#4276: [with patch, needs review] move number fields to new coercion, implement
embeddings
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Reporter: robertwb | Owner: robertwb
Type: defect | Status: new
Priority: major | Milestone: sage-3.2.1
Component: coercion | Resolution:
Keywords: |
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Comment (by robertwb):
No, my patch does not automatically compute compositums, just coercions
one direction or the other. This should be done, is on my (long) todo
list, and of course is especially easy for cyclotomic fields, but this
ticket is big enough already...
Note that Sage does not guarantee associativity of addition. Consider
{{{
sage: ZZ['t,x'].0 + ZZ['x'].0 + ZZ['t'].0
2*t + x
sage: ZZ['t,x'].0 + (ZZ['x'].0 + ZZ['t'].0)
Traceback (most recent call last):
...
TypeError: unsupported operand parent(s) for '+': 'Univariate Polynomial
Ring in x over Integer Ring' and 'Univariate Polynomial Ring in t over
Integer Ring'
}}}
This is because there is an ambiguous ordering of the variables if the
rightmost addition is performed first. What should be true, however, is if
both operations succeed then they should give equal answers.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4276#comment:8>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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