttributeError: 'sage.rings.polynomial.multi_polynomial_libsingular'
object
has no attribute 'numerator'
Although numerator and denominator are expectoed for rational
functions only
they might be needed, once would like to write an algorithm valid for
both
polynomials and rational functions, for example the following code in
the same
session:
sage: g=y
sage: h=1-y
sage: (f/(g)).numerator()
x + y
sage: (f/(g+h)).denominator()
---------------------------------------------------------------------------
AttributeError Traceback (most recent call
last)
/home/luisfe/.sage/temp/mychabol/5681/
_home_luisfe__sage_init_sage_0.py in
<module>()
AttributeError: 'sage.rings.polynomial.multi_polynomial_libsingular'
object
has no attribute 'denominator'
In the first case, the fraction is created and the numerator has a
meaning. In
the second the fraction is never created and the code fails.
I have writen a trivial patch for the class MPolynomial. I am not sure
if
denominator should return 1 or self.parent(one) I write 1 because it
seems
inoffensive to me
diff -r 2e793d2a0e12 sage/rings/polynomial/multi_polynomial.pyx
--- a/sage/rings/polynomial/multi_polynomial.pyx Thu Jun 18
23:52:34
2009 -0700
+++ b/sage/rings/polynomial/multi_polynomial.pyx Thu Jul 09
00:05:29
2009 -0700
@@ -980,6 +980,28 @@
from sage.structure.factorization import Factorization
return Factorization(v, unit)
+ def numerator(self):
+ """
+ Numerator of a polynomial
+
+ EXAMPLES:
+ sage: K.<x,y> = QQ['x,y']
+ sage: f = x + y
+ sage: f.numerator()
+ x + y
+ """
+ return self
+
+ def denominator(self):
+ """
+ Denominator of a polynomial
+ EXAMPLES:
+ sage: K.<x,y> = QQ['x,y']
+ sage: f = x + y
+ sage: f.denominator()
+ 1
+ """
+ return 1
cdef remove_from_tuple(e, int ind):
--~--~---------~--~----~------------~-------~--~----~
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