this is one of the strangest bugs i've seen. using sage 2.3, sometimes
constructing quotients in the rational function field CC(z) freezes, and
sometimes not. when i say freezes, i mean it justs sits there until i
press ctrl-C. no error, no stack overflow... just sits and runs forever.
once i press ctrl-C, there is a long traceback.
here are some random examples. the second set is especially
striking. from the behaviour, it seems as if a different algorithm is
being used depending on the value! either that, or there is a very subtle
bug deep in the basic arithmetic module???
Z.<z>=CC[]
1/z # ok
(1+z)/(I+z) # ok
(1+I*z)/(z+1) # ok
(1+I+z)/(z+I) # ok
(1+I+z)/(z+0.1*I) # freeze !
1.1/z # ok
1.1/(z+I) # ok
1.1/(z+1.1*I) # ok
1.1*z/(z+1.1*I) # ok
I*z/(z+1.1*I) # ok
(1+I*z)/(z+1.1*I) # ok
(1+I*z)/(z+1.1) # freeze!
(0+I*z)/(z+1.1) # ok
(2+I*z)/(z+1.1) # freeeze
(1+I*z)/(z+0.1*I) # ok
(1+I+z)/(z+1.1) # ok
(I-z)/(z+1.9) # freeze!
(I-z)/(z+1.8) # freeze!
(I-z)/(z+1.7) # ok
(I-z)/(z+1.6) # ok
(I-z)/(z+1.5) # ok
(I-z)/(z+1.4) # freeze!
(I-z)/(z+1.3) # freeze!
(I-z)/(z+1.2) # ok
(I-z)/(z+1.1) # freeze!
(I-z)/(z+1.0) # ok
anyway, i'd be verrrry interested in a fix to this. thanks!
-kyle
p.s. i tried to get around it by writing
FractionFieldElement(z.parent(),(I-z),(z+1.8),reduce=false)
but then a different error occurred:
'PolynomialRing_field' object has no attribute 'ring'
i don't know if that was a correct workaround attempt -- is this another
bug?
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