Hello,
I recently upgraded sage to the binary version 4.6.2 for Ubuntu i586,
and ran into the following error:
sage: (r,s,t,c,d,p,q) = var( 'r,s,t,c,d,p,q' )
sage: A = matrix( [ [r, -s, r, -s], [t, 0, t-p, -p], [r, -s-c, r, -s-d], [t,
-c, t-q, -q-d] ] )
sage: A
[ r -s r -s]
[ t 0 -p + t -p]
[ r -c - s r -d - s]
[ t -c -q + t -d - q]
sage: u = A.solve_right( vector([1,1,1,1]) )
---------------------------------------------------------------------------
NotImplementedError Traceback (most recent call last)
/home/duenez/Download/sage-4.6.2-linux-32bit-ubuntu_10.04_lts-i686-Linux-i686-Linux/<ipython
console> in <module>()
/home/duenez/Download/sage-4.6.2-linux-32bit-ubuntu_10.04_lts-i686-Linux-i686-Linux/local/lib/python2.6/site-packages/sage/matrix/matrix2.so
in sage.matrix.matrix2.Matrix.solve_right (sage/matrix/matrix2.c:3387)()
/home/duenez/Download/sage-4.6.2-linux-32bit-ubuntu_10.04_lts-i686-Linux-i686-Linux/local/lib/python2.6/site-packages/sage/rings/ring.so
in sage.rings.ring.Ring.is_integral_domain (sage/rings/ring.c:6035)()
NotImplementedError:
This was working perfectly in version 4.5.3 OpenSuSE 11.1, and it seems
that it has nothing to do with SuSE vs Ubuntu (I am on OpenSuSE 11.4).
It seems that the problem is in the Symbolic Ring (SR) not implementing
the *is_integral_domain *function. This changed from 4.3 to 4.6 in ticket
#10481 where they (correctly) changed the behavior of *is_integral_domain()
*to raise an exception. The problems seems to be that SR does not implement
this correctly. SR should be an integral domain for most practical uses,
right? Or am I missing something?
If this is truly a bug (or unintended feature), I think overriding *
is_integral_domain* in SymbolicRing to return *True* should be a good idea.
Thanks,
Edgar
--
Dr. Edgar A. Duenez-Guzman
Postdoctoral Fellow
Department of Organismic
and Evolutionary Biology
Harvard University
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